Overnight Pulse Ox results are surprising

My pullmonolgist gave me a pulse ox on my CPAP to test it and it is mostly at 92 to 90 and below into the 80’s while I’m sleeping. This is at 6cm to 15cm of H20.

Correct me if I’m wrong, but I should be way higher no? I was doing better before I was the APAP. My air says I have lower than one AHI. But my O2 sats disagree.

I don't monitor oxygen, so I have no direct experience. However, I would agree that it would be surprising to see O2 levels go down when your AHI is less less than one. You may want to view your detailed results in SleepyHead. One of the variables you can graph is Minute Ventilation. It is a measure of your air exchange. Apnea events normally cause it to go low and be unstable. It would be interesting to see if your Minute Ventilation is stable and if there is any correlation to your O2 measures. If your meter is compatible with SleepyHead you can graph the O2 along with your APAP results.

Those levels are lower than they should be. Unless you've been a heavy smoker for a few decades (or something similar), your oxygen saturation should be 90% or more. CPAP prevents your airway from collapsing, but if you are not breathing enough air in and out to keep you oxygen saturation up CPAP will not help. That's what BiPAP is for (or at least what it SHOULD be used for). It helps you breathe more air in and out with every breath, raising your oxygen levels and lowering your CO2.

I assume you are using a ResMed 10 AutoSet based on your comments? If so are you using the EPR function? If not you may want to try it with it set at 3. This will put your inhale pressure (IPAP) 3 cm of pressure higher than your exhale (EPAP). It is not a lot, but it should be better than no EPR, when you are not getting enough air. As sleeptech suggests, a BiLevel machine may be necessary. It can provide more differential between EPAP and IPAP.