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You may want to read the paper accompanying the following image:

Link to to figure 2: flow shapes

This was an attempt to score flow limitations not based on shape alone, but rather on viewing the shapes and the respiratory effort.

As for Resmed, the clinical manual for both AS10 and AS11 says

Flow limitation
As the upper airway begins to collapse, the shape of the inspiratory flow-time curve changes. The
AirSense 1x recognizes and treats traditional as well as less common flow-limited breath wave forms (my empahsis)

Miss Emerita wrote: ↑

Sun Mar 12, 2023 12:10 pm

To the OP: I think you're making too many changes in quick succession to judge what does or doesn't make a difference to your sleep. Pick some settings and the other variables you've changed, and then stick with them for a week. Sleep can be very different from one night to the next, so you need to be looking a trends, not data for just a night or two. When you make a change, make no other changes at the same time. That way you can isolate the effects of that change, if any.

It can be hard to have a subtle problem with getting restful sleep, but I worry that you may be going down too many rabbit holes. For that reason, I wouldn't recommend video-ing yourself during your sleep.

Ahh that is a fair point... truthfully, I am getting very impatient since I just want my life back. I want to create a startup before the summer (since that is the relevant season for this market) and am rushing to find a solution before then. I feel like I am wasting away my 20s and it is very frustrating. I know having only 2-3 days of data per parameter combination is not ideal, but I feel like it is good enough if I can reason with a bit of uncertainty, and since I can always dive deeper on competing hypotheses that are discovered from the data by isolating parameters afterwards. Similarly, I feel like video-ing myself may really help me get more data points for my experimentation and am inclined to proceed with it. Sorry if it seems like I am just dismissing your points; I really do appreciate your input. I believe it is the correct advice for the majority of cases.

That being said, do you have any thoughts on what could be causing the sudden increase in OAs? I am losing some confidence in my dental retainers hypothesis since I have been going to bed without it recently but it is not changing.. Three other hypotheses are:
1. I have been eating late at night frequently for the past week or two. I was not measuring this, so I don't know if this was an every-day occurrence or just some days. Perhaps GERD or something could be causing events..? This is easily testable - I will not eat late at night for the next few days and see if anything changes.
2. The increased pressure is causing the increased OAs, somehow. The events tend correspond with an increased pressure, sometimes even to my max of 16 IPAP. The increased pressure tends to follow the events, so it is probably a symptom, not the cause. But perhaps it is a negatively reinforcing loop that is simply initialized by a minor change, such as the increased PS to 4.4 on 2/28. If this were true though, how come 2/28 and 3/1 were okay? And what would be the actual mechanism of increased PS causing obstructive apneas..?
3. Unbeknown to me, I have been sleeping in a new position that I have never done before that is causing the OAs. The OAs do look positional. But I highly doubt this since throughout my 7 months of PAP, I have never ran into this issue. What are the odds that my sleep position has never caused this in the past, and that some random change in sleep position beginning to cause this, consistently?

I am feeling quite sad since I really am not confident in any of my hypotheses... The most plausible to me would still be the dental retainer hypothesis - that the presence of the new bottom retainer and/or replacement of my top retainer has changed my tongue positioning, causing OAs. Yet me stopping this for the past few nights has not reversed it. One way to consolidate that fact would be that maybe my tongue has already adapted and learned the new positioning. Or maybe my teeth have actually shifted from my retainers in a negative manner. I don't know though..

ozij wrote: ↑

Mon Mar 13, 2023 1:54 am

You may want to read the paper accompanying the following image:

Link to to figure 2: flow shapes

This was an attempt to score flow limitations not based on shape alone, but rather on viewing the shapes and the respiratory effort.

As for Resmed, the clinical manual for both AS10 and AS11 says

Flow limitation
As the upper airway begins to collapse, the shape of the inspiratory flow-time curve changes. The
AirSense 1x recognizes and treats traditional as well as less common flow-limited breath wave forms (my empahsis)

Many thanks, ozij. I hadn't ever before seen shapes sorted into normal/possible/certain. Most of what I've considered my unflagged FLs are in the "possible" category. I will now think of them that way!

The article is also very rich. I'm amazed to think we may yet see a way to establish a diagnosis of disordered breathing during sleep in the absence of a significant AHI. I hope other researchers are building this "library" and will arrive at some consensus about the diagnostic question.

To the OP: Could you post a link to a chart with the increased level of OAs? Thanks.

And I suggest changing one thing at a time for at least a few days/wk to see what it is that works, or changes, because I feel you're impatient (like me but will only go nuts if you don't give each change a chance... one night's never enough to be sure of anything.

Miss Emerita wrote: ↑

Tue Mar 14, 2023 11:42 am

To the OP: Could you post a link to a chart with the increased level of OAs? Thanks.

Great news! Last night my sleep returned back to normal (pre 3/2, still UARS though). Did min EPAP 7 - max EPAP 11, PS 4 (i.e fixed range) with humidity 4. Also, did not eat anything past 7 pm. Wore my retainer. So it is almost certainly either hypothesis 1 (increased pressure) and/or 2 (GERD). Probably primarily hypothesis 1 - probably the increased pressure wasn't nice to my turbinates.

Also another counterexample to hypothesis 2 is that I reported that I ate cookies/milk close to bedtime on 2/28 and that night was fine. Tonight I just treated myself to a massive meal of a burger, fries, and korean bbq at 10 pm to test out this hypothesis further, lol. One confounding variable to keep in mind is that I took 50 mg of Modafinil (for the first time ever) today at 11am since I am really behind at my workplace after being so tired for the past week.

One thing to note though is that I only tried increased pressure with humidity off (except for 3/12). I wonder, if I have increased pressure but with humidity on, if that would be nicer to my nose and actually see positive effects instead. Though on 3/12, I did turn humidity back on to 4 and that was the night that was so bad that I took off my mask in the middle of the night (note: I also increased my min EPAP to 9 that night). But even then, maybe one night is not enough to disprove this hypothesis - case in point, I'm still confused about how 2/28 and 3/1 were okay - without the clustered OAs - despite the increased pressure and lack of humidity. Only 3/2 did the clustered OAs start and were consistent for the next 11 days. So, I don't think that 2/28 and 3/1 could be explained by inter-night variance, since it shouldn't be so consistent afterwards in that case. The only explanation I can think of is that there must have been an additive negative effect from the increased pressure, which then crossed a "critical threshold" on 3/2. The critical threshold being the point in which the pressure raised far enough that it caused more events, causing more pressure increase, etc. until the ceiling. Not super confident on that explanation though - 3/1 doesn't look significantly worse than 2/28. And 2/28 doesn't look significantly worse than 2/27.

OSCAR of last night for reference: https://imgur.com/a/foljf9k

To reply to your question, the OSCAR of the OAs can be found on days 3/2 onwards, with close-ups at the very end: https://imgur.com/a/xqkL5pr

Those higher OA nights include OA clusters, which suggest a positional element. Possibly back-sleeping? Or chin-tucking? At any rate, you seem to be back in a better groove now.

I think you'd find it valuable to change two things: go to bed and get up and roughly the same time every day, and sleep for a minimum of 7 hours per night (which may mean spending more than 7 hours in bed).