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Some interesting differences between PAP resultes and sleep study results
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KSMatthew Offline

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Posts: 179
Joined: Jul 2016

Machine: PR DreamStation Auto
Mask Type: Nasal pillows
Mask Make & Model: ResMed Swift FX
Humidifier: none
CPAP Pressure: 7
CPAP Software: SleepyHead

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Sex: Male
Location: Kansas, United States

Post: #1
Some interesting differences between PAP resultes and sleep study results
This article mentions the differences in how AHI numbers are calculated, why they may differ from machine to machine, and why they will be different between a CPAP and a sleep study:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3274337/

I'm sure there are other explanations, but I came across this first while looking for something.

A PSG will also use oxygen levels for part of the formula to determine an AH event. A CPAP can't do that, so it has to estimate. This probably can lead to brand to brand differences. Also, a PSG scores only the AH events that occur after sleep begins, and a CPAP scores events that occur after the machine is turned on.

Automatic Event Detection (AED) from CPAPs was compared to manually scored events during a sleep study.

>>>
"The results of our study show that the AED tended to overestimate the AHI when the manually scored AHI was low and underestimate the AHI when the manually scored AHI was high."
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08-23-2016 02:19 PM
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PaytonA Offline
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Posts: 3,005
Joined: Dec 2013

Machine: ResMed S9 VPAP Auto
Mask Type: Full face mask
Mask Make & Model: Resmed Mirage Quattro
Humidifier: H5i(distilled-top up)
CPAP Pressure: VAuto MinE14.0 MaxI 20.6 PS4.0
CPAP Software: ResScan SleepyHead

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Sex: Male
Location: Orange County,California

Post: #2
RE: Some interesting differences between PAP resultes and sleep study results
Almost all of the difference was in hypopneas, due to things the CPAP can not measure and differences in definition. Even the article says,"Differences between manually scored and AED events were primarily due to different criteria for hypopnea detection". So if one compares AI to AI it should be pretty close.

Best Regards,

PaytonA
08-23-2016 03:28 PM
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zonk Offline

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Posts: 7,908
Joined: Feb 2012

Machine: A10 AutoSet
Mask Type: Nasal mask
Mask Make & Model: Activa LT
Humidifier: Integrated /ClimateLineAir
CPAP Pressure: 9/13
CPAP Software: ResScan

Other Comments: CPAP since Nov 2010

Sex: Male
Location: Australia

Post: #3
RE: Some interesting differences between PAP resultes and sleep study results
I've not read the whole article but read this and stopped wasting my time ....
Subjects enrolled in the parent study were randomized to one of three treatment arms: CPAP at the pressure determined by the titration PSG; APAP using a form of flexible positive pressure (A-Flex™), or APAP for 2 wks followed by CPAP treatment based on the results of the 2 wks of APAP treatment (pressure below which the patient spent 90% of the time). The same study device was used for all participants (REMstar Auto M-Series, Philips-Respironics, Murrysville PA) functioning in the CPAP, APAP, or AFlex™ modes10. The pressure range on the APAP units was set at 4 cm H2O to 20 cm H2O.
_____________________________________________________

Older machine used in a wide range settings ...
To get a better idea, they'll need to repeat the study using ResMed "AirSense 10 AutoSet and DreamStation Auto
Machines can distinguish between obstructive and clear airways events
For some people, pressure relief can skew AHI results somewhat and I have no faith in factory default pressure settings
08-23-2016 06:02 PM
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KSMatthew Offline

Advisory Members

Posts: 179
Joined: Jul 2016

Machine: PR DreamStation Auto
Mask Type: Nasal pillows
Mask Make & Model: ResMed Swift FX
Humidifier: none
CPAP Pressure: 7
CPAP Software: SleepyHead

Other Comments:

Sex: Male
Location: Kansas, United States

Post: #4
RE: Some interesting differences between PAP resultes and sleep study results
Yeah, I noticed this near the end:

>>>
DISCLOSURE STATEMENT

This study was sponsored by Philips-Respironics.
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(This post was last modified: 08-23-2016 06:46 PM by KSMatthew.)
08-23-2016 06:46 PM
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richb Online

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Posts: 525
Joined: Jun 2015

Machine: Resmed AirCurve 10 ASV
Mask Type: Nasal mask
Mask Make & Model: ResMed Mirage FX
Humidifier: Built in
CPAP Pressure: Epap 6 Ipap 8 Auto ASV
CPAP Software: ResScan SleepyHead

Other Comments: Idiopathic Central Apnea

Sex: Male
Location: Vermont

Post: #5
RE: Some interesting differences between PAP resultes and sleep study results
The training and experience of the Tech reading the PSG make all the difference in the world. If a Tech doesn't know the difference between Obstructive Hypopneas and Central Hypopneas the diagnosis can be completely wrong.

Rich

Apnea Board Member RobySue has posted a Beginners Guide to Sleepyhead Software here: http://www.apneaboard.com/wiki/index.php...SleepyHead
08-23-2016 07:16 PM
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