Question About Mouth Leak

[eLPete]

I am a new user of CPAP (nasal mask) and currently have a Respironics Auto Set II (with Resmed Comfort Gel mask, I think). I seem to tolerate the CPAP fine, though I do not feel such great benefit yet, after only 2 1/2 weeks. However, this brings me to my primary question. I experience a fair amount of mouth leakage. My DME resp. therapist stated that this was not an issue that would affect my therapy and that I should continue as I am doing. I tried a chin strap, and as I imagined, it did not affect the problem. It does seem to me, intuitively, anyway, that it does decrease the likelihood that I am mouth breathing, but that is a separate issue, as I can see it. When I inhale through my nose, I don't leak air through my mouth. When I am not inhaling, the air sometimes leaks through my mouth. Since this machine senses the difference between inhalation and exhalation (by the back pressure, presumably) why should this affect the efficacy of my CPAP insofar as stopping my snoring is concerned? I see opinions stated on several message boards that state openly or at least imply that mouth leak is a bad thing. Some of them state that it is bad insofar as dry mouth is concerned. But if my issue is primarily one of efficacy, what does it matter whether there is a mouth leak or not? Since I don't leak while I inhale, it does not seem to me that it should affect the pressure setting necessary for my CPAP. I have so far not been able to dig up any good information on this. Does anybody know whether there is any medical literature that addresses the fundamental question here, of whether there is truly any loss of efficacy with a mouth leak? I read of people taping their mouths and other techniques, but why go to such trouble? Is it to stop mouth breathing, or truly just to stop leakage?

I should probably (and may, yet) address my second question elsewhere, but here goes: Is there a good reason why I should try to insist on holding onto the Autoset machine beyond the initial period (of three months I think) after which they intend to switch me to a standard (i.e. preset pressure) machine? The resp. therapist states that the machine will still compensate for leaks, and that's all I really need to concern myself with. Setting aside the issue of being able to retrieve data for my own interest or edification, is there some other advantage that I'm missing here? I understand that the Autoset is a substantially more expensive machine, and the DME does not seem inclined to part with it for the long haul.

These questions may seem obvious, but I am a newbie. I have searched the message boards quite a bit and have not yet found good answers to these questions. I appreciate any guidance you might be able to give.

[jules]

Respironics does not make the AutoSet - Resmed does

Find out how to get into the clinical menu and start keeping a record of your data there - just set up a sheet of notebook paper with enough columns. You will need to figure that out the first time you get the data (I don't own this machine so don't know how much you get).

Track the data, post it over time here. See what kind of feed back you get.

Know also what mask you have in the menu - that matters for the Resmed machines and post that information with your data.

Mouth leaks are big trouble - if you are letting ANY air out your mouth and you are using a "nose only" mask, you are not getting adequate therapy.

[ozij]

Stopping you snoring is good, but the aim of cpap therapy is to supply pressure to you airway to keep it from collapsing. Snoring is usually a side effect of an airway on its way to collapse.

When you mouthleak, the pressurized air escapes into the room. You need that constant pressure to keep your airway open (patent) - but an open mouth keeps the pressure from building up. Whenever an obstruction starts, the cpap air blowing into your nose takes the easy way out of your mouth, and you're not getting the therapy you need.

Think of having a to blow a balloon - if you use a pump with a small leak (analogous to a mask leak), you'll have to work harder, but eventually the balloon will be as full as you want it. With a hole in the balloon (big gaping mouth) you may never achieve the necessary pressure.

The resp. therapist may be more used to treating people who only need supplemental oxygen. Since keeping their airway patent isn't a requirement of the treatment, a mouth leak doesn't affect their therapy - their wide open airway lets them get the oxygenated air they need even if some of it leaks into the room.


Mouth Breathing Compromises Adherence to Nasal Continuous Positive Airway Pressure Therapy]Mouth Breathing Compromises Adherence to Nasal Continuous Positive Airway Pressure Therapy
(Chest. 2004;126:1248-1254.)

Mouth opening increases upper-airway collapsibility during sleep and may contribute to the occurrence of SDB

Effect of nasal or oral breathing route on upper airway resistance during sleep

Eur Respir J 2003; 22:827-832
Copyright ©ERS Journals Ltd 2003

Upper airway resistance during sleep and the propensity to obstructive sleep apnoea are significantly lower while breathing nasally rather than orally. This mechanical advantage may explain the preponderance of nasal breathing during sleep in normal subjects.

And you'll find more studies in especially in the second paper.

O.

