CpapWiki - User contributions [en]

Cleaning CPAP Equipment

2009-12-17T21:13:09Z

Velbor: removal of an improper grammatical "correction" - maintaining plural consistency

= Introduction =

Few topics engender more diversity of approach than that of routine cleaning of CPAP equipment: humidifier chambers, tubing and masks. (I might dare also include the checking and periodic replacement of machine filters.)

Practices range from doing nothing (often accompanied by the claim that “…. and I’ve never been sick or had any problem”) to vigorous daily disassembly and thorough washing (often accompanied by the conclusion that therefore “…. I’ve never been sick or had any problem”).

Philosophies range from “people today would be a lot healthier if they ate more dirt” (which might or might not be so, but “back in the day” life expectancy surely was a lot shorter) to germophobic fatalism, to holistic health practices including homeopathy and nasal irrigation (reminds me of reading literature on the virtues of daily enemas).

The equipment manufacturers don’t help much. Almost all advise daily draining, washing, and rinsing of humidifier chambers and masks. (Perhaps because tubing isn’t often sold as a “branded” product, there is less emphasis on daily care in that realm.) They are often accused of taking that position as a litigation preventive measure; that may or may not be so. They rarely present actual research to support or explain their cleaning recommendations.

Recognizing that my complete objectivity and rationality is not infrequently called into question (even, or perhaps especially, by those who know me best), let’s take a stab at thinking through the issues. In that way, whatever decision we reach, we can pretend that it’s based on careful and deliberate thought, rather than on our own laziness or on our obsessive-compulsive inclinations.

== General Principles ==

● Microbes tend to grow in warm, moist, dark places.

● Our world, including the air we breathe, is full of microbes.

● The danger posed by commonly encountered microbes is directly proportional to the number of them that get inside us, and inversely proportional to our overall state of health. (This is true also of microbes normally found in our own bodies. Change the number or ratio of our internal microbial flora, or experience a general decline in health, and our own microbes can literally “eat us alive”.)

Based on these principles, let’s consider the equipment in our CPAP set-ups, in order from the most distant components to those closest to our bodies.

=== Air Filters ===

ResMed suggests, “Inspect the air filter every month to check if it is blocked by dirt or contains holes. With normal use of an S8 AutoSet II, the air filter needs to be replaced every six months (or more often if your device is in a dusty environment).”

Respironics states, “Under normal usage, you should clean the gray foam filter at least once every two weeks and replace it with a new one every six months. The white ultra-fine filter is disposable and should be replaced after 30 nights of use or sooner if it appears dirty. DO NOT clean the ultra-fine filter.”

Why does Respironics suggest so much more frequent checking and changing of filters? One explanation is that their filtering system is much more efficient than the open fiber filters – reminiscent of inexpensive filters used in my home HVAC system – employed by ResMed. Fine particulates appear much more likely to be blocked and kept out of the air stream – and thus much more likely to foul and block the filters – in the Respironics systems. Still, it does not necessarily follow that the presumed higher efficiency of the Respironics filtration is either necessary or helpful – do we need to breathe air that is cleaner than our room air?

Respironics nicely summarizes why filter cleaning is important:

----
'''Caution''': Operating the device with a dirty filter may keep the system from working
properly and may damage the device. …

'''Caution''': Dirty inlet filters may cause high operating temperatures that may affect
device performance. Regularly examine the inlet filters as needed for integrity
and cleanliness.
----

Ah, a reference to “cleanliness.” Comfortable, culturally correct, but still, just a bit …. vague.

=== CPAP Machine ===

No one recommends that we clean the CPAP machine (at least not beyond the careful application of a moist cloth to the exterior to remove grease, grime and dust). Isn’t that an oddly fortunate coincidence, since there’s no safe way in which we’re ABLE to clean the belly of the beast. Besides, though it may be dark inside and warm when it’s running, it’s dry, and nothing goes through it except filtered room air.

Well, that may not be quite exactly true. There are two ways in which moisture might get inside. The most serious is if there’s backflow into the machine from the humidifier. This, apparently, is most likely to happen if the set-up is moved while the machine is attached to a humidifier containing water. BIG OOPS. Not only is there danger of microbial growth wherever the water manages to ooze, but there is also danger of electrical component malfunction, corrosion, or even potential short-circuit and fire. The manufacturers are unanimous:

ResMed: “Water must be prevented from entering your flow generator. Do not transport the flow generator with the H4i attached.” …. “This Limited Warranty does not cover: …. d) any damage caused by water being spilled on or into a flow generator.”

Respironics: “If the device and humidifier fall and water gets into the device, drain all water out of the device and make sure it is completely dry before reapplying power. … If the device falls or water gets into the device upon falling, let the device dry completely and then restart it. If it does not operate correctly after falling, contact Respironics or an authorized service center.”

----

But there is a second, more subtly insidious, and perhaps more common way for moisture to enter the CPAP machine and cause any or all of the nasties described above. That is by diffusion. The physics is very simple and straightforward. Just as “nature abhors a vacuum,” nature abhors any difference in concentration of any substance.

You are using your CPAP with a heated humidifier. The CPAP blows air in one direction: away from the machine, over the water surface in the humidifier chamber, and towards you. You sleep well, with not a care in the world. In the morning, you wake up, turn everything off, and go about your business. (Or, similarly, you get up during the night for an extended period.) And diffusion goes about its business.

Water has a high “specific heat” – higher than almost any other common substance. That means that it takes more heat to raise the temperature of water, than it does to raise the temperature of an equal mass of any other substance, an equal amount. That also means that warm water stays warmer, longer than just about anything else. And THAT means that the moisture level – the absolute humidity – the concentration of water – in the air above the water in the humidifier chamber, will be greater than that in the air anywhere else in the room. That water vapor will want to get – everywhere, anywhere else.

If tubing is connected to the humidifier chamber under these conditions, that humid air will begin to diffuse into the tubing. And in both directions: since no air is flowing, it will equally seek to go into your main tubing, AND into your CPAP machine. In either direction, that warm, moist air will find cooler surfaces. And on cooler surfaces, water will precipitate out of the air. (Yes, right, just like rainout!) The amounts may be minute. Or not. Diffusion occurs on a molecular level, and the warm water vapor can find its way through the most minute cracks and crevices. Even into areas of the machine where little airflow moves – so that there may not be the “normal” opportunity for drying during normal machine use. Dangers of machine damage due to this water vapor diffusion are arguably small. Dangers of providing a habitat for microbial growth may also be arguably small.

Still, it’s simple enough, with most machine designs, to disconnect the direct connection between the humidifier and anything else. With a stand-alone humidifier, disconnect the tubes. With a ResMed Humidaire humidifier, lift the top cover to unseat the gasket and let the humid air pass harmlessly into the room. With Respironics humidifiers – sorry, I have never used an integrated Respironics humidifier, so I don’t know how best to take action. (By the way, if you use a Fisher & Paykel stand-alone humidifier with the HC-325 chamber, the blue plastic caps that come with each new chamber should be kept - they make an excellent cover for the chamber AFTER you remove the tubing. And an excellent cover for the CPAP machine blower port.)

This is a simple, proactive way to prevent even the small possibility of physical damage, and, more to the point of this article, to prevent even the small possibility of microbial growth inside the blower.
----

Aha! ResMed has already thought of this, though paradoxically they give what for all the world looks like a bogus reason for their very innovative response. In their manual for the HumidAire series of humidifiers (though generally NOT in the manuals for their CPAP machines themselves) they write:

“Note: In order to assist the heater plate in cooling, some flow generators continue to
blow air gently for up to an hour after treatment has stopped. However, you can unplug the device from the power outlet at any time and allow the heater plate to cool without airflow. ”

In fact, with water still present in the chamber, this slight blowing will have virtually no effect on the humidifier heater plate temperature. Their comment that this function can be easily aborted strongly suggests that there is no need to cool the heater plate. (The best way to cool the heater plate is to remove the reservoir chamber!) Nor is this function useful, as some have suggested, in drying the hose. To the contrary, it is still warm, moist air being gently blown INTO the hose, and rainout may result.

What this "gentle blowing" DOES accomplish is to keep warm moist air flowing AWAY from the machine, preventing diffusion of water vapor INTO the machine. Well done (though poorly explained), ResMed! But even better is to simply disconnect or remove the humidifier chamber from its connection to the blower.

=== Machine–to–Humidifier Hose ===

This component exists principally in systems which utilize a “stand-alone” rather than an integrated humidifier (though even with an integrated system, “something” connects the machine to the humidifier). Such a hose, if it exists, should be inspected periodically for physical integrity and leaks (run you hand along and around it while the machine is running to check for any airflow), and inspected visually for anything inside that should not be inside. The need for any active cleaning should be rare.

[http://www.cpaptalk.com/wiki/index.php/CPAP_FAQs#How_Do_I_dry_CPAP_Hoses_after_cleaning.3F How to dry CPAP Hoses]

=== Humidifier Chamber ===

Now the disputation begins in earnest. The “never empty or clean unless there’s an obvious reason to do so” advocates make some excellent points:
----
● even if the occasional microbe gets into the chamber, if you are using distilled water (as you probably should be), there’s nothing for them to feed and grow on.

● even if there is microbial growth in the water, there little likelihood that they can enter the airstream, and

● even if microbes did enter the airstream, there is little evidence that they could successfully navigate and survive the trip down the main tubing in sufficient number to cause illness.
----

On the other side of the table, activists may well claim:
----
● distilled water is not necessarily sterile water, and even if it were, it can no longer be considered sterile once the bottle has been opened

● even with filtration, air flowing through the system is neither microbe-free nor particulate free, and particulates (which may provide microbial nourishment) certainly have an opportunity to enter the humidifier during the filling process, and (depending on whether and how portals are covered) during the day.

● while it is true that humidifiers work by producing molecular water which “dissolves” in the overlying air, rather than water “particles” which can “carry” microbes “piggyback” down the tubing, there are other potential transport processes. Observation of the surface of CPAP humidifiers during respiration generally show “rippling” as airflow increases on inspiration. This non-laminar flow “rippling” is effectively wave generation with associated “spray” production – i.e., water particulates capable of carrying microbes. Convection within in the heated water will regularly carry microbes, if present within the water, to the surface, waiting for their “ride”.

● in addition to the presence of surface-effect “spray” water particulates as just described, “clumps” of microbes, even without water droplets as a transport vehicle, can be “lifted up” directly by the non-laminar airflow, either from the water surface, or from the humidifier chamber walls as the water level falls through the night.
----

There is little good, hard, convincing, available science upon which to base a firm preference for either of these two positions. A published study of radioisotopes placed in humidifier water was found to detect radiation as have traversed the tubing, but only at very high pressure (and correspondingly high flow-rate, due to increased venting flow at higher pressures) conditions.

In a brief departure from focusing on microbes, a mention of mineral precipitation is in order. In all but distilled water, there will be dissolved mineral ions. As molecular water is lost overnight through evaporation (whether in a heated or even in a passive pass-over system), the mineral concentration will increase. (It should be noted that periodically adding additional fresh water through the night will help to minimize this.) There may come a point when the minerals reach their saturation point, and begin to precipitate out of solution, potentially resulting in a build-up on the chamber walls and, more likely, on the heating plate. There are two principal down-sides to the deposition of mineral precipitates. First, they tend to form cavernous networks, which provide attractive housing for microbes. (So I lied; we are still talking about microbes.) Second, precipitation on the heater plate tends to decrease the efficiency of heat transfer. (That it may look unattractive is a personal problem; deal with it.) The general recommendation for removing such precipitate is rinsing in a dilute vinegar solution, with the acidic environment hopefully dissolving the minerals and allowing them to be rinsed away. (In addition it is claimed that the vinegar has mild antiseptic properties, helping to kill, yes, again, microbes.) It should also be noted that many insurance plans cover twice-yearly humidifier chamber replacement.

Thus, the range of options for humidifier chamber care and maintenance, from least interventionist to most conservative, runs something like:

● doing nothing; simply adding water each night
● draining out the leftover water and allowing to dry, each morning, or periodically
● draining, rinsing and allowing to dry, each morning, or periodically
● all the above, plus use of soap and/or vinegar, followed by thorough rinsing

A final comment on drying. If you are “drying out” the humidifier at all, the faster the drying process, the less likely that any microbes will find residual moisture and “settle in.” (The bathroom, by the way, may be the most convenient place for drying, but it is the least desirable, in view of typically higher moisture levels, typically higher levels of airborne particulates, and – yes – typically higher level of airborne microbes.) Drying can be accelerated by vigorous shaking, not only to remove excess water, but also to break up remaining water into smaller droplets. (Smaller droplets have a larger surface-area to volume ratio, and will therefore evaporate more rapidly.) Inserting a clean, thin, threadbare washcloth into the chamber prior to the shaking process will facilitate the removal of excess water. And blowing air through the chamber with a CPAP machine will greatly enhance the evaporation of any remaining water.

Where you choose to place yourself on this spectrum is largely a matter of choice, involving such factors as your overall health, your overall “tidiness”, and your overall risk tolerance preferences. It’s hard to imagine even the most “non-interventionist” CPAP user ignoring a humidifier chamber which begins to look cruddy or colorful. If a decision regarding action is based on what you see (or more precisely, on what you NOTICE), then we in fact are already operating on an analog basis – how much contamination is present – rather than on a yes/no digital basis - whether or not contamination is present. Even in our digital age, much of life remains analog.

=== Main Tubing: Humidifier to Mask ===

People often talk about cleaning their tubing, but few seem to do anything about it. I suspect that’s because the process is so cumbersome. And perhaps also because, arguably, it’s relatively unnecessary.

In the absence of rainout (precipitation of water from warm, moist air against the cooler walls of the tubing), the tubing interior typically remains dry. Mask venting and continuous airflow from the machine (and, for some masks, extension tubing) typically prevent any significant amounts of exhaled air from retrograde entry into the tubing. Under these “ideal” conditions, there’s nothing needing to be cleaned.

Unfortunately, conditions are sometimes less than ideal. (Descriptions on the CPAPTalk discussion forums of insects entering the tubing will be left for those interested to find on their own.)

It is a good practice to INSPECT your tubing on a regular basis. When turning the machine on at night, run your hand along the length of the tubing, feeling for leaks. In the morning, visually check the entire length of tubing. Look for evidence of water droplets or mist suggesting rainout; look for any dark or discolored areas or objects. Tubing which is transparent is obviously highly preferable to tubing which is more or less opaque in this regard. Tubing which is covered (to prevent or diminish rainout) should periodically be “undressed” so that it can be inspected.

If there has been ANY rainout, you now have a condition in your tubing which will arguably support microbial growth. (See the discussion about humidifier chambers, and the variety of opinions about whether microbes can in fact get into, and live in, the tubing. I will simply suggest that the longer you go without inspecting, drying or cleaning your tubing, the greater the possibility of microbial growth, survival, and migration down your tubing toward you face, becomes.)

If there has been rainout, it should be PROMPTLY and RAPIDLY dried. The hose should be first shaken, from the center toward each end, to remove as much water as possible. If you have sufficient room, twirling the hose, from the center toward each end, will also expel excess water. The most convenient technique for rapid drying is to run air from your CPAP blower through the tubing until all evidence of water is gone. (Some machines may automatically shut off when no resistance to flow is encountered. On some of these, it may be possible to disable and turn off that feature. It may also be possible to put a flow-limiting connector on the end of the tubing, but this will increase drying time, since maximal flow will product the most rapid evaporation.) Sucking air through the tubing (rather than blowing as with a CPAP machine) may be attempted; devising a connector to the suction of a household vacuum cleaner has been suggested. Another attractive suggestion (presented on the CPAPTalk forum) is that of connecting a weight to one end of a six-foot-plus length of fishing line, and connecting a thin, dry cloth to the other end of the fishing line. Drop the weight into one end of the tubing, let it pull the line through the tubing, and then the fishing line can be used to pull the dry cloth through the tubing. Special care may need to be taken with heated tubing, or with tubing having custom connectors on one or both ends.

All else failing, tubing can simply be left hung to dry, but passive diffusion of air through a narrow six-foot tubing is not an ideal methodology. Under such circumstances, it has been wisely recommended that one have a spare second tube to use while the first one is drying overnight.

Actually “cleaning” the tubing may occasionally be desirable, as for example when rainout droplets have been allowed to sit in the tubing for days, or even just hours. Some people "dunk" the tubing into a basin of soapy water; possibly a bit awkward due to the tubing length. Simply rinsing the interior by holding one end against a spigot, and allowing the other end to drain into the bathtub, may be sufficient. (Some people have described taking the tubing into the shower with them for rinsing!) If it is desired to use soap (or some other safe cleaning material), the use of a male-to-male adaptor makes the task much easier. (A male-to-male adaptor is typically a small plastic connector, both of whose ends will fit inside the rubber cuffs at the ends of the tubing, and which may be used to connect two hoses together. Some masks come with parts which may be usable for this purpose – e.g. the swivel assembly on a Mirage Activa. An adapter suitable for such use is sold by CPAP dot com at:
https://www.cpap.com/productpage/hose-coupling-swivel-adapter-cpap.html .)
After partially filling the hose with water, and adding a suitable amount of soap, use the adapter to connect the two ends so that the tubing forms a continuous loop. The cleaning solution can now be easily “swished” through the tubing, and allowed to stay inside for as long as is desired. After cleaning, rinse thoroughly and dry rapidly, as already described.

=== Mask ===

While the risk of microbes reaching us through the airstream is debatable, the risk of contamination of the mask is far less controversial. All night, every night, we are exhaling warm (at body temperature) moist (100% relative humidity) air, laden with microbes (yes, our own) from our upper airway, and proteins and enzymes and sloughed cellular debris, into the mask. The thought question with regard to mask cleaning is not so much, “Do you feel lucky?” as, “Why do you brush your teeth?” The conditions which can lead to halitosis, gingivitis, dental decay, and that grubby trench-mouth feeling, is now present on and in the surfaces and crevices of our masks. Further, he grease and grime on our facial skin is transferred to the cushions.

Despite the difficulty of making a convincing case AGAINST regular mask cleaning, CPAPTalk forum postings demonstrate a wide variety of practices (and a wide spectrum of embarrassment and guilt) for our failures to care for our equipment.

Mask manufacturers routinely provide their “instructions” for cleaning, which typically take the form of daily disassembly, cleaning with soap and water, drying and reassembly. As previously noted, whether this is done simply to ward off litigation, or whether there is actual science and research underlying these recommendations, they are generally presented to users without factual explanation of their basis or origin.

One specific area of contention is that of the extent of mask disassembly required for thorough cleaning. The inconsistencies in manufacturer recommendations are telling. ResMed, for example, instructs complete disassembly of the Activa mask. This is not unreasonable; there are only 10 parts (excluding headgear), only one relatively small, fairly easily disassembled and reassembled (though I have done it improperly with resulting leaks). On the other hand, ResMed instructs only partial disassembly of the UltraMirage Full Face mask. This too is not unreasonable; there are some 13 parts (excluding headgear), six of which are relatively small, and those involved in the elbow and anti-asphyxia valve assembly require some level of dexterity and competence to handle safely and correctly. Loss of small parts down the sink is not unheard of. Obviously, there is a balance between the goals of cleanliness, and the goals of correct and non-destructive disassembly and reassembly. Some appropriate degree of balance must be found by each user. (I still have trouble properly replacing the UMFF venting system and cushion, for which ResMed does recommend daily disassembly.)

Other areas of concern involve whether the life expectancy of the delicate plastic cushion membranes are enhanced or lessened by the handling involved in disassembly and cleaning. This, too, involves personal issues of dexterity and confidence, as well as the development of good, safe practices.

The preventive measures of facial washing (possibly including the use of special cleansers or alcohol wipes to remove skin oils) before donning masks, and of course appropriate oral hygiene before bed, would seem appropriate. At the very least, daily rinsing of the fully-assembled mask appears to be reasonable. Gentle cleansing of the cushion surfaces in contact with the face, to remove grease and oils, may help in minimizing leak (though there are some who insist that either cleaning itself, or the process of disassembly and cleaning, increases the likelihood of leak). Periodic more thorough cleaning, including soaking in soapy water, with an appropriate level of disassembly, should not be neglected.

Finally, an industry has arisen which provides convenient “wipes” and “sanitizers” specifically for CPAP masks. Certainly better than doing nothing, I can’t help but wonder what research has been done, and what the use of such products actually accomplishes.

=== Headgear Straps ===

Finally, we move out of the realm of microbes, and into the personal comfort zone of dealing with our own head and hair greases and oils. Whether regular cleansing increases or reduces the lifespan of headgear is not at all clear. Washing certainly appears to vary the size and elasticity of some headgear materials, necessitating periodic readjustment of the straps (which is probably a good idea in any case). If a basin of soapy water left is over after having just given your mask a periodic cleaning, it seems wasteful not to give the headgear a dunking as well.

= Concluding Comments =

In the absence of reliable data, risk / benefit analyses devolve to decisions about what feels comfortable, and how much time and effort that comfortable feeling is worth. The wide spectrum of equipment cleaning practices frequently described on the CPAPTalk forum emphasizes that there are no simple answers which are always right for everyone.

On the other hand, if there’s visible crud anywhere on your CPAP system, be ashamed. And if you’re not regularly LOOKING for visible crud, be ashamed. Hygiene can be overdone, but that generally costs only time. Those of us with Sleep Apnea have a chronic condition which threatens our health, and failure to take appropriate care of our equipment and ourselves is at best short-sighted and risky. I’m not necessarily against risky behavior per se, but it seems as though it should be based on positive decisions rather than on laziness, and should deliver a lot more benefit (and fun).

----

--[[User:Velbor|Velbor]] 23:45, 21 November 2009 (UTC)

updated --[[User:Velbor|Velbor]] 15:25, 25 November 2009 (UTC)

released --[[User:Velbor|Velbor]] 21:56, 29 November 2009 (UTC)

Total Recording Time

2009-12-14T19:05:03Z

Velbor: Added example of "usage" time differences

{{stub}}
'''Total Recording Time (TRT)''' is the amount of time that is recorded during a [[Polysomnogram]]. This statistic can be used to compare how long it takes a patient to fall asleep, and [[Total Sleep Time]] (TST).

[[Category:CPAP Definitions]]

----
Although this terminology is not often directly employed for home CPAP use, the concept is transportable, and CPAP machines and software often display the "total time" they are in use. However, the paradigms for figuring "usage time" differ between machine manufacturers.

If you turn the machine on, for example, at 11:30pm, do not turn it off overnight, and arise at 7:30am, machines can be expected to show 8:00 as the usage time.

