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Anatomy of an event - ResScan Data
#1
I zoomed in on the data surrounding an OA event on my Bilevel AirCurve10; this is what I see.
Flow and pressure are provided as very high rate data; the rest is slow rate.
The event is reported as a 12 sec OA.
It starts with the pressure doing it's periodic thing swinging smoothly from 6.5 to 10.5 and flow is leading it by maybe 0.25 sec at most.
The flow reaches its peak normally, no anomaly noted, but the pressure does not follow it. Instead it swings up and reports a sharp peak at 11.4 cmH2O and slides down sharply. The pressure then makes another anomalous rise and falls to 6.4 cm where it stays for 16 sec. It ocillates 0.1cm around 6.4 for the last 10 sec then starts up the correct swing again going from 7.3 to 11.3 The pressure stopped responding before the flow stopped.
Meanwhile the flow swings normally until the pressure locks at 6.4 and then it goes to around zero where it stays for 16 sec. A blip on the flow data after 16 sec seems to instigate the pressure swing again.
3 sec later the OA event is reported.
There are no flow limits or snores reported. The ventilation, tidal volume,RR all show decrease at the slower data rate. Leaks are around zero.

So... Why does it look like the machine pressure instigated this event?

I see the oscillation on the pressure data half way through an event on most instances of flow stoppage including those less than 10 sec which don't get reported.
How does this compare to your events?
if you can't decide then you don't have enough data.
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#2
Nice essay. A picture is worth 1000 words. Can you post a graph?

Flow direction triggers pressure from IPAP to/from EPAP.
Zero flow triggers the FOT algorithm to create a pressure oscillation after 4 seconds.
The reflected wave is used to type the apnea as OA or CA.
No apnea will be flagged less than 10 seconds.
Trigger from IPAP to/from EPAP is restored when the flow meter detects flow again; even a blip.

There are sensitivity settings for the pressure switch -- leave them at default.
(i.e. - never mess with them.)
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
(05-26-2015, 12:31 PM)justMongo Wrote: Nice essay. A picture is worth 1000 words. Can you post a graph?

Flow direction triggers pressure from IPAP to/from EPAP.
Zero flow triggers the FOT algorithm to create a pressure oscillation after 4 seconds.
The reflected wave is used to type the apnea as OA or CA.
No apnea will be flagged less than 10 seconds.
Trigger from IPAP to/from EPAP is restored when the flow meter detects flow again; even a blip.

There are sensitivity settings for the pressure switch -- leave them at default.
(i.e. - never mess with them.)

Great info on the ocillations. Thanks.
if you can't decide then you don't have enough data.
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#4
    The data
if you can't decide then you don't have enough data.
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#5
Looks like what I see for an OA.
There is a hint of impending OA at the very beginning of the plot. Flow went to zero for for about a second.
Then the flow and pressure are ragged just before the obstruction.
In the roughly 3 hour span in the top window, looks like you are doing quite well.
I'd say the machine is doing the job nicely for you.

Kindest regards,

Mongo
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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