Appreciate Any Insights / Suggestions

[purplebear]

I've been using the AirCurve 10 since October 2022. My AHI/ODI numbers were variable but generally in the high 20s, with regular desaturations into the 70s which clearly affected my heart and sleep quality. I have both OSs and CAs but the OAs drive the desaturations as they tend to be long...usually above 45 seconds. The BiPAP truly eliminated the desaturations from day 1 and with adjustments I was able to reduce my CAs considerably. Although I almost never have an AHI of 0, my AHI has nearly always been under 1 for months...until recently. About six weeks ago the OAs and desaturations started increasing, dipping into the low 80s. Looking at OSCAR, I thought they were probably positional, although that hadn't been an issue earlier and nothing had really changed. So I added a collar and tried adjusting my sleeping position but that didn't seem to help. My best pressure settings seem to be PS 4.0 over 6.0-11.0. I tried increasing my pressure to 7.0-11.0 but that didn't help either and triggered more mouth breathing which made my HR more irregular. 
    I attach an OSCAR screenshot. This is using a P10-S, an Aveela chin strap (also used to hold the P10 straps in place), Simply Breathe tape (this tape works best for me but is expensive) and a chin strap, with pressure at PS 4.0 over 6.0-11.0 and trigger set at "very high." Except for the collar, this has been my best set up since nearly the beginning (I do sometimes use the Brevida as it is more comfortable but I have a steady leak with it). The collar was firmly in place in the morning. The two clusters look rather positional to me but I don't think my chin could have fallen at any time. Also, I don't see much in the way of flow limitations or snoring (especially[attachment=50523] for the 4:30 am cluster), which I would think chin-tucking would trigger...but maybe not.
    Any suggestions? Is something else going on? Do you need additional data? Any thoughts appreciated.

   

[staceyburke]

When you have grouped O and/or H events it shows positional apnea. You are sleeping in a position where you are cutting off your own airway.

It is known as chin tucking - when your chin drops to your sternum cutting off your air. No pressure settings can help you must find a way not to chin tuck.

Sometimes it is as easy as not sleeping on your back or using a flatter pillow. If not you may need to use a collar. I have a link to collars in my signature

[purplebear]

Thank you so much for responding. Perhaps I was unclear (I often am...) but I was thinking that this pattern was likely positional since it started about six weeks ago (even though nothing seemed to have changed at that point), based on what I've learned on this forum, and I subsequently added a collar (I bought two...one like the Eliminator and the other the Corflex ULTRA that some like although the latter is uncomfortable for me) to my sleep arsenal. I was wearing the Eliminator-type collar in the OSCAR image I sent and it was secure around my neck when I awakened...couldn't imagine how my chin could have dropped but perhaps it did somehow. I've also lowered pillows and tried to sleep on my side, although the latter doesn't work well for me because of hip pain (I've always been a back sleeper primarily).
Initially when I saw the pattern I didn't worry...figured it was positional and I could fix it easily. I guess I wrote in part because, if it is positional, everything I've learned so far that might work isn't...and I don't know what else to do. But if that's the only thing the apnea clusters could be, that's truly helpful and I'll keep trying to address it with collars and sleep positions. If there is anything else that might work, I'd appreciate suggestions.