Mouth venting with nasal masks

My central question is: Are full masks better than nasal masks at higher pressure because you can't have "mouth venting" with a full mask.

I am defining "mouth venting" as letting the airway pressure out through your mouth unconsciously while asleep. It's not mouth breathing because you are not breathing in, just letting pressure out.

Here is how I see things. With any form of nasal mask (any mask that does not cover your mouth, your nasal passages and airway are pressurized at the machine pressure. You mouth is at ambient room pressure. So with a nasal mask you have to somehow hold that pressure so it doesn't vent out through your mouth. With a full mask, your mouth, nose, and airway are all at the same machine pressure so nothing at the back of your mouth has to hold the pressure and prevent venting through your mouth.

Here is what has been happening with me specifically. I am still trying to work out the best mask/pressure for me. I used a P10 for quite a while and had 2-ish AHI's but I was waking up a lot. I slept better (woke up less) with nasal masks or the Dreamware but my AHI's were higher (4-6). So mostly using the Dreamware, I have been working my minimum pressure up, starting at 7 and now at 10. My 90% pressures were routinely 10-11. So now with the pressure at 10, my AHI's are back down to 2-3 but I have been having increasing difficulty with waking several times per night up with dry mouth. Last night for sure I "caught" myself waking up with air rushing out through my mouth i.e. venting the airway pressure. It seems that as I increased the pressure, I am no longer able to keep the pressure in with whatever does that at the back of my mouth.

So I am going to pull out my old full mask and try that again.

But, I was wondering what others think about this. It seems that any form of nasal mask would be less likely to work well at higher pressures. The valve, or whatever at the back of your mouth has to work harder to keep the pressure in and not vent out through the mouth.

You may think you'll only vent outward with a nasal mask, but the fact is that if your mouth is open and if for any reason when you're asleep your system finds it easier to inhale through an open mouth than a covered nose, whatever the arrangement of that is, you'll be mouth breathing. I don't think it's something you can control or guarantee won't happen regardless of pressures or anything else. I think that whatever you work out, however you do it, it's probably not a great idea to 'kid' yourself about that.

rhodesengr wrote:I was wondering what others think about this. It seems that any form of nasal mask would be less likely to work well at higher pressures. The valve, or whatever at the back of your mouth has to work harder to keep the pressure in and not vent out through the mouth.

Not everyone using higher pressures has trouble keeping the mouth closed or trouble with air entering the mouth via the back door.
Now some people do but there's a lot of people using pressures exceeding 20 cm all night long and using a nasal interface mask that can keep their mouths shut just fine and they don't experience chipmunk cheeks or need to let the air escape the mouth.
It's not like the difference between 8 cm and 10 cm equals hurricane force wind change that just blows the door open despite it being locked.... or really even 20 cm which won't even inflate a balloon.

It isn't the force of the air movement...it's the relaxation that goes on at the back of the mouth/throat and that is something that can happen at any pressure. It can just as easily happen at 4 cm as 10 or 20.

Pressure 10 - 11 cm is not problem once you get used to it, it is not a high pressure at all.
Opening your mouth is a big issue. Once it is open you will be breathing through it.

If you really like nasal pillows then get an Inno Med Hybrid mask.

Pugsy wrote:It isn't the force of the air movement...it's the relaxation that goes on at the back of the mouth/throat and that is something that can happen at any pressure. It can just as easily happen at 4 cm as 10 or 20.

I understand what you mean but what me thinking about this is that the frequency of waking up from mouth dryness and air rushing out my mouth seems to have increased as I moved up from 7 to 10 cm's

BlackSpinner wrote:If you really like nasal pillows then get an Inno Med Hybrid mask.

Well I can't say that I do really like nasal pillows. I used the P10 for a number of months and while I had no trouble with mouth breathing or mouth dryness, I believe I never slept deeply with it. I always had to fiddle with the head band to keep it sealed so there were numerous wake-ups from air hissing. I figured it was maybe because its not adjustable and could not get it tight enough. So i bought a Res Med Fx that is adjustable but that one felt terrible.

A higher pressure will create a proportionally drier atmosphere in there, but the difference in your case is not huge and maybe a slight change in humidity would help.

why don't you try a chin strap to close your mouth (but not completely)
and see if it eliminate your mouth dryness?

Another option to close your mouth:

And I understand what you are saying but it may be that something else is causing that back door to open more or maybe it just seems like it is opening more because it is waking you up more.
Maybe one type of mask simply causes you to relax more and thus increase the chance of that back door opening.

