Gentlemen, I regret you are mixing many different issues and talking physiological nonsense. CPAP has nothing to do with oxyenation in OSA but may improve arterial oxygenation in the abnormal lung. Positive pressures cant simply be added to partial pressures and the phrase
lung muscles have very limited overcapacity to process that pressure
is just a mismash of words.
Bottom line is that sudden depressurisation at 35 to 40,000 feet will kill at least some without oxygen regardless of how fast you can expedite descent. A non venturi non pressurised mask providing 100% oxygen will prevent cerebral apoptosis. A pressurised mask will prevent fumes being inhaled and a demand valve pressurised system can allow normal function
I remain staggered that everyone isnt up in arms that passengers are in effect being put at risk in a seat lottery over a safety provision that has been mandatory for decades
I will now withdraw to prevent my repetition