Complex apnea?

[Gfox]

Dear all,

I am still struggling with mostly remainder "clear airway" events after using CPAP for ~5 years while still not feeling as refreshed as I could be (I had occasionally wonderful nights during this period -- with 0-2 AHI, but those are unfortunately seldom).

Now, recently I (finally) managed to completely control leaks using the Bleep mask and the right kind of mouth tape after my latest sleep study for which a pressure change was suggested (now 10 fixed from 9 fixed). Still mostly centrals remain each night with an AHI of between 3 and 8ish (and 50-90% clear airway events). Latest study suggested central AHI of 4 (but minority of events).

Would love to tap the collective wisdom here to see if I should chase down the ASV route assuming that those events are true central ones (and this might be a case of complex apnea) or whether there are other ways of optimizing this situation (and we're talking more about induced centrals etc.). Sleep doctor agrees that centrals could be an issue, but I feel like he's not very supportive since overall, the numbers were somewhat acceptable in the past with average AHI <5 for some periods (again with still high central share). Also, my normal breathing pattern (without events) looks somewhat irregular -- see one of the Zoom-ins posted below.

Posting links to last night and the night before and my latest sleep study:

Last night (please ignore that it started in the afternoon, not the actual sleep)
https://imgur.com/a/pfkkpQz

Previous night
https://imgur.com/a/QIzSoba

Sleep study
https://imgur.com/a/BRgOPsg

Any thoughts would be highly appreciated!

Thanks,
Gfox

[Gfox]

just bumping it up in case anybody has thoughts ... thanks!

[Miss Emerita]

Welcome! Thanks very much for including that recent split study. A few notes:

* During the baseline segment of the night, you clocked a little less than two hours of sleep, which makes the data less useful than they would be if you'd had longer. During any night, a two-hour segment may be unrepresentative of events during the entire night.

* You had a lot of RERAs -- respiratory effort related arousals -- and a lot of hypopneas identified as non-central. These were the main components of your RDI (respiratory disturbance index).

* You had a fair number of PLMs (periodic leg movements), though few of those resulted in arousals.

* During the therapy portion of the split night, I'd have said you did best at a pressure of 7, though the time at each pressure was limited so the data aren't that useful (as above). I'm not sure why your pressure was set at 9 (and now 10).

As for your charts, we see a fair sprinkling of CAs and a fair amount of flow limitation. There are also some bristly segments of your flow rate, where you have a fair number of deeper inhalations and exhalations in close succession. We see some hypopneas (impossible to know whether obstructive or not) and few OAs.

My suspicion is that the CAs are caused by arousals and are not themselves a cause of your unrestful sleep. I'd appreciate your posted two zoomed in views of about ten minutes each. One should capture several CAs, including the first CA in the group. The other should capture a bit of that bristly stuff (e.g., around one o-clock on 8/30).

A note about how arousals can cause CAs: arousal breathing tends to be deeper than regular asleep breathing. This blows off a bit of CO2. CO2 levels are what trigger your brain to issue the "breathe now" signals, so if you've blow off a bit of CO2, your breathing may pause a little until the CO2 builds back up. You may have a few more CAs as your breathing re-stabilizes.

Once we can take a look at those snippets, I think I might have a few suggestions, and I imagine others will too.

[Gfox]

Appreciate the comments! Yes, the sleep study was a bit of mess. I have a hard time sleeping in those conditions.
I do indeed seem to move around quite a bit at night -- not that I necessarily wake up a lot (consciously anyways). But I have shot videos of myself sleeping and I appear to roll around A LOT (much more than what my wife does).

Here are the 10-minute snapshots you were looking for:
https://imgur.com/t7D0qls
https://imgur.com/a/JCaWteG

Also posting last night's results, which were weird, but might be due to circumstances:
+ we had a bunch of wine (2 glasses on my end)
+ lots of Indian food
+ late to bed at around 1am
+ used the first time the new bleep eclipse mask (before I used the regular bleep)

https://imgur.com/PhO4RI2
https://imgur.com/i9f3tPb
https://imgur.com/5WYphye
https://imgur.com/ENeKEBU

Thanks again!!

