Recent switch to BiPAP -- need help w/ flow rate abnormalities and settings

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
mcrick
Posts: 13
Joined: Fri Nov 24, 2023 9:14 am

Recent switch to BiPAP -- need help w/ flow rate abnormalities and settings

Post by mcrick » Thu May 15, 2025 9:34 am

Hi all,

My overall goal is to find the lowest-stress pressure set-up that addresses those UARS-style flow limits so I finally wake up feeling rested.

Links below: My main ask: How would you interpret the disordered flow-rate shapes? Are they classic UARS flow-limits, “high loop-gain” wiggles, or just normal recovery breaths?

Background & context:
  • Goals: Minimize flow limitations / UARS arousals first, AHI second. AHI < 2 is typical; I still wake groggy.
  • Body position: Mostly side sleeper but roll supine; side-sleep “trainer” sometimes used but sometimes fragmenting sleep when I change positions / roll over.
  • Centrals: Not historically an issue, but becoming more frequent on bipap, though I don't know if they are true centrals or artifacts of something else.
About me (medical & PAP background):
  • Diagnosed two years ago with mild-to-moderate obstructive sleep-apnea (sleep-lab AHI ≈ 10) but symptoms point strongly to UARS / flow-limitation–driven arousals: unrefreshing sleep, daytime fatigue, and “choking/sigh” awakenings even when event index is low.
  • No significant cardiac, pulmonary or neurologic disease; BMI normal, active mid-20s male, 6'3". Narrow palate and large tongue (malampati class 3 or 4) but no major nasal obstruction. Previously had successful functional septorhinoplasty with septum correction and turbinate reduction.
  • P30i large mask + mouth-taping + mandibular advancement device (MAD) is my usual nightly toolkit.
  • Machine: ResMed AirCurve 11 VAuto since end of April 2025 (previously AirSense 11). Use OSCAR and SleepHQ for data.
  • Typical therapy metrics on fixed-pressure bilevel:
  • AHI 0.5 – 2.0 (usually mostly clear-airway flags)
  • Glasgow Index hovers 1.0 – 1.8.
What I’m seeing so far from 14 nights of bipap usage:
  • Combining the BiPAP with my mandibular device + mouth tape has given me a few OK nights (inconsistently), but whenever I push pressure-support above ~6 cm the AHI usually climbs—mostly from clear-airway flags. I’m not sure how clinically meaningful these CA events are.
  • EPAP above ~6 cm (especially with PS > 6 cm and a very-high trigger setting) seems to bring on aerophagia.
  • I’m still waking up groggy, with puffy nasal tissues and mild congestion.
What I’d love your help with:
  • Interpreting the flow-rate shape and the CA clusters—do they point to CO₂ wash-out or something else?
  • Pinpointing settings that could smooth the flow curve without driving aerophagia or CAI.
  • Whether a step down in humidity/tube temp might relieve the congestion without hurting comfort.
  • Reducing sleep fragmentation in general. My Apple watch data (as seen on the SleepHQ dashboard) seems to hint at lack of deep sleep with a lot of fragmented stages and bouncing between stages sporadically.
I realize my frequent setting changes make the picture messier, but any help in reading these traces would be much appreciated. Let me know if you need anything else from me.
Thanks a lot for taking a look.

P.S. I nerded out and wrote code to analyze my PAP data, run it through the Glasgow Index website, and analyze correlations. It might mean nothing, and it's only trained on my 14 nights of bipap data so far, but here is the correlation matrix if you find it interesting or helpful. https://imgur.com/a/5jhR18D

User avatar
ChicagoGranny
Posts: 15097
Joined: Sun Jan 29, 2012 1:43 pm
Location: USA

Re: Recent switch to BiPAP -- need help w/ flow rate abnormalities and settings

Post by ChicagoGranny » Thu May 15, 2025 1:37 pm

Too much obsession with data without much mention on how you do the next day.

You do mention you wake up groggy and not feeling rested. Many people (Including people who don't have sleep apnea) feel like this, but after a short time, they feel energetic and don't have excess sleepiness during the day. I feel like this, but after half a cup of coffee, I'm good until bedtime.

