danger of rebreathing at lower pressures?

[Zombie on my Lawn]

I am still working on finding the optimal pressure setting. Although my original doctor's recommendation was 8-12 based on APAP titration, I got an O2 ring and Muse headband and have been experimenting with lowering it, since I wasn't feeling that the 8-12 APAP was optimal. (Note: my original titration was with RedMed AirSense 10 but I now have Lowenstein Prisma Smart).

Fast-forward...Now I am using 4-8 APAP to try the titration process over again and getting some surprisingly low levels (4.42 last night). I had read somewhere that at the lower CPAP levels (closer to 4), there can be a danger of re-breathing and ending up with too much CO2. Now, I can't find where I read that or what it was about. (Was it only with certain mask types?)

My oxygen levels seems okay so far, but I am wondering if there is anything I should be watching out for at these lower levels.

Thanks for anything you might be able to point me to.

[Sleepster]

I got an O2 ring and Muse headband and have been experimenting with lowering it, since I wasn't feeling that the 8-12 APAP was optimal. (Note: my original titration was with RedMed AirSense 10 but I now have Lowenstein Prisma Smart).

Oximeters are inexpensive and much more reliable than the ring or headband. An oximeter, along with OSCAR, will give you all the data you need, and it will be far more reliable.

I had read somewhere that at the lower CPAP levels (closer to 4), there can be a danger of re-breathing and ending up with too much CO2.

As long as the exhalation ports on the mask are unobstructed and not modified, re-breathing your own exhaled air is not an issue AFAIK.

Thanks for anything you might be able to point me to.

The literature that comes with your mask. But it's not going to tell you anything you don't already know. No manufacturer would risk making a mask that allows the user to re-breathe their own exhaled air. This is the reason the minimum pressure for all CPAP machines is 4 cm. The masks are designed to purge exhaled air at that, or any higher, pressure.