[Miss Emerita]

We are seeing that frequently your CAs and Hs follow arousal breathing. Sometimes the arousal is little more than a deep sigh; other times it looks more like a brief wake-up. In addition, you do a lot of this sighing or arousal breathing even when you don't have CAs or Hs flagged. It's awfully hard to be sure, but it looks as though sometimes flow limitations kick off a period of unstable breathing.

I'm not sure how much PAP can do for your arousals, but I wonder whether you'd be game to try two experiments.

The first is to drop your fixed pressure to 7, while making no other changes. You may want to go down all at once, or you may want to go down bit by bit. I make this suggestion in light of the results of your titration in the split study.

See how that goes for a few days. You may see more flow limitations and even some obstructive events, but you may also see fewer CAs and Hs.

The next experiment would be to add EPR. This is a little counterintuitive, because for some people, EPR increases CAs. But I think it might be worth trying to see whether it can reduce your FLs and thus reduce the number of times you enter into a period of arousals and unstable breathing. As you may know, EPR drops your pressure when you exhale. I would start with EPR of 1 and see how it goes.

It's important to do these experiments sequentially so you can see what difference, if any, each change makes. And you want to try each change of settings for at least a few days, given how naturally variable sleep is from one night to the next.

[Gfox]

Thanks a lot for the suggestions. I originally had EPR on at varying levels between 1-3 (for most of my treatment) and found out recently that turning it off didn't really do much (negatively or positively). I actually turned it off as an experiment to see if it would help, but it does not

I'll try to lower my pressure again per your suggestion since my leaks seem to be quite controlled using the Bleep mask and good tape.
Will need to wait to do that until I finish another experiment at the end of this week that was suggested by my NP though.

In the meantime, what do people think about my slightly uneven breathing during regular sleep periods? I posted 2 or so snippets of Oscar data. It just looks weird that I breath a bit deeper every 8th breath or so. Reposting here:

See Zoom 1:
https://imgur.com/a/pfkkpQz

[dataq1]

A note about how arousals can cause CAs: arousal breathing tends to be deeper than regular asleep breathing. This blows off a bit of CO2. CO2 levels are what trigger your brain to issue the "breathe now" signals, so if you've blow off a bit of CO2, your breathing may pause a little until the CO2 builds back up. You may have a few more CAs as your breathing re-stabilizes.

In an interview with AASM, Dr. said that the arousal CO2 “blow off” may take 2 to 3 minutes before the brain suppresses the respiratory signals.

That delay or latency makes it difficult to associate an arousal clear airway apnea with CO2 “blow off” in absence of an actual PCO2 measurement.

[Rubicon]

In an interview with AASM, Dr. said that the arousal CO2 “blow off” may take 2 to 3 minutes before the brain suppresses the respiratory signals.

Can you cite that source please?

TIA.

[dataq1]

Can you cite that source please?

https://aasm.org/wp-content/uploads/202 ... script.pdf

....So there are types where we have an arousal, by the way, arousal after event is a normal
physiology. It's if it's an expected physiological response. Now, is it contributing to the
subsequent central apnea? If I see a period of hyperventilation. And again, you need you need
some time of this hyperventilation. Think of we're decreasing the arterial CO2, that low CO2 has
to travel all the way to the medulla. It's not going to get all the way to the medulla in five breaths.
It needs somewhere between 2 to 3 minutes to get there. So if I see that pattern, which is what
you see in Cheyne-Stokes respiration, then the arousal is contributing. There are times when I
see, and I think this is the one with at least many of my colleagues and our trainees identify
where they talk about the post arousal. They see a huge breath, and there is an apnea after that.
Now, that is a sigh and a sigh is a pause, is a is a is a large tidal volume. And it's maybe that
inhibition after that is vagal and not necessarily certainly related to CO2 that is probably
physiologic. Now, if that's all I see, I'm prepared to downgrade it and not consider it contributing
to the overall picture.... (emphasis added)

Seems to be suggesting that vagal response is a more likely the culprit where Clear Airway Apnea follows an arousal in close proximity (time-wise).

