[Diagnosis] Very high amounts of periodic breathing / CSR ?

[gregbe2000]

Hi SleepyBoi97 -

I went through a period about six months ago where I thought I should be on ASV. I discovered OSCAR then and saw all the CSRs and standalone CAs being flagged. I'm fairly healthy and don't have any heart-related issues but I made an appt with a cardiologist anyway and he did the basic tests (EKG and ultrasound) and those turned out normal. I came to the conclusion that the CSRs were being falsely flagged by my CPAP. I then thought I must have treatment emergent CA (complex sleep apnea) since my AHI was always dominated by CAs. I talked to my sleep doctor and he said he could prescribe an ASV or Bi-Pap for me and get insurance to cover it, but didn't think ASV was the right solution. I did a sleep study and they didn't flag CSR or a material amount of CAs. I've been looking at OSCAR data for about 6 months now and it's getting clear that my CAs are almost always triggered by an arousal first (there will be blip in my respiration before it). I always get clusters of CAs when I sleep on my back - that became obvious when I video'd my sleep. I now sleep with a vest with a ball in the back. I very rarely will have a CSR flagged if I"m not on my back. My CAs now are almost always 1) arousal first then the CA, or 2) in wake/sleep stage (e.g. right before or after I use the bathroom or in morning when I'm half awake). All of these CAs are arousal-based or transitional CAs. I have terrible sleep fragmentation with many arousals/awakenings at night. I now think a lot of these are from flow restrictions and then an eventual arousal (and then a CA or series of CAs afterwards). I'm experimenting on how to remove the flow restrictions that I may have due to UARS (this is never flagged, and no doctor has told me this, but I think it makes sense for me). If I use an EPR of 3 it greatly reduces the flow restriction metric in OSCAR as well as makes the flow more rounded at top. I plan on trying 10 cm up to 15cm - each for a few days. I don't have good data to compare yet. The issue is that I often have nights where I feel I'm awake a lot more than usual and the data for those nights aren't reliable. In any case, I think the solution to my problem with be finding the right pressure/EPR setting to minimize flow restrictions and addressing any other source of arousals that could be kicking off these "fake" CAs. The other thing to mention is that I had no idea how important mouth tape would be for me (I had only worn a chinstrap before). I normally get low leakage via the CPAP metrics but it went to zero with the mouth tape. Without stopping all mouth leakage, the experiment on pressures/EPR isn't worth doing. I may find that a bipap is needed for the additional pressure support, but for now I'm still trying to see if I can get my cpap to make me feel good in the morning. I suppose an ASV would force good respiration, but not sure it's necessary for me as I don't think my centrals are real and I don't like the idea of being on a respirator (probably just a psychological drawback). Does an ASV eliminate all the flagged CAs and the issue if you just don't feel good? Is the ASV eliminating your hypopneas, and therefore your arousals from them? I'm sure there must be a way to feel refreshed in the morning, for both of us....when that happens it will be a life-changer.

[SleepyBoi97]

You’ve basically come to the same conclusion I have! I need to stop any arousal breaths before they start (which feels very obvious to say). 

I’ve come to realize that my body is VERY prone to overreacting to changes in CO2 (i.e. high loop-gain). For a really long time I tried to convince myself that the <1.0 AHI reported by my ASV was accurate and I was being appropriately treated, but I knew that the way I felt each day was an indication that I was not. I had a few CAs on my sleep study, but they were always following an arousal. 

In many ways, my ASV charts look worse than my CPAP charts. Little to no true “apnea” events, but there’s a near endless amount of “static” and uneven breaths. There are tons of arousals preceded by flow limitations, and my tendency after an arousal breath is to hold my breath; however, this is counter to the ASV’s goal of maintaining a consistent minute ventilation, so it pushes a breath on me, which “resets” my body’s “time to breathe” clock. This results and a lot of inconsistent flow patterns.

My best nights on ASV are the ones where it doesn’t do much work at all (when I happen to have few arousals). Even if the AHI is higher, if I have longer stretches of “clean” breathing, I feel much, much better. This always happens when the ASV picks a pressure support and stays with it for a while; as soon as the PS drops a little too much, I have an arousal, which kick-starts the loop again. I suspect the “instantaneous” breath-to-breath nature of the ASV may lead to longer-periods of instability in my case. 

I actually tried an experiment last night with a constant CPAP pressure and a V-COM last night and, although my AHI went up a decent amount, I feel much better, with less aerophagia. I think the extended inspiration time reduces the likelihood that I will “overbreathe” and kick-start a loop-gain episode. I know there’s a similar behavior available on a BiLevel machine where you can extend your breath time/intensity, and that option does not exist on an ASV. I’m really interested in trying that out to see if that alleviates some of my issues. The other option is to keep increasing the minimum pressures on the ASV to see if I can prevent the arousals in the first place. 

It feels like the ASV is always a step ahead of me throughout the night, and I can never get in the correct breath “rhythm” for it, so I’m getting arousals all night. I’m playing catch-up and not able to regulate my breathing with all of the fast adjustments and instantaneous changes to my ventilation. 

Ultimately, this is all just my current working theory. We’ll both get it figured out sooner or later! I’ll respond back if I get any new developments.