If however, you arose 3 times, and turned the machine off for 3 minutes at each time, different machines may show different results. Respironics machines show "usage time" as "blower on time" for the session. Changes in the status of the blower are recorded to the second, and "usage time" is the difference between the first "blower-on" time and the last "blower off" time for the session. Thus, in the scenario proposed, Respironics machines would show a "usage time" of 7:51. ResMed, on the other hand, utilizes the concept of "mask on time". This is also based on "blower on" status, but ResMed does not "penalize" the user for short (documentation the precise cutoff time has not been found, but seems to be under 10 minutes) arisings. Thus, in the scenario proposed, ResMed machines would show a "usage time" of 8:00, ignoring the brief arisings. However, if you arose the same 3 times, but turned the machine off for 10 minutes each time, the two machines would display the same results - a "usage time" of 7:30.

[EDIT: There sometimes is a difference between cumulative "Therapy Time" and "Blower Time" with both Respironics and ResMed machines, and this difference can go in either direction. "Blower Time" would ordinarily be expected to be larger, since there can be no "therapy" when the blower is off, and "Blower Time" is "hard-wired" to a dedicated non-resettable clock. "Blower Time" may be larger for either machine when the unit is used for drying out tubing or other purposes during which the machine does not sense "breathing" patterns, and therefore does not credit any time to "therapy". When "Blower Time" is larger for apparently inexplicable reasons (which seems to predominate for Respironics), this may occur because "Therapy Time" may be linked to additional "soft" considerations, such as a slight delay in initiation of the "Therapy Time" clock while the machine moves toward its steady-state conditions, and/or while the sensors determine that an airflow pattern consistent with breathing is actually present. When "Therapy Time" is larger (which seems to predominate with ResMed), this seems to occur because the machine "credits" as therapy time short breaks
when the blower is in fact off. --[[User:Velbor|Velbor]] 15:27, 14 December 2009 (UTC) ]

A consequence of this difference is that ResMed calculation of respiratory event indices, in the presence of multiple short arisings, may be reported slightly on the low side, since the time factor includes minutes during which the machine was not actually blowing. However, ten minutes "extra" during an 8 hour night would result in a 2% "error" which would not likely be noticeable.

It is not always clear what "usage time" means. As an example, a ResMed S8 Auto machine reports "usage" as 8:04 on a night with two arisings. Review of the 60-second-reporting-window data shows that (presumably median) pressure was >0 for only 8:01. Similarly, pressure was >=10.0 cm (the minimum set pressure) for only 7:57. Which number is "correct" to use in evaluating respiratory disturbance indices?

It should be noted that while "usage time" can often be reset on a CPAP machine, total cumulative "blower on" time for a unit cannot be reset. It might also be noted here that ResMed machines cease recording pressure and leak data after 10 hours. This is apparently done to standardize the quantity of data which can be stored. Respiratory events, and usage time, continue to be recorded even after the 10 hour limit.

--[[User:Velbor|Velbor]] 15:33, 24 November 2009 (UTC)
----

Total Recording Time

2009-12-14T15:27:07Z

Velbor: Correction and expansion of the "Therapy Time" vs "Blower Time" issue

{{stub}}
'''Total Recording Time (TRT)''' is the amount of time that is recorded during a [[Polysomnogram]]. This statistic can be used to compare how long it takes a patient to fall asleep, and [[Total Sleep Time]] (TST).

[[Category:CPAP Definitions]]

----
Although this terminology is not often directly employed for home CPAP use, the concept is transportable, and CPAP machines and software often display the "total time" they are in use. However, the paradigms for figuring "usage time" differ between machine manufacturers.

If you turn the machine on, for example, at 11:30pm, do not turn it off overnight, and arise at 7:30am, machines can be expected to show 8:00 as the usage time.

If however, you arose 3 times, and turned the machine off for 3 minutes at each time, different machines may show different results. Respironics machines show "usage time" as "blower on time" for the session. Changes in the status of the blower are recorded to the second, and "usage time" is the difference between the first "blower-on" time and the last "blower off" time for the session. Thus, in the scenario proposed, Respironics machines would show a "usage time" of 7:51. ResMed, on the other hand, utilizes the concept of "mask on time". This is also based on "blower on" status, but ResMed does not "penalize" the user for short (documentation the precise cutoff time has not been found, but seems to be under 10 minutes) arisings. Thus, in the scenario proposed, ResMed machines would show a "usage time" of 8:00, ignoring the brief arisings. However, if you arose the same 3 times, but turned the machine off for 10 minutes each time, the two machines would display the same results - a "usage time" of 7:30.

[EDIT: There sometimes is a difference between cumulative "Therapy Time" and "Blower Time" with both Respironics and ResMed machines, and this difference can go in either direction. "Blower Time" would ordinarily be expected to be larger, since there can be no "therapy" when the blower is off, and "Blower Time" is "hard-wired" to a dedicated non-resettable clock. "Blower Time" may be larger for either machine when the unit is used for drying out tubing or other purposes during which the machine does not sense "breathing" patterns, and therefore does not credit any time to "therapy". When "Blower Time" is larger for apparently inexplicable reasons (which seems to predominate for Respironics), this may occur because "Therapy Time" may be linked to additional "soft" considerations, such as a slight delay in initiation of the "Therapy Time" clock while the machine moves toward its steady-state conditions, and/or while the sensors determine that an airflow pattern consistent with breathing is actually present. When "Therapy Time" is larger (which seems to predominate with ResMed), this seems to occur because the machine "credits" as therapy time short breaks
when the blower is in fact off. --[[User:Velbor|Velbor]] 15:27, 14 December 2009 (UTC) ]

A consequence of this difference is that ResMed calculation of respiratory event indices, in the presence of multiple short arisings, may be reported slightly on the low side, since the time factor includes minutes during which the machine was not actually blowing. However, ten minutes "extra" during an 8 hour night would result in a 2% "error"
which would not likely be noticeable.

It should be noted that while "usage time" can often be reset on a CPAP machine, total cumulative "blower on" time for a unit cannot be reset. It might also be noted here that ResMed machines cease recording pressure and leak data after 10 hours. This is apparently done to standardize the quantity of data which can be stored. Respiratory events, and usage time, continue to be recorded even after the 10 hour limit.

--[[User:Velbor|Velbor]] 15:33, 24 November 2009 (UTC)
----

Total Recording Time

2009-12-13T14:38:24Z

Velbor: Comment added regarding blower time vs therapy time differences

{{stub}}
'''Total Recording Time (TRT)''' is the amount of time that is recorded during a [[Polysomnogram]]. This statistic can be used to compare how long it takes a patient to fall asleep, and [[Total Sleep Time]] (TST).

[[Category:CPAP Definitions]]

----
Although this terminology is not often directly employed for home CPAP use, the concept is transportable, and CPAP machines and software often display the "total time" they are in use. However, the paradigms for figuring "usage time" differ between machine manufacturers.

If you turn the machine on, for example, at 11:30pm, do not turn it off overnight, and arise at 7:30am, machines can be expected to show 8:00 as the usage time.

If however, you arose 3 times, and turned the machine off for 3 minutes at each time, different machines may show different results. Respironics machines show "usage time" as "blower on time" for the session. Changes in the status of the blower are recorded to the second, and "usage time" is the difference between the first "blower-on" time and the last "blower off" time for the session. Thus, in the scenario proposed, Respironics machines would show a "usage time" of 7:51. ResMed, on the other hand, utilizes the concept of "mask on time". This is also based on "blower on" status, but ResMed does not "penalize" the user for short (documentation the precise cutoff time has not been found, but seems to be under 10 minutes) arisings. Thus, in the scenario proposed, ResMed machines would show a "usage time" of 8:00, ignoring the brief arisings. However, if you arose the same 3 times, but turned the machine off for 10 minutes each time, the two machines would display the same results - a "usage time" of 7:30.

[EDIT: There often is in fact a small difference between cumulative "Therapy Time" and "Blower Time" with both Respironics and ResMed machines, with "Blower Time" of course always being larger. This seems to occur because "Blower Time" is "hard-wired" to a time recorder, while "Therapy Time" may be linked to additional "soft" considerations. There may be a slight delay in initiation of the "Therapy Time" clock while the machine moves toward its steady-state conditions, and/or while the sensors determine that an airflow pattern consistent with breathing is actually present. --[[User:Velbor|Velbor]] 14:38, 13 December 2009 (UTC) ]

A consequence of this difference is that ResMed calculation of respiratory event indices, in the presence of multiple short arisings, may be reported slightly on the low side, since the time factor includes minutes during which the machine was not actually blowing. However, ten minutes "extra" during an 8 hour night would result in a 2% "error"
which would not likely be noticeable.

It should be noted that while "usage time" can often be reset on a CPAP machine, total cumulative "blower on" time for a unit cannot be reset. It might also be noted here that ResMed machines cease recording pressure and leak data after 10 hours. This is apparently done to standardize the quantity of data which can be stored. Respiratory events, and usage time, continue to be recorded even after the 10 hour limit.

--[[User:Velbor|Velbor]] 15:33, 24 November 2009 (UTC)
----

Mask Leaks

2009-12-01T14:33:49Z

Velbor: enhance discussion of FF mas as mouth leak solution

=Introduction to Leak=

Air is sucked into the CPAP machine from your room. It is drawn in through a filter, and is blown out at a controlled flow rate to provide the desired pressure. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

'''(1) Intentional venting'''. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. Your exhalations become part of the venting airflow. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak. Intentional venting is the only DESIRABLE way for air to return to your room.

'''(2) Seal leak'''. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

'''(3) Mouth leak'''. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is totally or partially exhaled through the mouth.

'''(4) A defect''' in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

----

=What Harm Does Leak Do?=

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

'''(1) Disruption of Sleep'''. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

'''(2) Drying of the Airway'''. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

'''(3) Pressure Loss'''. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

=How Do I Know If I'm Leaking?=

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening not remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement than is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

=What Does My Machine Tell Me About My Leak?=

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles vs. Averages''': ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. ResMed's practical goal is to encompass, in a single number on the LCD screen, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: with a ResMed machine, if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

Respironics machines, on the other hand (while reporting a very similar 90th centile leak on their software) presents on its LCD screen AVERAGE leak information (for the latest 7 and 30 days). The limitations of an "average" must be remembered: an average leak of 50 lpm may have been a leak of 40 lpm for half of each night and 60 lpm for the other half of each night - not terrible. Alternatively, that same average 50 lpm may mean a leak of 40 lpm for 3/4 of each night, and an unacceptable leak of 80 lpm for 1/4 of each night: for 2 hours out of 8, leak was excessive. Software is needed to tell which of the scenarios actually occurred.

'''Granularity''': Respironics divides time during which the machine is blowing into 30-second segments, and reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display average leak values on its LCD screen as running averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. Given normal night-to-night biological variability, there is some debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such cumulative information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

=What Does Software Tell Me About My Leak?=

While the LCD screen of a data-capable machine provides one “leak number” (the average or 95th centile, for each of several available time periods), with proprietary software a great deal of additional information about leak becomes available. While Respironics and ResMed software have some major differences, the bulk of the truly significant differences revolve around the different leak “paradigms” reviewed in the previous section. Software from either manufacturer (Encore from Respironics and ResScan from ResMed) offers the following advantages over their respective LCD displays:

'''(1) Time range selections'''. The Respironics LCD screen offers average leak information for only the past 7 days and the past 30 days, and the ResMed LCD screen offers 95th centile leak information only for the past night, the past week, month, six months and year. With either manufacturer’s software, information about any group of nights between freely-selectable start and stop dates can be reviewed. This is particularly advantageous for the Respironics user, since leak information for the past night only, which is NOT displayed on the LCD screen, is available.

'''(2) Additional statistics'''. Respironics Encore software offers (on the Sleep Therapy Long Term Trend Report), in addition to the average 90th centile leak information, the average MAXIMUM leak, the AVERAGE leak, and the average LARGE LEAK, for the selected date interval. (The time interval can be specified as a single night – the same start and stop dates – so that these statistics for a single night can be viewed.) On the single-night Daily Details report, the number of minutes, and the percent of the night spent, in LARGE LEAK, are displayed, along with AVERAGE leak. On the Therapy Data Summary, the “Average Time in Large Leak per Day” is displayed for the interval. (Each report appears to use different “rounding” rules, so the numbers are not always the same.) These parameters require some explanation. MAXIMUM leak is the highest “instantaneous” leak value encountered – it is NOT the highest 30-second time window value – so this number will not correspond with graphic displays of leak. (In fact, it must be said, this maximum leak number is quite useless.) The AVERAGE leak is clearest: it is the average of the 30-second time window leak values. LARGE LEAK is not well defined in Respironics documentation: it may be what corresponds to the trigger level for their “Mask Leak Alert” feature, or it may be a somewhat lower value. In either case, it reflects what Respironics considers to be an excessively high leak; its occurrence is displayed graphically with thick, dark “warning” lines.

ResMed ResScan software offers, in addition to the median 95th centile leak information, the MAXIMUM leak, and the MEDIAN leak, for the selected date interval. As with Respironics software, information for a single night can be viewed. Unlike the Respironics software, the maximum leak for ResMed is the maximum 60-second time window value, so it does correspond with graphically-presented information.

'''(3) Summary graphics'''. Both software packages provide graphic displays enabling an overview of the night-to-night summary leak statistics. These are set up in quite different formats, and while there may be individual preferences for one or the other, they provide by-and-large the same sorts of information. The value of these graphics is in the ability to see, visually, whether leak patterns over successive nights are increasing, decreasing, or, which is frankly most common, quite erratically variable. Still, such graphs can be useful in determining whether, over time, techniques for reducing or mitigating leak (such as those reviewed in the next section) are having the desired effect.

'''(4) Individual night graphics'''. Wisely or not, to an extent far exceeding the attention given to the offerings of CPAP monitoring software just listed, the leak graphs for individual nights are by far the major attraction for most users. And with good reason. Each 30-second or 60-second time window recording of average or median leak is displayed, for the entire night. Leak changes can be correlated with pressure changes, and (if there indeed is any correlation, which is debatable) with the occurrence of respiratory events. Brief, isolated leak event spikes can be distinguished from systematic recurrences, and generally ignored. Patterns of leak, which may be amenable to remediation, can sometimes be distinguished. Periodic “hills” of increased and decreased leak may be associated with mouth exhalation which may be more frequent during cycles of deeper sleep or dreaming. But most often, it’s simply interesting, but unactionable.

It must also be remembered, as reviewed in the preceding section, that Respironics presents “leak” as total flow – normal venting plus unintentional leak – while ResMed presents an “adjusted” leak, unintentional leak only, having already subtracted out the expected normal venting for the mask which has been selected (from among its list of ResMed masks). What each of the manufacturers nightly graphs show, therefore, is in fact somewhat different, and must be carefully interpreted.

Since Respironics Encore nightly graphs display total flow, they have a built-in “baseline” of venting. And with an AutoPAP, that baseline changes as pressure varies. This makes the interpretation of Respironics nightly graphs more complex; the interpreter must know and “mentally subtract out” the venting rate of the mask in use to view the unintentional leak. Or more often, the user simply looks at the leak line and subjectively decides (hopefully) that the variability isn’t TOO wide, suggesting that the leak is relatively stable through the night, suggesting (hopefully) that it isn’t TOO large. While as "flat" as possible a leak line is certainly desirable, it is not necessarily an essential goal. Getting a firm fix on the ABSOLUTE unintentional leak, using the Respironics nightly graph, is not a simple task. Again, more often, a user will simply decide that as long as the leak is largely under, say, 65 lpm (about 40 lpm as a working average for venting, and about 24 lpm as an “acceptable” unintentional leak), everything is probably OK. Some users consider up to 75 lpm an acceptable leak. And, probably, everything is OK. Also helpful and important is the Respironics “Large Leak” graphic indicator, a thick bar telling the user (who may have otherwise been unaware of any potential problem) that the machinery is unhappy with the extent of leak. These “Large Leak” indicators need to be taken seriously, even if we don’t know precisely what criteria are used when they are displayed. The Encore software Help File simply says, “If the chart shows leakage at the “LL” level (large leak), this is an excessive leak that will compromise therapy. This could be the result of a poor mask fitting.”

On the other hand, since Resmed ResScan nightly graphs display only net unintentional leak, the baseline leak rate could be (and ideally will be) zero. A constant, higher baseline suggests a systematic leak, likely due to a mechanical defect or an incorrectly assembled mask fixture. Not having a “Large Leak” indicator, the Resmed software places a horizontal red line at 0.40 lps (= 24 lpm), suggesting that if the leak graph exceeds that level for any significant period of time, leak may be excessive and may require remedial action.

Neither software package is consistently and markedly “better” than the other in all respects. What is important is that the user learn to understand and interpret what the software being used can and cannot, does and does not, tell you, and when, and how, to respond to the information. In any case, the software VASTLY increases the amount of information regarding leak (and other important CPAP parameters) available to the user. If you have a data-capable machine, and if the additional cost of software and associated data-transfer hardware is possible, this is a highly recommended investment.

----

=What Can (And Should) I Do About Leaking?=

OK, so you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Not every leak is a PROBLEM leak. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a "good vs. bad" dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Typically, the strap lengths on right and left should be symmetrical, to provide even pressure on each side. On the other hand, few of our faces are perfectly formed, and we often have sleeping positional preferences which might make an off-center strap configuration a better choice. Similarly, a fraction of an inch higher or lower may improve a mask’s leak characteristics significantly.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask! And remember that when an adjustable angle or length between the headpad and the body of the mask is provided, experimentation to find an ideal positioning to minimize leak may well be worth the time and effort. Again, read the instructions!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Silicone Ear Plugs (as well as other substances) to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Some CPAP users find that “special” pillows, with unique shapes or custom filling material, prevent displacement of their masks and consequent leakage. Others find that a conventional pillow “stabilizes” a mask against their face, preventing leak.

The most effective method of dealing with mouth leak is switching to a full-face mask, which encompasses both the nose and mouth inside the mask. With no pressure differential between mouth and nose, there's no added stimulus to exhale through the mouth. Most importantly, airflow through the mouth (while it still may result in dryness) does not impact the effectiveness of CPAP therapy on sleep apnea. However, there is a price to pay. The much larger cushion needed to surround both the mouth and nose greatly increases the area of skin contact, and thus increases the potential for seal leak. And there are sometimes comfort issues: straps often need to be tighter, irritation of the nasal bridge can become a concern, the masks are often larger and heavier, and covering both the mouth and nose is psychologically uncomfortable for some people. Still, a full-face mask is the "gold standard" solution to mouth leak problems.

Other methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

--[[User:Velbor|Velbor]] 16:24, 10 November 2009 (UTC)

--[[User:Velbor|Velbor]] 23:53, 19 November 2009 (UTC) edited by Velbor

----

= Mouth Breathing and Mouth Leaks =

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

----
Comment added by --[[User:Velbor|Velbor]] 21:57, 22 November 2009 (UTC) :
The above statement that "if air leaks out through your mouth, the PAP therapy will not work" is far to rigid. As described in the "Introduction to Leak" segment of this article, there are different types and severities of mouth leak. The following tracing (total time 7:09) involving use of a ResMed Activa nasal mask

[[Image:Velbor_Mouth_Exhalation.jpg]]

provides an example of an acceptable pattern of oral exhalation, sometimes referred to as "lip flutter" or "lip puffing", in which the jaw remains closed but the lips open with each exhalation as if blowing a bubble. AutoPAP is set at 10 - 20cm, with median pressure 10.8, 95% pressure 11.4, and maximum pressure 11.8. Note the periodicity of the leak and the return to zero baseline between episodes. This is presumably related to the cyclic variation in sleep stage or depth affecting orofacial musculature; note the latency after each brief arising before these patterns begin. Median leak for the night is 0.00 lps!! Seal leak is negligible. While maximum leak is 0.54 lps, above the "red line", the 95% leak is 0.38 lps, which indicates that the time spent above the 0.40 lps "alert" level is LESS THAN 5% of the night. Efficacy of treatment is excellent (particularly by ResMed standards): AHI = 5.3, AI = 0.0 and HI = 5.3 . While mouth leak is never desirable, care must be taken to avoid arbitrarily labeling it as terrible.
----

Cleaning CPAP Equipment

2009-11-29T21:56:09Z

Velbor: clean-ups, and release of article

== Introduction ==

Few topics engender more diversity of approach than that of routine cleaning of CPAP equipment: humidifier chambers, tubing and masks. (I might dare also include the checking and periodic replacement of machine filters.)

Practices range from doing nothing (often accompanied by the claim that “…. and I’ve never been sick or had any problem”) to vigorous daily disassembly and thorough washing (often accompanied by the conclusion that therefore “…. I’ve never been sick or had any problem”).

Philosophies range from “people today would be a lot healthier if they ate more dirt” (which might or might not be so, but “back in the day” life expectancy surely was a lot shorter) to germophobic fatalism, to holistic health practices including homeopathy and nasal irrigation (reminds me of reading literature on the virtues of daily enemas).

The equipment manufacturers don’t help much. Almost all advise daily draining, washing, and rinsing of humidifier chambers and masks. (Perhaps because tubing isn’t often sold as a “branded” product, there is less emphasis on daily care in that realm.) They are often accused of taking that position as a litigation preventive measure; that may or may not be so. They rarely present actual research to support or explain their cleaning recommendations.

Recognizing that my complete objectivity and rationality is not infrequently called into question (even, or perhaps especially, by those who know me best), let’s take a stab at thinking through the issues. In that way, whatever decision we reach, we can pretend that it’s based on careful and deliberate thought, rather than on our own laziness or on our obsessive-compulsive inclinations.

== General Principles ==

● Microbes tend to grow in warm, moist, dark places.

● Our world, including the air we breathe, is full of microbes.

● The danger posed by commonly encountered microbes is directly proportional to the number of them that get inside us, and inversely proportional to our overall state of health. (This is true also of microbes normally found in our own bodies. Change the number or ratio of our internal microbial flora, or experience a general decline in health, and our own microbes can literally “eat us alive”.)

Based on these principles, let’s consider the equipment in our CPAP set-ups, in order from the most distant components to those closest to our bodies.

== ● Air Filters ==

ResMed suggests, “Inspect the air filter every month to check if it is blocked by dirt or contains holes. With normal use of an S8 AutoSet II, the air filter needs to be replaced every six months (or more often if your device is in a dusty environment).”

Respironics states, “Under normal usage, you should clean the gray foam filter at least once every two weeks and replace it with a new one every six months. The white ultra-fine filter is disposable and should be replaced after 30 nights of use or sooner if it appears dirty. DO NOT clean the ultra-fine filter.”

Why does Respironics suggest so much more frequent checking and changing of filters? One explanation is that their filtering system is much more efficient than the open fiber filters – reminiscent of inexpensive filters used in my home HVAC system – employed by ResMed. Fine particulates appear much more likely to be blocked and kept out of the air stream – and thus much more likely to foul and block the filters – in the Respironics systems. Still, it does not necessarily follow that the presumed higher efficiency of the Respironics filtration is either necessary or helpful – do we need to breathe air that is cleaner than our room air?

