A few different questions, comments

Velbor wrote:

ResMed wrote:...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...

ResMed in the above quote believes any leak rates above 24 L/m is of concern. Now, is that strictly the reported leak rate or is it the discrepancy between the reported leak rate and the mask's intentional leak rate at the LED's reported pressure?

Velbor, is the leak rate reported on ResMed devices' LED indicating that 95% of the unintentional leaks were less than or equal to the displayed number (and 5% were higher)? And, for 95% of the night the pressure was less than or equal to the reported pressure on the LED (and 5% of the night it was higher)? I guess if one had to pick a variable to use, then the one at 95% is reasonable as it represents most of that reporting session's data given we're dealing with a very serious condition.

This whole leak business is hard for me to understand, so please excuse my 'denseness' as my cognition is not only affected by nightly apnea-hypop events but also my thyroid which has gone wonky again (disordered thinking is my most frustrating symptom) and right now anything with numbers is confusing...sorry!

On my sleep doc's loaner ResMed AutoSet Vantage, my leak rates have been 0.46, 0.44, 0.4 L/s, respectively 27.6, 26.4, 24 L/m, for the past few nights. My OptiLife mask' instuctional booklet's chart shows at 5cmH2O the intentional leak rate is about 19 L/m while a posted chart shows 16.1 for this mask. If I compare the LED readout of leak rate and pressure to my mask's intentional leak rate at that reported pressure to determine approximately how large my unintentional leaks were for the previous session, I appear to have an unintentional leak rate of about 11 L/m (27-16=11 using the most extreme numbers). Is an 11 L/m of unintentional leak, a concern? How small or large do unintentional leaks have to be before one starts taking action?

THANKS for helping me make sense of this.

Muse-Inc wrote:ResMed in the above quote believes any leak rates above 24 L/m is of concern. Now, is that strictly the reported leak rate or is it the discrepancy between the reported leak rate and the mask's intentional leak rate at the LED's reported pressure?

For ResMed machines, the REPORTED leak rate (whether instantaneous as in the graph, or the statistical summary for the entire night) is the difference between TOTAL FLOW and the mask's venting rate (as "known" to the machine). The leak reported by the machine has ALREADY factored in (or factored out!) the mask venting; there is no reason to do so a second time. In essence, ResMed makes a distinction between "venting", which is good and which you can't (or shouldn't) change, and "leak" which always reflects a sub-optimal situation. When ResMed talks "leak", they really mean "leak" in this somewhat negative sense. (When Respironics talks "leak", they are actually providing "total flow rate".)

Muse-Inc wrote: is the leak rate reported on ResMed devices' LED indicating that 95% of the unintentional leaks were less than or equal to the displayed number (and 5% were higher)? And, for 95% of the night the pressure was less than or equal to the reported pressure on the LED (and 5% of the night it was higher)? I guess if one had to pick a variable to use, then the one at 95% is reasonable as it represents most of that reporting session's data given we're dealing with a very serious condition.

It's hard to express the "centile" concept in words without it getting a bit convoluted, but you have it essentially correct. The notion of 95th centile (which is arbitrary; Respironics routinely uses 90th centile) is an attempt to reflect what's happening during the great bulk of the night, while excluding that small portion of the night which may display "atypical" results. It's similar to why ResMed also uses medians rather than averages: an effort to exclude, for example, those brief periods when you might have lifted your mask to scratch your nose. If your machine was running for 8 hours, the 95th centile shows what was happening for all but 24 minutes, excluding the 24 minutes with the highest leak (or highest pressure). Those "worst" times were hopefully irrelevant anomalies. The software also provides median and maximum values, so that everything can be kept in context.

Muse-Inc wrote: On my sleep doc's loaner ResMed AutoSet Vantage, my leak rates have been 0.46, 0.44, 0.4 L/s, respectively 27.6, 26.4, 24 L/m, for the past few nights. My OptiLife mask' instuctional booklet's chart shows at 5cmH2O the intentional leak rate is about 19 L/m while a posted chart shows 16.1 for this mask. If I compare the LED readout of leak rate and pressure to my mask's intentional leak rate at that reported pressure to determine approximately how large my unintentional leaks were for the previous session, I appear to have an unintentional leak rate of about 11 L/m (27-16=11 using the most extreme numbers). Is an 11 L/m of unintentional leak, a concern? How small or large do unintentional leaks have to be before one starts taking action?

