Technical Question about CA's

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
MMcG
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Technical Question about CA's

Post by MMcG » Wed Dec 01, 2021 11:13 am

I've been using a Devilbiss/Intellipap 2 machine for about 12 weeks now. I've noticed (via Oscar) that I get very little OA's (usually none or maybe one nightly). So mostly hypopneas, but some (average about 5) CA's too. I understand that some machines differentiate between CA's and OA's by giving a short pulse of increased pressure when apnea is detected. If no resistance, then assumed to be a CA. But my machine doesn't do that. So I'm guessing that the algorithm factors in the breathing pattern before and after the event, as well as perhaps snoring, flow limitations, etc. My guess is that there is a strong likelihood that most of these events are actually OA's that are just mis-categorised by the machine algorithm. I had a night recently when I had 13 flagged CA's and 2 flagged OA's (I was exhausted after a particularly stressful day - no meds or alcohol though). Hopefully, it's a blip, but it got me wondering whether my machine is a bit deficient. If it's wrongly labelling OA's as CA's, then it's not responding correctly (it's APAP). Any thoughts?

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Julie
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Re: Technical Question about CA's

Post by Julie » Wed Dec 01, 2021 3:58 pm

Show an Oscar report here.

MMcG
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Re: Technical Question about CA's

Post by MMcG » Thu Dec 02, 2021 1:44 am

Julie wrote:
Wed Dec 01, 2021 3:58 pm
Show an Oscar report here.
I'll take some screenshots for that night, Julie, and post them here.

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MMcG
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Re: Technical Question about CA's

Post by MMcG » Thu Dec 02, 2021 8:19 am

Here are some screen shots from the night I had thirteen flagged CA's. One of the two OA's was false - it was when I woke up and removed the mask briefly for a sip of water. But As far as I can see, at least 8-9 of the CA's are real events. My question was really about doubting the ability of my Devilbiss machine to differentiate between CA's and OA's and, accordingly, failing to react to prevent them. I'm considering increasing my minimum pressure to 7 assuming, I can tolerate it (can fall asleep) and perhaps raise the max to 10, although when my max pressure was 14 to begin with, I rarely exceeded 8.

This is just all the events, including the flow rate (not much use at this scale), the pressure and leak rate:-
Screen Shot 2021-12-02 at 13.57.14.png
Screen Shot 2021-12-02 at 13.57.14.png (286.14 KiB) Viewed 1964 times
And some close-ups of flow rate during flagged events (one fairly short OA and a dubious enough H). Looks like I can only show three attachments, so the two CA's are below in separate comment:-
Screen Shot 2021-12-02 at 14.01.38.png
Screen Shot 2021-12-02 at 14.01.38.png (167.92 KiB) Viewed 1964 times

_________________
Mask: AirFit™ N10 Nasal CPAP Mask with Headgear
Additional Comments: My machine is sold in Europe as Devilbliss Blue Auto Plus Automatic
Attachments
Screen Shot 2021-12-02 at 14.03.03.png
Screen Shot 2021-12-02 at 14.03.03.png (200.17 KiB) Viewed 1964 times

MMcG
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Re: Technical Question about CA's

Post by MMcG » Thu Dec 02, 2021 8:33 am

Screen shots of two flagged CA's, which. as far as I can tell, are just as likely to be OA's. From what I've read APAP machines are not really great at differentiating between OA's and CA's anyway, and the Devilbiss/Intellipap is probably the weakest of them (no pressure pulse or anything like that - just relies on computer algorithms).
Screen Shot 2021-12-02 at 14.28.09.png
Screen Shot 2021-12-02 at 14.28.09.png (214.6 KiB) Viewed 1961 times
Screen Shot 2021-12-02 at 14.28.09.png
Screen Shot 2021-12-02 at 14.28.09.png (214.6 KiB) Viewed 1961 times

_________________
Mask: AirFit™ N10 Nasal CPAP Mask with Headgear
Additional Comments: My machine is sold in Europe as Devilbliss Blue Auto Plus Automatic
Attachments
Screen Shot 2021-12-02 at 14.04.08.png
Screen Shot 2021-12-02 at 14.04.08.png (202.71 KiB) Viewed 1961 times

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Pugsy
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Re: Technical Question about CA's

Post by Pugsy » Thu Dec 02, 2021 8:51 am

You've zoomed in a little too close on those CAs.
The one timed at 01:07...that's a false positive. Can't really see enough of the other one to say for sure.

As for how does the Devilbiss decide?? Beats me but it has the same limitation as all other machines...it doesn't know if you are asleep or not.
Does it make mistakes and call an OA a CA....very possible...it can happen with the other brands as well.
These machines aren't perfect ....nothing ever is. They do the best they can with what was given to them though.

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MMcG
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Re: Technical Question about CA's

Post by MMcG » Thu Dec 02, 2021 9:10 am

Pugsy wrote:
Thu Dec 02, 2021 8:51 am
You've zoomed in a little too close on those CAs.
The one timed at 01:07...that's a false positive. Can't really see enough of the other one to say for sure.

