I have had a few thoughts about this missive and decided to make an addition. I will give a short summary first and then anyone who wants to read further may do so. First, as mentioned a number of times on this board, full face masks can be very difficult to seal and, if the PAP is high, they can be impossible to seal. Second, at high PAP the lips can not maintain the seal. Sealing with the tongue is more effective, if you can do it. It is possible to train oneself to do the tongue seal. Third, at high enough PAP, one will get some leakage regardless.
I started my treatment with a nasal mask. The first 2 nights with it, I woke up with my mouth so dry that it actually hurt. Talked to the DME and they sent me a FFM from the same manufacturer. I worked with it for quite a while and could not get it to stop leaking. The leakage would wake me up. I finally decided to do some analytical testing and found that at 20 cmH2O (which is my prescribed IPAP setting) I could not get the mask to stop leaking by the seal. I tried many different tightnesses and tightness patterns but nothing worked. I pulled out my original nasal mask and was easily able to obtain a leak free seal.
What does this mean? The way I see it, it means that at higher air pressures full face masks are much more difficult, if not impossible to make seal.
The next problem was the "open mouth" problem. I found through experimentation that keeping my mouth closed and my lips tightly pressed together would not keep air from leaking out between my lips. The pressure would eventually build up enough that I could not keep my lips sealed. When I reported this to the respiratory therapist (finally) at my DME, I was told that it was actually the tongue that made the best seal and that some people could do it and some could not. Through practice, I became proficient with making this seal with the tongue but I suspected that I was still getting some leakage. I resorted to more analytical testing. I found that I was able to make a reliable seal with my tongue but guess where the next source of leakage was - between my eyeball and my eye socket!!! I never even knew that this was a possibility. I decided that I would rather have a little leakage from my mouth than have leakage from my eye socket, so I did not push the seal problem any further.
One added observation – when I went back to the nasal mask and used the tongue sealing method I began getting a full night's sleep and felt invigorated.
And one final observation – I am extremely happy that I have found this forum with so many knowledgeable and very helpful people who share their knowledge and experience with those of us who need help and/or advice.