As noted above, when ResMed says "leak" they mean "leak" with "venting" already taken out. So, if your leak is reported as between 24 and 28 L/m, that is your leak. The 16 or 19 L/m venting (or something close to it; it is an approximation only for each mask brand, and any two of the same masks may differ, and who really knows what adjustment factor ResMed is actually using) has already been subtracted (by ResMed, not by Respironics) so it reflects no physical reality to subtract it again. Your leak rates are, in fact, above the 24 L/m "warning" proclaimed by ResMed. Your leak, therefore, is "significant" (and if your pressure is "only" 5cm, that is a pretty hefty leak for that pressure). Concern, yes, though not panic, would be reasonable. You will hopefully be able to find hints and suggestions from other OptiLife users. Regards.

I don't have the software, and can only go by the LED readout every day. I get a readout of 0.0 thru 0.28 leak rate, with the average leak at 0.16.

I'm thinking that's pretty good, am I right???????

Komodo wrote:I don't have the software, and can only go by the LED readout every day. I get a readout of 0.0 thru 0.28 leak rate, with the average leak at 0.16. I'm thinking that's pretty good, am I right???????

Forgive me for being a stickler, but the right words are important to avoid confusion. 0.16 L/s is not "average leak" but rather the "average of your 95th centile nightly leaks".

The numbers are good in the sense that you're well below the 0.40 L/s "concern" level. But remember that it's also important that even these "small" leaks are not bothering you. Having nights with 0.00 95th centile leak is great! That shows that your system is well fitted and being used properly. Congratulations!

Let me step back a moment, though. In this thread ,my comments have been focusing on questions about leak. It's always good to have leak numbers as low as possible, but remember that leak numbers are just a tool, not the goal: the goal is minimizing respiratory events, and sleeping well, and feeling well. Good luck.

Thank you so much, Velbor! This thread has been very educational.

Velbor wrote:...when ResMed says "leak" they mean "leak" with "venting" already taken out....

Thanks thanks thanks Velbor! I'm so glad I don't have to fiddle with numbers 'cause with the current state of my muddleg thinking I'd sure get it wrong ! On the other hand, I've got LEAK!!!

Velbor wrote:...Your leak rates are, in fact, above the 24 L/m "warning" proclaimed by ResMed...Your leak, therefore, is "significant"...

Interesting that I haven't gotten the ResMed warning message...yet . Will be interesting to see what sleep doc says/recommends. APAP goes back tomorrow & my Escape is going in to have the ramp set to 6 as some nights I seldom needed the 8 which is the current ramp pressure.

Thanks again Velbor!

Muse-Inc wrote: .... On the other hand, I've got LEAK!!! .... Interesting that I haven't gotten the ResMed warning message...yet :D . Will be interesting to see what sleep doc says/recommends. APAP goes back tomorrow & my Escape ....

Yes, but keep it in context. Your 95th centile leak is over 0.4 L/s. That means, assuming that you use the machine for 8 hours, all we know for certain at this point is that for at least 25 minutes your leak was over 0.4. What we don't know without the software is how much higher than that it went for those 25 minutes, and we know almost nothing about what your leak was like for the remaining 7.5 hours. It could have been 0.00 for those entire 7.5 hours! (Nah, I don't believe it, either.) Or it might have been 0.40 for up to almost 2.4 hours (30% of the time, which would have triggered a "message" from the machine which you say you didn't get). Or anything in between. That's why the software can be so helpful. At least ask your clinician to give you printouts of what's been going on these last few days.

ResMed wrote: 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.

But even just the information from the LCD screen does gives some useful indication of where you are. Unfortunately, the Escape has no data capability. You might want to "lean" a bit on your clinician to prescribe an Elite, so that at least (s)he will have data available to better manage your therapy (to say nothing of your own obvious interest). Best of luck with your clinician tomorrow.

Velbor wrote:...You might want to "lean" a bit on your clinician to prescribe an Elite, so that at least (s)he will have data available to better manage your therapy (to say nothing of your own obvious interest). Best of luck with your clinician tomorrow.

Thank Velbor, I just turn it in tomorrow & get my Escape ramp set to 6. They'll do the printouts and compare to the oximeter data (turned that in today), then figure out what next. I want to talk to him about the data, he knows I'm recovered enough to want to take an active role in my treatment beyond slapping on the mask & hitting Start...like getting a full-data device (and eventually the software and reader, even a recording oximeter when funds permit) to optimize my therapy. I was thinking the Elite II, he suggested I might need an APAP (astute doc)...lost 50#s noticeably smaller face...so pressure likely needs changing. The wt loss might be why I can't maintain my mouth seal anymore, in addition to the pressure being too high. He, like my cardiologist, still believe the apnea and it's side kicks will likely disappear when enough wt is gone.