It is very possible that for you and your situation a full face mask would work better but it won't fix the dry mouth. It would fix the chance of the therapy pressure being lost out the mouth.
What bothered me about your comment was that it sort of bought into what a lot of DMEs say...people using higher pressures can't get effective therapy with a nasal interface mask and that is simply not true.
I was afraid a newbie might read it and not understand that it isn't necessarily true. That's why I rebutted your statement...not because I don't believe that for you it's impossible for it to be the cause of your problem.

For you in your situation maybe that slight difference between 7 cm pressure and 10 cm pressure along with the mask simply lets that back door open more easily. Maybe there are other factors involved also.

There are a lot of factors involved with the mouth opening and/or air entering the mouth via the back door.
Sleeping position is an important factor I think. I know I am much more likely to have my mouth fall open if I am on my back. The type of mask and the strap placement also plays an important factor.

For you in your situation though...whatever the reason it is a problem for you and it is waking you up and the dry mouth is causing discomfort so it needs to be fixed.
It's up to you how you wish to proceed to try to fix the problem.

I am defining "mouth venting" as letting the airway pressure out through your mouth unconsciously while asleep. It's not mouth breathing because you are not breathing in, just letting pressure out.

Here is what has been happening with me specifically. I am still trying to work out the best mask/pressure for me. I used a P10 for quite a while and had 2-ish AHI's but I was waking up a lot. I slept better (woke up less) with nasal masks or the Dreamware but my AHI's were higher (4-6). So mostly using the Dreamware, I have been working my minimum pressure up, starting at 7 and now at 10. My 90% pressures were routinely 10-11. So now with the pressure at 10, my AHI's are back down to 2-3 but I have been having increasing difficulty with waking several times per night up with dry mouth. Last night for sure I "caught" myself waking up with air rushing out through my mouth i.e. venting the airway pressure. It seems that as I increased the pressure, I am no longer able to keep the pressure in with whatever does that at the back of my mouth.

I've been using cpap/apap for almost 4 mos. Mouth breathing is the first thing I said to my doctor when he told me he was ordering me a nasal pillow mask. Then sure enough, while trying nasal pillows for my titration study, I was woken with air rushing from my mouth. Of course I complained of this during the followup appt. and he said that would eventually stop on its own. I didn't quite believe it at the time but he was right. Somehow my "sleep self" learned what to ignore and the air rushing stopped. It took awhile though, I think wks later was the last time I woke with air leaking from one corner of my mouth and then it stopped altogether. But then I had also gotten a better quality chinstrap that helps somewhat but won't keep the mouth completely closed. I also wake with dry mouth but that's not every night and not as often anymore. I keep a glass of water nearby and a small spray bottle of Biotene. It's all trial and error.

Right now I'm experiencing the chipmunk cheeks with a new kind of mouth leaking. It doesn't happen every night and I don't sleep the same every night. Most likely it's because earlier this month I switched from straight pressure of 7 to variable pressure up to 11. But I think this too shall pass as my "sleep self" figures out how to handle the change. I think any change, whether it's changing the mask, pressure, sleep position, or adding a chinstrap etc., your brain needs time to adjust. It learns what to ignore over time. So what I suggest is, when you make any kind of change give it time, and (in your case) especially if you prefer nasal pillows to FF mask. Good Luck.

Pugsy wrote:What bothered me about your comment was that it sort of bought into what a lot of DMEs say...people using higher pressures can't get effective therapy with a nasal interface mask and that is simply not true.
I was afraid a newbie might read it and not understand that it isn't necessarily true. That's why I rebutted your statement...not because I don't believe that for you it's impossible for it to be the cause of your problem.

see I didn't know that DME's tend to say that. What I posted I came up with on my own. I work with gases and pressure and vacuum at work so I have quite a bit of lab experience with all that. I am not saying the higher pressure was a cause or that nasal masks can't handle higher pressures but I wanted to talk about it.

And Julie, I don't know about your comment that higher pressure means lower humidity. I can't think of any physics that would explain that although I'd be open to hear your explanation. I know that higher temperature air holds more water. So warm air with an RH of say 50 contains more water than cold air with the same RH. The air is already pressurized when it enters the humidifier section. I don't know but I would think denser air would pick up more water vapor while passing through the humidifier (more collisions at the air/water interface. But it doesn't strike me that these CPAP humidifiers do much to control or regulate the rate at which water enters the air. You sort of get what you get.