Respironics nicely summarizes why filter cleaning is important:

----
'''Caution''': Operating the device with a dirty filter may keep the system from working
properly and may damage the device. …

'''Caution''': Dirty inlet filters may cause high operating temperatures that may affect
device performance. Regularly examine the inlet filters as needed for integrity
and cleanliness.
----

Ah, a reference to “cleanliness.” Comfortable, culturally correct, but still, just a bit …. vague.

== ● CPAP Machine ==

No one recommends that we clean the CPAP machine (at least not beyond the careful application of a moist cloth to the exterior to remove grease, grime and dust). Isn’t that an oddly fortunate coincidence, since there’s no safe way in which we’re ABLE to clean the belly of the beast. Besides, though it may be dark inside and warm when it’s running, it’s dry, and nothing goes through it except filtered room air.

Well, that may not be quite exactly true. There are two ways in which moisture might get inside. The most serious is if there’s backflow into the machine from the humidifier. This, apparently, is most likely to happen if the set-up is moved while the machine is attached to a humidifier containing water. BIG OOPS. Not only is there danger of microbial growth wherever the water manages to ooze, but there is also danger of electrical component malfunction, corrosion, or even potential short-circuit and fire. The manufacturers are unanimous:

ResMed: “Water must be prevented from entering your flow generator. Do not transport the flow generator with the H4i attached.” …. “This Limited Warranty does not cover: …. d) any damage caused by water being spilled on or into a flow generator.”

Respironics: “If the device and humidifier fall and water gets into the device, drain all water out of the device and make sure it is completely dry before reapplying power. … If the device falls or water gets into the device upon falling, let the device dry completely and then restart it. If it does not operate correctly after falling, contact Respironics or an authorized service center.”

----

But there is a second, more subtly insidious, and perhaps more common way for moisture to enter the CPAP machine and cause any or all of the nasties described above. That is by diffusion. The physics is very simple and straightforward. Just as “nature abhors a vacuum,” nature abhors any difference in concentration of any substance.

You are using your CPAP with a heated humidifier. The CPAP blows air in one direction: away from the machine, over the water surface in the humidifier chamber, and towards you. You sleep well, with not a care in the world. In the morning, you wake up, turn everything off, and go about your business. (Or, similarly, you get up during the night for an extended period.) And diffusion goes about its business.

Water has a high “specific heat” – higher than almost any other common substance. That means that it takes more heat to raise the temperature of water, than it does to raise the temperature of an equal mass of any other substance, an equal amount. That also means that warm water stays warmer, longer than just about anything else. And THAT means that the moisture level – the absolute humidity – the concentration of water – in the air above the water in the humidifier chamber, will be greater than that in the air anywhere else in the room. That water vapor will want to get – everywhere, anywhere else.

If tubing is connected to the humidifier chamber under these conditions, that humid air will begin to diffuse into the tubing. And in both directions: since no air is flowing, it will equally seek to go into your main tubing, AND into your CPAP machine. In either direction, that warm, moist air will find cooler surfaces. And on cooler surfaces, water will precipitate out of the air. (Yes, right, just like rainout!) The amounts may be minute. Or not. Diffusion occurs on a molecular level, and the warm water vapor can find its way through the most minute cracks and crevices. Even into areas of the machine where little airflow moves – so that there may not be the “normal” opportunity for drying during normal machine use. Dangers of machine damage due to this water vapor diffusion are arguably small. Dangers of providing a habitat for microbial growth may also be arguably small.

Still, it’s simple enough, with most machine designs, to disconnect the direct connection between the humidifier and anything else. With a stand-alone humidifier, disconnect the tubes. With a ResMed Humidaire humidifier, lift the top cover to unseat the gasket and let the humid air pass harmlessly into the room. With Respironics humidifiers – sorry, I have never used an integrated Respironics humidifier, so I don’t know how best to take action. (By the way, if you use a Fisher & Paykel stand-alone humidifier with the HC-325 chamber, the blue plastic caps that come with each new chamber should be kept - they make an excellent cover for the chamber AFTER you remove the tubing. And an excellent cover for the CPAP machine blower port.)

This is a simple, proactive way to prevent even the small possibility of physical damage, and, more to the point of this article, to prevent even the small possibility of microbial growth inside the blower.
----

Aha! ResMed has already thought of this, though paradoxically they give what for all the world looks like a bogus reason for their very innovative response. In their manual for the HumidAire series of humidifiers (though generally NOT in the manuals for their CPAP machines themselves) they write:

“Note: In order to assist the heater plate in cooling, some flow generators continue to
blow air gently for up to an hour after treatment has stopped. However, you can unplug the device from the power outlet at any time and allow the heater plate to cool without airflow. ”

In fact, with water still present in the chamber, this slight blowing will have virtually no effect on the humidifier heater plate temperature. Their comment that this function can be easily aborted strongly suggests that there is no need to cool the heater plate. (The best way to cool the heater plate is to remove the reservoir chamber!) Nor is this function useful, as some have suggested, in drying the hose. To the contrary, it is still warm, moist air being gently blown INTO the hose, and rainout may result.

What this "gentle blowing" DOES accomplish is to keep warm moist air flowing AWAY from the machine, preventing diffusion of water vapor INTO the machine. Well done (though poorly explained), ResMed! But even better is to simply disconnect or remove the humidifier chamber from its connection to the blower.

== ● Machine–to–Humidifier Hose ==

This component exists principally in systems which utilize a “stand-alone” rather than an integrated humidifier (though even with an integrated system, “something” connects the machine to the humidifier). Such a hose, if it exists, should be inspected periodically for physical integrity and leaks (run you hand along and around it while the machine is running to check for any airflow), and inspected visually for anything inside that should not be inside. The need for any active cleaning should be rare.

== ● Humidifier Chamber ==

Now the disputation begins in earnest. The “never empty or clean unless there’s an obvious reason to do so” advocates make some excellent points:
----
● even if the occasional microbe gets into the chamber, if you are using distilled water (as you probably should be), there’s nothing for them to feed and grow on.

● even if there is microbial growth in the water, there little likelihood that they can enter the airstream, and

● even if microbes did enter the airstream, there is little evidence that they could successfully navigate and survive the trip down the main tubing in sufficient number to cause illness.
----

On the other side of the table, activists may well claim:
----
● distilled water is not necessarily sterile water, and even if it were, it can no longer be considered sterile once the bottle has been opened

● even with filtration, air flowing through the system is neither microbe-free nor particulate free, and particulates (which may provide microbial nourishment) certainly have an opportunity to enter the humidifier during the filling process, and (depending on whether and how portals are covered) during the day.

● while it is true that humidifiers work by producing molecular water which “dissolves” in the overlying air, rather than water “particles” which can “carry” microbes “piggyback” down the tubing, there are other potential transport processes. Observation of the surface of CPAP humidifiers during respiration generally show “rippling” as airflow increases on inspiration. This non-laminar flow “rippling” is effectively wave generation with associated “spray” production – i.e., water particulates capable of carrying microbes. Convection within in the heated water will regularly carry microbes, if present within the water, to the surface, waiting for their “ride”.

● in addition to the presence of surface-effect “spray” water particulates as just described, “clumps” of microbes, even without water droplets as a transport vehicle, can be “lifted up” directly by the non-laminar airflow, either from the water surface, or from the humidifier chamber walls as the water level falls through the night.
----

There is little good, hard, convincing, available science upon which to base a firm preference for either of these two positions. A published study of radioisotopes placed in humidifier water was found to detect radiation as have traversed the tubing, but only at very high pressure (and correspondingly high flow-rate, due to increased venting flow at higher pressures) conditions.

In a brief departure from focusing on microbes, a mention of mineral precipitation is in order. In all but distilled water, there will be dissolved mineral ions. As molecular water is lost overnight through evaporation (whether in a heated or even in a passive pass-over system), the mineral concentration will increase. (It should be noted that periodically adding additional fresh water through the night will help to minimize this.) There may come a point when the minerals reach their saturation point, and begin to precipitate out of solution, potentially resulting in a build-up on the chamber walls and, more likely, on the heating plate. There are two principal down-sides to the deposition of mineral precipitates. First, they tend to form cavernous networks, which provide attractive housing for microbes. (So I lied; we are still talking about microbes.) Second, precipitation on the heater plate tends to decrease the efficiency of heat transfer. (That it may look unattractive is a personal problem; deal with it.) The general recommendation for removing such precipitate is rinsing in a dilute vinegar solution, with the acidic environment hopefully dissolving the minerals and allowing them to be rinsed away. (In addition it is claimed that the vinegar has mild antiseptic properties, helping to kill, yes, again, microbes.) It should also be noted that many insurance plans cover twice-yearly humidifier chamber replacement.

Thus, the range of options for humidifier chamber care and maintenance, from least interventionist to most conservative, runs something like:

● doing nothing; simply adding water each night
● draining out the leftover water and allowing to dry, each morning, or periodically
● draining, rinsing and allowing to dry, each morning, or periodically
● all the above, plus use of soap and/or vinegar, followed by thorough rinsing

A final comment on drying. If you are “drying out” the humidifier at all, the faster the drying process, the less likely that any microbes will find residual moisture and “settle in.” (The bathroom, by the way, may be the most convenient place for drying, but it is the least desirable, in view of typically higher moisture levels, typically higher levels of airborne particulates, and – yes – typically higher level of airborne microbes.) Drying can be accelerated by vigorous shaking, not only to remove excess water, but also to break up remaining water into smaller droplets. (Smaller droplets have a larger surface-area to volume ratio, and will therefore evaporate more rapidly.) Inserting a clean, thin, threadbare washcloth into the chamber prior to the shaking process will facilitate the removal of excess water. And blowing air through the chamber with a CPAP machine will greatly enhance the evaporation of any remaining water.

Where you choose to place yourself on this spectrum is largely a matter of choice, involving such factors as your overall health, your overall “tidiness”, and your overall risk tolerance preferences. It’s hard to imagine even the most “non-interventionist” CPAP user ignoring a humidifier chamber which begins to look cruddy or colorful. If a decision regarding action is based on what you see (or more precisely, on what you NOTICE), then we in fact are already operating on an analog basis – how much contamination is present – rather than on a yes/no digital basis - whether or not contamination is present. Even in our digital age, much of life remains analog.

== ● Main Tubing: Humidifier to Mask ==

People often talk about cleaning their tubing, but few seem to do anything about it. I suspect that’s because the process is so cumbersome. And perhaps also because, arguably, it’s relatively unnecessary.

In the absence of rainout (precipitation of water from warm, moist air against the cooler walls of the tubing), the tubing interior typically remains dry. Mask venting and continuous airflow from the machine (and, for some masks, extension tubing) typically prevent any significant amounts of exhaled air from retrograde entry into the tubing. Under these “ideal” conditions, there’s nothing needing to be cleaned.

Unfortunately, conditions are sometimes less than ideal. (Descriptions on the CPAPTalk discussion forums of insects entering the tubing will be left for those interested to find on their own.)

It is a good practice to INSPECT your tubing on a regular basis. When turning the machine on at night, run your hand along the length of the tubing, feeling for leaks. In the morning, visually check the entire length of tubing. Look for evidence of water droplets or mist suggesting rainout; look for any dark or discolored areas or objects. Tubing which is transparent is obviously highly preferable to tubing which is more or less opaque in this regard. Tubing which is covered (to prevent or diminish rainout) should periodically be “undressed” so that it can be inspected.

If there has been ANY rainout, you now have a condition in your tubing which will arguably support microbial growth. (See the discussion about humidifier chambers, and the variety of opinions about whether microbes can in fact get into, and live in, the tubing. I will simply suggest that the longer you go without inspecting, drying or cleaning your tubing, the greater the possibility of microbial growth, survival, and migration down your tubing toward you face, becomes.)

If there has been rainout, it should be PROMPTLY and RAPIDLY dried. The hose should be first shaken, from the center toward each end, to remove as much water as possible. If you have sufficient room, twirling the hose, from the center toward each end, will also expel excess water. The most convenient technique for rapid drying is to run air from your CPAP blower through the tubing until all evidence of water is gone. (Some machines may automatically shut off when no resistance to flow is encountered. On some of these, it may be possible to disable and turn off that feature. It may also be possible to put a flow-limiting connector on the end of the tubing, but this will increase drying time, since maximal flow will product the most rapid evaporation.) Sucking air through the tubing (rather than blowing as with a CPAP machine) may be attempted; devising a connector to the suction of a household vacuum cleaner has been suggested. Another attractive suggestion (presented on the CPAPTalk forum) is that of connecting a weight to one end of a six-foot-plus length of fishing line, and connecting a thin, dry cloth to the other end of the fishing line. Drop the weight into one end of the tubing, let it pull the line through the tubing, and then the fishing line can be used to pull the dry cloth through the tubing. Special care may need to be taken with heated tubing, or with tubing having custom connectors on one or both ends.

All else failing, tubing can simply be left hung to dry, but passive diffusion of air through a narrow six-foot tubing is not an ideal methodology. Under such circumstances, it has been wisely recommended that one have a spare second tube to use while the first one is drying overnight.

Actually “cleaning” the tubing may occasionally be desirable, as for example when rainout droplets have been allowed to sit in the tubing for days, or even just hours. Some people "dunk" the tubing into a basin of soapy water; possibly a bit awkward due to the tubing length. Simply rinsing the interior by holding one end against a spigot, and allowing the other end to drain into the bathtub, may be sufficient. (Some people have described taking the tubing into the shower with them for rinsing!) If it is desired to use soap (or some other safe cleaning material), the use of a male-to-male adaptor makes the task much easier. (A male-to-male adaptor is typically a small plastic connector, both of whose ends will fit inside the rubber cuffs at the ends of the tubing, and which may be used to connect two hoses together. Some masks come with parts which may be usable for this purpose – e.g. the swivel assembly on a Mirage Activa. An adapter suitable for such use is sold by CPAP dot com at:
https://www.cpap.com/productpage/hose-coupling-swivel-adapter-cpap.html .)
After partially filling the hose with water, and adding a suitable amount of soap, use the adapter to connect the two ends so that the tubing forms a continuous loop. The cleaning solution can now be easily “swished” through the tubing, and allowed to stay inside for as long as is desired. After cleaning, rinse thoroughly and dry rapidly, as already described.

== ● Mask ==

While the risk of microbes reaching us through the airstream is debatable, the risk of contamination of the mask is far less controversial. All night, every night, we are exhaling warm (at body temperature) moist (100% relative humidity) air, laden with microbes (yes, our own) from our upper airway, and proteins and enzymes and sloughed cellular debris, into the mask. The thought question with regard to mask cleaning is not so much, “Do you feel lucky?” as, “Why do you brush your teeth?” The conditions which can lead to halitosis, gingivitis, dental decay, and that grubby trench-mouth feeling, is now present on and in the surfaces and crevices of our masks. Further, he grease and grime on our facial skin is transferred to the cushions.

Despite the difficulty of making a convincing case AGAINST regular mask cleaning, CPAPTalk forum postings demonstrate a wide variety of practices (and a wide spectrum of embarrassment and guilt) for our failures to care for our equipment.

Mask manufacturers routinely provide their “instructions” for cleaning, which typically take the form of daily disassembly, cleaning with soap and water, drying and reassembly. As previously noted, whether this is done simply to ward off litigation, or whether there is actual science and research underlying these recommendations, they are generally presented to users without factual explanation of their basis or origin.

One specific area of contention is that of the extent of mask disassembly required for thorough cleaning. The inconsistencies in manufacturer recommendations are telling. ResMed, for example, instructs complete disassembly of the Activa mask. This is not unreasonable; there are only 10 parts (excluding headgear), only one relatively small, fairly easily disassembled and reassembled (though I have done it improperly with resulting leaks). On the other hand, ResMed instructs only partial disassembly of the UltraMirage Full Face mask. This too is not unreasonable; there are some 13 parts (excluding headgear), six of which are relatively small, and those involved in the elbow and anti-asphyxia valve assembly require some level of dexterity and competence to handle safely and correctly. Loss of small parts down the sink is not unheard of. Obviously, there is a balance between the goals of cleanliness, and the goals of correct and non-destructive disassembly and reassembly. Some appropriate degree of balance must be found by each user. (I still have trouble properly replacing the UMFF venting system and cushion, for which ResMed does recommend daily disassembly.)

Other areas of concern involve whether the life expectancy of the delicate plastic cushion membranes are enhanced or lessened by the handling involved in disassembly and cleaning. This, too, involves personal issues of dexterity and confidence, as well as the development of good, safe practices.

The preventive measures of facial washing (possibly including the use of special cleansers or alcohol wipes to remove skin oils) before donning masks, and of course appropriate oral hygiene before bed, would seem appropriate. At the very least, daily rinsing of the fully-assembled mask appears to be reasonable. Gentle cleansing of the cushion surfaces in contact with the face, to remove grease and oils, may help in minimizing leak (though there are some who insist that either cleaning itself, or the process of disassembly and cleaning, increases the likelihood of leak). Periodic more thorough cleaning, including soaking in soapy water, with an appropriate level of disassembly, should not be neglected.

Finally, an industry has arisen which provides convenient “wipes” and “sanitizers” specifically for CPAP masks. Certainly better than doing nothing, I can’t help but wonder what research has been done, and what the use of such products actually accomplishes.

== ● Headgear Straps ==

Finally, we move out of the realm of microbes, and into the personal comfort zone of dealing with our own head and hair greases and oils. Whether regular cleansing increases or reduces the lifespan of headgear is not at all clear. Washing certainly appears to vary the size and elasticity of some headgear materials, necessitating periodic readjustment of the straps (which is probably a good idea in any case). If a basin of soapy water left is over after having just given your mask a periodic cleaning, it seems wasteful not to give the headgear a dunking as well.

== Concluding Comments ==

In the absence of reliable data, risk / benefit analyses devolve to decisions about what feels comfortable, and how much time and effort that comfortable feeling is worth. The wide spectrum of equipment cleaning practices frequently described on the CPAPTalk forum emphasizes that there are no simple answers which are always right for everyone.

On the other hand, if there’s visible crud anywhere on your CPAP system, be ashamed. And if you’re not regularly LOOKING for visible crud, be ashamed. Hygiene can be overdone, but that generally costs only time. Those of us with Sleep Apnea have a chronic condition which threatens our health, and failure to take appropriate care of our equipment and ourselves is at best short-sighted and risky. I’m not necessarily against risky behavior per se, but it seems as though it should be based on positive decisions rather than on laziness, and should deliver a lot more benefit (and fun).

----

--[[User:Velbor|Velbor]] 23:45, 21 November 2009 (UTC)

updated --[[User:Velbor|Velbor]] 15:25, 25 November 2009 (UTC)

released --[[User:Velbor|Velbor]] 21:56, 29 November 2009 (UTC)

Cleaning CPAP Equipment

2009-11-25T15:25:33Z

Velbor: Completion of remaining subtopics; awaiting final clean-up

This new topic is under construction by Velbor.

Your patience and courtesy in not tearing it apart until I have finished putting it together would be appreciated.

Just a bit more time for final clean-up, please.

== Introduction ==

Few topics engender more diversity of approach than that of routine cleaning of CPAP equipment: humidifier chambers, tubing and masks. (I might dare also include the checking and periodic replacement of machine filters.)

Practices range from doing nothing (often accompanied by the claim that “…. and I’ve never been sick or had any problem”) to vigorous daily disassembly and thorough washing (often accompanied by the conclusion that therefore “…. I’ve never been sick or had any problem”).

Philosophies range from “people today would be a lot healthier if they ate more dirt” (which might or might not be so, but “back in the day” life expectancy surely was a lot shorter) to germophobic fatalism, to holistic health practices including homeopathy and nasal irrigation (reminds me of reading literature on the virtues of daily enemas).

The equipment manufacturers don’t help much. Almost all advise daily draining, washing, and rinsing of humidifier chambers and masks. (Perhaps because tubing isn’t often sold as a “branded” product, there is less emphasis on daily care in that realm.) They are usually accused of taking that position as a litigation preventive measure; that may or may not be so. They surely hardly ever present actual research to support or explain their recommendations.

Recognizing that my complete objectivity and rationality is not infrequently called into question (even, or perhaps especially, by those who know me best), let’s take a stab at thinking through the issues. In that way, whatever decision we reach, we can pretend that it’s based on careful and deliberate thought, rather than on our own laziness or on our obsessive-compulsive inclinations.

== General Principles ==

● Microbes tend to grow in warm, moist, dark places.

● Our world, including the air we breathe, is full of microbes.

● The danger posed by commonly encountered microbes is directly proportional to the number of them that get inside us, and inversely proportional to our overall state of health. (This is true also of microbes normally found in our own bodies. Change the number or ratio of our internal microbial flora, or experience a general decline in health, and our own microbes can literally “eat us alive”.)

Based on these principles, let’s consider the equipment in our CPAP set-ups, in order from the most distant components to those closest to our bodies.

== ● Air Filters ==

ResMed suggests, “Inspect the air filter every month to check if it is blocked by dirt or contains holes. With normal use of an S8 AutoSet II, the air filter needs to be replaced every six months (or more often if your device is in a dusty environment).”

Respironics states, “Under normal usage, you should clean the gray foam filter at least once every two weeks and replace it with a new one every six months. The white ultra-fine filter is disposable and should be replaced after 30 nights of use or sooner if it appears dirty. DO NOT clean the ultra-fine filter.”

Why does Respironics suggest so much more frequent checking and changing of filters? My guess is that their filtering system is much more efficient than the open fiber filters – reminiscent of inexpensive filters used in my home HVAC system – employed by ResMed. Fine particulates appear much more likely to be blocked and kept out of the air stream – and thus much more likely to foul and block the filters – in the Respironics systems. Still, it does not necessarily follow that the presumed higher efficiency of the Respironics filtration is either necessary or helpful – do we need to breathe air that is cleaner than our room air?

Respironics nicely summarizes why filter cleaning is important:

----
'''Caution''': Operating the device with a dirty filter may keep the system from working
properly and may damage the device. …

'''Caution''': Dirty inlet filters may cause high operating temperatures that may affect
device performance. Regularly examine the inlet filters as needed for integrity
and cleanliness.
----

Ah, a reference to “cleanliness.” Still, just a bit …. vague. Comfortable, culturally correct, but …. vague.

== ● CPAP Machine ==

No one recommends that we clean the CPAP machine (at least not beyond the careful application of a moist cloth to the exterior to remove grease, grime and dust). Isn’t that an oddly fortunate coincidence, since there’s no safe way in which we’re ABLE to clean the belly of the beast. Besides, though it may be dark inside and warm when it’s running, it’s dry, and nothing goes through it except filtered room air.

