The oxygen prescription was for 1 liter. I've been on it a week now. One big difference is that I wake up just a couple of times a night (versus 5 or more) and can usually go back to sleep pretty easily. I've had a couple of nights where I didn't need to get up to pee, which is almost unprecedented. I did have problems at first waking up with a horrendous dry mouth, until I figured out that the pressure settings were causing my cheeks to blow up with air, and I was opening my mouth just enough to let the air out. Taping didn't help because I barely parted my lips. It finally occurred to me that the addition of oxygen called for less pressure on the ASV. I lowered the minimum EPAP back to 5 and the minimum PS to 4, which seems to have pretty much solved the dry mouth problem. My AHI is running around 0.6 most nights, and when it's higher I am pretty sure it's due to artifacts from moving around, etc. So I am sleeping better and have better numbers. Still tired and sleepy a lot, but it's also the holidays, and I am in the middle of a course of cluster allergy shots, both of which could be factors. And it's early days (nights) yet. But since you were predicting a prescription of 2 liters I am wondering if 1 is enough, especially as the minute vent. is up only slightly. I am going to go ahead and get a pulse oximeter and see what the objective numbers are.
But -- now I have some concerns. I had never thought about altitude as a factor in my sleep issues. Since from the first PSG I had mostly centrals with very few OAs, I am now wondering if I am dealing with altitude-induced central apnea. I've lived in the Denver area most of my life and never thought I had a problem. My daytime levels are fine, 97-98%. I don't know that age (I'm 68) is that much of a factor since I've had sleep issues forever, but the first sleep study was six years ago when I was already in my 60s.
The concern here is that we have been planning to move to Santa Fe, which is at least 2000 feet higher than here. I know that a lot of people end up leaving Santa Fe, and even Denver, because they can't tolerate the altitude. And now I am wondering if SF is really an option for me, or we should look at someplace lower like Oregon. That is, can the ASV and oxygen sufficiently treat the apnea at an altitude of 7200-7600 feet, one, and two, is it likely that over time the problems would spill over into waking and I would need supplemental oxygen all the time -- not an appealing prospect.