A few different questions, comments

[RMinOntario]

I was using a ResMed Escape unit for a trial in June for 2-3 weeks. I tried about 4 different masks in this time and my face was always soaking when I got up to pee or in the morning. I had the Humidaire set at 1.5 or 2 which is fairly low. Is this rainout? From reading the forum, I 'thought' rainout happened in the hose. Now that I have my own Elite II and Humidaire unit, I have the Humidaire set to 3 and my face stays dry, which is much more comfortable.

I was originally set to a pressure of 8 & got head-aches. The RT asked the doc about it so for whatever reason he moved my pressure to 15. I didn't really feel good at this pressure. I had a 7 day trial on F&P APAP, and had leak rates 90th percentile of 88l/min, excessive leak 15% of time, pressure 90th percentile 14.7cm. Wouldn't that high a pressure be because of the high leak rate? After that I had my appt with the doc after a 3 month wait after my sleep study, and he said to go back to CPAP, start at 11, then increase as needed to 15 max.

Are leaks measured only from the mask (I have a nasal mask) or does it take into account mouth breathing?

I printed out my results from the ResScan software for the last 3 nights (I've only had it 3 nights).

How do you know what is an acceptable leak rate? I see people mention that at X pressure the leak rate should be so & so. Now with my own unit, pressure set to 12cm
night 1 leaks 90th perc is 8.4 max is 25.2 AI 1.5 HI 10.0 AHI 11.5 % time in apnea 0.5 (whatever that means)
night 2 leaks 90th perc is 9.6 max is 19.2 AI 1.9 HI 11.0 AHI 12.9 % time in apnea 0.6
night 3 leaks 90th perc is 7.2 max is 19.2 AI 3.7 HI 6.9 AHI 10.6 % time in apnea 1.3

I asked the RT what was a good leak rate to aim for after seeing my APAP study and she said anything below 60. Isn't that high? Seeing what people here on the forum mention, that seems high for a pressure of 12.

Is this amount of time (3 nights) with the results I mentioned enough time to adjust the machine up to 13? If so, I was given permission to do it (up to a max of 15 but I don't know how they'd know). And then, is that info somewhere as to how I would increase the pressure on the forum?

Also, the internal clock is set 2 hours off of the correct time. Is this something I have to live with or is it adjustable?

Do people with software actually print out 4 - 5 pages of the report on a daily basis to keep, or do you just check it out on the computer?

I know these are a lot of questions, but any answers would help. I have received a lot of help already and I thank everyone.
Rosemary

[Hawthorne]

I'll try to answer some of your questions but I don't know much about Resmeds!

It appears you are having some rainout problems. I live in Ontario as well and I almost always use my humidifier in pass over mode (water in the chamber - no heat). This is especially true for me in the warmer weather but I use pass over most of the year. Even in the winter, I use a setting of 1 or 1 1/2 on my humidifier once in a while. Any higher and I get congested. I use a Repironics machine.

Leak rate is determined by your mask and your pressure. In your mask manual there is a graph/chart that tells you what the acceptable leak rate is atyour pressure setting (or your 90 (95)% if you are using a machine set at an auto range. The Resmed measures the leak rate differently and you have to do some math. I'm no good at math, especially Resmed math!

Leak rates on the machine are measuring all leaks. If your leak rate is very high, compared to the graph/chart in your mask manual, and you are using a nasal mask you could be mouth breathing. As I said, I'm not good at Resmed math but your leak rates look very high and you are probably mouth breathing.

I know that Resmeds register more Hypopneas (HI) that other machines. Your AHI is made up of mostly Hypopneas, which is to be expected on a Resmed. Your Apneas (AI) seem to be quite good (quite well controlled by your machine).

It usually takes about a week for the body to adjust to changes in the machine settings but if things were really bad, changes could be made sooner than that. Your data is quite good (except for the leak rate), although it was up on the third night and may be a trend that would indicate a needed change. That is too soon to tell with 3 nights of data. Given that your leak rate is as high as I think it is, your data is not reliable.

I don't know how to change the pressure on a Resmed but some of the Resmed people will be along to tell you how to do that.

I live with any time discrepency on my machine.

I don't print out my data every day. I check it every day and save it in my "Documents" in PDF form using PrimoPDF (a free program). Not being that "computer literate", I don't know if that would work with Resmed reports.

Don't know if I hit all your questions or not but the "Resmed" people will be along to set me straight on the strictly Resmed questions.

[RMinOntario]

Thanks Hawthorne, I am saving the pdf reports as I understand that only 4 or 5 days of detail data stays on the card, and after that it's summary data. Right now being all excited about the software & info, I have been printing out everything.