Well, that may not be quite exactly true. There are two ways in which moisture might get inside. The most serious is if there’s backflow into the machine from the humidifier. This, apparently, is most likely to happen if the set-up is moved with the machine attached to a humidifier containing water. BIG OOPS. Not only is there danger of microbial growth wherever the water manages to ooze, but there is also danger of electrical component malfunction, corrosion, or even potential short-circuit and fire. The manufacturers are unanimous:

ResMed: “Water must be prevented from entering your flow generator. Do not transport the flow generator with the H4i attached.” …. “This Limited Warranty does not cover: …. d) any damage caused by water being spilled on or into a flow generator.”

Respironics: “If the device and humidifier fall and water gets into the device, drain all water out of the device and make sure it is completely dry before reapplying power. … If the device falls or water gets into the device upon falling, let the device dry completely and then restart it. If it does not operate correctly after falling, contact Respironics or an authorized service center.”

----

But there is a second, more subtle, more insidious, and perhaps more common way for moisture to enter the CPAP machine and cause any or all of the nasties described above. That is by diffusion. The physics is very simple and straightforward. Just as “nature abhors a vacuum,” nature abhors any difference in concentration of any substance.

You are using your CPAP with a heated humidifier. The CPAP blows air in one direction: away from the machine, over the water surface in the humidifier chamber, and towards you. You sleep well, with not a care in the world. In the morning, you wake up, turn everything off, and go about your business. And diffusion goes about its business.

Water has a high “specific heat” – higher than almost any other common substance. That means that it takes more heat to raise the temperature of water, than it does to raise the temperature of an equal mass of any other substance an equal amount. That also means that warm water stays warmer, longer than just about anything else. And THAT means that the moisture level – the absolute humidity – the concentration of water – in the air above the water in the humidifier chamber, will be greater than that in the air anywhere else in the room. That water vapor will want to get – everywhere, anywhere else.

If you have left tubing connected to your humidifier chamber under these conditions, that humid air will begin to diffuse. In both directions: since no air is flowing, it will equally seek to go into your main tubing, AND into your CPAP machine. In either direction, that warm, moist air will find cooler surfaces. And on cooler surfaces, water will precipitate out of the air. (Yes, right, just like rainout!) The amounts may be minute. Or not. Diffusion occurs on a molecular level, and the warm water vapor can find its way through the most minute cracks and crevices. Even into areas of the machine where airflow rarely occurs – so that there may not be the “normal” opportunity for drying during normal machine use. Dangers of machine damage due to this water vapor diffusion are arguably small, Dangers of providing a habitat for microbial growth may also be arguably small.

But to my mind: why argue? It’s simple enough, with most machine designs, to disconnect the direct connection between the humidifier and anything else. With a stand-alone humidifier, disconnect the tubes. With a ResMed Humidaire humidifier, lift the top cover to unseat the gasket and let the humid air pass harmlessly into the room. With Respironics humidifiers – I have never used an integrated Respironics humidifier, so I don’t know how best to take action. (By the way, if you use a Fisher & Paykel stand-alone humidifier with the HC-325 chamber, the blue plastic caps that come with the chamber make an excellent cover for the chamber AFTER you remove the tubing.)

This is a simple, proactive way to prevent even the small possibility of physical damage, and, more to the point of this article, to prevent even the small possibility of microbial growth inside the blower.
----

Aha! ResMed has already thought of this, though paradoxically they give what for all the world looks like a bogus reason for their very innovative response. In their manual for the HumidAire series of humidifiers (though generally NOT in the manuals for their CPAP machines themselves) they write:

“Note: In order to assist the heater plate in cooling, some flow generators continue to
blow air gently for up to an hour after treatment has stopped. However, you can unplug the device from the power outlet at any time and allow the heater plate to cool without airflow. ”

In fact, with water still present in the chamber, this slight blowing will have virtually no effect on the humidifier heater plate temperature. Their comment that this function can be easily aborted strongly suggests that there is no need to cool the heater plate. (The best way to cool the heater plate is to remove the reservoir chamber!) Nor is this function useful, as some have suggested, in drying the hose. It is still warm, moist air being blown INTO the hose.

What this “gently blowing DOES accomplish is to keep warm moist air flowing AWAY from the machine, preventing diffusion of water vapor INTO the machine. Well done (though poorly explained), ResMed! But even better is to simply disconnect or remove the humidifier chamber from its connection to the blower.

== ● Machine–to–Humidifier Hose ==

This component exists principally in systems which utilize a “stand-alone” rather than an integrated humidifier (though even with an integrated system, “something” connects the machine to the humidifier). Such a hose, if it exists, should be inspected periodically for physical integrity and leaks (run you hand along and around it while the machine is running to check for any airflow), and inspected visually for anything inside that should not be inside. I would propose that the need for any active cleaning should be rare.

== ● Humidifier Chamber ==

Now the disputation begins in earnest. The “never empty or clean unless there’s an obvious reason to do so” advocates make some excellent points:
----
● even if the occasional microbe gets into the chamber, if you are using distilled water (as you probably should be), there’s nothing for them to feed and grow on.

● even if there is microbial growth in the water, there little likelihood that they can enter the airstream, and

● even if microbes did enter the airstream, there is little evidence that they could successfully navigate and survive the trip down the main tubing in sufficient number to cause illness.
----

On the other side of the table, activists may well claim:
----
● distilled water is not necessarily sterile water, and even if it were, it can no longer be considered sterile once the bottle has been opened

● even with filtration, air flowing through the system is neither microbe-free nor particulate free, and particulates (which may provide microbial nourishment) certainly have an opportunity to enter the humidifier during the filling process, and (depending on whether and how portals are covered) during the day.

● while it is true that humidifiers work by producing molecular water which “dissolves” in the overlying air, rather than water “particles” which can “carry” microbes “piggyback” down the tubing, there are other potential transport processes. Observation of the surface of CPAP humidifiers during respiration generally show “rippling” as airflow increases on inspiration. This non-laminar flow “rippling” is effectively wave generation with typical associated “spray” production – i.e., water particulates capable of carrying microbes. Convection within in the heated water will regularly carry microbes, if present within the water, to the surface, waiting for their “ride”.

● in addition to the presence of surface-effect “spray” water particulates as just described, “clumps” of microbes, even without water droplets as a transport vehicle, can be “lifted up” directly by the non-laminar airflow, either from the water surface, or from the humidifier chamber walls as the water level falls through the night.
----

There is little good, hard, convincing published science upon which to base a firm preference for either of these two positions. A published study of radioisotopes placed in humidifier water was found to detect radiation as have traversed the tubing, but only at very high pressure (and correspondingly high flow-rate, due to increased venting flow at higher pressures) conditions.

In a brief departure from focusing on microbes, a mention of mineral precipitation is in order. In all but distilled water, there will be dissolved mineral ions. As molecular water is lost overnight through evaporation (whether in a heated or even in a passive pass-over system), the mineral concentration will increase. (It should be noted that periodically adding additional fresh water through the night will help to minimize precipitation.) There may come a point when the minerals reach their saturation point, and begin to precipitate out of solution, potentially resulting in a build-up on the chamber walls and, more likely, on the heating plate. There are two principal down-sides to the deposition of mineral precipitates. First, they tend to form cavernous networks, which provide attractive housing for microbes. (So I lied; we are still talking about microbes.) Second, precipitation on the heater plate tends to decrease the efficiency of heat transfer. (That it may look unattractive is a personal problem; deal with it.) The general recommendation for such precipitation is rinsing in a dilute vinegar solution, with the acidic environment hopefully dissolving the minerals and allowing them to be rinsed away. (In addition it is claimed that the vinegar has mild antiseptic properties, helping to kill, yes, again, microbes.) It should also be noted that many insurance plans cover twice-yearly humidifier chamber replacement.

Thus, the range of options for humidifier chamber care and maintenance, from least interventionist to most conservative, runs something like:

● doing nothing; simply adding water each night
● draining out the leftover water and allowing to dry, each morning, or periodically
● draining, rinsing and allowing to dry, each morning, or periodically
● all the above, plus use of soap and/or vinegar, followed by thorough rinsing

A final comment on drying. If you are “drying out” the humidifier at all, the faster the drying process, the less likely that any microbes will find residual moisture and “settle in.” (The bathroom, by the way, may be the most convenient place for drying, but it is the least desirable, in view of typically higher moisture levels, typically higher levels of airborne particulates, and – yes – typically higher level of airborne microbes.) Drying can be accelerated by vigorous shaking, not only to remove excess water, but also to break up remaining water into smaller droplets. (Smaller droplets have a larger surface-area to volume ratio, and will therefore evaporate more rapidly.) Inserting a clean, thin washcloth into the chamber prior to the shaking process will facilitate the removal of excess water. And blowing air through the chamber with a CPAP machine will greatly enhance the evaporation of any remaining water.

Where you choose to place yourself on this spectrum is largely a matter of choice, involving such factors as your overall health, your overall “tidiness”, and your overall risk tolerance preferences. It’s hard to imagine even the most “non-interventionist” CPAP user ignoring a humidifier chamber which begins to look cruddy or colorful. If a decision regarding action is based on what you see (or more precisely, on what you NOTICE), then we in fact are already operating on an analog basis – how much – rather than on a yes/no digital basis. Even in our digital age, much of life remains analog.

== ● Main Tubing: Humidifier to Mask ==

People often talk about cleaning their tubing, but few seem to do anything about it. I suspect that’s because the process is so cumbersome. And perhaps also because, arguably, it’s relatively unnecessary.

In the absence of rainout (precipitation of water from warm, moist air against the cooler walls of the tubing), the tubing interior typically remains dry. Mask venting and continuous airflow from the machine (and, for some masks, extension tubing) typically prevent any significant amounts of exhaled air from retrograde entry into the tubing. Under these “ideal” conditions, there’s nothing needing to be cleaned.

Unfortunately, conditions are sometimes less than ideal. (Descriptions on the CPAPTalk discussion forums of insects entering the tubing will be left for those interested to find on their own.)

It is a good practice to INSPECT your tubing on a regular basis. When turning the machine on at night, run your hand along the length of the tubing, feeling for leaks. In the morning, visually check the entire length of tubing. Look for evidence of water droplets or mist suggesting rainout; look for any dark or discolored areas or objects. Tubing which is transparent is obviously highly preferable to tubing which is more or less opaque in this regard. Tubing which is covered (to prevent or diminish rainout) should periodically be “undressed” so that it can be inspected.

If there has been ANY rainout, you now have a condition in your tubing which will arguably support microbial growth. (See the discussion about humidifier chambers, and the variety of opinions about whether microbes can in fact get into, and live in, the tubing. I will simply suggest here that the longer you go without inspecting, drying or cleaning your tubing, the greater the possibility of microbial growth, survival, and migration down your tubing toward you face, becomes.)

If there has been rainout, it should be PROMPTLY and RAPIDLY dried. The hose should be first shaken, from the center toward each end, to remove as much water as possible. If you have sufficient room, twirling the hose, from the center toward each end, will also expel excess water. The most convenient technique for rapid drying is to run air from your CPAP blower through the tubing until all visual evidence of water is gone. (Some machines may automatically shut off when no resistance to flow is encountered. On some of these, it may be possible to disable and turn off that feature. It may also be possible to put a flow-limiting connector on the end of the tubing, but this will increase drying time, since maximal flow will product the most rapid evaporation.) Sucking air through the tubing (rather than blowing as with a CPAP machine) may be attempted; devising a connector to the suction of a household vacuum cleaner has been suggested. Another attractive suggestion (presented on the CPAPTalk forum) is that of connecting a weight to one end of a six-foot-plus length of fishing line, and connecting a dry cloth to the other end of the fishing line. Drop the weight into one end of the tubing, let it pull the line through the tubing, and then the fishing line can be used to pull the dry cloth through the tubing. Special care may need to be taken with heated tubing, or with tubing having custom connectors on one or both ends.

All else failing, tubing can simply be left hung to dry, but passive diffusion of air through a narrow six-foot tubing is not an ideal methodology. Under such circumstances, it has been wisely recommended that one have a spare second tube to use while the first one is drying overnight.

Actually “cleaning” the tubing may occasionally be desirable. Simply rinsing the interior by holding one end against a spigot, and allowing the other end to drain into the bathtub, may be sufficient. If it is desired to use soap (or some other safe cleaning material), the use of a male-to-male adaptor makes the task much easier. (A male-to-male adaptor is typically a small plastic connector, both of whose ends will fit inside the rubber cuffs at the ends of the tubing, and which may be used to connect two hoses together. Some masks come with parts which may be usable for this purpose – e.g. the swivel assembly on a Mirage Activa. An adapter suitable for such use is sold by CPAP dot com at:
https://www.cpap.com/productpage/hose-coupling-swivel-adapter-cpap.html .)
After partially filling the hose with water, and adding a suitable amount of soap, use the adapter to connect the two ends so that the tubing forms a continuous loop. The cleaning solution can now be easily “swished” through the tubing, and allowed to stay inside for as long as is desired. After cleaning, rinse thoroughly and dry rapidly, as already described.

== ● Mask ==

While the risk of microbes reaching us through the airstream is debatable, the risk of contamination of the mask is far less controversial. All night, every night, we are exhaling warm (at body temperature) moist (100% relative humidity) air, laden with microbes (yes, our own) from our upper airway, and proteins and enzymes and sloughed cellular debris, into the mask. The thought question with regard to mask cleaning is not so much, “Do you feel lucky?” as, “Why do you brush your teeth?” The conditions which can lead to halitosis, gingivitis, dental decay, and that grubby trench-mouth feeling, is now present on and in the surfaces and crevices of our masks. Further, he grease and grime on our facial skin is transferred to the cushions.

Despite the difficulty of making a convincing case AGAINST regular mask cleaning, CPAPTalk forum postings demonstrate a wide variety of practices (and a wide spectrum of embarrassment and guilt) for our failures to care for our equipment.

Mask manufacturers routinely provide their “instructions” for cleaning, which typically take the form of daily disassembly, cleaning with soap and water, drying and reassembly. As previously noted, whether this is done to ward of litigation, or whether there is actual science and research underlying these recommendations, generally devolves to expressions of opinion with little basis in available fact.

One specific area of contention is that of the extent of mask disassembly required for thorough cleaning. The inconsistencies in manufacturer recommendations are telling. ResMed, for example, instructs complete disassembly of the Activa mask. This is not unreasonable; there are only 10 parts (excluding headgear), only one relatively small, fairly easily disassembled and reassembled (though I have done it improperly with resulting leaks). On the other hand, ResMed instructs only partial disassembly of the UltraMirage Full Face mask. This too is not unreasonable; there are some 13 parts (excluding headgear), six of which are relatively small, and those involved in the elbow and anti-asphyxia valve assembly require some level of dexterity and competence to handle safely and correctly. Loss of small parts down the sink is not unheard of. Obviously, there is a balance between the goals of cleanliness, and the goals of correct and non-destructive disassembly and reassembly. Some appropriate degree of balance must be found by each user. (I still have trouble properly replacing the UMFF venting system and cushion, for which ResMed does recommend daily disassembly.)

Other areas of concern involve whether the life expectancy of the delicate plastic cushion membranes are enhanced or lessened by the handling involved in disassembly and cleaning. This, too, involves personal issues of dexterity and confidence, as well as the development of good, safe practices.

The preventive measures of facial washing (cleansers, or even use of alcohol wipes) before donning masks, and of course appropriate oral hygiene before bed, would seem appropriate. At the very least, daily rinsing of the fully-assembled mask appears to be reasonable. Gentle cleansing of the cushion surfaces in contact with the face, to remove grease and oils, may help in minimizing leak (though there are some who insist that cleaning increases leak). Periodic more thorough cleaning, including soaking in soapy water, with an appropriate level of disassembly, should not be neglected.

Finally, an industry has arisen which provides convenient “wipes” and “sanitizers” specifically for CPAP masks. Certainly better than doing nothing, I can’t help but wonder what research has been done, and what use of such products actually accomplishes.

== ● Headgear Straps ==

Finally, we move out of the realm of microbes, and into the personal comfort zone of dealing with our own head and hair greases and oils. Whether regular cleansing increases or reduces the lifespan of headgear is not at all clear. Washing certainly appears to vary the size and elasticity of some headgear materials, necessitating periodic readjustment of the straps (which is probably a good idea in any case). My own sense is that, if I have a basin of soapy water left over after having just given my mask a periodic cleaning, it seems wasteful not to give my headgear a dunking as well.

== Concluding Comments ==

In the absence of reliable data, risk / benefit analyses devolve to decisions about what feels comfortable, and how much time and effort that comfortable feeling is worth. The wide spectrum of equipment cleaning practices frequently described on the CPAPTalk forum emphasizes that there are no simple answers which are always right for everyone.

On the other hand, if there’s visible crud anywhere on your CPAP system, be ashamed. And if you’re not regularly LOOKING for visible crud, be ashamed. Hygiene can be overdone, but that generally costs only time. Those of us with Sleep Apnea have a chronic condition which threatens our health, and failure to take appropriate care of our equipment and ourselves is at best short-sighted and risky. I’m not necessarily against risky behavior per se, but it seems as though it should be based on positive decisions rather than on laziness, and should deliver a lot more benefit (and fun).

----

This new topic is under construction by Velbor.

Your patience and courtesy in not tearing it apart until I have finished putting it together would be appreciated.

Just a bit more time for final clean-up, please.

--[[User:Velbor|Velbor]] 23:45, 21 November 2009 (UTC)

updated --[[User:Velbor|Velbor]] 15:25, 25 November 2009 (UTC)

Total Recording Time

2009-11-24T15:33:19Z

Velbor: Usage Time for CPAP machines

Mask Leaks

2009-11-22T21:57:49Z

Velbor: minor clean-up

=Introduction to Leak=

Air is sucked into the CPAP machine from your room. It is drawn in through a filter, and is blown out at a controlled flow rate to provide the desired pressure. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

'''(1) Intentional venting'''. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. Your exhalations become part of the venting airflow. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak. Intentional venting is the only DESIRABLE way for air to return to your room.

'''(2) Seal leak'''. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

'''(3) Mouth leak'''. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is totally or partially exhaled through the mouth.

'''(4) A defect''' in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

----

=What Harm Does Leak Do?=

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

'''(1) Disruption of Sleep'''. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

'''(2) Drying of the Airway'''. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

'''(3) Pressure Loss'''. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

=How Do I Know If I'm Leaking?=

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening not remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement than is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

=What Does My Machine Tell Me About My Leak?=

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles vs. Averages''': ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. ResMed's practical goal is to encompass, in a single number on the LCD screen, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: with a ResMed machine, if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

Respironics machines, on the other hand (while reporting a very similar 90th centile leak on their software) presents on its LCD screen AVERAGE leak information (for the latest 7 and 30 days). The limitations of an "average" must be remembered: an average leak of 50 lpm may have been a leak of 40 lpm for half of each night and 60 lpm for the other half of each night - not terrible. Alternatively, that same average 50 lpm may mean a leak of 40 lpm for 3/4 of each night, and an unacceptable leak of 80 lpm for 1/4 of each night: for 2 hours out of 8, leak was excessive. Software is needed to tell which of the scenarios actually occurred.

'''Granularity''': Respironics divides time during which the machine is blowing into 30-second segments, and reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display average leak values on its LCD screen as running averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. Given normal night-to-night biological variability, there is some debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such cumulative information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

=What Does Software Tell Me About My Leak?=

While the LCD screen of a data-capable machine provides one “leak number” (the average or 95th centile, for each of several available time periods), with proprietary software a great deal of additional information about leak becomes available. While Respironics and ResMed software have some major differences, the bulk of the truly significant differences revolve around the different leak “paradigms” reviewed in the previous section. Software from either manufacturer (Encore from Respironics and ResScan from ResMed) offers the following advantages over their respective LCD displays:

'''(1) Time range selections'''. The Respironics LCD screen offers average leak information for only the past 7 days and the past 30 days, and the ResMed LCD screen offers 95th centile leak information only for the past night, the past week, month, six months and year. With either manufacturer’s software, information about any group of nights between freely-selectable start and stop dates can be reviewed. This is particularly advantageous for the Respironics user, since leak information for the past night only, which is NOT displayed on the LCD screen, is available.

'''(2) Additional statistics'''. Respironics Encore software offers (on the Sleep Therapy Long Term Trend Report), in addition to the average 90th centile leak information, the average MAXIMUM leak, the AVERAGE leak, and the average LARGE LEAK, for the selected date interval. (The time interval can be specified as a single night – the same start and stop dates – so that these statistics for a single night can be viewed.) On the single-night Daily Details report, the number of minutes, and the percent of the night spent, in LARGE LEAK, are displayed, along with AVERAGE leak. On the Therapy Data Summary, the “Average Time in Large Leak per Day” is displayed for the interval. (Each report appears to use different “rounding” rules, so the numbers are not always the same.) These parameters require some explanation. MAXIMUM leak is the highest “instantaneous” leak value encountered – it is NOT the highest 30-second time window value – so this number will not correspond with graphic displays of leak. (In fact, it must be said, this maximum leak number is quite useless.) The AVERAGE leak is clearest: it is the average of the 30-second time window leak values. LARGE LEAK is not well defined in Respironics documentation: it may be what corresponds to the trigger level for their “Mask Leak Alert” feature, or it may be a somewhat lower value. In either case, it reflects what Respironics considers to be an excessively high leak; its occurrence is displayed graphically with thick, dark “warning” lines.

ResMed ResScan software offers, in addition to the median 95th centile leak information, the MAXIMUM leak, and the MEDIAN leak, for the selected date interval. As with Respironics software, information for a single night can be viewed. Unlike the Respironics software, the maximum leak for ResMed is the maximum 60-second time window value, so it does correspond with graphically-presented information.

'''(3) Summary graphics'''. Both software packages provide graphic displays enabling an overview of the night-to-night summary leak statistics. These are set up in quite different formats, and while there may be individual preferences for one or the other, they provide by-and-large the same sorts of information. The value of these graphics is in the ability to see, visually, whether leak patterns over successive nights are increasing, decreasing, or, which is frankly most common, quite erratically variable. Still, such graphs can be useful in determining whether, over time, techniques for reducing or mitigating leak (such as those reviewed in the next section) are having the desired effect.

'''(4) Individual night graphics'''. Wisely or not, to an extent far exceeding the attention given to the offerings of CPAP monitoring software just listed, the leak graphs for individual nights are by far the major attraction for most users. And with good reason. Each 30-second or 60-second time window recording of average or median leak is displayed, for the entire night. Leak changes can be correlated with pressure changes, and (if there indeed is any correlation, which is debatable) with the occurrence of respiratory events. Brief, isolated leak event spikes can be distinguished from systematic recurrences, and generally ignored. Patterns of leak, which may be amenable to remediation, can sometimes be distinguished. Periodic “hills” of increased and decreased leak may be associated with mouth exhalation which may be more frequent during cycles of deeper sleep or dreaming. But most often, it’s simply interesting, but unactionable.

