Anomalous CA/CSR output from OSCAR?

[SunMesa]

This is a follow-up to my post yesterday (How Does ResMed APAP distinguish OSA vs. CSA?), in which I noted that immediately upon starting APAP therapy, I was seeing zero OSA's but a substantial number of CSA's (whereas a previous pre-APAP sleep test showed only OSA's, and a negligible number of CSA's). I gather this is not entirely unexpected when starting PAP therapy.

But now last night, after a seemingly minor settings change from the previous night (max pressure reduced from 8.0 to 7.6 cmH2O, EPR level increased from 1 to 2), the data show a whole proliferation of CSA's appearing in the morning, and moreover they are identified with intervals of CSR (Cheyne Stokes Respiration). I've attached the snipped Event Flags plot:

   

What is even more bizarre is that I had actually woken up just before this flurry of CSA's, and I'm fairly certain I was either awake or semi-awake until the end of the data stream!

I wasn't sure what other associated OSCAR plots were relevant, but happy to provide some or all. I have read the possibly-relevant post Suddenly I am seeing CSR on new ResMed 10. Thanks for any feedback/guidance.

[Jay51]

There is TECSA.  It is fairly common with new pap users.  Because of the increased ventilation (and expelling more CO2 than normal), respiratory drive to breath decreases.  It usually resolves in most people in a few weeks or more.  

There is also a term called, "sleep wake junk".  When a person transitions from awake to sleep and vice versa, the "handoff" or "exchange" in the brain, chemoreceptors do not work 100% correctly all the time. 

CSR is usually falsely flagged on the vast majority of users.  If you have a heart condition like Congestive Heart Failure, etc. then the CSR may be true and real.  A diagnosis of CSR takes several things into consideration. 

The best thing to do would be to continue to monitor your CA's.  Keep posting some OSCAR's.  If they don't decrease (your CA's) in a few weeks, other things may need to be done.

[SarcasticDave94]

How long have you been on CPAP?

What did your sleep study show regarding events and count?

It might be treatment emergent CA or sleep wake junk and Jay mentioned. Both the sleep study and include a non zoomed OSCAR that includes left panel, these will help reveal the issue a bit more.

[SunMesa]

I've only just started PAP... used the AirSense 10 a grand total of 3 nights so far.

Here is the Snap report (consolidated) for data recorded 09 May 2024:

   

The SpO2 readings (as monitored by my own Wellue O2Ring) have deteriorated substantially since that test, and indeed that's what ultimately drove me to PAP therapy.

Here is the OSCAR from last night, in full detail from end to end:

   

Here's the corresponding one for the night before that:

   

Above I claimed that the only change I made between the two was to reduce the maximum pressure from 8.0 to 7.6 cmH2O, and to increase EPR from 1 to 2 cmH2O... I recall now I also turned on the humidity, set to level 2.

[SarcasticDave94]

OK, with one Central on the test, these won't be predominant in nature. This places this CA mess as the other possibilities mentioned above.

[SunMesa]

Just to finish the story (but not necessarily answer the question of the post), here is the OSCAR output for last night, after returning all the settings back to where they were on the night of 24 Jul (the yellow highlights in the plots indicate where I was awake):

   

The AHI (0.93) is the best I've had so far, the CSA's are very sparse (4 total), and there are no CSR episodes at all. It's difficult to believe I could respond so sensitively to such minor settings changes, I guess for now I'm going to assume that the results from the night of 25 Jul (actually morning of 26 Jul) represent spurious data or some other anomaly.

[SarcasticDave94]

CA according to the machine points to Central Apnea as Apnea events. CA will always be consistently inconsistent, meant to indicate up then down random CA regardless of pressure settings.

Onward to the settings, they're not ideal now. Min 4 is child level, you'll probably want 7. Then EPR up to and including 3 can actually work. Ramp is going to hinder therapy as it's locked to 4 for 20 minutes. I'd consider removing it.

[Dormeo]

I agree with Dave about turning off the ramp and raising your minimum pressure. You could sneak up on 7 as your minimum by seeing how 5 and 6 feel first.

I'm not so sure I agree about EPR of 3. For some people, higher levels of EPR can increase CAs. For now, I think I'd recommend sticking with 1. Once things settle down, you could experiment with 2 and then 3. Our bodies often adapt over time to CPAP and EPR and produce fewer CAs. Also over time using CPAP, we often have fewer arousals during sleep. This is relevant to CAs because arousals often trigger them. (When they do, it's really the arousal and not the CA that's the problem.)

The "CSR" shading rarely flags Cheyne-Stokes breathing, which is a very distinctive pattern. Instead, it flags waxing and waning breath in general. Sounds like you had a stretch of unstable breathing, with deeper recovery breathing after a CA setting off another CA, and so on and so on. Of course if you were awake, none of this would indicate any form of SLEEP apnea.

[SarcasticDave94]

That's fine on EPR. I wasn't quite clear about this a bit ago. What I'd actually meant to comment regarding EPR, OP may not need or want EPR 3, but pressure moved up to 7 will permit EPR 3 to function.

[SunMesa]

Thanks Dave and Dormeo for your feedback.

As far as the settings go, I guess my first reaction is, should I argue with success? If (a big if) my current settings were to consistently achieve AHI < 1, with no OSA's and few or no CSA's, would it really make any sense to change them? Or to put it another way, shouldn't I be striving for the minimum level of intervention (i.e., pressure in excess of the ambient atmosphere) that achieves the desired result?

As far as EPR, perhaps I'm not interpreting it correctly. My understanding was that an EPR level of 1, 2, or 3 will make the machine reduce the expiratory pressure by 1, 2, or 3 cmH2O relative to whatever the inspiratory pressure is (which itself may be varying from breath to breath when in APAP mode, as I am). So, if my minimum pressure was 7 cmH2O and my maximum was 9 cmH2O, an EPR set to 3 wouldn't seem to make sense (i.e., you'd be telling the machine to reduce the expiratory pressure below your specified minimum).