[twokatmew]

Hi Rosemary, I have the same machine as you and have been using the software for a couple weeks. First, Resmed machines report leaks based on mask type. Since you're using a Resmed mask, your machine should be set accordingly, and the machine's LCD will only show the leak rate beyond what's expected for your mask & pressure.

If you're using the software, however, you don't have to do any math, because the software reports the total leak rate. By comparing this number to the leak rate for your mask & pressure, you can see immediately how you're doing from the software. Here's the link to ResMed's table of leak rates: http://www.resmed.com/us/assets/html/pr ... c=patients

I'm using three different masks based on the condition of my nares and sinuses, and since I have the software, I just leave the mask type set to "Standard," on the machine.

Your leak rates don't look too bad to me. I've had several nights that were much worse, though the average night is pretty close to yours, and my pressure is only 9cm! I'm working on fixing leaks right now. I don't print anything out. I just look at my results on the computer each day. When I get things stabilized, I'll probably check less frequently. I expect I'll print reports to take to my sleep doc when I see him toward the end of August.

I think your RT is pulling numbers out of the sky to say an acceptable leak rate in anything up to 60l/min!

The clinician's manuals for ResMed machines are on the ResScan software CD, though I can't remember the exact location. I have the manual for the Elite II saved to my hard disk, so PM me if you want me to email it to you. Also, to change pressure (and other settings), press the down arrow and right arrow buttons for about three seconds. This will take you to the clinician menu.

Have fun....

[RMinOntario]

Does that mean flow rate & leak rate are related or mean the same thing? I don't seem to get info labeled flow rate in the charts.

[twokatmew]

Flow rate = expected leak rate. Anything above this number is a leak from the mouth or a poorly adjusted/fitted mask. And, of course, if you read the fine print, all rates are approximate.

[RMinOntario]

Just to be clear. ... In English (not CPAP talk) leak rates sound to me that the lower the # the better. And flow rate means to me how much air should flow through the mask. Why would you want a leak rate = to inflow, or am I not following right? So does that mean my leak rates for the last 3 nights of 7.2 - 9.6 are too low? According to the chart the flow rate s/b 34 at 12 cm pressure.

[cflame1]

Resmed math:

In rescan... the leaks are measured in Liters/second.

Most leak rate charts are done in Liters/minute

So take your 7.2 to 9.6 and multiply it by 60... that will give you what you need to compare it against.

[RMinOntario]

The ResScan charts are reporting the leak rates of 7.2 - 9.6 as l/min.

[twokatmew]

Just to be clear. ... In English (not CPAP talk) leak rates sound to me that the lower the # the better. And flow rate means to me how much air should flow through the mask. Why would you want a leak rate = to inflow, or am I not following right? So does that mean my leak rates for the last 3 nights of 7.2 - 9.6 are too low? According to the chart the flow rate s/b 34 at 12 cm pressure.

In general, yes, the lower your leak rate, the better. However, as I understand it, masks are designed with a certain amount of expected leak (flow rate) to flush out the C02 that's exhaled into the mask (and out the vent). There are a couple other threads I've seen where leak rates were lower than expected, and another where changing to a new, otherwise identical mask resulted in higher leak rates. Why? I don't know. Perhaps the more experienced forum members can answer this question. There are variations between different masks and sometimes otherwise identical masks. I only worry about leaks that are too high. Since I haven't died on the few nights my leak rates were very low, I figure it's sufficient to flush out the CO2.

Anyway, hope this helps.

[Velbor]

Hi. Let's try starting over.

CPAP machines blow air. They know the amount of air they blow, which they figure in terms of liters per minute or liters per second. Generally, they don't tell us "flow rate", or at least not as such.

They can blow all they want to into a room; if no resistance is encountered, the pressure this flow produces is zero.

Or you can put your palm over the outlet. Then, there will be zero flow. But the machine's efforts result in a build-up of pressure. That pressure will go as high as the CPAP's set pressure.

In between these extremes, the machine can blow into a mask on your face. For now, hold your breath, please. The mask has holes in it - a "venting" system. Air will always flow through the vents. This keeps air always flowing through the tubing and through your mask. This is necessary so that when you do begin to breathe (not yet, keep holding your breath a bit longer), your exhaled air can be flushed out of the mask, and fresh air can fill the mask for your next breath. The vents provide enough resistance that there is pressure against the machine's attempt to blow. The CPAP blows with just enough flow to maintain the pressure which is set for the machine. Due to the physics of the situation, the higher the pressure, the greater the airflow through the vent. This relationship between pressure and flow is known to the manufacturer for each mask design, and each mask should come with a pressure / flow chart. At a given pressure your machine is trying to maintain, there will be a known, essentially constant, venting flow for any particular mask. Sometimes this is called the mask's "venting leak" or "intentional leak".

