I initially took a home test (Sept.) followed by a week trial of Resmed Airsense 11 which I did not tolerate due to exhalation anxiousness. I was scheduled for poly (Nov.) with report mid. Dec. While waiting I bought a Wellue ring (using since Sept.) . I also bought an O2 concentrator received in late Dec.
Poly report 5 obs, 2 mixed and 35 central. Hypopneas 240, for AHI 51.3/hr. , SpO2 nadir. 78%, Cheyenne Stokes present, moderate PLM index 41/hr., frequent PVCs.
I do not think the bi-level is the answer but will do the free trial, 3 weeks usage, then overnight poly titration.
Meanwhile using O2 I see 4%+ events always under 5 and a few under 1 per hour. O2 mostly over 95%, seldom under 90%.
I see the issue you point out of suppressing CO2 using O2 (set for 2/l per hr.). That puts out 78% O2. I will play a bit with that but with only oximeter data how to measure results may be tough for a layman.
My basic question is "if low O2 is harmful to heart and tissues, even if high O2 suppresses CO2 and affects the O2/CO2 cycle (and apparently prevents loop gain cycles) why should I care. In other words as long as O2 is high what's the harm. I am concerned I am missing something.
Regards

I have had 5 complete sleep studies in a sleep clinic.
I started with a Lung doctor because I thought it was a lung problem with O2 being low a lot and I told him I think I have Central Sleep apnea. My O2 ring would show O2 going from 98 to 88 in a cycle every 15 seconds of so while I'm awake but almost falling asleep. He told me to throw that thing away. You need a home sleep study, and I told him, don't bother I need a full overnight study in a sleep clinic which he did finally order. Within the first hour of the sleep clinic Tech came in and said I had severe sleep apnea and slapped a mask on and spent the rest of the night trying to find what pressure would work. Results said central sleep apnea with some obstruction. Doctor called me by phone and said he was ordering an CPAP. I said NO, I need to discuss the results. At appointment I said I want to see the data. All he had was printout. I said I need to see the graph. He said no one ever asked before and he then came back and said he doesn't have it. I basically got in fight with him and did manage to get an appointment to another doctor in group who was the sleep specialist. She also wanted me to start with a CPAP machine. I then got appointment with a sleep clinic at a university hospital setting, figuring they had access to anything I might need such as neural exam etc. I would meet with an intern first, then the head of the department. I said I wanted them to study me the whole night, do not interrupt and try to control it.. They did that and also added a CO2 sensor (Sleep clinic #2).
Also came up with Central Sleep apnea with some Obstructions and decided to use a BIPAP. I went for a 3rd sleep study where they would try to titrate what pressures to use on the BIPAP. Turns out I had a bleeding hemorrhoid and my hemoglobin was like 7.2 but they did not have any of this information.
They ordered a BIPAP and I used it for 6 months. my events (AHI) were between 20 and 30 all the time. They refused to let me try supplimental O2.
I was getting Cheynes Stokes events with no breath for 20-30 seconds at a time. They then wanted to eliminate RLS problems before getting into a new machine and order a home test just to check leg movments etc.
They finally felt an ASV machine would be best but my insurance required a sleep lab test which showed it would work. So I had a 4th sleep clinic study. They finally ordered a RESMED 11 ASV with setting at Epap 13-15 PS 4 - 10. First night my AHI was 2.14 with the ASV machine while the the night before with the BIPAP my AHI was 37.13
I actually felt better the next day, not sleepy etc.
The only problem was that the pressures were so high, going to 24 as needed that the mask would leak. Making it tight enough to stop the leaks was to much to were like that all night. Still working on that. getting better.
At this point in time (Jan 2025) I'm playing with the setting on the ASV machine trying to find a sweet spot that will keep AHI low and Also O2 levels up. I tried using lower pressure setting while allowing it to got up if needed.
7-11 4-17 for example. This kept AHI within around the 5 range but my o2 ring showed o2 between 90-100 with a little to 85. With the high pressure settings the o2 was 95-100.
So to put it all together. Central Apnea are controlled with the RESMED ASV machine. Actually there are no central or obstructive apnea and what does show up are Hypopnea which,l I think, is an artifact of how the machine is suppressing the tendency to go into the Cheynes Stokes pattern.
I'm still interested in trying some O2 but so far they are not interested and seem happy with the results of the ASV.
I did convince one of the doctors to do a Pulmonary Function Test.
FVC was good. actually above expected.
LVM was above expected abut FRC was barely above LLN
DLCO-c and DLCO/VA was barely above LLN while VA was above expected.