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AHI Discrepency - Machine vs SD Card
#1
Hello again,

I just finished my 10th night on CPAP with 100% compliance. Thus far, I have been fortunate in that my AHI has been consistently [Edit] 0.24 or lower (only one night of .24 and one night of 0.16--I'm usually 0.1 - 0.13).

After getting what I thought was a pretty good night's sleep, I was surprised to see my ResMed show AHI reading 1.6. I had to look twice to make sure I saw the decimal in the right place. I then checked MyAir site and it showed 1.6 in larger numbers LOL.

So, I decided to pull the SD card and see what the heck happened because the night before I registered my first 0.0 AHI in a session greater than 7.5 hours.

I import last night's data and it shows an AHI of 0.12 with one OA at 6:45 AM.

Here is last night's stats from SleepyHead:

Details Most Recent

CPAP Usage
Average Hours per Night 8:30
Compliance 100%

Therapy Efficacy
AHI 0.12
Obstructive Index 0.12
Hypopnea Index 0
Clear Airway Index 0
RERA Index 0

Leak Statistics
Average Leak Rate 0
90% Leak Rate 0
% of time above Leak Rate threshold 0.00%

Pressure Statistics
Average Pressure 7
Min Pressure 7
Max Pressure 7
90% Pressure 7


MyAir also shows 2 mask offs which is odd as last night was the first time since starting my cpap therapy that I didn't have to get up to use the restroom and as I can tell, I didn't take my mask off and put it back on twice last night.

My nostrils are irritated, a little red, and sore. I am guessing there was some movement of the pillows last night which may have registered as a mask off instead of a leak (0.0 leaks last night).

I assume the SD card data is authoritative and there isn't some bug in SleepyHead which would cause to report some but not all of the events (would be very odd bug to report one out of an estimated 13.6 events).

I am not overly concerned about it, but I would like to understand this phenomenon more.

Does anyone know why there may be a discrepancy? It really doesn't seem to make sense that that the data the machine displays and transmits to MyAir is so different than what is recorded on the SD card.

Thanks in advance. You all have been very helpful and patient with my questions thus far.
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#2
Has anyone else had the machine show one AHI number and the data on the SD card show another?
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#3
Try downloading ResScan and see what it reports. See which report ResScan corresponds to. Also, you can be selective and turn off sleep sessions on the daily view of SH which will change the reported AHI for that day.
______________________
Useful Links -or- When All Else Fails:
Posting SleepyHead Charts in 5 Easy Steps
Robysue's Beginner's Guide to Sleepyhead
Apnea Helpful Tips
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#4
I've heard of it. Many times it is due to the time on the CPAP not matching current time and Sleepyhead using the noon cutoff which ends up slicing the day up in a way that the CPAP doesn't.

I would check the time of your CPAP, the time of your computer using Sleepyhead and you might pull the power on the CPAP for about 20-30 seconds and see if that resets something. You can also try using ResScan to see what it sees.
With regards to sleep sessions, when looking at Sleepyhead for a day, there will be at the bottom left of the display a list of sessions it saw for that period of time. The bar next to each session can be red or green. Green it is showing up in the stats, Red it won't.

Looks something like:
[Image: iFLC1Vp.png]
Current Settings PS 4.0 over 10.6-18.0 (cmH2O) BiLevel Auto
TNET Sleep Resource Pages
CPAP Machine Database
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#5
Also if you are looking at sleep report screen on the Airsense be sure the time frame agrees......the default average on the machine is 30 day time period averages.......this setting can be changed to one day, one week, one month, one year average.

And be aware if power is interrupted to machine either by unplugging it or a power failure it will default back to thirty day average.......that often catches people because they thought they set the time frame to one day.
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