It must also be remembered, as reviewed in the preceding section, that Respironics presents “leak” as total flow – normal venting plus unintentional leak – while ResMed presents an “adjusted” leak, unintentional leak only, having already subtracted out the expected normal venting for the mask which has been selected (from among its list of ResMed masks). What each of the manufacturers nightly graphs show, therefore, is in fact somewhat different, and must be carefully interpreted.

Since Respironics Encore nightly graphs display total flow, they have a built-in “baseline” of venting. And with an AutoPAP, that baseline changes as pressure varies. This makes the interpretation of Respironics nightly graphs more complex; the interpreter must know and “mentally subtract out” the venting rate of the mask in use to view the unintentional leak. Or more often, the user simply looks at the leak line and subjectively decides (hopefully) that the variability isn’t TOO wide, suggesting that the leak is relatively stable through the night, suggesting (hopefully) that it isn’t TOO large. While as "flat" as possible a leak line is certainly desirable, it is not necessarily an essential goal. Getting a firm fix on the ABSOLUTE unintentional leak, using the Respironics nightly graph, is not a simple task. Again, more often, a user will simply decide that as long as the leak is largely under, say, 65 lpm (about 40 lpm as a working average for venting, and about 24 lpm as an “acceptable” unintentional leak), everything is probably OK. Some users consider up to 75 lpm an acceptable leak. And, probably, everything is OK. Also helpful and important is the Respironics “Large Leak” graphic indicator, a thick bar telling the user (who may have otherwise been unaware of any potential problem) that the machinery is unhappy with the extent of leak. These “Large Leak” indicators need to be taken seriously, even if we don’t know precisely what criteria are used when they are displayed. The Encore software Help File simply says, “If the chart shows leakage at the “LL” level (large leak), this is an excessive leak that will compromise therapy. This could be the result of a poor mask fitting.”

On the other hand, since Resmed ResScan nightly graphs display only net unintentional leak, the baseline leak rate could be (and ideally will be) zero. A constant, higher baseline suggests a systematic leak, likely due to a mechanical defect or an incorrectly assembled mask fixture. Not having a “Large Leak” indicator, the Resmed software places a horizontal red line at 0.40 lps (= 24 lpm), suggesting that if the leak graph exceeds that level for any significant period of time, leak may be excessive and may require remedial action.

Neither software package is consistently and markedly “better” than the other in all respects. What is important is that the user learn to understand and interpret what the software being used can and cannot, does and does not, tell you, and when, and how, to respond to the information. In any case, the software VASTLY increases the amount of information regarding leak (and other important CPAP parameters) available to the user. If you have a data-capable machine, and if the additional cost of software and associated data-transfer hardware is possible, this is a highly recommended investment.

----

=What Can (And Should) I Do About Leaking?=

OK, so you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Not every leak is a PROBLEM leak. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a "good vs. bad" dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Typically, the strap lengths on right and left should be symmetrical, to provide even pressure on each side. On the other hand, few of our faces are perfectly formed, and we often have sleeping positional preferences which might make an off-center strap configuration a better choice. Similarly, a fraction of an inch higher or lower may improve a mask’s leak characteristics significantly.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask! And remember that when an adjustable angle or length between the headpad and the body of the mask is provided, experimentation to find an ideal positioning to minimize leak may well be worth the time and effort. Again, read the instructions!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Silicone Ear Plugs (as well as other substances) to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Some CPAP users find that “special” pillows, with unique shapes or custom filling material, prevent displacement of their masks and consequent leakage. Others find that a conventional pillow “stabilizes” a mask against their face, preventing leak.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

--[[User:Velbor|Velbor]] 16:24, 10 November 2009 (UTC)

--[[User:Velbor|Velbor]] 23:53, 19 November 2009 (UTC) edited by Velbor

----

= Mouth Breathing and Mouth Leaks =

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

----
Comment added by --[[User:Velbor|Velbor]] 21:57, 22 November 2009 (UTC) :
The above statement that "if air leaks out through your mouth, the PAP therapy will not work" is far to rigid. As described in the "Introduction to Leak" segment of this article, there are different types and severities of mouth leak. The following tracing (total time 7:09) involving use of a ResMed Activa nasal mask

[[Image:Velbor_Mouth_Exhalation.jpg]]

provides an example of an acceptable pattern of oral exhalation, sometimes referred to as "lip flutter" or "lip puffing", in which the jaw remains closed but the lips open with each exhalation as if blowing a bubble. AutoPAP is set at 10 - 20cm, with median pressure 10.8, 95% pressure 11.4, and maximum pressure 11.8. Note the periodicity of the leak and the return to zero baseline between episodes. This is presumably related to the cyclic variation in sleep stage or depth affecting orofacial musculature; note the latency after each brief arising before these patterns begin. Median leak for the night is 0.00 lps!! Seal leak is negligible. While maximum leak is 0.54 lps, above the "red line", the 95% leak is 0.38 lps, which indicates that the time spent above the 0.40 lps "alert" level is LESS THAN 5% of the night. Efficacy of treatment is excellent (particularly by ResMed standards): AHI = 5.3, AI = 0.0 and HI = 5.3 . While mouth leak is never desirable, care must be taken to avoid arbitrarily labeling it as terrible.
----

Mask Leaks

2009-11-22T21:52:21Z

Velbor: minor clean-up

=Introduction to Leak=

Air is sucked into the CPAP machine from your room. It is drawn in through a filter, and is blown out at a controlled flow rate to provide the desired pressure. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

'''(1) Intentional venting'''. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. Your exhalations become part of the venting airflow. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak. Intentional venting is the only DESIRABLE way for air to return to your room.

'''(2) Seal leak'''. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

'''(3) Mouth leak'''. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is totally or partially exhaled through the mouth.

'''(4) A defect''' in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

----

=What Harm Does Leak Do?=

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

'''(1) Disruption of Sleep'''. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

'''(2) Drying of the Airway'''. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

'''(3) Pressure Loss'''. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

=How Do I Know If I'm Leaking?=

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening not remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement than is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

=What Does My Machine Tell Me About My Leak?=

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles vs. Averages''': ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. ResMed's practical goal is to encompass, in a single number on the LCD screen, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: with a ResMed machine, if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

Respironics machines, on the other hand (while reporting a very similar 90th centile leak on their software) presents on its LCD screen AVERAGE leak information (for the latest 7 and 30 days). The limitations of an "average" must be remembered: an average leak of 50 lpm may have been a leak of 40 lpm for half of each night and 60 lpm for the other half of each night - not terrible. Alternatively, that same average 50 lpm may mean a leak of 40 lpm for 3/4 of each night, and an unacceptable leak of 80 lpm for 1/4 of each night: for 2 hours out of 8, leak was excessive. Software is needed to tell which of the scenarios actually occurred.

'''Granularity''': Respironics divides time during which the machine is blowing into 30-second segments, and reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display average leak values on its LCD screen as running averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. Given normal night-to-night biological variability, there is some debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such cumulative information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

=What Does Software Tell Me About My Leak?=

While the LCD screen of a data-capable machine provides one “leak number” (the average or 95th centile, for each of several available time periods), with proprietary software a great deal of additional information about leak becomes available. While Respironics and ResMed software have some major differences, the bulk of the truly significant differences revolve around the different leak “paradigms” reviewed in the previous section. Software from either manufacturer (Encore from Respironics and ResScan from ResMed) offers the following advantages over their respective LCD displays:

'''(1) Time range selections'''. The Respironics LCD screen offers average leak information for only the past 7 days and the past 30 days, and the ResMed LCD screen offers 95th centile leak information only for the past night, the past week, month, six months and year. With either manufacturer’s software, information about any group of nights between freely-selectable start and stop dates can be reviewed. This is particularly advantageous for the Respironics user, since leak information for the past night only, which is NOT displayed on the LCD screen, is available.

'''(2) Additional statistics'''. Respironics Encore software offers (on the Sleep Therapy Long Term Trend Report), in addition to the average 90th centile leak information, the average MAXIMUM leak, the AVERAGE leak, and the average LARGE LEAK, for the selected date interval. (The time interval can be specified as a single night – the same start and stop dates – so that these statistics for a single night can be viewed.) On the single-night Daily Details report, the number of minutes, and the percent of the night spent, in LARGE LEAK, are displayed, along with AVERAGE leak. On the Therapy Data Summary, the “Average Time in Large Leak per Day” is displayed for the interval. (Each report appears to use different “rounding” rules, so the numbers are not always the same.) These parameters require some explanation. MAXIMUM leak is the highest “instantaneous” leak value encountered – it is NOT the highest 30-second time window value – so this number will not correspond with graphic displays of leak. (In fact, it must be said, this maximum leak number is quite useless.) The AVERAGE leak is clearest: it is the average of the 30-second time window leak values. LARGE LEAK is not well defined in Respironics documentation: it may be what corresponds to the trigger level for their “Mask Leak Alert” feature, or it may be a somewhat lower value. In either case, it reflects what Respironics considers to be an excessively high leak; its occurrence is displayed graphically with thick, dark “warning” lines.

ResMed ResScan software offers, in addition to the median 95th centile leak information, the MAXIMUM leak, and the MEDIAN leak, for the selected date interval. As with Respironics software, information for a single night can be viewed. Unlike the Respironics software, the maximum leak for ResMed is the maximum 60-second time window value, so it does correspond with graphically-presented information.

'''(3) Summary graphics'''. Both software packages provide graphic displays enabling an overview of the night-to-night summary leak statistics. These are set up in quite different formats, and while there may be individual preferences for one or the other, they provide by-and-large the same sorts of information. The value of these graphics is in the ability to see, visually, whether leak patterns over successive nights are increasing, decreasing, or, which is frankly most common, quite erratically variable. Still, such graphs can be useful in determining whether, over time, techniques for reducing or mitigating leak (such as those reviewed in the next section) are having the desired effect.

'''(4) Individual night graphics'''. Wisely or not, to an extent far exceeding the attention given to the offerings of CPAP monitoring software just listed, the leak graphs for individual nights are by far the major attraction for most users. And with good reason. Each 30-second or 60-second time window recording of average or median leak is displayed, for the entire night. Leak changes can be correlated with pressure changes, and (if there indeed is any correlation, which is debatable) with the occurrence of respiratory events. Brief, isolated leak event spikes can be distinguished from systematic recurrences, and generally ignored. Patterns of leak, which may be amenable to remediation, can sometimes be distinguished. Periodic “hills” of increased and decreased leak may be associated with mouth exhalation which may be more frequent during cycles of deeper sleep or dreaming. But most often, it’s simply interesting, but unactionable.

It must also be remembered, as reviewed in the preceding section, that Respironics presents “leak” as total flow – normal venting plus unintentional leak – while ResMed presents an “adjusted” leak, unintentional leak only, having already subtracted out the expected normal venting for the mask which has been selected (from among its list of ResMed masks). What each of the manufacturers nightly graphs show, therefore, is in fact somewhat different, and must be carefully interpreted.

Since Respironics Encore nightly graphs display total flow, they have a built-in “baseline” of venting. And with an AutoPAP, that baseline changes as pressure varies. This makes the interpretation of Respironics nightly graphs more complex; the interpreter must know and “mentally subtract out” the venting rate of the mask in use to view the unintentional leak. Or more often, the user simply looks at the leak line and subjectively decides (hopefully) that the variability isn’t TOO wide, suggesting that the leak is relatively stable through the night, suggesting (hopefully) that it isn’t TOO large. While as "flat" as possible a leak line is certainly desirable, it is not necessarily an essential goal. Getting a firm fix on the ABSOLUTE unintentional leak, using the Respironics nightly graph, is not a simple task. Again, more often, a user will simply decide that as long as the leak is largely under, say, 65 lpm (about 40 lpm as a working average for venting, and about 24 lpm as an “acceptable” unintentional leak), everything is probably OK. Some users consider up to 75 lpm an acceptable leak. And, probably, everything is OK. Also helpful and important is the Respironics “Large Leak” graphic indicator, a thick bar telling the user (who may have otherwise been unaware of any potential problem) that the machinery is unhappy with the extent of leak. These “Large Leak” indicators need to be taken seriously, even if we don’t know precisely what criteria are used when they are displayed. The Encore software Help File simply says, “If the chart shows leakage at the “LL” level (large leak), this is an excessive leak that will compromise therapy. This could be the result of a poor mask fitting.”

On the other hand, since Resmed ResScan nightly graphs display only net unintentional leak, the baseline leak rate could be (and ideally will be) zero. A constant, higher baseline suggests a systematic leak, likely due to a mechanical defect or an incorrectly assembled mask fixture. Not having a “Large Leak” indicator, the Resmed software places a horizontal red line at 0.40 lps (= 24 lpm), suggesting that if the leak graph exceeds that level for any significant period of time, leak may be excessive and may require remedial action.

Neither software package is consistently and markedly “better” than the other in all respects. What is important is that the user learn to understand and interpret what the software being used can and cannot, does and does not, tell you, and when, and how, to respond to the information. In any case, the software VASTLY increases the amount of information regarding leak (and other important CPAP parameters) available to the user. If you have a data-capable machine, and if the additional cost of software and associated data-transfer hardware is possible, this is a highly recommended investment.

----

=What Can (And Should) I Do About Leaking?=

OK, so you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Not every leak is a PROBLEM leak. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a "good vs. bad" dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Typically, the strap lengths on right and left should be symmetrical, to provide even pressure on each side. On the other hand, few of our faces are perfectly formed, and we often have sleeping positional preferences which might make an off-center strap configuration a better choice. Similarly, a fraction of an inch higher or lower may improve a mask’s leak characteristics significantly.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask! And remember that when an adjustable angle or length between the headpad and the body of the mask is provided, experimentation to find an ideal positioning to minimize leak may well be worth the time and effort. Again, read the instructions!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Silicone Ear Plugs (as well as other substances) to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Some CPAP users find that “special” pillows, with unique shapes or custom filling material, prevent displacement of their masks and consequent leakage. Others find that a conventional pillow “stabilizes” a mask against their face, preventing leak.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

--[[User:Velbor|Velbor]] 16:24, 10 November 2009 (UTC)

--[[User:Velbor|Velbor]] 23:53, 19 November 2009 (UTC) edited by Velbor

----

= Mouth Breathing and Mouth Leaks =

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

----
Comment added by --[[User:Velbor|Velbor]] 21:52, 22 November 2009 (UTC) :
The statement that "if air leaks out through your mouth, the PAP therapy will not work" is far to rigid. As described above in the [[Introduction to Leak]] segment above, there are different types and severities of mouth leak. The following tracing (total time 7:09) involving use of a ResMed Activa nasal mask

[[Image:Velbor_Mouth_Exhalation.jpg]]

provides an example of an acceptable pattern of oral exhalation, sometimes referred to as "lip flutter" or "lip puffing", in which the jaw remains closed but the lips open with each exhalation as if blowing a bubble. AutoPAP is set at 10 - 20cm, with median pressure 10.8, 95% pressure 11.4, and maximum pressure 11.8. Note the periodicity of the leak and the return to zero baseline between episodes. This is presumably related to the cyclic variation in sleep stage or depth affecting orofacial musculature; note the latency after each brief arising before these patterns begin. Median leak for the night is 0.00 lps!! While maximum leak is 0.54 lps, above the "red line", the 95% leak is 0.38 lps, which indicates that the time spent above the 0.40 lps "alert" level is LESS THAN 5% of the night. Efficacy of treatment is excellent (particularly by ResMed standards): AHI = 5.3, AI = 0.0 and HI = 5.3 . While mouth leak is never desirable, care must be taken to avoid arbitrarily labeling it as terrible.
----

Mask Leaks

2009-11-22T21:49:20Z

Velbor: Mouth Leakage response / comment

=Introduction to Leak=

Air is sucked into the CPAP machine from your room. It is drawn in through a filter, and is blown out at a controlled flow rate to provide the desired pressure. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

'''(1) Intentional venting'''. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. Your exhalations become part of the venting airflow. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak. Intentional venting is the only DESIRABLE way for air to return to your room.

'''(2) Seal leak'''. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

'''(3) Mouth leak'''. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is totally or partially exhaled through the mouth.

'''(4) A defect''' in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

----

=What Harm Does Leak Do?=

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

'''(1) Disruption of Sleep'''. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

'''(2) Drying of the Airway'''. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

'''(3) Pressure Loss'''. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

=How Do I Know If I'm Leaking?=

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening not remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement than is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

=What Does My Machine Tell Me About My Leak?=

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles vs. Averages''': ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. ResMed's practical goal is to encompass, in a single number on the LCD screen, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: with a ResMed machine, if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

Respironics machines, on the other hand (while reporting a very similar 90th centile leak on their software) presents on its LCD screen AVERAGE leak information (for the latest 7 and 30 days). The limitations of an "average" must be remembered: an average leak of 50 lpm may have been a leak of 40 lpm for half of each night and 60 lpm for the other half of each night - not terrible. Alternatively, that same average 50 lpm may mean a leak of 40 lpm for 3/4 of each night, and an unacceptable leak of 80 lpm for 1/4 of each night: for 2 hours out of 8, leak was excessive. Software is needed to tell which of the scenarios actually occurred.

'''Granularity''': Respironics divides time during which the machine is blowing into 30-second segments, and reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display average leak values on its LCD screen as running averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. Given normal night-to-night biological variability, there is some debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such cumulative information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

=What Does Software Tell Me About My Leak?=

While the LCD screen of a data-capable machine provides one “leak number” (the average or 95th centile, for each of several available time periods), with proprietary software a great deal of additional information about leak becomes available. While Respironics and ResMed software have some major differences, the bulk of the truly significant differences revolve around the different leak “paradigms” reviewed in the previous section. Software from either manufacturer (Encore from Respironics and ResScan from ResMed) offers the following advantages over their respective LCD displays:

'''(1) Time range selections'''. The Respironics LCD screen offers average leak information for only the past 7 days and the past 30 days, and the ResMed LCD screen offers 95th centile leak information only for the past night, the past week, month, six months and year. With either manufacturer’s software, information about any group of nights between freely-selectable start and stop dates can be reviewed. This is particularly advantageous for the Respironics user, since leak information for the past night only, which is NOT displayed on the LCD screen, is available.

'''(2) Additional statistics'''. Respironics Encore software offers (on the Sleep Therapy Long Term Trend Report), in addition to the average 90th centile leak information, the average MAXIMUM leak, the AVERAGE leak, and the average LARGE LEAK, for the selected date interval. (The time interval can be specified as a single night – the same start and stop dates – so that these statistics for a single night can be viewed.) On the single-night Daily Details report, the number of minutes, and the percent of the night spent, in LARGE LEAK, are displayed, along with AVERAGE leak. On the Therapy Data Summary, the “Average Time in Large Leak per Day” is displayed for the interval. (Each report appears to use different “rounding” rules, so the numbers are not always the same.) These parameters require some explanation. MAXIMUM leak is the highest “instantaneous” leak value encountered – it is NOT the highest 30-second time window value – so this number will not correspond with graphic displays of leak. (In fact, it must be said, this maximum leak number is quite useless.) The AVERAGE leak is clearest: it is the average of the 30-second time window leak values. LARGE LEAK is not well defined in Respironics documentation: it may be what corresponds to the trigger level for their “Mask Leak Alert” feature, or it may be a somewhat lower value. In either case, it reflects what Respironics considers to be an excessively high leak; its occurrence is displayed graphically with thick, dark “warning” lines.

ResMed ResScan software offers, in addition to the median 95th centile leak information, the MAXIMUM leak, and the MEDIAN leak, for the selected date interval. As with Respironics software, information for a single night can be viewed. Unlike the Respironics software, the maximum leak for ResMed is the maximum 60-second time window value, so it does correspond with graphically-presented information.

'''(3) Summary graphics'''. Both software packages provide graphic displays enabling an overview of the night-to-night summary leak statistics. These are set up in quite different formats, and while there may be individual preferences for one or the other, they provide by-and-large the same sorts of information. The value of these graphics is in the ability to see, visually, whether leak patterns over successive nights are increasing, decreasing, or, which is frankly most common, quite erratically variable. Still, such graphs can be useful in determining whether, over time, techniques for reducing or mitigating leak (such as those reviewed in the next section) are having the desired effect.

'''(4) Individual night graphics'''. Wisely or not, to an extent far exceeding the attention given to the offerings of CPAP monitoring software just listed, the leak graphs for individual nights are by far the major attraction for most users. And with good reason. Each 30-second or 60-second time window recording of average or median leak is displayed, for the entire night. Leak changes can be correlated with pressure changes, and (if there indeed is any correlation, which is debatable) with the occurrence of respiratory events. Brief, isolated leak event spikes can be distinguished from systematic recurrences, and generally ignored. Patterns of leak, which may be amenable to remediation, can sometimes be distinguished. Periodic “hills” of increased and decreased leak may be associated with mouth exhalation which may be more frequent during cycles of deeper sleep or dreaming. But most often, it’s simply interesting, but unactionable.

It must also be remembered, as reviewed in the preceding section, that Respironics presents “leak” as total flow – normal venting plus unintentional leak – while ResMed presents an “adjusted” leak, unintentional leak only, having already subtracted out the expected normal venting for the mask which has been selected (from among its list of ResMed masks). What each of the manufacturers nightly graphs show, therefore, is in fact somewhat different, and must be carefully interpreted.

Since Respironics Encore nightly graphs display total flow, they have a built-in “baseline” of venting. And with an AutoPAP, that baseline changes as pressure varies. This makes the interpretation of Respironics nightly graphs more complex; the interpreter must know and “mentally subtract out” the venting rate of the mask in use to view the unintentional leak. Or more often, the user simply looks at the leak line and subjectively decides (hopefully) that the variability isn’t TOO wide, suggesting that the leak is relatively stable through the night, suggesting (hopefully) that it isn’t TOO large. While as "flat" as possible a leak line is certainly desirable, it is not necessarily an essential goal. Getting a firm fix on the ABSOLUTE unintentional leak, using the Respironics nightly graph, is not a simple task. Again, more often, a user will simply decide that as long as the leak is largely under, say, 65 lpm (about 40 lpm as a working average for venting, and about 24 lpm as an “acceptable” unintentional leak), everything is probably OK. Some users consider up to 75 lpm an acceptable leak. And, probably, everything is OK. Also helpful and important is the Respironics “Large Leak” graphic indicator, a thick bar telling the user (who may have otherwise been unaware of any potential problem) that the machinery is unhappy with the extent of leak. These “Large Leak” indicators need to be taken seriously, even if we don’t know precisely what criteria are used when they are displayed. The Encore software Help File simply says, “If the chart shows leakage at the “LL” level (large leak), this is an excessive leak that will compromise therapy. This could be the result of a poor mask fitting.”

