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Should I believe the APAP readings?
#11
RE: Should I believe the APAP readings?
It would be quite helpful if you would repost per the guidance you've been given. It is hard to analyze a chart when it is in bits and pieces. Please include the left panel as well as all and only these graphs:

Events
Flow rate
Pressure
Leaks
Snores
Flow limitations.

Be sure you are zoomed all the way out so that all graphs will show information for the whole night.
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#12
RE: Should I believe the APAP readings?
Sorry I've been so long. I've had to connect up a monitor, to get a bit more screen resolution on this old laptop.

Hopefully, I've got it roughly right this time!


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#13
RE: Should I believe the APAP readings?
Good job on the chart. When you post the next one, you can substitute Pressure for Mask Pressure, but since you're using a fixed pressure, it doesn't much matter.

I'm not myself spotting what might explain that burst of CAs. Could you zoom in on a 10 minute stretch of that period and post so we can look in more detail? To zoom in, select a period and use the up/down/right/left arrows on your keyboard to get a 10 minute stretch with a bunch of CAs in it.

You're having a lot of large leaks too. Any known problems of mask fit or movement?
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#14
RE: Should I believe the APAP readings?
"You're having a lot of large leaks too. Any known problems of mask fit or movement?"

Very good question. I have been having an awful lot of problems with leaks, which is why I am using the APAP in CPAP mode. In CPAP mode I can adjust the straps to balance the pressure. It's a full face mask.

I sleep on my side, and I prop myself with pillows to try to remain on my side. However, of course, I do move whilst asleep, and it's not unknown for me to find myself on my back in the morning.

New screenshot attached. Smile

I haven't included the pressure chart, as it's a dead straight line.

I also did a second screenshot, during an uneventful part of the night for comparison.


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#15
RE: Should I believe the APAP readings?
May I inquire of the OP -- why do you suspect the machine is incorrectly reporting centrals? Also, controlling large leaks may be a worthwhile objective.
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#16
RE: Should I believe the APAP readings?
(07-01-2022, 11:40 PM)clownbell Wrote: May I inquire of the OP -- why do you suspect the machine is incorrectly reporting centrals? Also, controlling large leaks may be a worthwhile objective.


I was surprised at the large number of central apneas - basically that I don't really fit the bill for centrals, but I do fit the bill for obstructives.

I totally agree that controlling the leaks would be an excellent idea. I have tried several different masks without much success.

What has helped has been turning down the pressure. My hospital had set it at 13, and suggested I try a higher setting still (which I did for one night!). I was getting leaks of 70-80 to 80 lpm at those pressures, and the machine was reporting virtually only central apneas.

I have attached the output from last night. I have reduced the pressure still further, from 10 to 9. I am now getting fewer centrals, but more obstructives, with quite a lot of RERAs. Not sure I can win!

Sorry, I only wanted to attach one of those two almost-identical screenshots, but the remove button doesn't seem to work the way I expected.


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#17
RE: Should I believe the APAP readings?
In your most recent results, you reduced pressure and implemented EPR at 1, and your results improved fairly significantly by about 40% with a distinct movement away from CA to H and OA. We are uncertain what is causing the occasional clusters of CA events, but it seems unrelated to the EPR. I think we are almost in a trial and error mode here, and it would be interesting to see how you respond to an EPR setting of 2 with no other changes.
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#18
RE: Should I believe the APAP readings?
I moved to EPR 2 for last night. The results are much better, although I am not feeling particularly well rested this morning.

In the past I have experimented with EPR 2, and not been terribly happy with it.


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#19
RE: Should I believe the APAP readings?
I do not think your clustered "centrals" are real - you are probably experiencing periods of sleep/wake junk. The clustered centrals occur after the end of an extended period of large leaks. You probably were aroused by the leaks, adjusted the mask and are settling back to sleep. your inspiration time chart shows great excursions during these clusters, strongly suggesting wakefulness. Your most recent result (EPR of 2) are much better but the flow limits are high during your events. You probably could increase EPR to 3 to improve the flow limits. It may take a while to determine in the optimal settings (varying fixed pressure). It is not the numbers but how you feel that should be important. I found that lower flow limit and Lower H levels correlated best to How rested I felt. Also you may want to change your profile name to an alias as it appears on top of all posted charts.
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#20
RE: Should I believe the APAP readings?
Unlike most people here, I'm extremely skeptical of everything that the machine is doing when my mask is leaking. I question ALL of these things
  • The accuracy of the sensors -- whether the sensors are really operating correctly -- because sometimes we've seen data so internally inconsistent that a sensor must be broken.
  • The accuracy of the internal calculations that the machine records e.g. a resmed machine calculates the respiration rate from counting as the flow rate goes from a state of greater than 3.5 to zero and back to greater than 3.5, in other words it ignores the expiration part of the curve when calculating the respiration rate.
  • The programming of the machine as to how it is supposed to react to data that it is measuring directly and calculating.
My experience is that if I look at all of the data together, when there are leaks going on the data can range from "questionable" to "obvious nonsense".

The first question that you need to answer is what the heck your mask is in fact doing. I know from experience that my husband will tell me that my mask was doing the trombone thing and I slept right through it and had no idea. And I've seen data that is just obviously wrong, too -- that the flow rate curve reports that I'm exhaling way more air than I'm inhaling, but the leak is minimal. Um, no, I believe in the law of conservation of mass, and since I'm neither creating or destroying air the leak has to be a lot bigger than the machine thinks that it is!

If you can set up a camera to record (even the camera on your laptop propped up) or even recording audio, that will give you an independent measurement. Even without a recording, step zero is to make sure that when you are awake and you know that the mask was not leaking you need to look at the data and make sure that the machine recorded that the mask wasn't leaking!

What we do know is that a machine has pretty complex algorithms for interpreting sensor data and then deciding how to react to what the data is telling it. A malfunctioning sensor makes a total mess of this. More subtly, you as a patient doing something that the machine designers & engineers didn't expect could happen might just break everything! My experience is with 3 ResMed machines -- a 2014 airsense 10, a 2018 aircurve vauto, and a 2022 airsense 11. A huge weakness in these machines is that they will record themselves being in a state of utter confusion, but then they will not report anywhere that this happened.

For a medical device, this is terrifyingly bad engineering.
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