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AHI measurement
#1
Hi all.

I awakened this morning and looked at the usage, mask fit and AHI data for my Resmed S9 machine with a nasal pillows mask. It showed 7.9 hours of use and an AHI of 1.1. Now fully awake, I kept my CPAP machine on, with my the nasal pillows mask on for an additional 20 minutes and re-read the display. The AHI had jumped to 1.4. Since I was fully awake, I think I would have noticed if I had stopped breathing. I did not. Is the increase in the AHI reasonable under these circumstances?
Additionally, the display showed a "frown" for mask fit. I did remove the mask with the machine still running (i.e., not turned off) twice during the night for about 2 to 3 minutes each time. How do such disruptions effect the AHI? I use the auto-start feature with the S9, which will stop the machine when I remove the mask, and restart it again when I replace it and it senses I'm breathing. Each time the machine is restarted under these circumstances, I run the test to determine if there is a mask leak. There was no leak indicated.


Thanks in advance any replies.
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#2
Hi pstoloff,
WELCOME! to the forum.!
Hang in there for answers to your questions and best of luck.
trish6hundred
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#3
It raised because our breathing during awake is different than our breathing during sleep. The machine does not know if you are awake or not.

Look at the data via ResScan or SleepyHead and see what changed during that time frame. A jump from 1.1 to 1.4 is not that large so it might have noted one possible event. Perhaps as you sat up and looked at the machine's screen, you held your breath just enough that it registered it as a hypopnea event.
PaulaO2
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Breathe deeply and count to zen.

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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#4
(05-30-2013, 10:12 AM)pstoloff Wrote: Additionally, the display showed a "frown" for mask fit. I did remove the mask with the machine still running (i.e., not turned off) twice during the night for about 2 to 3 minutes each time. How do such disruptions effect the AHI?
Thanks in advance any replies.
Events scored while wake are meaningless and be discarded for true AHI value. Also data is not reliable with leaks above 30 L/min

Mr Red Frowny face shows up if your 70% leak rate is greater than 24 L/min.
Mt Green smiley face shows up if your 70% leak rate is less than or equal to 24 L/min

As long as you are leaking at a rate of less than or equal to 24 L/min above your mask's intentional leak rate, ResMed do not believe there is a problem and Mr Green Smiley face shows up on the LCD "Sleep Quality" report

As for masks, everyone is different. I too sleep on my side and find chinstrap worn over the mask helps keeps the mask in place and the Activa LT cushion very flexible perfect for keeping a good seal with movement and the vents extremely quiet





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#5
(05-30-2013, 03:26 PM)PaulaO2 Wrote: It raised because our breathing during awake is different than our breathing during sleep. The machine does not know if you are awake or not.

Look at the data via ResScan or SleepyHead and see what changed during that time frame. A jump from 1.1 to 1.4 is not that large so it might have noted one possible event. Perhaps as you sat up and looked at the machine's screen, you held your breath just enough that it registered it as a hypopnea event.

How do mask leaks effect the AHI?
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#6
(06-18-2013, 08:53 AM)pstoloff Wrote: How do mask leaks effect the AHI?

Without providing some sort of detailed technical info, the leaks affect AHI in that if the leaks are too high, you will not be getting the full amount of pressure needed to open up your airway (in order to stop apnea events). Thus AHI will generally rise the more leaks you have.

For instance, if you put several one-inch round holes in your CPAP tubing, that would induce so much air leakage that the pressure differential between the outside air and the air coming through the end of the hose into your mask will be next to nothing - and would have the same effect as having no pressure at all.

Modern CPAPs can account for some degree of leak and still provide effective therapy by making on-the-fly pressure adjustments to bring AHI into line (remaining below 5.0) - but once the leaks become major - no amount of CPAP auto-adjustments will help to lower AHI much.

SuperSleeper
Apnea Board Administrator
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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#7
Does a yawn where your mouth is open and you breathing through your mouth, trigger an AHI event?
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#8
(06-20-2013, 12:14 AM)xwindowuser Wrote: Does a yawn where your mouth is open and you breathing through your mouth, trigger an AHI event?

Hello and welcome to the forum xwindowuser....

Since there is a minimum duration for an event to be flagged the question becomes...

Does the yawn last for more than ten seconds?

Even if it does it may not be seen as a Hypopnea nor an apnea... I think it would show in the .
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