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Session Information AHI
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ICEMAN Offline

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Post: #11
RE: Session Information AHI
Well had a sleep on it and now think I have worked it out.

Appears the AHI for individual sessions is calculated by the No events in each single individual session but / the total of all session hours.

Sleepy head shows AHI of 0.78 for (Session 1) which is the No of events / both (session 1 & 2) total hrs = 6 / 7.70 = AHI 0.78, But the actual 6 (events) / (session1) hrs = 6/3.68 = "AHI" 1.63
Sleepy head shows AHI of 1.94 for (Session 2) which is the No of events / both (session 1 & 2) total hrs =15/ 7.70 = AHI 1.94, But the actual 15 (events) / (session 2) hrs = 15/4.02 = "AHI 3.73

Average AHI for both sessions is still as Sleepyhead shows = total session events / total session hrs = 21 events / 7.70 hrs = 2.72 AH

Happy for any comments and thanks Trish6, Mongo & Palerider for your response also a big thank you to Sleep Apnea board, Sleepyhead creators, is great site and excellent monitoring tool. I have been just lurking the site sucking up the sites useful information and playing learning to understand Sleepy head and intend get around to make donation over the next few days to show my appreciation for the hard work and dedication that must take to construct and keep site operational. Smile

Iceman
03-11-2016 07:32 PM
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PaytonA Online
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Post: #12
RE: Session Information AHI
(03-11-2016 06:44 PM)DariaVader Wrote:  
(03-11-2016 06:48 AM)ICEMAN Wrote:  6 events/3.68 hours = 1.63 ahi Single Session
15 events/4.02 hours = 3.73 ahi Single Session
21 events / 7.7 hours= 2.72 ahi Total for Both Sessions

Yes Palerider that is what con fuses me if Sleep head shows Information session shows
Single session (1) 6 apnea events / 3hrs 41min or 3.68hrs as "AHI" 0.78 ?
Single session (2) 15 apnea events 4hrs 01min or 4.02hrs " AHI" 1.94 ?

But total of sessions 21 events / 7.70 hrs = 2.72 AHI

you are leaving the middle session out of your calculation and it has a higher AHI and has skewed the average (which is for 3 sessions and not 2)

I believe that Iceman is calculating the 2 separate sessions and then the AHI for both sessions combined and that is correct.
03-11-2016 07:41 PM
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ICEMAN Offline

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Post: #13
RE: Session Information AHI
DariaVader, PaytonA has it got was only 2 sessions and the 21/7.7 =2.72 is 2 session combined to average AHI over that time period.
03-11-2016 07:48 PM
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eseedhouse Offline

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Post: #14
RE: Session Information AHI
For calculating AHI the number of sleep sessions is ignored. You divide the total of events for the entire time you were using the machine by the total number of hours you were using the machine.

Doesn't matter how many sessions there were. Add them all up, then add up the events for all sessions and divide the latter sum by the former sum.

AHI is a relatively crude method which, while informative, can be misleading until you look at other things. For instance if you woke up three or four times to use the bathroom, as I often do, a nice low AHI doesn't necessarily mean you are going to feel great that day. On the other hand you will feel better than if you didn't use the machine at all.

Ed Seedhouse
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I am neither a Doctor, nor any other kind of medical professional.

Actually you know, it is what it isn't.
03-11-2016 08:32 PM
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palerider Offline

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Post: #15
RE: Session Information AHI
(03-11-2016 06:48 AM)ICEMAN Wrote:  
(03-11-2016 05:39 AM)palerider Wrote:  [quote='ICEMAN' pid='153529' dateline='1457688097']Thanks Mongo I thought I had it worked for while but still confused. Example:Sleepyhead shows:
Single session (1) 3hrs 41min or 3.68hrs "AHI" 0.78 is 6 apnea events
Single session (2) 4hrs 01min or 4.02hrs " AHI" 1.94 is 15 apnea events

Total session shows AHI= 2.72 and total hrs as 7.70hrs if I calculate the 21 events / 7.70 hrs = 2.72 AHI same as Sleepy head.

But cant calculate the individual sessions to match? must be averaging it on the No Events per session can any one explain ?

6 events/3.68 hours = 1.63 ahi
15 events/4.02 hours = 3.73 ahi
21 events / 7.7 hours= 2.72 ahi

Yes Palerider that is what con fuses me if Sleep head shows Information session shows
Single session (1) 6 apnea events / 3hrs 41min or 3.68hrs as "AHI" 0.78 ?
Single session (2) 15 apnea events 4hrs 01min or 4.02hrs " AHI" 1.94 ?

But total of sessions 21 events / 7.70 hrs = 2.72 AHI

please confirm for me what version of sleepyhead you're using (should be in the upper left corner, and then zip up the entire contents of your SD card and upload them to me using this address:
https://www.dropbox.com/request/MPAgpT7t33HK0tlCW3mu
so that I can see what you're seeing.
03-11-2016 08:38 PM
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ICEMAN Offline

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Post: #16
RE: Session Information AHI
Hi eseedhouse was /have been locked out, new poster limited to 5 post and yeah mate understand what you saying but clicking on the individual session for the AHI on Nights with multiple sessions show a AHI that is miss leading. I have now worked out sleepyhead calculates your AHI for the individual event over the TOTAL hrs of sleep you had in the one nights "data period" say you had 2 x 4hrs session of sleep,both sessions had 20 events sleepyhead shows 1st session 20events / 8hrs AHI of 2.5 and again say the 2nd session was 20events/8hrs which would also be AHI of 2.5 but in fact the individual session should have a AHI of 5 and while adding the 2 individual sessions of sleep together gives you the correct AHI the total of all session events/all session hrs the individual session events/individual session hrs is actually incorrect or lets say misleading.

