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AHI Question- "Average" vs Graph.
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lmoretti Offline

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Posts: 75
Joined: May 2015

Machine: PR System One 60 with AFlex
Mask Type: Nasal pillows
Mask Make & Model: Resmed P10
Humidifier: PR
CPAP Pressure: 9
CPAP Software: SleepyHead

Other Comments:

Sex: Male
Location:

Post: #1
AHI Question- "Average" vs Graph.
So the AHI that shows up on my machine and in the detailed summary in SleepyHead is pretty good; averaging 2-3 overall.

The issue is that when I look at the data graph my AHI many nights spikes into the 11-16 range during the middle of the night. A few of my worst nights I wake up, go to the bathroom, and when I come back the AHI graph appears to have plummeted because I took the mask off for a bit.

Is this pattern "normal" or should I talk to the sleep clinic about it? I have 4 weeks until my first "follow up" appointment. I'm already planning to talk to them about putting my machine from fixed 9cm into "Auto" with a range of ~8-14 to observe what pressures it uses.
06-24-2015 08:35 AM
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justMongo Offline

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Posts: 3,848
Joined: Sep 2013

Machine: ResMed VPAP Auto (S9)
Mask Type: Full face mask
Mask Make & Model: ResMed Mirage Quattro
Humidifier: ResMed H5i
CPAP Pressure: 18 IPAPmax - 11 EPAPmin, PS=5
CPAP Software: Other Software

Other Comments: μολὼν λαβέ

Sex: Male
Location: Калифорния

Post: #2
RE: AHI Question- "Average" vs Graph.
It's normal. The detailed summary for a night is averaged over the entire time on the machine.
The AHI graph is a moment in time. That graph is sort of useless.

Sort of like your car speedometer telling you you are going 85 miles per hour at an instant; when the cop pulls you over and says: "Do you know you were going 85 MPH?" And, you answer, "That's impossible; I've only been driving 10 minutes." /joke

Or, making the analogy more serious: At a point in a car trip you might register 85 MPH on the speedometer; but averaged over the trip, your average speed might be only 45 MPH.

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.
06-24-2015 09:01 AM
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AshSF Online

Advisory Members

Posts: 356
Joined: Oct 2014

Machine: PRS1 D560TS
Mask Type: Nasal pillows
Mask Make & Model: ResMed P10, Bkup: Airfit F10 & Quattro Air
Humidifier: PRS1 60 series with Heated Tube
CPAP Pressure: 8 - 8 w/ Aflex 3
CPAP Software: SleepyHead

Other Comments: Using APAP mode with fixed pressure

Sex: Male
Location:

Post: #3
RE: AHI Question- "Average" vs Graph.
You should post your sleepyhead graph for the night. An AHI zooming to 10-16 for an hour may mean that your cpap pressure is not fending off clusters of apnea and/or hypopnea events when that AHI zooms. You may need to raise the pressure by a modest amount to fend off such clusters of events.

Started APAP 4-20, Closed range to 7.5-14, then straight 8.0 w/ Aflex 3
RDI always below 1. But sleep much much better at straight pressure.
Started on F10, Tried Quattro Air successfully. Finally settled on P10.
06-24-2015 10:26 AM
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Homerec130 Offline

Advisory Members

Posts: 444
Joined: Mar 2012

Machine: Philips/Resperonics BiPAP auto SV Advanced System One (950P)
Mask Type: Full face mask
Mask Make & Model: ResMed Quatro FX
Humidifier: Philips Respironics System 1
CPAP Pressure: 6-16
CPAP Software: SleepyHead

Other Comments: But it is a dry heat.

Sex: Male
Location: Tucson, AZ

Post: #4
RE: AHI Question- "Average" vs Graph.
Another thing to take into consideration is what were you doing at the time? Were you really asleep or were you lying there awake and trying to get back to sleep? The machine doesn't know when you are asleep or not and often treats your normal awake breathing pattern as apneas. I see that quite a bit in mine when my wife wakes me up and I just lie there. See the spikes in my AHI.
06-24-2015 12:48 PM
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