After 473 CPAP Therapy Sessions, need help!

I have a severe case of sleep apnea but I am not satisfied with the treatment I am getting from my CPAP machine. I would like to be able to stay awake when I am reading and when I am attending an evening meeting with a speaker presenting a topic of interest to me instead of falling asleep and falling off my chair!! I hope I can get some encouragement and/or advice on how to proceed. Also, if my observations are correct, I think I have a way of testing whether or not the machine has adequate pressure for my particular case. But, first, some history:

On 11/10/2009 I started using a REMstar PLUS M series CPAP machine with a heated humidifier. As of 4/22/2011 the machine had logged 3057 Therapy hours during 473 sessions, so I have been using it for some time. I immediately noticed an improvement in the quality of my sleep which is why I continue to use it every night and even some times when I take a nap. I had to try several “mask” types during a 2 month period before I settled on a ResMed Swift LT Nasal Pillows system which I use with a chin strap. The CPAP machine initially was set to 15 cm of H2O. At that pressure it was too noisy for my wife to tolerate so I had to sleep by myself. Although I remember having some good sleep experiences, I was not completely satisfied with the result. So my doctor sent me to a sleep lab for an “Attended Sleep Study” where they determined that I only needed about 7 cm of H2O using the same machine type and “mask” that I use at home. By the way, my sleep in the sleep lab was great. I did not wake up until I was awakened by the technician. I had wonderful night sleep. When my machine was adjusted (in April of 2010) to the 7 cm pressure, my wife could tolerate the noise level so I moved back into our bedroom! However, I have not been able to get as good a night’s sleep as I had in the sleep lab. By the way, I always sleep on my back because of a back problem, including the test in the sleep lab and my home is in a very quiet neighborhood.

My understanding of sleep apnea is that when your body is completely relaxed during sleep, the air passages to your lungs become blocked causing you to snore or to wake up, so you never or seldom reach REM sleep. I have found, after several learning trials, that, while I am awake, I can relax my chin and neck to the point that the blockage will occur and that I will either make snoring sounds when I breathe or, if I don’t try hard enough, the air passages to my lungs will block completely. I can also do this with the CPAP machine running at 7 cm H2O and with my chin strap on and no leakage from the Swift LT Nasal Pillows. Am I wrong in assuming that the pressure differential produced by the CPAP machine should keep the air passages open?

It may be that, aside from the noise, my problem with the machine at 15 cm H2O was due to “mask” leakage. Unfortunately, I don’t know how to adjust the machine pressure to see if the passages remain open at some pressure between 7 and 15 cm H2O. Does one of the other machine types adjust the pressure automatically?

Cal Yawner