On the other hand, since Resmed ResScan nightly graphs display only net unintentional leak, the baseline leak rate could be (and ideally will be) zero. A constant, higher baseline suggests a systematic leak, likely due to a mechanical defect or an incorrectly assembled mask fixture. Not having a “Large Leak” indicator, the Resmed software places a horizontal red line at 0.40 lps (= 24 lpm), suggesting that if the leak graph exceeds that level for any significant period of time, leak may be excessive and may require remedial action.

Neither software package is consistently and markedly “better” than the other in all respects. What is important is that the user learn to understand and interpret what the software being used can and cannot, does and does not, tell you, and when, and how, to respond to the information. In any case, the software VASTLY increases the amount of information regarding leak (and other important CPAP parameters) available to the user. If you have a data-capable machine, and if the additional cost of software and associated data-transfer hardware is possible, this is a highly recommended investment.

----

=What Can (And Should) I Do About Leaking?=

OK, so you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Not every leak is a PROBLEM leak. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a "good vs. bad" dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Typically, the strap lengths on right and left should be symmetrical, to provide even pressure on each side. On the other hand, few of our faces are perfectly formed, and we often have sleeping positional preferences which might make an off-center strap configuration a better choice. Similarly, a fraction of an inch higher or lower may improve a mask’s leak characteristics significantly.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask! And remember that when an adjustable angle or length between the headpad and the body of the mask is provided, experimentation to find an ideal positioning to minimize leak may well be worth the time and effort. Again, read the instructions!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Silicone Ear Plugs (as well as other substances) to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Some CPAP users find that “special” pillows, with unique shapes or custom filling material, prevent displacement of their masks and consequent leakage. Others find that a conventional pillow “stabilizes” a mask against their face, preventing leak.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

--[[User:Velbor|Velbor]] 16:24, 10 November 2009 (UTC)

--[[User:Velbor|Velbor]] 23:53, 19 November 2009 (UTC) edited by Velbor

----

= Mouth Breathing and Mouth Leaks =

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

----
Comment added by --[[User:Velbor|Velbor]] 21:49, 22 November 2009 (UTC):
The statement that "if air leaks out through your mouth, the PAP therapy will not work" is far to rigid. As described above in the [[Introduction to Leak]] segment above, there are different types and severities of mouth leak. The following tracing (total time 7:09)

[[Image:Velbor_Mouth_Exhalation.jpg]]

provides an example of an acceptable pattern of oral exhalation, sometimes referred to as "lip flutter" or "lip puffing", in which the jaw remains closed but the lips open with each exhalation as if blowing a bubble. AutoPAP is set at 10 - 20cm, with median pressure 10.8, 95% pressure 11.4, and maximum pressure 11.8. Note the periodicity of the leak and the return to zero baseline between episodes. This is presumably related to the cyclic variation in sleep stage or depth affecting orofacial musculature; note the latency after each brief arising before these patterns begin. Median leak for the night is 0.00 lps!! While maximum leak is 0.54 lps, above the "red line", the 95% leak is 0.38 lps, which indicates that the time spent above the 0.40 lps "alert" level is LESS THAN 5% of the night. Efficacy of treatment is excellent (particularly by ResMed standards): AHI = 5.3, AI = 0.0 and HI = 5.3 . While mouth leak is never desirable, care must be taken to avoid arbitrarily labeling it as terrible.
----

File:Velbor Mouth Exhalation.jpg

2009-11-22T21:17:13Z

Velbor: Example of acceptable pattern of oral exhalation. Activa nasal mask. Leak max = 0.54 lps, 95% = 0.38 lps, median = 0.00 lps. Note periodicity, presumed related to sleep level depth. AHI = 5.3, AI = 0.0, HI = 5.3. AutoPAP 10 - 20cm.

Example of acceptable pattern of oral exhalation. Activa nasal mask. Leak max = 0.54 lps, 95% = 0.38 lps, median = 0.00 lps. Note periodicity, presumed related to sleep level depth. AHI = 5.3, AI = 0.0, HI = 5.3. AutoPAP 10 - 20cm.

Cleaning CPAP Equipment

2009-11-21T23:45:28Z

Velbor: New Article

This new topic is under construction by Velbor.

Your patience and courtesy in not tearing it apart until I have finished putting it together would be appreciated.

== Introduction ==

Few topics engender more diversity of approach than that of routine cleaning of CPAP equipment: humidifier chambers, tubing and masks. (I might dare also include the checking and periodic replacement of machine filters.)

Practices range from doing nothing (often accompanied by the claim that “…. and I’ve never been sick or had any problem”) to vigorous daily disassembly and thorough washing (often accompanied by the conclusion that therefore “…. I’ve never been sick or had any problem”).

Philosophies range from “people today would be a lot healthier if they ate more dirt” (which might or might not be so, but “back in the day” life expectancy surely was a lot shorter) to germophobic fatalism, to holistic health practices including homeopathy and nasal irrigation (reminds me of reading literature on the virtues of daily enemas).

The equipment manufacturers don’t help much. Almost all advise daily draining, washing, and rinsing of humidifier chambers and masks. (Perhaps because tubing isn’t often sold as a “branded” product, there is less emphasis on daily care in that realm.) They are usually accused of taking that position as a litigation preventive measure; that may or may not be so. They surely hardly ever present actual research to support or explain their recommendations.

Recognizing that my complete objectivity and rationality is not infrequently called into question (even, or perhaps especially, by those who know me best), let’s take a stab at thinking through the issues. In that way, whatever decision we reach, we can pretend that it’s based on careful and deliberate thought, rather than on our own laziness or on our obsessive-compulsive inclinations.

== General Principles ==

● Microbes tend to grow in warm, moist, dark places.

● Our world, including the air we breathe, is full of microbes.

● The danger posed by commonly encountered microbes is directly proportional to the number of them that get inside us, and inversely proportional to our overall state of health. (This is true also of microbes normally found in our own bodies. Change the number or ratio of our internal microbial flora, or experience a general decline in health, and our own microbes can literally “eat us alive”.)

Based on these principles, let’s consider the equipment in our CPAP set-ups, in order from the most distant components to those closest to our bodies.

== ● Air Filters ==

ResMed suggests, “Inspect the air filter every month to check if it is blocked by dirt or contains holes. With normal use of an S8 AutoSet II, the air filter needs to be replaced every six months (or more often if your device is in a dusty environment).”

Respironics states, “Under normal usage, you should clean the gray foam filter at least once every two weeks and replace it with a new one every six months. The white ultra-fine filter is disposable and should be replaced after 30 nights of use or sooner if it appears dirty. DO NOT clean the ultra-fine filter.”

Why does Respironics suggest so much more frequent checking and changing of filters? My guess is that their filtering system is much more efficient than the open fiber filters – reminiscent of inexpensive filters used in my home HVAC system – employed by ResMed. Fine particulates appear much more likely to be blocked and kept out of the air stream – and thus much more likely to foul and block the filters – in the Respironics systems. Still, it does not necessarily follow that the presumed higher efficiency of the Respironics filtration is either necessary or helpful – do we need to breathe air that is cleaner than our room air?

Respironics nicely summarizes why filter cleaning is important:

----
'''Caution''': Operating the device with a dirty filter may keep the system from working
properly and may damage the device. …

'''Caution''': Dirty inlet filters may cause high operating temperatures that may affect
device performance. Regularly examine the inlet filters as needed for integrity
and cleanliness.
----

Ah, a reference to “cleanliness.” Still, just a bit …. vague. Comfortable, culturally correct, but …. vague.

== ● CPAP Machine ==

No one recommends that we clean the CPAP machine (at least not beyond the careful application of a moist cloth to the exterior to remove grease, grime and dust). Isn’t that an oddly fortunate coincidence, since there’s no safe way in which we’re ABLE to clean the belly of the beast. Besides, though it may be dark inside and warm when it’s running, it’s dry, and nothing goes through it except filtered room air.

Well, that may not be quite exactly true. There are two ways in which moisture might get inside. The most serious is if there’s backflow into the machine from the humidifier. This, apparently, is most likely to happen if the set-up is moved with the machine attached to a humidifier containing water. BIG OOPS. Not only is there danger of microbial growth wherever the water manages to ooze, but there is also danger of electrical component malfunction, corrosion, or even potential short-circuit and fire. The manufacturers are unanimous:

ResMed: “Water must be prevented from entering your flow generator. Do not transport the flow generator with the H4i attached.” …. “This Limited Warranty does not cover: …. d) any damage caused by water being spilled on or into a flow generator.”

Respironics: “If the device and humidifier fall and water gets into the device, drain all water out of the device and make sure it is completely dry before reapplying power. … If the device falls or water gets into the device upon falling, let the device dry completely and then restart it. If it does not operate correctly after falling, contact Respironics or an authorized service center.”

But there is a second, more subtle, more insidious, and perhaps more common way for moisture to enter the CPAP machine and cause any or all of the nasties described above. That is by diffusion. The physics is very simple and straightforward. Just as “nature abhors a vacuum,” nature abhors any difference in concentration of any substance.

You are using your CPAP with a heated humidifier. The CPAP blows air in one direction: away from the machine, over the water surface in the humidifier chamber, and towards you. You sleep well, with not a care in the world. In the morning, you wake up, turn everything off, and go about your business. And diffusion goes about its business.

Water has a high “specific heat” – higher than almost any other common substance. That means that it takes more heat to raise the temperature of water, than it does to raise the temperature of an equal mass of any other substance an equal amount. That also means that warm water stays warmer, longer than just about anything else. And THAT means that the moisture level – the absolute humidity – the concentration of water – in the air above the water in the humidifier chamber, will be greater than that in the air anywhere else in the room. That water vapor will want to get – everywhere, anywhere else.

If you have left tubing connected to your humidifier chamber under these conditions, that humid air will begin to diffuse. In both directions: since no air is flowing, it will equally seek to go into your main tubing, AND into your CPAP machine. In either direction, that warm, moist air will find cooler surfaces. And on cooler surfaces, water will precipitate out of the air. (Yes, right, just like rainout!) The amounts may be minute. Or not. Diffusion occurs on a molecular level, and the warm water vapor can find its way through the most minute cracks and crevices. Even into areas of the machine where airflow rarely occurs – so that there may not be the “normal” opportunity for drying during normal machine use. Dangers of machine damage due to this water vapor diffusion are arguably small, Dangers of providing a habitat for microbial growth may also be arguably small.

But to my mind: why argue? It’s simple enough, with most machine designs, to disconnect the direct connection between the humidifier and anything else. With a stand-alone humidifier, disconnect the tubes. With a ResMed Humidaire humidifier, lift the top cover to unseat the gasket and let the humid air pass harmlessly into the room. With Respironics humidifiers – I have never used an integrated Respironics humidifier, so I don’t know how best to take action.

This is a simple, proactive way to prevent even the small possibility of physical damage, and, more to the point of this article, to prevent even the small possibility of microbial growth. I can’t think of any good reason NOT to perform this simple action.

Aha! ResMed has already thought of this, though paradoxically they give what for all the world looks like a bogus reason for their very innovative response. In their manual for the HumidAire series of humidifiers (though generally NOT in the manuals for their CPAP machines themselves) they write:

“Note: In order to assist the heater plate in cooling, some flow generators continue to
blow air gently for up to an hour after treatment has stopped. However, you can unplug the device from the power outlet at any time and allow the heater plate to cool without airflow. ”

In fact, with water still present in the chamber, this slight blowing will have virtually no effect on the humidifier heater plate temperature. Their comment that this function can be easily aborted strongly suggests that there is no need to cool the heater plate. (The best way to cool the heater plate is to remove the reservoir chamber!) Nor is this function useful, as some have suggested, in drying the hose. It is still warm, moist air being blown INTO the hose.

What this “gently blowing DOES accomplish is to keep warm moist air flowing AWAY from the machine, preventing diffusion of water vapor INTO the machine. Well done (though poorly explained), ResMed! But even better is to simply disconnect or remove the humidifier chamber from its connection to the blower.

== ● Machine–to–Humidifier Hose ==

This component exists principally in systems which utilize a “stand-alone” rather than an integrated humidifier (though even with an integrated system, “something” connects the machine to the humidifier). Such a hose, if it exists, should be inspected periodically for physical integrity and leaks (run you hand along and around it while the machine is running to check for any airflow), and inspected visually for anything inside that should not be inside. I would propose that the need for any active cleaning should be rare.

== ● Humidifier Chamber ==

Now the disputation begins in earnest. The “never empty or clean unless there’s an obvious reason to do so” advocates make some excellent points:
----
● even if the occasional microbe gets into the chamber, if you are using distilled water (as you probably should be), there’s nothing for them to feed and grow on.

● even if there is microbial growth in the water, there little likelihood that they can enter the airstream, and

● even if microbes did enter the airstream, there is little evidence that they could successfully navigate and survive the trip down the main tubing in sufficient number to cause illness.
----

On the other side of the table, activists may well claim:
----
● distilled water is not necessarily sterile water, and even if it were, it can no longer be considered sterile once the bottle has been opened

● even with filtration, air flowing through the system is neither microbe-free nor particulate free, and particulates (which may provide microbial nourishment) certainly have an opportunity to enter the humidifier during the filling process, and (depending on whether and how portals are covered) during the day.

● while it is true that humidifiers work by producing molecular water which “dissolves” in the overlying air, rather than water “particles” which can “carry” microbes “piggyback” down the tubing, there are other potential transport processes. Observation of the surface of CPAP humidifiers during respiration generally show “rippling” as airflow increases on inspiration. This non-laminar flow “rippling” is effectively wave generation with typical associated “spray” production – i.e., water particulates capable of carrying microbes. Convection within in the heated water will regularly carry microbes, if present within the water, to the surface, waiting for their “ride”.

● in addition to the presence of surface-effect “spray” water particulates as just described, “clumps” of microbes, even without water droplets as a transport vehicle, can be “lifted up” directly by the non-laminar airflow, either from the water surface, or from the humidifier chamber walls as the water level falls through the night.
----

There is little good, hard, convincing published science upon which to base a firm preference for either of these two positions. A published study of radioisotopes placed in humidifier water was found to detect radiation as have traversed the tubing, but only at very high pressure (and correspondingly high flow-rate, due to increased venting flow at higher pressures) conditions.

In a brief departure from focusing on microbes, a mention of mineral precipitation is in order. In all but distilled water, there will be dissolved mineral ions. As molecular water is lost overnight through evaporation (whether in a heated or even in a passive pass-over system), the mineral concentration will increase. (It should be noted that periodically adding additional fresh water through the night will help to minimize precipitation.) There may come a point when the minerals reach their saturation point, and begin to precipitate out of solution, potentially resulting in a build-up on the chamber walls and, more likely, on the heating plate. There are two principal down-sides to the deposition of mineral precipitates. First, they tend to form cavernous networks, which provide attractive housing for microbes. (So I lied; we are still talking about microbes.) Second, precipitation on the heater plate tends to decrease the efficiency of heat transfer. (That it may look unattractive is a personal problem; deal with it.) The general recommendation for such precipitation is rinsing in a dilute vinegar solution, with the acidic environment hopefully dissolving the minerals and allowing them to be rinsed away. (In addition it is claimed that the vinegar has mild antiseptic properties, helping to kill, yes, again, microbes.) It should also be noted that many insurance plans cover twice-yearly humidifier chamber replacement.

Thus, the range of options for humidifier chamber care and maintenance, from least interventionist to most conservative, runs something like:

● doing nothing; simply adding water each night
● draining out the leftover water and allowing to dry, each morning, or periodically
● draining, rinsing and allowing to dry, each morning, or periodically
● all the above, plus use of soap and/or vinegar, followed by thorough rinsing

A final comment on drying. If you are “drying out” the humidifier at all, the faster the drying process, the less likely that any microbes will find residual moisture and “settle in.” (The bathroom, by the way, may be the most convenient place for drying, but it is the least desirable, in view of typically higher moisture levels, typically higher levels of airborne particulates, and – yes – typically higher level of airborne microbes.) Drying can be accelerated by vigorous shaking, not only to remove excess water, but also to break up remaining water into smaller droplets. (Smaller droplets have a larger surface-area to volume ratio, and will therefore evaporate more rapidly.) Inserting a clean, thin washcloth into the chamber prior to the shaking process will facilitate the removal of excess water. And blowing air through the chamber with a CPAP machine will greatly enhance the evaporation of any remaining water.

Where you choose to place yourself on this spectrum is largely a matter of choice, involving such factors as your overall health, your overall “tidiness”, and your overall risk tolerance preferences. It’s hard to imagine even the most “non-interventionist” CPAP user ignoring a humidifier chamber which begins to look cruddy or colorful. If a decision regarding action is based on what you see (or more precisely, on what you NOTICE), then we in fact are already operating on an analog basis – how much – rather than on a yes/no digital basis. Even in our digital age, much of life remains analog.

== ● Main Tubing: Humidifier to Mask ==

People often talk about cleaning their tubing, but few seem to do anything about it. I suspect that’s because the process is so cumbersome. And perhaps also because, arguably, it’s relatively unnecessary.

In the absence of rainout (precipitation of water from warm, moist air against the cooler walls of the tubing), the tubing interior typically remains dry. Mask venting and continuous airflow from the machine (and, for some masks, extension tubing) typically prevent any significant amounts of exhaled air from retrograde entry into the tubing. Under these “ideal” conditions, there’s nothing needing to be cleaned.

Unfortunately, conditions are sometimes less than ideal. (Descriptions on the CPAPTalk discussion forums of insects entering the tubing will be left for those interested to find on their own.)

It is a good practice to INSPECT your tubing on a regular basis. When turning the machine on at night, run your hand along the length of the tubing, feeling for leaks. In the morning, visually check the entire length of tubing. Look for evidence of water droplets or mist suggesting rainout; look for any dark or discolored areas or objects. Tubing which is transparent is obviously highly preferable to tubing which is more or less opaque in this regard. Tubing which is covered (to prevent or diminish rainout) should periodically be “undressed” so that it can be inspected.

If there has been ANY rainout, you now have a condition in your tubing which will arguably support microbial growth. (See the discussion about humidifier chambers, and the variety of opinions about whether microbes can in fact get into, and live in, the tubing. I will simply suggest here that the longer you go without inspecting, drying or cleaning your tubing, the greater the possibility of microbial growth, survival, and migration down your tubing toward you face, becomes.)

If there has been rainout, it should be PROMPTLY and RAPIDLY dried. The hose should be first shaken, from the center toward each end, to remove as much water as possible. If you have sufficient room, twirling the hose, from the center toward each end, will also expel excess water. The most convenient technique for rapid drying is to run air from your CPAP blower through the tubing until all visual evidence of water is gone. (Some machines may automatically shut off when no resistance to flow is encountered. On some of these, it may be possible to disable and turn off that feature. It may also be possible to put a flow-limiting connector on the end of the tubing, but this will increase drying time, since maximal flow will product the most rapid evaporation.) Sucking air through the tubing (rather than blowing as with a CPAP machine) may be attempted; devising a connector to the suction of a household vacuum cleaner has been suggested. Another attractive suggestion (presented on the CPAPTalk forum) is that of connecting a weight to one end of a six-foot-plus length of fishing line, and connecting a dry cloth to the other end of the fishing line. Drop the weight into one end of the tubing, let it pull the line through the tubing, and then the fishing line can be used to pull the dry cloth through the tubing. Special care may need to be taken with heated tubing, or with tubing having custom connectors on one or both ends.

All else failing, tubing can simply be left hung to dry, but passive diffusion of air through a narrow six-foot tubing is not an ideal methodology. Under such circumstances, it has been wisely recommended that one have a spare second tube to use while the first one is drying overnight.

Actually “cleaning” the tubing may occasionally be desirable. Simply rinsing the interior by holding one end against a spigot, and allowing the other end to drain into the bathtub, may be sufficient. If it is desired to use soap (or some other safe cleaning material), the use of a male-to-male adaptor makes the task much easier. (A male-to-male adaptor is typically a small plastic connector, both of whose ends will fit inside the rubber cuffs at the ends of the tubing, and which may be used to connect two hoses together. Some masks come with parts which may be usable for this purpose – e.g. the swivel assembly on a Mirage Activa. An adapter suitable for such use is sold by CPAP dot com at:
https://www.cpap.com/productpage/hose-coupling-swivel-adapter-cpap.html .)
After partially filling the hose with water, and adding a suitable amount of soap, use the adapter to connect the two ends so that the tubing forms a continuous loop. The cleaning solution can now be easily “swished” through the tubing, and allowed to stay inside for as long as is desired. After cleaning, rinse thoroughly and dry rapidly, as already described.

== ● Mask ==

subtopic under construction

== ● Headgear Straps ==

subtopic under construction

== Concluding Comments ==

subtopic under construction

----

This new topic is under construction by Velbor.

Your patience and courtesy in not tearing it apart until I have finished putting it together would be appreciated.

--[[User:Velbor|Velbor]] 23:45, 21 November 2009 (UTC)

Mask Leaks

2009-11-19T23:53:00Z

Velbor: Corrections, clarifications, clean-ups

=Introduction to Leak=

Air is sucked into the CPAP machine from your room. It is drawn in through a filter, and is blown out at a controlled flow rate to provide the desired pressure. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

'''(1) Intentional venting'''. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. Your exhalations become part of the venting airflow. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak. Intentional venting is the only DESIRABLE way for air to return to your room.

'''(2) Seal leak'''. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

'''(3) Mouth leak'''. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is totally or partially exhaled through the mouth.

'''(4) A defect''' in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

----

=What Harm Does Leak Do?=

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

'''(1) Disruption of Sleep'''. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

'''(2) Drying of the Airway'''. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

'''(3) Pressure Loss'''. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

=How Do I Know If I'm Leaking?=

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening not remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement than is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

=What Does My Machine Tell Me About My Leak?=

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles vs. Averages''': ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. ResMed's practical goal is to encompass, in a single number on the LCD screen, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: with a ResMed machine, if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

Respironics machines, on the other hand (while reporting a very similar 90th centile leak on their software) presents on its LCD screen AVERAGE leak information (for the latest 7 and 30 days). The limitations of an "average" must be remembered: an average leak of 50 lpm may have been a leak of 40 lpm for half of each night and 60 lpm for the other half of each night - not terrible. Alternatively, that same average 50 lpm may mean a leak of 40 lpm for 3/4 of each night, and an unacceptable leak of 80 lpm for 1/4 of each night: for 2 hours out of 8, leak was excessive. Software is needed to tell which of the scenarios actually occurred.