How do you do after the morning grogginess is over?
"It's not the number of breaths we take, it's the number of moments that take our breath away."

Cuando cuentes cuentos, cuenta cuántas cuentos cuentas.

mcrick
Posts: 13
Joined: Fri Nov 24, 2023 9:14 am

Re: Recent switch to BiPAP -- need help w/ flow rate abnormalities and settings

Post by mcrick » Fri May 16, 2025 11:44 am

The fatigue lasts throughout the day, converting from sleepiness in the morning to tiredness thereafter; like feeling physically depleted. Eye twitches and dryness are common. Inability to recover from rigorous workouts such as weightlifting, lack of endurance despite prior training and good physical shape. All blood panels, thyroid, etc are normal. By the evening it's near impossible to socialize and I look gaunt. Cognitive abilities are reduced and I am more irritable and wiped out overall. I also often notice fluid retention in my nose and some level of overall facial puffiness.

In general I find that using PS 3-7 is comfortable. I am sensitive to aerophagia if I push any of PS, EPR, IPR too high.

There are other more private effects on my health but suffice to say that I don't just feel crappy for the morning. That's why I have come here for help. Thanks for your time.

User avatar
robysue1
Posts: 1311
Joined: Sun Sep 18, 2022 3:39 pm
Location: Buffalo, NY

Re: Recent switch to BiPAP -- need help w/ flow rate abnormalities and settings

Post by robysue1 » Fri May 16, 2025 1:41 pm

mcrick wrote:
Fri May 16, 2025 11:44 am
The fatigue lasts throughout the day, converting from sleepiness in the morning to tiredness thereafter; like feeling physically depleted. Eye twitches and dryness are common. Inability to recover from rigorous workouts such as weightlifting, lack of endurance despite prior training and good physical shape. All blood panels, thyroid, etc are normal. By the evening it's near impossible to socialize and I look gaunt. Cognitive abilities are reduced and I am more irritable and wiped out overall. There are other more private effects on my health but suffice to say that I don't just feel crappy for the morning. That's why I have come here for help. Thanks for your time.
So there's something clearly going on, and because you've already had the blood work done, there's a good reason to suspect that you are still dealing with symptoms related to OSA and/or your overall sleep quality.

You wrote:
mcrick wrote:
Thu May 15, 2025 9:34 am
Links below:
In both sets of data that you've posted, the remaining flagged events are CAs, but there is evidence that those CAs are post arousal events. Now whether those arousals are respiratory related or just bad-sleep related is an important question, and it's not entirely clear if we have enough data to rule out bad-sleep that is not respiratory related.

Here's what I mean: The following CA seems to be a post arousal event and the arousal doesn't seem to be respiratory related:
Image

In addition to that, the data over on SleepHQ shows little or no activity in the Flow Limitation graph, even when the handful of CAs are flagged. That too would indicate that UARS is probably not the culprit of your ongoing daytime fatigue and daytime sleepiness issues.

Now you specifically say:
My main ask: How would you interpret the disordered flow-rate shapes? Are they classic UARS flow-limits, “high loop-gain” wiggles, or just normal recovery breaths?
I'll be honest, I'm not sure what you mean by "high loop-gains". If you mean the behavior shown in this piece of your data:

Image

then I think the data we have around that first arousal (the first big breaths scored around 0:39:30) makes it look like that first arousal was not respiratory related---the breathing right before that arousal appears to be reasonably regular with reasonably shaped inhalations and the inhalations don't seem to be getting significantly smaller right before the arousal. What might explain that first arousal is the small leak: By itself the leak is both too small and too short lived to matter in terms of efficacy of xPAP therapy, but it may very well be that either the leak woke you up OR after you woke up, you moved around enough in bed to trigger the leak. Having said all that, I think what's shown here is that you're having trouble getting back to a continuous sleep after the first arousal. And that's more of a problem of bad sleep (i.e. SWJ) than anything respiratory related.