The leak and nightly events have got to stop, can't be healthy to have 103 pulse following a hypop. I breathe so much easier on the APAP, more like 'normal' at least for me , that I miss it already..tonight's my last night with it . If I had the funds, I'd buy now it but living on unemployment right now sorta precludes that option. The data, depending on what it indicates, is absolutely essential to making a case to my insurance carrier -- my 95th pressures were 6.9, 9.2, 7.7, 9.4 (mask sliding on hair with pillows losing seal); those variances suggest APAP to me for max effectiveness. Too, a hybrid-style mask (FFMs are terrifying with my fear of suffocation & claustrophobia) and a whopping dose of all my relaxation techniques, self-hypnosis, and guided imagery to handle my phobia about something covering my mouth.

Thanks Velbor! I am so grateful to have found this forum with so many helpful people willing to share their wisdom -- thanks to all of you!

Velbor wrote: Forgive me for being a stickler, but the right words are important to avoid confusion. 0.16 L/s is not "average leak" but rather the "average of your 95th centile nightly leaks".
The numbers are good in the sense that you're well below the 0.40 L/s "concern" level. But remember that it's also important that even these "small" leaks are not bothering you. Having nights with 0.00 95th centile leak is great! That shows that your system is well fitted and being used properly. Congratulations!

Let me step back a moment, though. In this thread ,my comments have been focusing on questions about leak. It's always good to have leak numbers as low as possible, but remember that leak numbers are just a tool, not the goal: the goal is minimizing respiratory events, and sleeping well, and feeling well. Good luck.

That's what I meant, you just state it much better than I do.

Thank you for all your input in this thread! It is extremely educational and helpful!!!!!!!


While I have your attention......in addition to my nasal mask that I wear most of the time, I also have a comfortgel FF for occasional use. I don't change the mask info on my cpap from nasal to FF when I use it, does that make a BIG difference in the leak/AHI numbers? (I know that my leak numbers are way up there when I use the FF, that's why It's not my usual mask.)

Komodo wrote:....in addition to my nasal mask that I wear most of the time, I also have a comfortgel FF for occasional use. I don't change the mask info on my cpap from nasal to FF when I use it, does that make a BIG difference in the leak/AHI numbers? (I know that my leak numbers are way up there when I use the FF, that's why It's not my usual mask.)

Ah, there are two separate questions in there, both good.

First, does changing or not changing the mask information on a ResMed machine affect the leak/AHI numbers? That itself is two questions. (1) The leak numbers are affected by identifying your mask to the machine, since the machine "knows" the pressure-flow relationship for each mask in its memory, and it "subtracts out" the normal venting for the specified mask at the pressure in use. How much of a difference this makes is arguable. In the chart I posted earlier, for example, at 10cm pressure, the highest (~43) and lowest (~27) flow rates differ by about 16 L/m (=0.27 L/s). These are the amounts the machine subtracts from the total flow. If the wrong mask is entered, the leak reported by the machine will be either too high, or too low, by this amount. This is an extreme example. Also, in general, since FF masks are larger, and so there is a larger volume of CO2 that has to be "flushed out", so the venting tends to be higher for FF masks than for nasal masks at equivalent pressures. (2) The AHI numbers should NOT be affected by the mask settings. The definitions of AHI, AI and HI are fixed in the machine, and the operation of the sensors which detect their presence, are not dependent on the mask setting.

And then the second question: does ACTUALLY USING a Full Face rather than a nasal mask change the leak or AHI numbers? And this also has two parts. (1) FF masks sometimes (not always, but often) will exhibit higher leak than a "comparable" nasal mask. This is due to seal leak: leak between the cushion and the skin. FF masks have a larger area, and a more "topographically diverse" (in English, that means "bumpy") area, over which they have to seal. Not an easy job! On the other hand, FF masks eliminate mouth leak, since the mouth is within the mask and pressure is the same both inside and outside the lips. So some folks actually have less leak with some FF masks since mouth leak is eliminated. But more commonly, seal leak is higher. (2) Does using a FF rather than a nasal mask result in different AHI, AI and HI numbers? In theory the answer should be no. In theory, the mask is simply a passive device which provides a comfortable way to deliver CPAP pressure with minimal leak. In theory, respiratory disturbances come from the sleeping airway, and the mask should be irrelevant. Surprisingly, I have found that this is not the case, though I cannot explain why. With a modest amount of humility (and with the caution that my personal data may not be relevant for everyone), I would direct your attention to two of my posts:

