CPAP + O2 Concentrator Issue?

[mogulman]

Resmed Autosense 10 CPAP (9-11.0) + Respironics Everflo Oxygen Concentrator (2L/min) user since around 2015.  I live in CO at around 6200 ft.  I only use Oxygen at night.  Resmed ClimatelineAir Oxy Tube, although I've been using it unheated.  Humidy level 5.

Previously, when I would turn on the O2 Concentrator (prior to starting the CPAP), I could feel air coming out of the CPAP mask in my nose from the O2 Concentrator.  Noticed that I couldn't really feel it anymore.  Could be my imagination though, or air temp.  Also, maybe since I switched to newer N30i (more silicone/less plastic nose piece a while), it is just different?

Anyway, pulled out my old CMS50f Oxymeter to measure my O2 levels throughout the night.   Haven't tested my O2 since 2018.   Figured I would test with the O2 Concentrator, and without.  To see if there is much difference.  Anyway.  This is what I ended up with.  Looks like my O2 dipped below 88% quite a bit.   Makes me a little worried?  I have gained some weight over the last few years.

AHI seems pretty good.  Maybe I need to up my O2 level?  3 L/min. I don't really want to pay for another sleep study, although I haven't had one in 7 years. 

Any suggestions?  Attached is my screenshot from last night.

[G. Szabo]

Your flow limit is okay, but the oxygen saturation is concerning. I suggest increasing your minimum pressure to 10.4 to be closer to your 95% value, which is 10.7. Then, compare the saturations. I expect it will improve.
Your EPR should be 3, and your maximum pressure should be 12 cm because you are occasionally close to your 11 cm  limit.