Now if "high loop-gains" means stuff that looks like this:

Image

then I'll admit it's not clear to me what's going on, beyond restless sleep. There's not a clear arousal before that first CA is scored, but this stretch doesn't look like high quality sleep breathing either. Only one small flow limitation is scored, but I also don't see any really "big" recovery breaths anywhere near that flow limitation. And we can't blame any of this restlessness on leaks because there aren't any leaks. If you were feeling fine, then it would be easy to just write this off as a bit of bad sleep that happens to everybody now and then and just not worry about. it.


You also write:
  • Diagnosed two years ago with mild-to-moderate obstructive sleep-apnea (sleep-lab AHI ≈ 10) but symptoms point strongly to UARS / flow-limitation–driven arousals: unrefreshing sleep, daytime fatigue, and “choking/sigh” awakenings even when event index is low.
Some people with untreated, but very mild OSA have pretty bad symptoms even if UARS is not an issue. In other words, I would not be inclinded to blame your pre-treated problems on UARS/flow limitations rather than just plain old OSA, even though your diagnostic AHI was only 10.


You also write:
  • Centrals: Not historically an issue, but becoming more frequent on bipap, though I don't know if they are true centrals or artifacts of something else.
and
  • Combining the BiPAP with my mandibular device + mouth tape has given me a few OK nights (inconsistently), but whenever I push pressure-support above ~6 cm the AHI usually climbs—mostly from clear-airway flags. I’m not sure how clinically meaningful these CA events are.
The data you've posted indicates that even if every one of your CAs was real, it's not enough of a problem to say treatment emergent central sleep apnea is a problem.

Your current settings based on the Oscar and SleepyHQ data you posted are:

min EPAP = 7;
max IPAP = 13,
PS = 6

The PS setting is on the high side for people who have a diagnosis of plain old OSA.

And it is worth pointing out that larger PS settings can lead to additional CAs in some people because a PS that is too large can lead some people to (occasionally) blow off too much CO2 during the exhalations, and that can trigger the CAs. Hence, your PS setting may explain many of the CAs you see in your data that don't seem to be post arousal CAs.

So I ask the obvious questions: Why use such a large PS? Was it in hopes that raising the PS might eliminate your (already nonexistent) flow limitations and your suspected, but not proven UARS problems? And did you settle on such a large PS on your own? Or was this based on a titration study with a bilevel machine?


You also write about your current settings:
[*]EPAP above ~6 cm (especially with PS > 6 cm and a very-high trigger setting) seems to bring on aerophagia.[/list]
If EPAP above 6 cm can trigger the aerophagia, why is your min EPAP = 7?

Aerophagia (my old nemesis) can trigger a lot of SWJ restlessness even if you don't remember waking up in the middle of the night with a bloated stomach. And unfortunately, because it's not uncommon to swallow when you arouse, aerophagia and multiple (non respiratory related) arousals can set up a very bad positive feed back loop:

.... more arousals lead to more swallowing which leads to more aerophagia which leads to more arousals which leads to more swallowing which leads to more aerophagia which leads to ...

The net result, of course, is a miserable night's sleep which can easily lead to a miserable day following that miserable nights sleep.

So again I ask some obvious questions: If EPAP > 6 can lead to aerophagia, why are you using EPAP = 7? Do the number of OAs and H's increase significantly if you set EPAP = 6? Did you have a titration study that indicated you needed EPAP = 7? Or was min EPAP = 7 just plucked out of thin air?


Now to get down to what you're really after. You write:
What I’d love your help with:
  • Interpreting the flow-rate shape and the CA clusters—do they point to CO₂ wash-out or something else?
  • Pinpointing settings that could smooth the flow curve without driving aerophagia or CAI.
  • Whether a step down in humidity/tube temp might relieve the congestion without hurting comfort.
  • Reducing sleep fragmentation in general. My Apple watch data (as seen on the SleepHQ dashboard) seems to hint at lack of deep sleep with a lot of fragmented stages and bouncing between stages sporadically.
As noted above, I think many of your CA clusters are likely triggered by an non-respiratory related arousal followed by your inability to quickly get back to a continuous sleep. In other words, my guess is that most (but not necessarily all) of your CAs and CA clusters are part of SWJ. But I also think that with PS = 6, you may be having a bit of CO2 wash-out, but its not so persistent as to earn you a diagnosis of treatment emergent central sleep apnea.