'''Granularity''': Respironics divides time during which the machine is blowing into 30-second segments, and reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display average leak values on its LCD screen as running averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. Given normal night-to-night biological variability, there is some debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such cumulative information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

=What Does Software Tell Me About My Leak?=

While the LCD screen of a data-capable machine provides one “leak number” (the average or 95th centile, for each of several available time periods), with proprietary software a great deal of additional information about leak becomes available. While Respironics and ResMed software have some major differences, the bulk of the truly significant differences revolve around the different leak “paradigms” reviewed in the previous section. Software from either manufacturer (Encore from Respironics and ResScan from ResMed) offers the following advantages over their respective LCD displays:

'''(1) Time range selections'''. The Respironics LCD screen offers average leak information for only the past 7 days and the past 30 days, and the ResMed LCD screen offers 95th centile leak information only for the past night, the past week, month, six months and year. With either manufacturer’s software, information about any group of nights between freely-selectable start and stop dates can be reviewed. This is particularly advantageous for the Respironics user, since leak information for the past night only, which is NOT displayed on the LCD screen, is available.

'''(2) Additional statistics'''. Respironics Encore software offers (on the Sleep Therapy Long Term Trend Report), in addition to the average 90th centile leak information, the average MAXIMUM leak, the AVERAGE leak, and the average LARGE LEAK, for the selected date interval. (The time interval can be specified as a single night – the same start and stop dates – so that these statistics for a single night can be viewed.) On the single-night Daily Details report, the number of minutes, and the percent of the night spent, in LARGE LEAK, are displayed, along with AVERAGE leak. On the Therapy Data Summary, the “Average Time in Large Leak per Day” is displayed for the interval. (Each report appears to use different “rounding” rules, so the numbers are not always the same.) These parameters require some explanation. MAXIMUM leak is the highest “instantaneous” leak value encountered – it is NOT the highest 30-second time window value – so this number will not correspond with graphic displays of leak. (In fact, it must be said, this maximum leak number is quite useless.) The AVERAGE leak is clearest: it is the average of the 30-second time window leak values. LARGE LEAK is not well defined in Respironics documentation: it may be what corresponds to the trigger level for their “Mask Leak Alert” feature, or it may be a somewhat lower value. In either case, it reflects what Respironics considers to be an excessively high leak; its occurrence is displayed graphically with thick, dark “warning” lines.

ResMed ResScan software offers, in addition to the median 95th centile leak information, the MAXIMUM leak, and the MEDIAN leak, for the selected date interval. As with Respironics software, information for a single night can be viewed. Unlike the Respironics software, the maximum leak for ResMed is the maximum 60-second time window value, so it does correspond with graphically-presented information.

'''(3) Summary graphics'''. Both software packages provide graphic displays enabling an overview of the night-to-night summary leak statistics. These are set up in quite different formats, and while there may be individual preferences for one or the other, they provide by-and-large the same sorts of information. The value of these graphics is in the ability to see, visually, whether leak patterns over successive nights are increasing, decreasing, or, which is frankly most common, quite erratically variable. Still, such graphs can be useful in determining whether, over time, techniques for reducing or mitigating leak (such as those reviewed in the next section) are having the desired effect.

'''(4) Individual night graphics'''. Wisely or not, to an extent far exceeding the attention given to the offerings of CPAP monitoring software just listed, the leak graphs for individual nights are by far the major attraction for most users. And with good reason. Each 30-second or 60-second time window recording of average or median leak is displayed, for the entire night. Leak changes can be correlated with pressure changes, and (if there indeed is any correlation, which is debatable) with the occurrence of respiratory events. Brief, isolated leak event spikes can be distinguished from systematic recurrences, and generally ignored. Patterns of leak, which may be amenable to remediation, can sometimes be distinguished. Periodic “hills” of increased and decreased leak may be associated with mouth exhalation which may be more frequent during cycles of deeper sleep or dreaming. But most often, it’s simply interesting, but unactionable.

It must also be remembered, as reviewed in the preceding section, that Respironics presents “leak” as total flow – normal venting plus unintentional leak – while ResMed presents an “adjusted” leak, unintentional leak only, having already subtracted out the expected normal venting for the mask which has been selected (from among its list of ResMed masks). What each of the manufacturers nightly graphs show, therefore, is in fact somewhat different, and must be carefully interpreted.

Since Respironics Encore nightly graphs display total flow, they have a built-in “baseline” of venting. And with an AutoPAP, that baseline changes as pressure varies. This makes the interpretation of Respironics nightly graphs more complex; the interpreter must know and “mentally subtract out” the venting rate of the mask in use to view the unintentional leak. Or more often, the user simply looks at the leak line and subjectively decides (hopefully) that the variability isn’t TOO wide, suggesting that the leak is relatively stable through the night, suggesting (hopefully) that it isn’t TOO large. While as "flat" as possible a leak line is certainly desirable, it is not necessarily an essential goal. Getting a firm fix on the ABSOLUTE unintentional leak, using the Respironics nightly graph, is not a simple task. Again, more often, a user will simply decide that as long as the leak is largely under, say, 65 lpm (about 40 lpm as a working average for venting, and about 24 lpm as an “acceptable” unintentional leak), everything is probably OK. Some users consider up to 75 lpm an acceptable leak. And, probably, everything is OK. Also helpful and important is the Respironics “Large Leak” graphic indicator, a thick bar telling the user (who may have otherwise been unaware of any potential problem) that the machinery is unhappy with the extent of leak. These “Large Leak” indicators need to be taken seriously, even if we don’t know precisely what criteria are used when they are displayed. The Encore software Help File simply says, “If the chart shows leakage at the “LL” level (large leak), this is an excessive leak that will compromise therapy. This could be the result of a poor mask fitting.”

On the other hand, since Resmed ResScan nightly graphs display only net unintentional leak, the baseline leak rate could be (and ideally will be) zero. A constant, higher baseline suggests a systematic leak, likely due to a mechanical defect or an incorrectly assembled mask fixture. Not having a “Large Leak” indicator, the Resmed software places a horizontal red line at 0.40 lps (= 24 lpm), suggesting that if the leak graph exceeds that level for any significant period of time, leak may be excessive and may require remedial action.

Neither software package is consistently and markedly “better” than the other in all respects. What is important is that the user learn to understand and interpret what the software being used can and cannot, does and does not, tell you, and when, and how, to respond to the information. In any case, the software VASTLY increases the amount of information regarding leak (and other important CPAP parameters) available to the user. If you have a data-capable machine, and if the additional cost of software and associated data-transfer hardware is possible, this is a highly recommended investment.

----

=What Can (And Should) I Do About Leaking?=

OK, so you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Not every leak is a PROBLEM leak. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a "good vs. bad" dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Typically, the strap lengths on right and left should be symmetrical, to provide even pressure on each side. On the other hand, few of our faces are perfectly formed, and we often have sleeping positional preferences which might make an off-center strap configuration a better choice. Similarly, a fraction of an inch higher or lower may improve a mask’s leak characteristics significantly.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask! And remember that when an adjustable angle or length between the headpad and the body of the mask is provided, experimentation to find an ideal positioning to minimize leak may well be worth the time and effort. Again, read the instructions!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Silicone Ear Plugs (as well as other substances) to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Some CPAP users find that “special” pillows, with unique shapes or custom filling material, prevent displacement of their masks and consequent leakage. Others find that a conventional pillow “stabilizes” a mask against their face, preventing leak.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

--[[User:Velbor|Velbor]] 16:24, 10 November 2009 (UTC)

--[[User:Velbor|Velbor]] 23:53, 19 November 2009 (UTC) edited by Velbor

----

= Mouth Breathing and Mouth Leaks =

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

Talk:Mask Leaks

2009-11-11T23:36:59Z

Velbor:

Katherine: it appears that you changed an instance of my use of "95th centile" to "95th percentile." While statisticians may debate which is the most technically correct terminology, I have tried (though perhaps not fully successfully) to consistently utilize the terminology used by the manufacturers in their documentation. While Respironics avoids using either term, from ResMed literature:

• pressure (95th centile value for mask-on time only)
• leak (95th centile value for mask-on time only)

Unless you have specific reason otherwise, I'd appreciate your restoration of my original wording. Thanks. Velbor

Talk:Mask Leaks

2009-11-11T23:33:45Z

Velbor: Centile vs Percentile

Katherine: it appears that you changed an instance of my use of "95th centile" to "95th percentile." While statisticians may debate which is the most technically correct terminology, I have tried to consistently utilize the terminology used by the manufacturers in their documentation. While Respironics avoids using eithr term, from ResMed literature:

• pressure (95th centile value for mask-on time only)
• leak (95th centile value for mask-on time only)

Unless you have specific reason otherwise, I'd appreciate your restoration of my original wording. Thanks. Velbor

Mask Leaks

2009-11-11T01:02:41Z

Velbor: Revision of Katherine's topic-titling formatting

=Introduction to Leak=

Air enters the CPAP machine from your room. It is drawn in through a filter, and is blown out in a controlled manner. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

'''(1) A defect''' in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

'''(2) Intentional venting'''. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak.

'''(3) Seal leak'''. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

'''(4) Mouth leak'''. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is partially or totally exhaled through the mouth.

----

=What Harm Does Leak Do?=

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

'''(1) Disruption of Sleep'''. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

'''(2) Drying of the Airway'''. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

'''(3) Pressure Loss'''. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

=How Do I Know If I'm Leaking?=

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement that is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

=What Does My Machine Tell Me About My Leak?=

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles''': Respironics machines generally display leak as the 90th centile value, while ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 90% or 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way: Respironics divides time during which the machine is blowing into 30-second segments, computes the average leak during each 30-seconds, ranks them from lowest to highest, and reports the highest value encountered for 90% of the night. Similarly, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. The practical goal is to encompass, in a single number, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

'''Granularity''': Respironics reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display centile leak values on its LCD screen as averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. There is vigorous debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

=What Does Software Tell Me About My Leak?=

While the LCD screen of a data-capable machine provides one “leak number” (the 90th or 95th centile, for each of several available time periods), with proprietary software a great deal of additional information about leak becomes available. While Respironics and ResMed software have some major differences, the bulk of the truly significant differences revolve around the different leak “paradigms” reviewed in the previous section. Software from either manufacturer (Encore from Respironics and ResScan from ResMed) offers the following advantages over their respective LCD displays:

'''(1) Time range selections'''. The Respironics LCD screen offers 90th centile leak information for only the past 7 days and the past 30 days, and the ResMed LCD screen offers 95th centile leak information only for the past night, the past week, month, six months and year. With either manufacturer’s software, information about any group of nights between freely-selectable start and stop dates can be reviewed. This is particularly advantageous for the Respironics user, since leak information for the past night only, which is NOT displayed on the LCD screen, is available.

'''(2) Additional statistics'''

Respronics Encore software offers (on the Sleep Therapy Long Term Trend Report), in addition to the average 90th centile leak information, the average MAXIMUM leak, the AVERAGE leak, and the average LARGE LEAK, for the selected date interval. (The time interval can be specified as a single night – the same start and stop dates – so that these statistics for a single night can be viewed.) On the single-night Daily Details report, the number of minutes, and the percent of the night spent, in LARGE LEAK, are displayed, along with AVERAGE leak. On the Therapy Data Summary, the “Average Time in Large Leak per Day” is displayed for the interval. (Each report appears to use different “rounding” rules, so the numbers are not always the same.) These parameters require some explanation. MAXIMUM leak is the highest “instantaneous” leak value encountered – it is NOT the highest 30-second time window value – so this number will not correspond with graphic displays of leak. (In fact, it must be said, this maximum leak number is quite useless.) The AVERAGE leak is clearest: it is the average of the 30-second time window leak values. LARGE LEAK is not well defined in Respironics documentation: it may be what corresponds to the trigger level for their “Mask Leak Alert” feature, or it may be a somewhat lower value. In either case, it reflects what Respironics considers to be an excessively high leak; its occurrence is displayed graphically with thick, dark “warning” lines.

ResMed ResScan software offers, in addition to the median 95th centile leak information, the MAXIMUM leak, and the MEDIAN leak, for the selected date interval. As with Respironics software, information for a single night can be viewed. Unlike the Respironics software, the maximum leak for ResMed is the maximum 60-second time window value, so it does correspond with graphically-presented information.

'''(3) Summary graphics'''. Both software packages provide graphic displays enabling an overview of the night-to-night summary leak statistics. These are set up in quite different formats, and while there may be individual preferences for one or the other, they provide by-and-large the same sorts of information. The value of these graphics is in the ability to see, visually, whether leak patterns over successive nights are increasing, decreasing, or, which is frankly most common, quite erratically variable. Still, such graphs can be useful in determining whether, over time, techniques for reducing or mitigating leak (such as those reviewed in the next section) are having the desired effect.

'''(4) Individual night graphics'''. Wisely or not, to an extent far exceeding the attention given to the offerings of CPAP monitoring software just listed, the leak graphs for individual nights are by far the major attraction for most users. And with good reason. Each 30-second or 60-second time window recording of average or median leak is displayed, for the entire night. Leak changes can be correlated with pressure changes, and (if there indeed is any correlation, which is debatable) with the occurrence of respiratory events. Brief, isolated leak event spikes can be distinguished from systematic recurrences, and generally ignored. Patterns of leak, which may be amenable to remediation, can sometimes be distinguished. Periodic “hills” of increased and decreased leak may be associated with mouth exhalation which may be more frequent during cycles of deeper sleep or dreaming. But most often, it’s simply interesting, but unactionable.

It must also be remembered, as reviewed in the preceding section, that Respironics presents “leak” as total flow – normal venting plus unintentional leak – while ResMed presents an “adjusted” leak, unintentional leak only, having already subtracted out the expected normal venting for the mask which has been selected (from among its list of ResMed masks). What each of the manufacturers nightly graphs show, therefore, is in fact somewhat different, and must be carefully interpreted.

Since Respironics Encore nightly graphs display total flow, they have a built-in “baseline” of venting. And with an AutoPAP, that baseline changes as pressure varies. This makes the interpretation of Respironics nightly graphs more complex; the interpreter must know and “mentally subtract out” the venting rate of the mask in use to view the unintentional leak. Or more often, the user simply looks at the leak line and subjectively decides (hopefully) that the variability isn’t TOO wide, suggesting that the leak is relatively stable through the night, suggesting (hopefully) that it isn’t TOO large. Getting a firm fix on the ABSOLUTE unintentional leak, using the Respironics nightly graph, is not a simple task. Again, more often, a user will simply decide that as long as the leak is largely under, say, 65 lpm (about 40 lpm as a working average for venting, and about 24 lpm as an “acceptable” unintentional leak), everything is probably OK. And, probably, everything is OK. Also helpful and important is the Respironics “Large Leak” graphic indicator, a thick bar telling the user (who may have otherwise been unaware of any potential problem) that the machinery is unhappy with the extent of leak. These “Large Leak” indicators need to be taken seriously, even if we don’t know precisely what criteria are used when they are displayed. The Encore software Help File simply says, “If the chart shows leakage at the “LL” level (large leak), this is an excessive leak that will compromise therapy. This could be the result of a poor mask fitting.”

On the other hand, since Resmed ResScan nightly graphs display only net unintentional leak, the baseline leak rate could be (and ideally will be) zero. A constant, higher baseline suggests a systematic leak, likely due to a mechanical defect or an incorrectly assembled mask fixture. Not having a “Large Leak” indicator, the Resmed software places a horizontal red line at 0.40 lps (= 24 lpm), suggesting that if the leak graph exceeds that level for any significant period of time, leak may be excessive and may require remedial action.

Neither software package is consistently and markedly “better” than the other in all respects. What is important is that the user learn to understand and interpret what the software being used can and cannot, does and does not, tell you, and when, and how, to respond to the information. In any case, the software VASTLY increases the amount of information regarding leak (and other important CPAP parameters) available to the user. If you have a data-capable machine, and if the additional cost of software and associated data-transfer hardware is possible, this is a highly recommended investment.

----

=What Can (And Should) I Do About Leaking?=

OK, so you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Not every leak is a PROBLEM leak. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a good vs. bad dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Typically, the strap lengths on right and left should be symmetrical, to provide even pressure on each side. On the other hand, few of our faces are perfectly formed, and we often have sleeping positional preferences which might make an off-center strap configuration a better choice. Similarly, a fraction of an inch higher or lower may improve a mask’s leak characteristics significantly.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask! And remember that when an adjustable angle or length between the headpad and the body of the mask is provided, experimentation to find an ideal positioning to minimize leak may well be worth the time and effort. Again, read the instructions!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Ear Plugs to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Some CPAP users find that “special” pillows, with unique shapes or custom filling material, prevent displacement of their masks and consequent leakage. Others find that a conventional pillow “stabilizes” a mask against their face, preventing leak.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

--[[User:Velbor|Velbor]] 16:24, 10 November 2009 (UTC)

----

= Mouth Breathing and Mouth Leaks =

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

Mask Leaks

2009-11-10T16:24:29Z

Velbor: Added discussion of leak software. Planned article is now largely complete.

'''Introduction to Leak'''

Air enters the CPAP machine from your room. It is drawn in through a filter, and is blown out in a controlled manner. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

(1) A defect in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

(2) Intentional venting. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak.

(3) Seal leak. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

(4) Mouth leak. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is partially or totally exhaled through the mouth.

----

'''What Harm Does Leak Do?'''

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

(1) Disruption of Sleep. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

(2) Drying of the Airway. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

(3) Pressure Loss. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

'''How Do I Know If I'm Leaking?'''

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement that is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

'''What Does My Machine Tell Me About My Leak?'''

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles''': Respironics machines generally display leak as the 90th centile value, while ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 90% or 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way: Respironics divides time during which the machine is blowing into 30-second segments, computes the average leak during each 30-seconds, ranks them from lowest to highest, and reports the highest value encountered for 90% of the night. Similarly, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. The practical goal is to encompass, in a single number, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

'''Granularity''': Respironics reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display centile leak values on its LCD screen as averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. There is vigorous debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

'''What Does Software Tell Me About My Leak?'''

While the LCD screen of a data-capable machine provides one “leak number” (the 90th or 95th centile, for each of several available time periods), with proprietary software a great deal of additional information about leak becomes available. While Respironics and ResMed software have some major differences, the bulk of the truly significant differences revolve around the different leak “paradigms” reviewed in the previous section. Software from either manufacturer (Encore from Respironics and ResScan from ResMed) offers the following advantages over their respective LCD displays:

'''(1) Time range selections'''. The Respironics LCD screen offers 90th centile leak information for only the past 7 days and the past 30 days, and the ResMed LCD screen offers 95th centile leak information only for the past night, the past week, month, six months and year. With either manufacturer’s software, information about any group of nights between freely-selectable start and stop dates can be reviewed. This is particularly advantageous for the Respironics user, since leak information for the past night only, which is NOT displayed on the LCD screen, is available.

'''(2) Additional statistics'''.

Respronics Encore software offers (on the Sleep Therapy Long Term Trend Report), in addition to the average 90th centile leak information, the average MAXIMUM leak, the AVERAGE leak, and the average LARGE LEAK, for the selected date interval. (The time interval can be specified as a single night – the same start and stop dates – so that these statistics for a single night can be viewed.) On the single-night Daily Details report, the number of minutes, and the percent of the night spent, in LARGE LEAK, are displayed, along with AVERAGE leak. On the Therapy Data Summary, the “Average Time in Large Leak per Day” is displayed for the interval. (Each report appears to use different “rounding” rules, so the numbers are not always the same.) These parameters require some explanation. MAXIMUM leak is the highest “instantaneous” leak value encountered – it is NOT the highest 30-second time window value – so this number will not correspond with graphic displays of leak. (In fact, it must be said, this maximum leak number is quite useless.) The AVERAGE leak is clearest: it is the average of the 30-second time window leak values. LARGE LEAK is not well defined in Respironics documentation: it may be what corresponds to the trigger level for their “Mask Leak Alert” feature, or it may be a somewhat lower value. In either case, it reflects what Respironics considers to be an excessively high leak; its occurrence is displayed graphically with thick, dark “warning” lines.

ResMed ResScan software offers, in addition to the median 95th centile leak information, the MAXIMUM leak, and the MEDIAN leak, for the selected date interval. As with Respironics software, information for a single night can be viewed. Unlike the Respironics software, the maximum leak for ResMed is the maximum 60-second time window value, so it does correspond with graphically-presented information.

'''(3) Summary graphics'''. Both software packages provide graphic displays enabling an overview of the night-to-night summary leak statistics. These are set up in quite different formats, and while there may be individual preferences for one or the other, they provide by-and-large the same sorts of information. The value of these graphics is in the ability to see, visually, whether leak patterns over successive nights are increasing, decreasing, or, which is frankly most common, quite erratically variable. Still, such graphs can be useful in determining whether, over time, techniques for reducing or mitigating leak (such as those reviewed in the next section) are having the desired effect.

'''(4) Individual night graphics'''. Wisely or not, to an extent far exceeding the attention given to the offerings of CPAP monitoring software just listed, the leak graphs for individual nights are by far the major attraction for most users. And with good reason. Each 30-second or 60-second time window recording of average or median leak is displayed, for the entire night. Leak changes can be correlated with pressure changes, and (if there indeed is any correlation, which is debatable) with the occurrence of respiratory events. Brief, isolated leak event spikes can be distinguished from systematic recurrences, and generally ignored. Patterns of leak, which may be amenable to remediation, can sometimes be distinguished. Periodic “hills” of increased and decreased leak may be associated with mouth exhalation which may be more frequent during cycles of deeper sleep or dreaming. But most often, it’s simply interesting, but unactionable.

It must also be remembered, as reviewed in the preceding section, that Respironics presents “leak” as total flow – normal venting plus unintentional leak – while ResMed presents an “adjusted” leak, unintentional leak only, having already subtracted out the expected normal venting for the mask which has been selected (from among its list of ResMed masks). What each of the manufacturers nightly graphs show, therefore, is in fact somewhat different, and must be carefully interpreted.

Since Respironics Encore nightly graphs display total flow, they have a built-in “baseline” of venting. And with an AutoPAP, that baseline changes as pressure varies. This makes the interpretation of Respironics nightly graphs more complex; the interpreter must know and “mentally subtract out” the venting rate of the mask in use to view the unintentional leak. Or more often, the user simply looks at the leak line and subjectively decides (hopefully) that the variability isn’t TOO wide, suggesting that the leak is relatively stable through the night, suggesting (hopefully) that it isn’t TOO large. Getting a firm fix on the ABSOLUTE unintentional leak, using the Respironics nightly graph, is not a simple task. Again, more often, a user will simply decide that as long as the leak is largely under, say, 65 lpm (about 40 lpm as a working average for venting, and about 24 lpm as an “acceptable” unintentional leak), everything is probably OK. And, probably, everything is OK. Also helpful and important is the Respironics “Large Leak” graphic indicator, a thick bar telling the user (who may have otherwise been unaware of any potential problem) that the machinery is unhappy with the extent of leak. These “Large Leak” indicators need to be taken seriously, even if we don’t know precisely what criteria are used when they are displayed. The Encore software Help File simply says, “If the chart shows leakage at the “LL” level (large leak), this is an excessive leak that will compromise therapy. This could be the result of a poor mask fitting.”

