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.

[staceyburke]

Yes raise the oxygen to 4 or 5. More is not a problem. Test and move down IF you can. The oxygen bleeding in the Cpap is much lower than a cannula.

[ArcherNeedsSleep]

We really should make a Colorado/High Altitude section for those of us who have to add oxygen to our PAP machines just because we live high above sea level! There are a lot of us floating around here.

Fellow Colorado resident here.  I'm at ~7300 ft.  At 2.5L/min bled into my PAP, using the P10 pillows, I get my oxygen back up to 95% pretty readily.  As you described in your post, I always feel the movement of air through my mask from the oxygen concentrator before I turn on the PAP machine.  I feel it in my P10 and my N20 when I swap out masks, so I doubt your mask swap is the issue in this case.  If you're not feeling that flow it seems to indicate a different problem.

If it was me with a dropping SpO2, I would swap out my oxygen tubing first.  With all of the smoke and pollen in the air, and the changes in temps and humidity as fall has arrived, I would assume that gunk has made it through the filters and airflow is being reduced.  Or, that the tubing has become bent or trapped behind furniture and pinched off.   I've also had a couple of instances where I had inadvertently loosened the end of my oxygen tubing without realizing it, and the flow was reduced without any other sign.  (I would have expected some noise from the leaky tube, but it wasn't making any sound that I could hear.)

I have played around with my O2 flow in an attempt to keep it at the minimum level required to keep my SpO2 above 90%.  I noticed that it doesn't take much change in flow rate to cause a big difference in my SpO2 levels.  For example, dropping by .25 L/min was enough of a change to drop my levels into the 80's.  Bumping up by .25 L/min pushed my SpO2 above 95% all night long...but it also gave me headaches, so I suspect it was too much oxygen for me.  If your concentrator is getting old and isn't pushing as much flow as it used to, I would expect that you could be seeing a drop-off of at least .25 L/min without realizing it.  That's just a guess - I don't know if flow actually reduces over time.

Hopefully you can resolve the issues and get back to better oxygen levels.