You should still be holding your breath. Your mask may fit well, or perhaps not so well. As you move around, a gap may open between the mask and your skin. This is "seal leak", where air leaks out around the seal between the mask and your skin. Ideally it should not occur, but when it does (up to a point) the machine will increase the airflow, enabling it to hold the pressure at the CPAP level it is set for.

Finally, now, breathe! As you inhale, the pressure in the mask "drops" a bit, and the machine increases its flow to maintain the set pressure. As you exhale, the pressure in the mask "increases" a bit, and the machine lowers its flow to maintain the set pressure. The machine alters its flow with each breath, in and out, to hold the pressure in the mask, and the pressure inside your mouth and nose and windpipe, constant. The amount you breathe in equals the amount you breathe out. The air you breathe out into the mask exits through the mask vents.

If you are using a nasal mask (i.e. NOT a "full face mask" which covers both mouth and nose), it is possible that the pressure will cause your lips to open slightly, and air may escape through your mouth. This is called "mouth leak".

So: air coming out of the machine, into the tubing, gets into your bedroom one of three ways:
-- through the mask venting system - venting leak or "intentional" leak, which includes the air you breathe,
-- through seal leak - an "unintentional" leak between mask and skin, or
-- through mouth leak - an "unintentional" leak from your lips (this is irrelevant in a full-face mask).

One of the goals in CPAP therapy is to keep "unintentional" leak as low as possible. Even small leaks blowing across your face or into your eyes can arouse you from sleep; not good. Even small leaks through your lips can dry your mouth and nose; not good. Larger leaks can possibly surpass the machine's ability to maintain the set CPAP pressure: if too much air is leaking out of the system, the machine may not be able to provide enough airflow to maintain the pressure.

ResMed tells us that UNINTENTIONAL leaks begin to be of concern to the machinery (they may be of concern to us at much lower levels) starting at about 0.40 L/s = 24 L/m. Above 0.70 L/s = 42 L/m for UNINTENTIONAL leaks, all bets are off, and the machinery may fail. Respironics doesn't give us specific information regarding their machines.

When ResMed machines or software display leak information (either in L/s or in L/m), they display UNINTENTIONAL leak ONLY. If you tell the ResMed machine which ResMed mask you are using, the "computer" in the CPAP machine "subtracts" out the expected, intentional leak of the mask at whatever pressure is being maintained. If you're using a non-ResMed mask, the machine subtracts out a "standard" generic pressure-based intentional leak. So when ResMed presents leak numbers, they exclude normal venting flow; they reflect an estimate of UNINTENTIONAL leak only - which should ideally be minimized.

Respironics machines, on the other hand, don't make this sort of adjustment. When Respironics machines or software report leak numbers (always in L/m), they are giving TOTAL leak: both expected, normal venting, plus unintentional, undesired leak. So with Respironics machines, one either needs to subtract the expected venting flow of the mask being used from the total, or ignore the numbers altogether and just focus on variations: ideally the leak should be fairly steady and consistent through the night (as well as not far above the expected mask venting rate).

ResMed machine LCD screens provide you with a single leak number for the night: the 95th centile leak. This is the highest unintentional leak which you experienced during the best 95% of the night. You were at this leak rate, or higher, for the remaining "worst" 5% of the night. ResScan software also gives you maximum unintentional leak, and median unintentional leak. And the ResScan software graph gives you actual unintentional leak on a minute-by-minute basis, to the nearest 0.02 L/s = 1.2 L/m. Respironics software similarly provides 90th centile, maximum, and average TOTAL leak statistics for the night, and the graph shows you actual total leak on a 30-second basis, to the nearest 7 L/m.

Leak 101 completed. Hope this has been clear. Hope that you are breathing. The issues involved can be discussed with LOTS more detail. But that's for an advanced course, if and when it's needed, at some other time. Best wishes, Velbor

[Muse-Inc]

...Leak 101...

Velbor thanks thanks thanks!

[twokatmew]

When ResMed machines or software display leak information (either in L/s or in L/m), they display UNINTENTIONAL leak ONLY. If you tell the ResMed machine which ResMed mask you are using, the "computer" in the CPAP machine "subtracts" out the expected, intentional leak of the mask at whatever pressure is being maintained. If you're using a non-ResMed mask, the machine subtracts out a "standard" generic pressure-based intentional leak. So when ResMed presents leak numbers, they exclude normal venting flow; they reflect an estimate of UNINTENTIONAL leak only - which should ideally be minimized.

