(11-15-2020, 10:40 AM)fredkahan Wrote: Can the physiological harm of sleep apnea be attributed solely to oxygen starvation?

(11-15-2020, 10:40 AM)fredkahan Wrote: Can the physiological harm of sleep apnea be attributed solely to oxygen starvation? If so, why isn't pulse-oximetry a sufficient measure, replacing the AHI summary statistic (for those of us who have this adjunct equipment)? Can an "area under the curve" number be derived or is it sufficient to count the number of episodes below some red-line, say SpO2 < 90.  

Largely, yes.  The reduced oxygen availability produces a strain on all the systems and organs, not least of which are the heart and brain.  The brain consumes roughly 25% of your oxygen uptake at any one time.  It's by far the heaviest user.  The brain requires a sense of security, calm, and reduced activity, but also a circadian rhythm, to enter sleep and to derive the benefits from the ensuing stages.  Not just ensuing stages, but multiple cascades of them.  I am not familiar with any metric that uses the area under part of a curve to establish a diagnosis, but it doesn't mean the case hasn't been made.  It's just not promulgated by the industry.

And what of the pulse rate data? Do regions of elevated pulse rate truly indicate REM sleep, and if that is a desirable property, should its extent be totaled as an index of improvement?

Elevated pulse rate might mean REM, but it could also mean over-training effect for athletes, illness (flu, other diseases), and it could also mean a building de-sat.  You'd want to couple it, or associate it, with de-sats to establish that there is a deleterious condition and to then decide how to ameliorate that condition.  REM takes place cyclically, de-sats not so much.

I say all this as a newbie, with horrible AHI's (which I attribute to mask leaking), but who nevertheless feels much better during the day! 
Of course I may be deluding myself, but my oximetry data look very clean.

It is good that your oximetry is looking good.  The leaks are only an issue if they work against the machine and if you can link them to a chronic diminishment of treatment.  If the leaks awaken you, or leave you feeling less-than-easy about them, if you feel anxious or vexed by them, then you should probably deal with them constructively.  They will possibly affect your mood or your ability to place faith in your treatment and the machine.

(11-15-2020, 08:52 PM)fredkahan Wrote: Thanks! That was a thorough workout on cardiopulmonary physiology! The potential aggravation of congestive heart failure by intrapleural (intrathoracic) negative pressure extremes was new to me. 

Regarding the expectation of enhanced quality of sleep, I presently face the impasse that while under the masks I have used to date I have yet to achieve sleep at all!  But how would I really know? I wonder what hallmarks in the APAP or pulse oximetry traces are indicative of periods of sleep?