As someone who has experienced significant aerophagia problems, I understand your desire to pinpoint settings that will work for you without triggering the aerophagia.

Whether changing the humidity and tube temp settings will make any difference with respect to either congestion or comfort is highly variable. Tweaking the humidity and hose temp settings can do a lot for your comfort, which in turn can make it easier to get into and stay in a nice continuous sleep. But there aren't magic settings that work for even a majority of people. In general, if your nose loves a hot steamy shower, then turning down the humidity might be counterproductive. (And your nose may very well want additional humidity.) But if hot steamy showers leave your nose feeling congested, then turning down the humidity might very well reduce the congestion and increase your comfort. As for the tube temperature? If you feel like you're sleeping in a swamp, turn the tube temp down. If you feel like the air coming out of the vents is making you chilly when it hits your arms or chest, consider turning the tube temp up.

Now for your main concern: Help with pinpointing settings that could smooth the flow curve without driving aerophagia or CAI.

Here are my suggestions, along with my rationale for making each suggestion.

1) Reduce the Min EPAP to 5 or 6. Since EPAP > 6 is a potential trigger for aerophagia, see what happens if you set Min EPAP to 5 or 6. (My own aerophagia plagued stomach says use Min EPAP = 5, but 6 may be a more reasonable choice.) If the OAI or HI goes up significantly or if snores become an issue, you can always increase Min EPAP back to 7.

2) Reduce the PS to 4.. That's usually enough for people to gain substantial exhalation relief, but not enough to trigger problems with CAs. This should go a long way in preventing any minor CO2 washout problems that are being caused by your current PS = 6 setting.

3) Reduce Max IPAP to 10 or 11. This will prevent the EPAP from being raised to above 7cm. (My stomach says, reduce Max IPAP to 10 so that EPAP never is allowed to go above 6, and then see what happens to the OAI, HI, and the flow limitation curve.)

4) Don't microanalyze the shapes of the inhalations looking for potential flow limitations or minor variations in breathing every time you download the data. If your problem is fragmented sleep caused by SWJ cycles that are triggered by either aerophagia or minor CO2 washout issues, then "fixing" the shape of the flow rate curve by "smoothing" it out is not going to fix the root causes of your fragmented sleep. In other words, work harder on making sure you aren't getting caught in prolonged SWJ cycles that stem from either aerophagia issues and/or multiple non-respiratory related arousals.

5) Consider your own behavior in the middle of the night. What do you typically do when you find yourself awake in the middle of the night? Do you ever struggle to get back to sleep in a timely manor? And when you find yourself awake in the middle of the night, do you become anxious? If so, what are you anxious about? Remember that lying in bed half-awake while worrying is a good way to trigger a lot of unpleasant SWJ and destroy a decent night's sleep. So if your in the habit of worrying about your sleep every time you find yourself awake, you'll need to work on that issue.

My main rational for recommending setting Min EPAP = 5 or 6; PS = 4; and Max IPAP = 10 or 11 is the following: I think your current problems of waking up feeling tired and feeling sleepy and tired during the day are more likely caused by bad sleep rather than residual flow limitations/UARS related RERAs. And it's possible that you don't need as much pressure as you are currently using. Less pressure will mean less aerophagia, which should lead to better sleep. Less PS will lead to less of a possible (minor) problem with CO2 washout as well as less IPAP pressure which should also mean less aerophagia. And really thinking about what goes on in your head if/when you find yourself awake in the middle of the night may help pinpoint other possible causes of your continued problem of bad sleep.

Best of luck as you try to sort out what might make you feel better.
Joined as robysue on 9/18/10. Forgot my password & the email I used was on a machine that has long since died & gone to computer heaven.

Correct number of posts is 7250 as robysue + what I have as robysue1

Profile pic: Frozen Niagara Falls