[lazarus]

Seems to be suggesting

Doc, in context, as I read it, was differentiating the technicalities of (1) what triggers the longer waxing and waning pattern of Cheyne-Stokes respiration and (2) the normal immediate pause after a large breath, which can be an immediate reaction because of how the nervous system monitors CO2. Those are two related but very different things.

Therefore, in my opinion, there is no reason for any "correction" for the wording of Miss Emerita in her context, in which "brain" and "nervous system" (which the brain sort of supervises) can be considered basically synonymous in a simple explanation to a non-pro. Otherwise, it would be a persnickity distinction without a difference based on a technicality, one that is not made in most public-facing prose in most discussions.

Learning is fine if you don't let it drive you mad and confuse others along the way.

In my opinion.

And there is no dark side of the moon. It's all dark.

[Miss Emerita]

In the meantime, what do people think about my slightly uneven breathing during regular sleep periods? I posted 2 or so snippets of Oscar data. It just looks weird that I breath a bit deeper every 8th breath or so. Reposting here:

See Zoom 1:
https://imgur.com/a/pfkkpQz

Yes, that's from what I was calling the bristly pattern that shows up for a while in the charts you've posted. I'm afraid I don't know how to explain the pattern, and I hope an expert will weigh in on that. My general hope is that if we can get your arousals and unstable breathing addressed, other anomalies will either disappear or stop seeming significant.

Let us know how the NP's experiment goes (and what it is) once you have a chance to see its results.

[Gfox]

Thanks for all inputs ... yes, the bristly pattern is weird. It's not there 100% of the time but compared to nice and smooth curves I have seen from other folks during regular uninterrupted sleep, it appears unusual.

A bit more background on the experiment: during my recent check-up appointment after sleep study in December and adjusting pressure to 10, the Dr. noticed that my AHI increased quite a bit over the last 8 weeks or so and she wanted to find out what was potentially driving that since no pressure settings changed. But since I used different masks at different days intermittently (full-face vs. Bleep), the idea was to isolate what mask works better for me and stick with each for 2 weeks straight or so. Hence, I wanted to stick with the Bleep at same pressure for that, and essentially in a few days will change to full face and see how the results turn out with same settings for the next 2 weeks. Then I'll be trying to lower pressure again as suggested.

Not sure there is a ton to learn from the mask experience, especially since I have very good control over leaks with the Bleep by now and only mediocre control with the full-face mask (and I'd definitely would prefer to use the former), but maybe there is more behind this than I realize. We discussed the relatively high share of centrals as well (and that I had 4-5 during my study) and she was concerned about it but did not go into any of the data details, which worried me (e.g., not attempt to look at the Oscar detail level data despite me having it all there). She was more concerned with the rise of average AHI levels and wanted to figure out what was behind it. I tried to tell her that even with the relatively lower AHI scores, I was not feeling rested either, so even fixing that might not be a huge help...

[Gfox]

Just as follow-up, here's the long-term (March to latest) time series from Oscar:
+ one can see that AHI has increased over the last couple of weeks
+ also, it's apparent that the majority of my residuals are flagged as centrals
+ my leak rates are way down recently (but were not necessarily that terrible in first place)
https://imgur.com/a/V3hI1IG

[dataq1]

So how long does it take for deep breath (for example a "sigh) to deplete CO2 to a level that would suppress breathing? (assuming that the pre-deep breath is within normal bounds)

[lazarus]

I don't consider Gfox's thread to be an appropriate place for a technical quiz. So no comment from me.