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Sleepyhead question: A vs OA vs CA
#1
Mr Daily Report (no, not Jon Stewart) says:
AHI = AI+HI+CAI+UAI
AI = Obstructed Apnea Index
HI = Hypopnea Index
CAI = Clear Airway Index (Central?)
UAI = Unobstructed Airway Index????

The last item just showed up > 0 for the first time last night.

It is a small number & I probably should ignore it, but...

Anyone know what it means?

Thx,
PaBlum
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#2
Never heard of it. It looks like maybe it's an unidentified event? I dunno.
Sleepster
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#3
It is shown just as "Apnea" on the screen version of the report. You may be right because when I saw it on the screen, my guess was that it was an Apnea event that the machine couldn't decide whether it was Obstructive or Clear. I'll go with that theory unless someone chimes in with either a better theory or knows the answer.
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#4
The determination of these types of apneas may be different depending on the manufacturer (I'm not sure), but at least for the S9 series they are defined as:

Quote:An unknown apnea is an apnea
during which a leak higher than 30
L/min occurs, precluding accurate
determination of whether the apnea is
obstructive or central.

http://www.resmed.com/us/assets/document...er_eng.pdf

SleepyHead calls these "Unspecified" apneas, and in ResScan they're called "Unknown" apneas.
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#5
Thank you!
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#6
Welcome, though after looking through my own data to find one (was a lot like looking for a needle in a haystack) I'm wondering if there are maybe more reasons that an apnea can be flagged this way besides a high leak. Thinking-about

At the time that this event occurred in the picture, my leak rate seems well controlled. I'm guessing the flow signal was too noisy for the machine to make an accurate call, but what caused the noise?

[Image: Unspecified_Apnea.jpg]
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#7
Pressure pulses are sent to determine if the airway is open or closed. I think that how the flow rate changes in response to these pulses is used to make the determination of open versus closed. It could be that for some of the pulses the airway appeared open, and that for the others it appeared closed. Thus a determination couldn't be made.
Sleepster
Apnea Board Moderator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#8
Another thought about OA vs CA is something I just found out: I'm pretty sure I was getting false readings from my software, so now I take my readings with a grain of salt and I'm using how I actually feel as my 'gold standard'.
For instance, I just discovered I have a problem with air leaking out my mouth and the first night I used a chin strap all my 'CA' events disappeared. I think it's most likely that keeping my mouth closed made the software reporting more accurate, rather than the alternative theory that keeping my mouth closed 'cured' my CA.
So anyway, I'm tending to ignore weird little 'glitches' that turn up on the graphs, as long as I feel okay.

Further idea: With the chin strap my OA events have reduced quite a bit according to my software. I believe the results because it makes sense that when all the positive pressure leaks out though your mouth then there's nothing left to open the sagging airway.
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#9
What you say makes sense. In my case, I use a full face mask so I don't have a problem with leaking from my mouth, but as I tend to turn a lot, small leaks may be confusing the computer.

I seem to have given myself a serious case of tinnitus and have been backing down on the pressure. If it hasn't mostly cleared by Monday, I'll go see my ENT.

BTW, I noticed something interesting. The pressure varies up and down during the course of the night, but if I draw a trend line, it is moving upward. I'm not sure what that means.
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#10
(09-06-2013, 08:57 PM)awakeiam Wrote: I think it's most likely that keeping my mouth closed made the software reporting more accurate, rather than the alternative theory that keeping my mouth closed 'cured' my CA.

You're correct. And this is something essential to interpreting the data.

If your leak rates are not under control, the AHI data reported by your machine is garbage.

To take the measurements used to determine the indices that add up to the AHI, the machine uses readings from its flow rate meter and its pressure sensor. When the leak rate is too large the readings can no longer be used to make those determinations. The machine cannot reliably distiguish between the types of apneas you're having, or tell the difference between an apnea and a hypopnea, or even determine if you're having an apnea or a hypopnea.

Effective therapy can be achieved only if your leak rates are under control.
Sleepster
Apnea Board Moderator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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