"AutoPAP, Activa, UMFF and Mouth Taping" at viewtopic.php?f=1&t=37954 and
"Respironics :: Activa, UMFF :: ResMed" at viewtopic.php?f=1&t=42646

Blessings, Velbor

Velbor wrote:

Komodo wrote:....in addition to my nasal mask that I wear most of the time, I also have a comfortgel FF for occasional use. I don't change the mask info on my cpap from nasal to FF when I use it, does that make a BIG difference in the leak/AHI numbers? (I know that my leak numbers are way up there when I use the FF, that's why It's not my usual mask.)

Ah, there are two separate questions in there, both good.

First, does changing or not changing the mask information on a ResMed machine affect the leak/AHI numbers? That itself is two questions. (1) The leak numbers are affected by identifying your mask to the machine, since the machine "knows" the pressure-flow relationship for each mask in its memory, and it "subtracts out" the normal venting for the specified mask at the pressure in use. How much of a difference this makes is arguable. In the chart I posted earlier, for example, at 10cm pressure, the highest (~43) and lowest (~27) flow rates differ by about 16 L/m (=0.27 L/s). These are the amounts the machine subtracts from the total flow. If the wrong mask is entered, the leak reported by the machine will be either too high, or too low, by this amount. This is an extreme example. Also, in general, since FF masks are larger, and so there is a larger volume of CO2 that has to be "flushed out", so the venting tends to be higher for FF masks than for nasal masks at equivalent pressures. (2) The AHI numbers should NOT be affected by the mask settings. The definitions of AHI, AI and HI are fixed in the machine, and the operation of the sensors which detect their presence, are not dependent on the mask setting.

And then the second question: does ACTUALLY USING a Full Face rather than a nasal mask change the leak or AHI numbers? And this also has two parts. (1) FF masks sometimes (not always, but often) will exhibit higher leak than a "comparable" nasal mask. This is due to seal leak: leak between the cushion and the skin. FF masks have a larger area, and a more "topographically diverse" (in English, that means "bumpy") area, over which they have to seal. Not an easy job! On the other hand, FF masks eliminate mouth leak, since the mouth is within the mask and pressure is the same both inside and outside the lips. So some folks actually have less leak with some FF masks since mouth leak is eliminated. But more commonly, seal leak is higher. (2) Does using a FF rather than a nasal mask result in different AHI, AI and HI numbers? In theory the answer should be no. In theory, the mask is simply a passive device which provides a comfortable way to deliver CPAP pressure with minimal leak. In theory, respiratory disturbances come from the sleeping airway, and the mask should be irrelevant. Surprisingly, I have found that this is not the case, though I cannot explain why. With a modest amount of humility (and with the caution that my personal data may not be relevant for everyone), I would direct your attention to two of my posts:

"AutoPAP, Activa, UMFF and Mouth Taping" at viewtopic.php?f=1&t=37954 and
"Respironics :: Activa, UMFF :: ResMed" at viewtopic.php?f=1&t=42646

Blessings, Velbor

Like...WOW!!!!!!

You've got all the data to prove there shouldn't be a difference, and yet, I agree with you that there is in fact, a difference. Going by my personal experience, I breathe "differently" depending on which mask I use, nasal vs FF. Prior to using a cpap, I was a mouth breather, and now, I usually use the nasal mask and breathe through my nose. However, when I use the FF, I go back to breathing through my mouth (at least while I'm awake, and aware of what I'm doing). That may, in some way, affect the numbers. While I'm awake, I have to breathe through my mouth because I don't get enough air in through my nose. When I'm asleep w/the nasal mask, I don't have that problem. I assume, that when I use the FF mask, I go back to my "habit" of mouth breathing, rather than through my nose. Prior to useing a cpap, I would breathe through my mouth, and have all the symptoms of OSA. Maybe my mouth breathing was a serious problem, that could have been lessened by my breathing through my nose. I don't know, but it is a thought.

One more ResMed leak data idiosyncracy:

On the LCD leak is reported in L/sec, but the software reports L/min.

Only someone down under knows why.

jdm2857 wrote:One more ResMed leak data idiosyncracy:
On the LCD leak is reported in L/sec, but the software reports L/min.
Only someone down under knows why.

In ResScan >> Tools >> Options you are able to choose which leak reporting units you prefer.
ResMed did this aspect of its software right!

Another tip of the hat to Velbor!