Velbor, I am aware that the ResMed LCD shows only unintentional leak, but I thought the software displayed total leak rates. If I'm wrong on this, I guess I need to reset the mask type when I change masks.... I'd read in other threads that for the "standard" mask type, ResMed machines subtract 0.4L/s or 24L/min. I assumed this was why there's a red line at 24L/min on the leak graph in ResScan. But ... flow rates go up along with pressure, so why only subtract a flat 24L/min? Is this info that I read incorrect? And why the red line in ResScan at 24L/min?

I guess it's time for Leak 102....

[RMinOntario]

Velbor,
What a great explanation! I didn't know if I was going to be able to keep holding my breath as I was re-reading parts of your write-up . So then, my leak rates of 7.2 - 9.6 are unintentional and (I am assuming) pretty good?? A couple people have mentioned seeing the leak rate on the LCD. Mine doesn't show leak rate. It does show that my mask fit is excellent. Can I assume (and yes I know what assume spells) that the leaks are from my mouth as I use a nasal mask. Sign me up for Leak 102.
RM

[Velbor]

I am aware that the ResMed LCD shows only unintentional leak, but I thought the software displayed total leak rates. If I'm wrong on this, I guess I need to reset the mask type when I change masks.... I'd read in other threads that for the "standard" mask type, ResMed machines subtract 0.4L/s or 24L/min. I assumed this was why there's a red line at 24L/min on the leak graph in ResScan. But ... flow rates go up along with pressure, so why only subtract a flat 24L/min? Is this info that I read incorrect? And why the red line in ResScan at 24L/min?

Leak rates on the ResScan graphs can be zero, so they can't include venting. I have never seen evidence to suggest that ResMed's definition of leak is inconsistent between machine and software.

I have also read other postings which assert that there is a "flat", non-pressure-dependent adjustment for the "standard" mask setting. However, I have never seen evidence to support this. In part I base my statements on the processes described more fully in older S7 literature; there is no evidence that these processes have changed. Unfortunately, the more recent S8 manuals do not present some of these technical details which were included in the S7 manuals. In particular, the manual for the S7 AutoSet Spirit machine describes just four options for mask setting:

MIRAGE
ULTRA
STANDARD (modular)
MIR FULL

There are additional mask options on more modern machines. But the key is that in the back of the manual, in the Technical Specifications section, ResMed provided the following chart, demonstrating the pressure/flow adjustment characteristics of these four options:



Similar charts, as far as I know, simply do not appear in the S8 manuals. Further, the S7 manual provides the following text, which is still present in the S8 series manuals:

Leak is derived by analyzing inspiratory and expiratory airflows (via the flow sensor located in the unit). Theoretically, inspiratory and expiratory volumes should be equal. A net airflow greater than the expected mask vent flow is equal to the leak. 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.

NOTES If the leak exceeded 0.4 L/s (24 L/min) for more than 30% of the previous session, the following message will appear on the LCD: High leak in last session. The Leak Alert feature, if enabled, will alert the patient when mask leak exceeds 0.7 L/s (42 L/min) for more than 20 seconds. When the leak exceeds this level, the autotitrating algorithm ceases to perform optimally.

The text hilighted in red reaffirms the definition of leak as "unintentional", and the specification of 0.4L/s (=24 L/m) without reference to mask explains the "red line" on the graphs, indicating "unintentional" leak levels of potential concern, again without reference to mask.

Whether the differences are relevant enough to make it worth your while to change the mask settings every time, I leave to you.

So then, my leak rates of 7.2 - 9.6 are unintentional and (I am assuming) pretty good?? A couple people have mentioned seeing the leak rate on the LCD. Mine doesn't show leak rate. It does show that my mask fit is excellent. Can I assume (and yes I know what assume spells) that the leaks are from my mouth as I use a nasal mask.

Remembering that those leak rates are 95th centile numbers, and that any single number for the entire night loses a lot of the detail (which the software graphic provides), they sound fine to me. Look also a the maximum (and the graph for when and how often it occurs) and at the median (which is hopefully close to zero). There are data options which can be turned off or on controlling what you see on the machine. If you press the left and right arrows simultaneously, you should see leak (and other) data, unless that option has been turned off (which is easily reversible). The "excellent" fit sounds like it's coming from ResMed's mask fitting test option, which is better than nothing, but doesn't tell what happens as you move around during the night. I don't know that you can distinguish between "seal leak" and "mouth leak" just on that basis. Again, the software graph will give you a better "visual" for that, and the presence of dry mouth would provides other clues.

Hope this too is helpful. Best of luck. Velbor