Can Itamar WatchPAT distinguish types of events?

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Darth Lady
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Can Itamar WatchPAT distinguish types of events?

Post by Darth Lady » Tue Apr 07, 2015 8:16 pm

I asked a more involved question that included this as an element, and didn't get a lot of response. So I'm breaking it down.

My machine says my AHI is under 1 every night. Sometimes even zero! A follow-up home study with a WatchPAT, on the other hand, said my AHI was 12 and my RDI was 22!

Now I'm going in for a re-titration study where, of course, they are going to crank the pressure to fix the "events" that the WatchPat study said I was having.

So here's the question: Can WatchPAT distinguish between obstructive/CA events, and "events" generated by, say, plain old O2 desaturation (which it found a lot of) from some other cause, like, say, insufficient respiratory effort while sleeping?

I've searched older threads here, but haven't found a definitive answer.

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Re: Can Itamar WatchPAT distinguish types of events?

Post by archangle » Tue Apr 07, 2015 11:11 pm

Darth Lady wrote:I asked a more involved question that included this as an element, and didn't get a lot of response. So I'm breaking it down.

My machine says my AHI is under 1 every night. Sometimes even zero! A follow-up home study with a WatchPAT, on the other hand, said my AHI was 12 and my RDI was 22!
Were you using your CPAP when you took the WatchPAT test?
Darth Lady wrote:So here's the question: Can WatchPAT distinguish between obstructive/CA events, and "events" generated by, say, plain old O2 desaturation (which it found a lot of) from some other cause, like, say, insufficient respiratory effort while sleeping?
I thought the WatchPAT was quackery when I first heard about it, but after a little reading, I think there's some real science there. I'm not entirely convinced that there's enough real world experience yet on how well it works in real life.

Does it claim to distinguish central from obstructive?

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Darth Lady » Wed Apr 08, 2015 6:33 am

Yes, I was using my xPAP when I took the WatchPAT test. We ran it because I'm still not feeling rested at night, or even much better than before I started therapy, even though my numbers are great.

I don't think Itamar claims that WatchPAT can distinguish types of apnea. But when they have run it head to head against polysomnograpy, it has been a pretty accurate reflection of what the full-scale study gives for AHI/RDI numbers.

My issue is that I suspect I'm just not breathing deeply enough to get enough oxygen, and that WatchPAT was reading the desaturations and resulting arousals as events (fair enough), and that the sleep lab is reading those events as obstructive and/or central (perhaps not warranted by the evidence).

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Re: Can Itamar WatchPAT distinguish types of events?

Post by archangle » Wed Apr 08, 2015 10:35 am

Do you have your data from the ASV the night of the WatchPAT test? Be sure and save a copy of the SD card from that date.

If the ASV says no apneas on that night, and the WatchPAT says yes, the WatchPAT is wrong. It might be interesting to look at your flow rate waveforms and other data at the times the WatchPAT shows events.

However, you might have some more subtle problem that the WatchPAT is seeing. Not "apnea," but some other problem such as hypoventillation.

Do you have real data from the WatchPAT, such as graphs of SpO2 or whatever it records?

It might be worthwhile for you to get one of the CMS recording oximeters that works with SleepyHead and get some more data.

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Janknitz » Wed Apr 08, 2015 12:41 pm

Darthlady, you can get your print out of the detailed WatchPat report with all the graphs. I think you're Kaiser, so you can request it, and may be able to get it electronically.
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Re: Can Itamar WatchPAT distinguish types of events?

Post by kaiasgram » Wed Apr 08, 2015 1:01 pm

Janknitz wrote:Darthlady, you can get your print out of the detailed WatchPat report with all the graphs. I think you're Kaiser, so you can request it, and may be able to get it electronically.
Yes. And you can also walk into the Member Services office of your local Kaiser and they should be able to print it out for you.

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Darth Lady » Wed Apr 08, 2015 4:12 pm

archangle wrote:Do you have your data from the ASV the night of the WatchPAT test? Be sure and save a copy of the SD card from that date.

If the ASV says no apneas on that night, and the WatchPAT says yes, the WatchPAT is wrong. It might be interesting to look at your flow rate waveforms and other data at the times the WatchPAT shows events.

However, you might have some more subtle problem that the WatchPAT is seeing. Not "apnea," but some other problem such as hypoventillation.

Do you have real data from the WatchPAT, such as graphs of SpO2 or whatever it records?

It might be worthwhile for you to get one of the CMS recording oximeters that works with SleepyHead and get some more data.
I've got all the data; I download it into SleepyHead regularly. I don't have real data from the WatchPAT, just the hypercondensed printout they stick in the report. I actually do suspect that I'm hypoventilating rather than having obstructive events, and I suspect (don't know, which is why I started this thread) that WatchPAT uses desats along with circulatory changes/arousals to flag events. I also suspect (but don't know) that it can't tell hypoventilation from an obstructive event.