As for how does the Devilbiss decide?? Beats me but it has the same limitation as all other machines...it doesn't know if you are asleep or not.
Does it make mistakes and call an OA a CA....very possible...it can happen with the other brands as well.
These machines aren't perfect ....nothing ever is. They do the best they can with what was given to them though.
Thanks Pugsy. I see what you mean about the CA at 1-07 am. Looks like arousal breathing prior to the event, although I have no recollection of waking at that time (I do a regular sleep diary every morning). But it also coincides with a small leak, so perhaps I turned over on my side and moved the mask briefly. And, yes, I know that it's really only a sleep lab test that can differentiate between OA's and CA's. But it's got me thinking that I need to raise my minimum pressure a little (maybe 6.5 first for a week and then 7.00) if I can tolerate it. Wider screen shots below:-
Screen Shot 2021-12-02 at 15.05.58.png
Screen Shot 2021-12-02 at 15.05.58.png (204.84 KiB) Viewed 1954 times

_________________
Mask: AirFit™ N10 Nasal CPAP Mask with Headgear
Additional Comments: My machine is sold in Europe as Devilbliss Blue Auto Plus Automatic
Attachments
Screen Shot 2021-12-02 at 15.06.51.png
Screen Shot 2021-12-02 at 15.06.51.png (241.19 KiB) Viewed 1954 times

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Pugsy
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Re: Technical Question about CA's

Post by Pugsy » Thu Dec 02, 2021 9:48 am

We can, and do, have arousals that we don't remember. Just because we don't remember it happening doesn't mean it didn't happen.

Your reports do seem to show a lot of "clutter" which on the face of it might point to a need for more baseline/minimum pressure but you also report evidence of a lot of arousal related flagging and while we like to think that more pressure is the key...it's not always the fix. Lots of things can cause arousals and apnea events is just one item on a very long list.

My AHI last night...per the sleep report LCD screen...was 3.0 but I already know I had a rough night last night.
I haven't downloaded yet to go look but I fully expect that at least 75% of that AHI is going to be false positives.
Lots of arousals that I remember last night which means even more arousals that I don't remember.
More pressure isn't the answer...fixing the bad back and the pain...that's my answer.

Your sleep reports just scream poor sleep quality to me. As to why? That's the million dollar question isn't it?
Gotta figure out the problem first to have any chance of fixing it.
You can always try more pressure just to see if it helps or not...easy experiment as long as more pressure doesn't cause a problem like aerophagia.
And remember...aerophagia itself can cause arousals.
Damned if you do and damned if you don't.

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Machine: AirCurve™ 10 VAuto BiLevel Machine with HumidAir™ Heated Humidifier
Additional Comments: Mask Bleep Eclipse https://bleepsleep.com/the-eclipse/
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MMcG
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Re: Technical Question about CA's

Post by MMcG » Thu Dec 02, 2021 11:43 am

Pugsy wrote:
Thu Dec 02, 2021 9:48 am
We can, and do, have arousals that we don't remember. Just because we don't remember it happening doesn't mean it didn't happen.

Your reports do seem to show a lot of "clutter" which on the face of it might point to a need for more baseline/minimum pressure but you also report evidence of a lot of arousal related flagging and while we like to think that more pressure is the key...it's not always the fix. Lots of things can cause arousals and apnea events is just one item on a very long list.

My AHI last night...per the sleep report LCD screen...was 3.0 but I already know I had a rough night last night.
I haven't downloaded yet to go look but I fully expect that at least 75% of that AHI is going to be false positives.
Lots of arousals that I remember last night which means even more arousals that I don't remember.
More pressure isn't the answer...fixing the bad back and the pain...that's my answer.

Your sleep reports just scream poor sleep quality to me. As to why? That's the million dollar question isn't it?
Gotta figure out the problem first to have any chance of fixing it.
You can always try more pressure just to see if it helps or not...easy experiment as long as more pressure doesn't cause a problem like aerophagia.
And remember...aerophagia itself can cause arousals.
Damned if you do and damned if you don't.
A strange pattern seems to have crept in, Pugsy. On those night's (such as the one above) where I felt I slept fairly well, just waking a couple of times, I seem to have had a lot more events. Then when I feel I've woken up a lot, or strangely having had a couple of glasses of wine with dinner (fairly rare these days!), I have very few events, but feel really tired next day. My sleep technician feels that my brain may still be adapting to the new more benign regime, i.e. it's been starved of oxygen every three minutes or so for God knows how many years and probably remains "alert" to some extent as a result. I'll be seeing my consultant in a couple of weeks time and she may be able to offer better insights. Thanks for the feedback. Very much appreciated.

_________________
Mask: AirFit™ N10 Nasal CPAP Mask with Headgear
Additional Comments: My machine is sold in Europe as Devilbliss Blue Auto Plus Automatic