On the other hand, since Resmed ResScan nightly graphs display only net unintentional leak, the baseline leak rate could be (and ideally will be) zero. A constant, higher baseline suggests a systematic leak, likely due to a mechanical defect or an incorrectly assembled mask fixture. Not having a “Large Leak” indicator, the Resmed software places a horizontal red line at 0.40 lps (= 24 lpm), suggesting that if the leak graph exceeds that level for any significant period of time, leak may be excessive and may require remedial action.

Neither software package is consistently and markedly “better” than the other in all respects. What is important is that the user learn to understand and interpret what the software being used can and cannot, does and does not, tell you, and when, and how, to respond to the information. In any case, the software VASTLY increases the amount of information regarding leak (and other important CPAP parameters) available to the user. If you have a data-capable machine, and if the additional cost of software and associated data-transfer hardware is possible, this is a highly recommended investment.

----

'''What Can (And Should) I Do About Leaking?'''

OK, so you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Not every leak is a PROBLEM leak. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a good vs. bad dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Typically, the strap lengths on right and left should be symmetrical, to provide even pressure on each side. On the other hand, few of our faces are perfectly formed, and we often have sleeping positional preferences which might make an off-center strap configuration a better choice. Similarly, a fraction of an inch higher or lower may improve a mask’s leak characteristics significantly.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask! And remember that when an adjustable angle or length between the headpad and the body of the mask is provided, experimentation to find an ideal positioning to minimize leak may well be worth the time and effort. Again, read the instructions!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Ear Plugs to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Some CPAP users find that “special” pillows, with unique shapes or custom filling material, prevent displacement of their masks and consequent leakage. Others find that a conventional pillow “stabilizes” a mask against their face, preventing leak.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

--[[User:Velbor|Velbor]] 16:24, 10 November 2009 (UTC)

----

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

Mask Leaks

2009-11-10T01:04:16Z

Velbor: Multiple small clean-ups

'''Introduction to Leak'''

Air enters the CPAP machine from your room. It is drawn in through a filter, and is blown out in a controlled manner. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

(1) A defect in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

(2) Intentional venting. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak.

(3) Seal leak. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night, or as pressure increases (as with an AutoPAP). This is the first type of "unintentional leak," which should ideally be minimized.

(4) Mouth leak. This is the second type of "unintentional leak," which also should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is partially or totally exhaled through the mouth.

----

'''What Harm Does Leak Do?'''

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomena; the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

(1) Disruption of Sleep. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

(2) Drying of the Airway. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow blowing WITHIN the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

(3) Pressure Loss. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is always everywhere the same. If a "small" leak develops in the system, the pressure drops, though it still remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in a loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

'''How Do I Know If I'm Leaking?'''

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement that is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

'''What Does My Machine Tell Me About My Leak?'''

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles''': Respironics machines generally display leak as the 90th centile value, while ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 90% or 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way: Respironics divides time during which the machine is blowing into 30-second segments, computes the average leak during each 30-seconds, ranks them from lowest to highest, and reports the highest value encountered for 90% of the night. Similarly, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. The practical goal is to encompass, in a single number, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how severe the leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance. (And, regretably, this discussion is a bit of an oversimplification.)

'''Granularity''': Respironics reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display centile leak values on its LCD screen as averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. There is vigorous debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

'''What Does Software Tell Me About My Leak?'''

(in progress)

----

'''What Can (And Should) I Do About Leaking?'''

So, you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a good vs. bad dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Different masks may require different strap-tightening techniques. Some masks (e.g. ResMed's Activa) need to be set up very loosely - "ballooning" under air pressure provides the seal. Other masks simply have to be strapped fairly firmly. Read the instructions which come with each mask!

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor in mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe on the facial skin areas where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Ear Plugs to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Reports of effectiveness of chin straps are mixed. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip-taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

----

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

Mask Leaks

2009-11-09T16:25:47Z

Velbor: Action suggestions for leaking

'''Introduction to Leak'''

Air enters the CPAP machine from your room. It is drawn in through a filter, and is blown out in a controlled manner. Air blown out of the CPAP machine eventually leaves the machine - tubing - interface - person system and returns to your room. There are four possible routes by which air is returned to the room:

(1) A defect in the equipment, or equipment defectively assembled. This is always bad, and should be guarded against by frequent inspection, and periodic listening and feeling for extraneous airflow.

(2) Intentional venting. Virtually all commercial CPAP interface systems are designed so that air ALWAYS blows through them. This enables the moisture-laden, oxygen depleted, and carbon dioxide-rich air which you exhale into the interface to be continually "washed out" so that it is not re-inhaled. This venting is part of the interface design, with greater volumes of air being vented at higher pressures. Most manufacturers provide information as to how much leak will occur at various pressure levels. While often referred to as "leak," this normal, intentional venting should not be confused with "unintentional" leak.

(3) Seal leak. Virtually every interface device involves some sort of contact, a "seal," between a plastic "cushion" or "pillow" and the user's skin. Air can easily leak out through these seal contact points, particularly as the user moves around during the course of the night. This is the first type of "unintentional leak" which should ideally be minimized.

(4) Mouth leak - the second type of "unintentional lead" which should ideally be minimized. Since the mouth and the nose are connected in the pharynx, unless a "Full Face Mask" (or other special interfaces which cover both the mouth and the nose) is used, air which enters the nose may leak out of the mouth. This can occur in several different ways (or in combinations) which may more-or-less affect the effectiveness of CPAP, and which may require different strategies for dealing with the leak:

(a) with "mouth breathing," in which unpressurized room air is inhaled - and exhaled - through the mouth,

(b) with "open mouth flow," in which air pressurized air entering through the nose more-or-less continually escapes through an open mouth, or

(c) with "mouth exhalation," in which pressurized CPAP air which is inhaled through the nose is partially or totally exhaled through the mouth.

----

'''What Harm Does Leak Do?'''

There are three mechanisms by which unintentional leak can detract from CPAP therapy. One or more of these mechanisms may be present. None are "all or nothing" phenomenon - the nature, extent and freqeuncy of leak will determine the negative effect - if any - of the leak. It may accurately be stated that, "Leak is a problem only if leak is a problem."

(1) Disruption of Sleep. Leak involves the blowing of air where air "should not" be blowing. This is usually related to seal leak, but may also be applicable to mouth leak. If air is blowing across the face or into the eyes, this is likely to arouse or awaken you from sleep. Blowing air also creates sound, ranging from rushing torrents to "musical" tones when the edges of the plastic cushion vibrate. These sounds too can arouse or awaken you, interfering with sleep.

(2) Drying of the Airway. Mouth leak has the special disadvantage of the leak taking place AFTER the pressurized air is already within the body. While all leak involves additional airflow, mouth leak produces additional airflow within the nose and mouth. This often results in drying of the membranes. If the nasal membranes become dried and irritated, increased resistance to breathing may ensue, with resultant congestion. Drying of the mouth may be uncomfortable, and add to sleep disruption.

(3) Pressure Loss. This problem is sometimes overemphasized and often misunderstood. To understand it properly, a bit of physics needs to be reviewed. In a small, passive, closed, pressurized system (think of a car tire, perhaps), the pressure is everywhere the same. If a "small" leak develops in the system, the pressure drops, though it remains the same everywhere in the system, regardless of the site of the leak. CPAP is a "small" system, and for all practical purposes the pressure everywhere - in the tubing, in the mask, in your airway - is always instantaneously the same, regardless of where the leak originates. But CPAP is not a "passive" system. The technology works by increasing or decreasing air flow in order to maintain the target pressure the machine is trying to deliver. This is important: CPAP "uses" airflow but CPAP "works" by maintaining airway pressure. Leak is the loss of airflow, but leak does not necessarily result in any loss of pressure. Modern CPAP machines are robust, and can compensate for significant loss of airflow from leaks by increasing their output airflow. In this way they maintain their desired pressure, even in the presence of substantial leak, and regardless of the location of that leak. (Thus a "mouth leak" is not necessarily any more relevant in terms of pressure than is a "seal leak.") However, if the leak is too large, it may overwhelm the machine's ability to compensate and maintain pressure. This is arguably the most severe and important consequence of leak, though its frequency may be exaggerated. It takes a LOT of leak to result in failure of the machine's ability to maintain pressure and/or the ability of the machine's sensors to accurately detect pressure and flow information. When this happens, however, the effectiveness of CPAP therapy can be markedly compromised.

Respironics documentation summarizes the above information nicely: "System leak is a combination of intentional and unintentional air leak. Intentional leak is the expected leak at the exhalation port. Some leak is required to minimize CO2 rebreathing. Unintentional leak occurs around the patient interface. If there is a large increase in the amount of leak .... the patient may need a mask refitting. Leaks that should be fixed include leaks into the eyes, leaks that bother the patient, or leaks that affect pressure stability."

----

'''How Do I Know If I'm Leaking?'''

Unfortunately, we're not always aware of whether or not, or of how significantly, we may be experiencing unintentional leakage. The blowing of air, or the sound created by blowing air, doesn't always awaken us. We may not be aware of, or on awakening remember being aware of, a dry mouth caused by mouth leak (particularly if the leak is intermittent).

Fortunately, chances are that if leak is not frequent enough or large enough to cause symptoms, it's probably not significant enough to be of concern. Still, the possibility of an unrecognized large leak, which might interfere with effective therapy, cannot be discounted entirely.

Many CPAP machines provide an audible "Leak Alert" alarm function. If given a choice, and unless there is a particular reason NOT to use it, this option should generally be turned "on."

Many ResMed (S7, S8) machines offer a "Leak Alert" which can be enabled or disabled. "When enabled, leaks > 0.7 L/s for > 20s result in an audible alert and a high leak message in the LCD. Note: when Leak Alert is enabled, SmartStart/Stop is automatically disabled." We will talk more, in a subsequent section, about what these numbers mean. For the present, we might simply note that 0.7 liters per second (equal to 42 liters per minute) is a sizeable airflow. Given that a typical adult breath moves about 500 cc of air (Tidal Volume), and that we might perhaps be taking 10 breaths per minute, the amount of air moved by normal breathing is about 5 liters per minute, or 0.08 liters per second. Thus, the machinery quite reasonably becomes concerned when leakage accounts for over eight times more air movement that is produced by our breathing. Particularly for AutoPAP machines, ResMed notes that "When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally."

Again, simply to keep this number in context (pending more detailed discussion below), ResMed notes that "Generally, a leak rate of more than 0.4 L/s (24 L/min) is associated with patient discomfort, disturbed sleep, and reduced efficacy of treatment."

Many Respironics machines (M-Series) also provide a "Mask Leak Alert" feature: "Mask Leak Alert – This flashing text displays on the Active Display screen if the Mask Alert setting is enabled and the device detects an excessive mask leak. .... If this feature is enabled, then the [ ] symbol flashes on the Active display screen if a significant mask leak is detected, and an audible alert sounds." Unfortunately, available Respironics documentation does not define their criteria for "excessive" or "significant" leak.

----

'''What Does My Machine Tell Me About My Leak?'''

More information than simply a “high leak alarm” may be available to those with “data-capable” CPAP machines (which have been configured to display such information). Such machines typically reduce to a single number, and display this number on the machine’s LCD panel, a measure of the severity and frequency of leak over a period of machine use. Discussion is complicated by the employment of different reporting paradigms by the major CPAP machine manufacturers.

'''Units''': Respironics machines generally display leak in liters per minute (lpm or L/m), while ResMed machines generally display leak in liters per second (lps or L/s). This is not a major conceptual problem; the numbers simply differ by a factor of 60.

'''Centiles''': Respironics machines generally display leak as the 90th centile value, while ResMed machines generally display leak as the 95th centile value. These, technically, are the HIGHEST leak values which the machine encountered during the BEST 90% or 95% of the night, “best” meaning the portion of the night with the LOWEST leaks. Put another way: Respironics divides time during which the machine is blowing into 30-second segments, computes the average leak during each 30-seconds, ranks them from lowest to highest, and reports the highest value encountered for 90% of the night. Similarly, ResMed divides the time during which the machine is blowing into 60-second segments, computes the median leak during each 60-seconds, ranks them from lowest to highest, and reports the highest value encountered for 95% of the night.

Admittedly, not very clear. The practical goal is to encompass, in a single number, the seemingly impossible task of reflecting some sense of what leak has been like for an entire night. Is the mean or median leak helpful (software generally does display these)? These measures of “central tendency” don’t reflect how leak might have been, for how long. Is the maximum leak helpful (software generally does display this)? A high maximum may have lasted for only a brief period, with low leak during most of the night. What the centile value attempts to reflect (albeit imperfectly) is HOW GOOD or HOW BAD leak was for HOW LONG.

So: if, for example, for the past seven days, your centile leak was 0.10 l/s (or 6 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Not at all shabby. And if, for the past seven nights, your centile leak was 0.40 l/s (or 24 l/m), you know that, overall, for 90% or 95% of therapy time, your leak was NO HIGHER than these levels. Well, according at least to ResMed, that’s beginning to enter into questionable territory for some significant portions of the nights. Higher values are plausibly warning signs. An imperfect system, to be sure, but not as totally irrational and unusable as might appear at first glance.

'''Granularity''': Respironics reports its 30-second average leak data to a precision of 7 lpm (or about 0.12 lps). ResMed reports its 60-second median leak data to a precision of 0.02 lps (or about 1.2 lpm). These differences in level of detail are reflected in the leak number displayed on the LCD panels.

'''Duration''': Respironics machines display centile leak values on its LCD screen as averages for the past 7 days or the past 30 days. ResMed machines display centile leak values on its LCD screen as medians for these same time periods (as well as for six months and one year), but also for the SINGLE most recent night. There is vigorous debate as to whether information for a single night is useful (though if one tracks and records the data for each night, it is hard to deny the value of such information), or whether only when looking at data compiled over multiple nights can valid information be evaluated.

'''Gross vs. Net''': Arguably the most significant difference between the two major manufacturers has been left intentionally for last. Respironics displays as “leak” what is best conceptualized as the TOTAL AIRFLOW leaving the machine. (Remember from the introduction that all air leaving the machine eventually returns to the room, either through the interface ports as intentional “venting,” or as unintentional “leak.”) ResMed, on the other hand, asks the user to identify to the machine WHAT MASK is being used, and the processor SUBTRACTS the expected venting (at the appropriate pressure), displaying as “leak” only the UNINTENTIONAL leak. (Naturally, only ResMed masks are included, so users of non-ResMed interfaces need to select the ResMed mask which is closest in pressure/flow characteristics to the mask they are using.) This distinction makes a great difference in the interpretation of leak numbers presented by the LCD panels of the two machines.

'''The bottom line''': of this long discussion (which will carry over into the topic to follow) is that data-capable machines do make available quantified information about leak. However, how best to utilize that information, and even whether that information is valuable, interpretable and actionable, is subject to much debate. In general, any information is better than no information, but that is true only if the information is capable of being understood and evaluated in a knowledgeable and valid manner.

----

'''What Does Software Tell Me About My Leak?'''

(in progress)

----

'''What Can (And Should) I Do About Leaking?'''

So, you have leak. Well, we all have leak. The most important thing is to keep it in perspective. Don’t allow yourself to be bullied by the pundits who proclaim, “The first thing you need to do is to get your leak under control.” This is often the first comment of those with nothing better to say, and not enough sense to keep quiet. They usually have no objective or consistent standards on which to base their rants. Still, it is possible that they are right!

ResMed provides a good perspective for thinking about leak. Some of their machines offer a “Mask Fitting Feature” (which is a good place to start if you happen to have such a machine). They clearly indicate that leak is not simply a good vs. bad dichotomy, but a spectrum. Some degree of leak is quite acceptable:

Star Rating Description leak l/s leak l/m

* * * * * Excellent 0.00 - 0.18 0.0 - 10.8
* * * * _ Very good 0.19 - 0.26 10.9 - 15.9
* * * _ _ Good 0.27 - 0.34 15.7 - 20.4
* * _ _ _ Adjust mask 0.35 - 0.41 20.5 - 24.6
* _ _ _ _ Adjust mask 0.42 - 0.49 24.7 - 29.9
_ _ _ _ _ Adjust mask ≥ 0.50 ≥ 30

Practical suggestions:

The place to start is with selection of a mask. There are several different types (nasal mask, nasal pillows, full-face mask, etc.) and lots of different brands. There are few up-front criteria for making a first decision. You’ll likely be pushed one way or the other by your prescriber or distributor. Not much opportunity or basis for taking control at this point. But what you can and should insist upon is a professional FITTING. Whatever the type and brand of mask, the supplier should assure that you are getting the CORRECT SIZE mask, and that the straps are properly adjusted. Ideally, the mask should be tested with the machine running, to assure a proper fit.

Adjustment of mask straps is not a one-time event. What works well while you’re sitting up is not necessarily what will work well when you’re lying down and moving around. Strap adjustment is always a compromise between minimizing leak and maximizing comfort. Additionally, over time, with use and with washing, the length and elasticity of straps change. Set-it-and-forget-it may work for a while, but periodic readjustment of the straps will likely be necessary.

Sometimes, the straps supplied with a mask may simply not be adequate. Additional supportive material (ranging from elastic bandages to panty-hose) to hold the mask in place, have been recommended and found effective.

Masks can be very durable, but they aren’t designed to last forever. Periodically check your cushions for tears, or changes in texture and flexibility which can cause increased leaking. Replace them when necessary.

Similarly, check other equipment – particularly the condition of the rubber cuffs on the ends of tubing. And when you reassemble a mask after cleaning, check that all parts fit smoothly and without leak. Some masks have been reported to have “design flaws” which result in excessive leak, which can be easily corrected with such items as Teflon plumbing tape.

Facial oils can be a factor is mask seal leak. Washing the face with soap prior to applying the mask, and/or using an alcohol wipe around the nose where the mask will be in contact, may prove helpful. Similarly, oils should be gently cleaned off the cushion in the morning after use. (Note that most mask manufacturers do NOT recommend using alcohol directly on mask parts.)

Facial hair can be a challenge in obtaining a good mask seal with minimal leak. Some masks have been reported to present less leak problems than others, with mustaches and beards. Shaving before bed may also help to obtain a better seal.

Various substances have been recommended as “gaskets” to help achieve a better seal. Procedures can be found for using Macks Ear Plugs to build a more air-tight facial seal around cushions. For users of nasal pillows, a variety of commercial products have been suggested for reducing leak as well as enhancing comfort.

Methods of dealing with mouth leak are widely debated. Many commercial “chin straps” or home-made devices will reportedly help hold the jaw in place so that the mouth does not fall open. Many varieties of tape, and different taping techniques, have been recommended to hold the lips closed. That lip-taping will reduce or eliminate mouth leak is clear. The absolute safety of this practice is less clear, though the theoretical dangers involved tend to be greatly overstated. There are also indications that for some individuals, lip taping may paradoxically worsen the efficacy of CPAP therapy. “Training” for the tongue to reduce leak has been suggested, though there is precious little good published science available in this area.

Additional details about the suggestions mentioned above for dealing with leak will be easily found by suitable searches of the forum archives at cpaptalk dot com.

In conclusion, remember that leak is not a problem unless it is a problem. Otherwise, it’s just another four-letter word.

----

'''Mouth breathing''' and '''mouth leaks''' are closely related, but not necessarily the same thing.

Mouth breathing must occur when the nasal passages are blocked, so the only way for any air to get into the lungs is through the mouth. People with blocked noses breathe through their mouth, not through their nose. The solution to mouth breathing is to use a full face mask. Some effort and time may be required to find the best full face mask, fit it, and adjust to it. Use of nasal irrigation and humidified CPAP, especially with nasal pillows, may open nasal passages that were previously chronically blocked. The person can then learn to breathe through the nose.

Mouth leaks may occur if the person is breathing through their nose, but opens their mouth during sleep. If leakage through the mouth is a persistent problem, CPAP treatment can be rendered completely ineffective. CPAP air detouring out the mouth does nothing to keep the airway open. Either mouth breathing or mouth leakage can also cause feelings of suffocation from apneas still happening and/or just the choking feeling of air rushing out the mouth unexpectedly. The safest solution to mouth leakage is to use a full face mask.

http://www.cpaptalk.com/viewtopic/t23863/Why-dont-more-people-use-a-full-face-mask.html

Other remedies including using a homemade or commercial chinstrap in hopes that the tongue will maintain an airtight seal inside the mouth if the jaw is kept up. Many people find that chinstraps don’t work to prevent mouth leakage.

Another remedy is to use the tongue to maintain an airtight seal inside the mouth. Some people train the tongue by positioning the tip of the tongue behind the upper front teeth or on the roof of the mouth, and let the tongue spread out in back to seal the throat air passage, even if the lips open. Others use a dental splint, custom made by a dentist, or a do-it-yourself mouth guard to help the tongue maintain an airtight seal.

“The safety of taping the mouth shut has not been proven and there are potential risks of regurgitation and aspiration of food and of suffocation.” TS Johnson MD et al, Sleep Apnea – The Phantom of the Night, p. 167. Mouth taping is especially dangerous for anyone who ever gets blocked nasal passages during the night. If air can’t get in through the nose, it needs to get in through the mouth. Mouth taping is also risky in case of a hose disconnect or power outage.

= Warning against mouth leakage =
Whether you use a nasal mask or nasal pillows (or any other kind of mask except a full face), if air leaks out through your mouth, the PAP therapy will not work. There are two safe options. The first is to learn to keep your mouth closed while sleeping. Since the feel of pressurized air exiting your mouth is an unpleasant sensation, PAP aids in this. Some people position the tongue behind the top teeth and let it spread out in back to cover the throat opening and make a seal so the PAP works. The second option is to use a full face mask. If you are a mouth breather, breathing in through your mouth instead of your nose, a full face mask is required. An alternative practice for mouth leaks, mouth taping or sealing, is understandable but not advisable, and is not safe if your nose gets stuffy at night, you have acid reflux, need to regurgitate; or you have a hose disconnect or lose machine power and need to breathe through your mouth.

See also [[Mask Leaks Blow onto Partner]]

Mask Leaks

2009-11-09T03:09:27Z

Velbor: Leak information in LCD screens

Mask Leaks

2009-11-09T00:53:41Z

Velbor:

Mask Leaks

2009-11-08T21:05:48Z

Velbor: Discussion of awareness of leak, and machine "leak alert" alarm systems

Mask Leaks

2009-11-07T14:00:05Z

Velbor:

Mask Leaks

2009-11-07T01:55:45Z

Velbor:

Mask Leaks

2009-11-07T01:53:54Z

Velbor: A general introduction to the concept of leak has been added. Further edits are anticipated.