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Darth Lady » Wed Apr 08, 2015 4:15 pm

kaiasgram wrote:
Janknitz wrote:Darthlady, you can get your print out of the detailed WatchPat report with all the graphs. I think you're Kaiser, so you can request it, and may be able to get it electronically.
Yes. And you can also walk into the Member Services office of your local Kaiser and they should be able to print it out for you.
I'm not Kaiser; I'm BCBS, but I can ask my sleep doc for the whole data set/extended report. I'm seeing her tomorrow, to discuss whether more pressure is really the answer to everything

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Morbius » Thu Apr 09, 2015 4:42 am

Darth Lady wrote:Can WatchPAT distinguish between obstructive/CA events, and "events" generated by, say, plain old O2 desaturation (which it found a lot of) from some other cause, like, say, insufficient respiratory effort while sleeping?
If you have real central apnea (cycling) the PAT signal may have the same waxing/waning characteristics:

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Morbius » Thu Apr 09, 2015 5:18 am

Darth Lady wrote:My machine says my AHI is under 1 every night. Sometimes even zero! A follow-up home study with a WatchPAT, on the other hand, said my AHI was 12 and my RDI was 22!
That's the ASV Fallacy (Cover It With A Band Aid - If You Don't See It, It Must Not Be There).

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Darth Lady » Thu Apr 09, 2015 7:44 am

I do have a periodicity to my breathing, sometimes quite pronounced, that the machine tries to correct, that doesn't "grow up" into anything it considers flag-able. As for the rest of it, I guess I'll have to put up with yet another sleep study . I just hope I can get my doc to look for underlying causes, and at other solutions besides "crank the pressure."

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Darth Lady » Thu Apr 09, 2015 8:18 am

Morbius wrote:
Darth Lady wrote:My machine says my AHI is under 1 every night. Sometimes even zero! A follow-up home study with a WatchPAT, on the other hand, said my AHI was 12 and my RDI was 22!
That's the ASV Fallacy (Cover It With A Band Aid - If You Don't See It, It Must Not Be There).
Oh, and I'm curious to know what it is about the ASV algorithms that would make it so inaccurate, if that's the issue.

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Morbius » Fri Apr 10, 2015 3:47 am

Darth Lady wrote:Oh, and I'm curious to know what it is about the ASV algorithms that would make it so inaccurate...
I did not say it was inaccurate.

I said there is a Fallacy.

This was disclosed during the famous State of Confusion v. ASV (2005) trial where, during brisk cross examination, it was revealed:

Prosecution: Did you send in nice-looking breaths?

ASV: Yes.

Prosecution: Did they actually do anything?

ASV: No.

ASV technology was designed to break the chain of central events, thus solving the problem. It will rapidly attack central apneas and back off during normal breathing until the chain is broken and only normal breathing ensues.

However, if your machine is attacking all night the problem is never getting solved. The ASV will put up some nice waveforms and read it as acceptable breathing, but the underlying event persists.

I am postulating that's why the discrepancy exists between the ASV readings and Watch PAT(which can look under the Band-Aid).

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Re: Can Itamar WatchPAT distinguish types of events?

Post by robysue » Fri Apr 10, 2015 10:42 am

Morbius wrote: ASV technology was designed to break the chain of central events, thus solving the problem. It will rapidly attack central apneas and back off during normal breathing until the chain is broken and only normal breathing ensues.

However, if your machine is attacking all night the problem is never getting solved. The ASV will put up some nice waveforms and read it as acceptable breathing, but the underlying event persists.

I am postulating that's why the discrepancy exists between the ASV readings and Watch PAT(which can look under the Band-Aid).
Morbius,

Are you saying the ASV is reporting a nice low AHI because it's confusing the "nice regular waveform" that's being generated by the ASV's aggressive attacking of the central apneas with real normal breathing? And the Watch PAT is not confused by the ASV-generated "nice regular waveform" because it's looking at different data? And the Watch PAT can see that in spite of the ASV-triggered inhalations which smooth the waveform out, the desats are still happening?

And a more general question for you: When is "ASV confusion" most likely to happen?

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Re: Can Itamar WatchPAT distinguish types of events?

Post by Darth Lady » Fri Apr 10, 2015 4:16 pm

I'm also looking forward to the answer to that question.

Saw the sleep doc yesterday. She seems convinced that I'm having obstructive events although she also says that WatchPAT can't tell what kind of event you're having. I told her that my concern is that this may be part of other neurological problems I am having; that the muscles I use for breathing are being affected and when I am asleep I can't compensate. I will just have to see how Sleep Study No. 4 goes.

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