Thanks palerider old mate,was have been locked out as new poster limited to 5 post I have SleepyHead v0.9.8-1-Testing OpenGL

PS hope understand what have posted mate had a few scotch's Smile
03-12-2016 07:09 AM
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OpalRose Offline

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Post: #17
RE: Session Information AHI
ICEMAN,
The AHI showing for individual sessions is not misleading.

You said you worked shifts, so that may be adding to your confusion. The Cpap calculates a 24 hour day to start at noon.

The AHI is an AVERAGE...calculated for the ENTIRE NIGHT, regardless of how many sessions you have.

Simple calculation: Add up all the events (for all sessions). Divide the total events by the total hours slept (for all sessions). This equals your AHI for the day.

OpalRose
(This post was last modified: 03-12-2016 09:27 AM by OpalRose.)
03-12-2016 09:25 AM
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palerider Offline

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Post: #18
RE: Session Information AHI
(03-12-2016 07:09 AM)ICEMAN Wrote:  Thanks palerider old mate,was have been locked out as new poster limited to 5 post I have SleepyHead v0.9.8-1-Testing OpenGL

PS hope understand what have posted mate had a few scotch's Smile


where are you seeing sleepyhead apparently miscalculate AHI for sessions.. share some screen shots.
03-12-2016 05:34 PM
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eseedhouse Offline

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Post: #19
RE: Session Information AHI
(03-12-2016 07:09 AM)ICEMAN Wrote:  Hi eseedhouse was /have been locked out, new poster limited to 5 post and yeah mate understand what you saying but clicking on the individual session for the AHI on Nights with multiple sessions show a AHI that is miss leading. I have now worked out sleepyhead calculates your AHI for the individual event over the TOTAL hrs of sleep you had in the one nights "data period" say you had 2 x 4hrs session of sleep,both sessions had 20 events sleepyhead shows 1st session 20events / 8hrs AHI of 2.5 and again say the 2nd session was 20events/8hrs which would also be AHI of 2.5 but in fact the individual session should have a AHI of 5 and while adding the 2 individual sessions of sleep together gives you the correct AHI the total of all session events/all session hrs the individual session events/individual session hrs is actually incorrect or lets say misleading.

I don't see anything except the over all AHI in my version of SleepyHead. If you are looking at the strange graph at the bottom with the triangles I'd advise you to ignore it as no one I know understands what that is trying to tell us. I certainly don't.

Ed Seedhouse
VA7SDH

I am neither a Doctor, nor any other kind of medical professional.

Actually you know, it is what it isn't.
03-12-2016 09:32 PM
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ICEMAN Offline

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Post: #20
RE: Session Information AHI
(03-12-2016 09:25 AM)OpalRose Wrote:  ICEMAN,
The AHI showing for individual sessions is not misleading.

You said you worked shifts, so that may be adding to your confusion. The Cpap calculates a 24 hour day to start at noon.

The AHI is an AVERAGE...calculated for the ENTIRE NIGHT, regardless of how many sessions you have.

Simple calculation: Add up all the events (for all sessions). Divide the total events by the total hours slept (for all sessions). This equals your AHI for the day.

(03-12-2016 05:34 PM)palerider Wrote:  
(03-12-2016 07:09 AM)ICEMAN Wrote:  Thanks palerider old mate,was have been locked out as new poster limited to 5 post I have SleepyHead v0.9.8-1-Testing OpenGL

PS hope understand what have posted mate had a few scotch's Smile


where are you seeing sleepyhead apparently miscalculate AHI for sessions.. share some screen shots.

(03-12-2016 09:32 PM)eseedhouse Wrote:  
(03-12-2016 07:09 AM)ICEMAN Wrote:  Hi eseedhouse was /have been locked out, new poster limited to 5 post and yeah mate understand what you saying but clicking on the individual session for the AHI on Nights with multiple sessions show a AHI that is miss leading. I have now worked out sleepyhead calculates your AHI for the individual event over the TOTAL hrs of sleep you had in the one nights "data period" say you had 2 x 4hrs session of sleep,both sessions had 20 events sleepyhead shows 1st session 20events / 8hrs AHI of 2.5 and again say the 2nd session was 20events/8hrs which would also be AHI of 2.5 but in fact the individual session should have a AHI of 5 and while adding the 2 individual sessions of sleep together gives you the correct AHI the total of all session events/all session hrs the individual session events/individual session hrs is actually incorrect or lets say misleading.

Check this Screen shoot see if works and should explain ?

I don't see anything except the over all AHI in my version of SleepyHead. If you are looking at the strange graph at the bottom with the triangles I'd advise you to ignore it as no one I know understands what that is trying to tell us. I certainly don't.

OK think have now worked out posting screen shots Smile now just hope i can explain what I am eluding to so you can grasp what I mean.

http://s1172.photobucket.com/user/hotcoal/library/?sort=9&page=1

1st screen shot of both sleep sessions and correct AHI

2nd Screen shot is of 1st sleep session, SH shows and calculates the AHI using the single sleep session events but using both sleep session total hrs such as: 6/7.7= AHI0.78 to me it should be calculated for single sessions to identify the actual individual sleep session AHI which would be the 6 events / the single sleep session hrs =6/3.68hrs = AHI 1.63 for the actual sleep session 1

3rd Screen shot is of the 2nd sleep session and SH also calculates AHI for this by single session events / combined hours of both the sleep sessions and not as and individual sleep session as explained in earlier post's
03-13-2016 12:49 AM
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