[Guest]

These papers look interesting, but what I'm interested in is mouth leakage, not mouth breathing. You seem to be implying that they are synonomous. I believe that I am inhaling through my nose only, though I'm not awake to observe it. While I inhale through my nose, I don't think I am leaking through my mouth. Only when I exhale do I mouth leak (again, can't tell when I'm truly asleep). Short of another sleep lab trial, is there a way to know (from the machine's data, perhaps)? If I'm correct about all this, why should the mouth leak compromise the therapy, as without mouth leak during inhalation, appropriate pressures should be achieved.

[Wulfman]

These papers look interesting, but what I'm interested in is mouth leakage, not mouth breathing. You seem to be implying that they are synonomous. I believe that I am inhaling through my nose only, though I'm not awake to observe it. While I inhale through my nose, I don't think I am leaking through my mouth. Only when I exhale do I mouth leak (again, can't tell when I'm truly asleep). Short of another sleep lab trial, is there a way to know (from the machine's data, perhaps)? If I'm correct about all this, why should the mouth leak compromise the therapy, as without mouth leak during inhalation, appropriate pressures should be achieved.

Trust us on this one.......mouth-leaking or mouth-breathing DOES compromise the therapy. As ozij stated, if you were trying to blow up a balloon with a big hole in it, you'd never get it blown up. Another problem with the machine you have is that with the leakage, the machine will keep raising the pressure to try to compensate. So, you have too much unneeded pressure going into you and the therapy is still being compromised. To be positive, you'll need to tape your mouth shut or get a full face mask. Also, as was previously mentioned, getting the nightly data to display in the LCD the following morning will sort of help get an idea.

Den

[ozij]

<snip> I believe that I am inhaling through my nose only, though I'm not awake to observe it. While I inhale through my nose, I don't think I am leaking through my mouth. Only when I exhale do I mouth leak (again, can't tell when I'm truly asleep). <snip>

If I'm correct about all this, why should the mouth leak compromise the therapy, as without mouth leak during inhalation, appropriate pressures should be achieved.

I'm not sure I understand. Do you believe you close your mouth each and every time you inhale? Or do you believe that when you inhale pressurised, air does not escpape through your open mouth? Or are you experiencing what Slinky had termed "lip flutters" - air forcing your lips open only when you exhale. I've never experieced the third - once my lips are forced open, the stay like that till I wake up with my tongue firmly and painfully glued to the top of roof of my parched mouth - even without my jaw having dropped. Which is why I have to tape my lips shut.

Short of another sleep lab trial, is there a way to know (from the machine's data, perhaps)?

Not that I know of.

O.

[rested gal]

When I inhale through my nose, I don't leak air through my mouth.

What happens while you're awake and deliberately paying attention to it is quite different from what might be happening when you are in the unconscious, fully relaxed state of sleep.

One of the big problems with mouth air leaks during sleep is that if CPAP air is leaking out the mouth OR being exhaled out the mouth, the seal the tongue has to form to prevent mouth breathing is "broken", and you're just a small step away from inhaling through your mouth, too.

I think the RT is misunderstanding what it means when she reads in the machine literature about how they "compensate" for slight, or even moderate, leaks. True, the machine's motor will blow harder when presented with a leak, in an attempt to keep the pressure up where it is set for. I think (could be wrong about this) that that "compensation for leak" is aimed primarily to deal with mask leaks. I don't think the machine designers intended the leak compensation feature to deliver effective treatment in the face of mouth air leaks that may very well turn into complete mouth breathing at times during sleep.

The problem is compounded when using an autopap (which your ResMed AutoSet II is) in autotitrating mode. Autopaps rely on sensing the airflow going both ways to determine what to do. If there are mouth air leaks, and especially if the out-the-mouth air leaks become mouth inhalations from time to time, the machine can have a hard time figuring out what to do pressure-wise.

Software, software, software -- best way to see what the leak situation really is.

[ozij]

I'd like to clarify my previous statement about the software:
I know of no possiblitly to use a cpap's software to tell whether you're leaking only on exhale, or or on both inhale an exhale.

I do absolutely agree with Den and Rested Gal that cpap software will give you important information about leaks occuring when you sleep - far more - necessary - info that you get from looking at the number on the LCD.

O.

[Raj]

One of several factors you might consider if you are only leaking on exhalation, aside from those already mentioned, is what happens during the transition from exhalation to inhalation. Your machine's motor has a certain degree of hysteresis, some inertia to overcome, to correctly adjust the pressure required for inhalation. If you leak on the exhale, the machine's calibration will be thrown off and for a brief time, you won't be getting the correct pressure. The leakage will also affect the biomechanics of your mouth and throat, making your physical transition to inhalation a bit more difficult because the loose tissues in your mouth and throat are, more or less, blowing the other way far more than in a normal exhalation. And, of course, the arid mouth and tongue you'll get with leakage will interfere with your sleep.