OK I am a bit confused.

So when I check my S8 autoset II it says AI 0.6 does that mean that 0.6 percent of the time I was sleeping that I was having an apnea?

Lou Cypher wrote:So when I check my S8 autoset II it says AI 0.6 does that mean that 0.6 percent of the time I was sleeping that I was having an apnea?

It means you had less than one "apnea" per hour.

You need software to see how long an apnea lasts.

#2 oops was rushing the post between meetings & put the formula the wrong way (tks Jules )


The 0.6 is calculated this way (am talking of obstructive apneas & not hypopneas (AIs not HIs))

Take the number of hours you slept (say 8 )
Look at the number of Obstructive Apneas scored in that period (say it was 13 apneas)

#2 Then the AI score is 13 / 8 = 1.6 (expressed as apneas per hour)
#2 At 1 apnea per hour the score would be AI = 1.0 ( 8/8)
#2 For an AI 0.6 the formula is 4.8 apneas in 8 hrs (4.8 / 8 = 0.6)

What this scoring doesn't take into account is how long each scored apnea is but if you are able
to extract the nightly data off the machine you can see how long each one is.

The importance of how long an apnea is can be illustrated as follows ...

say I sleep 8 hrs & have 13 apneas (scored by the machine) & each of those apneas lasts 7 seconds
then the total period in Apnea (not breathing normally) would add up to 13 * 7 = 91 seconds or 1.5 mins.

But, if the 13 apneas each lasted 15 seconds, the total time in Apnea would be 13 * 15 = 195 seconds or over 3 mins.

So the AI score would be identical but the harm done by the longer apneas is obviously going to be significantly worse.

So, even AI scores are relative (relative to how long the apneas are lasting & the different level of harm done).

Cheers

DSM

OK. I do have the software and almost every apnea I have since 30 Sep is marked 10, I presume that to be 10 seconds?

Can I join the confusion? I was under the impression that the machine doesn't even score an apnea if it's not at least 10seconds long. Am I wrong?

Lou Cypher wrote:OK. I do have the software and almost every apnea I have since 30 Sep is marked 10, I presume that to be 10 seconds?

Yes, exactly. Same here. Anything shorter than that doesn't meet the definition of apnea used by your machine.

Doric wrote

Can I join the confusion? I was under the impression that the machine doesn't even score an apnea if it's not at least 10seconds long. Am I wrong?

PST answered

Yes, exactly. Same here. Anything shorter than that doesn't meet the definition of apnea used by your machine.

Respironics machines can and do report Apneas that are shorter than 10 seconds. Velbor and I had an exchange of posts in early July on whether the accumulated Time-in-Apnea seconds value recorded by Respironics for a sleep session is accurate or not based on the 10 seconds or more definition for an Apnea. I've concluded, after continuing to analyze my Time-in-Apnea data, that Respironics reports "something" because other brands do! Here is one of my posts from the "Respironics / EncoreViewer Data Error?" thread that Velbor started in July.

------------------------------------------------------------------------

Re: Respironics / EncoreViewer Data Error ?
by cinco777 on Sun Jul 12, 2009 8:01 pm

Velbor wrote
My thanks to you both!! It would be astonishing if this explanation were correct; unfortunately, it would make the "Time in Apnea Per Day" information virtually useless. Other explanations or comments remain very much welcome.
Velbor

I use EncorePro not Encore Viewer. There is a "SecondsInApnea" field (Column 16) in the SleepTrendEventLog2 SQL table. I use some data from this table in my CPAP charting spreadsheet. This field shows, for each compliance session (Respironics parlance), the # of Seconds in Apnea. The first thing that caught my attention is that all the values are multiples of 6: 6, 12, 18, 24, ... This Respironics recording/reporting has some similarity to the recorded/reported leak values of 4, 11, 18, 25, 32, 39, ... in which all are 7 apart. After reading your last post in this thread, I created a spreadsheet that shows the number of apneas for each "Seconds in Apnea" value, and how many occurences of each were reported. As input, I used my EncorePro data from 4/30/09 through 7/9/09. For 6 Seconds in Apnea, the apnea count was always 1 for that session - there were 39 occurences in my date range. For 12 seconds in Apnea, the apnea count was always 1 for that session - there were 12 occurences. For 18 seconds in Apnea, the apnea count was always 2 - there were 14 occurences. For 24 seconds in Apnea, there were two results: there was 1 occurence where the Apnea count was 2 and 1 occurence where the Apnea count was 3. For 30 seconds in Apnea, the apnea count was always 3 - there were 5 occurences. For 36 seconds in Apnea, there were two results: there were 3 occurences where the Apnea count was 3 and 2 occurences where the Apnea count was 4. For 42 seconds in Apnea, there were also two results: there were 3 occurences with a count of 4 apneas and 1 occurence with a count of 5 apneas. For all subsequent seconds in my Apnea values - a range from 48 apnea seconds to 156 apnea seconds - there was only one result for the Apnea count. Based on these results, I believe that the avg duration of an Apnea recorded/reported by Respironics/EP/EPA is best predicted by how many Apneas occurred in the session - with the lowest apnea durations being reported for the lowest count of apneas (always 6 seconds when 1 is reported) in a session. I believe that Respironics chose this recording/reporting approach because they did not have sufficient uprocessor power or smartcard memory to process and record at shorter time intervals (I would like 1 second recording/reporting).

PST wrote:

Lou Cypher wrote:OK. I do have the software and almost every apnea I have since 30 Sep is marked 10, I presume that to be 10 seconds?

Yes, exactly. Same here. Anything shorter than that doesn't meet the definition of apnea used by your machine.

This matches my results. I show many apneas from my Resmed software over the past few months, and none of my reported Apneas are less than a value of 10. (No disrepect meant to Cinco, but just sayin...)

GaryG wrote

This matches my results. I show many apneas from my Resmed software over the past few months, and none of my reported Apneas are less than a value of 10. (No disrepect meant to Cinco, but just sayin...)

_________________
Machine: S8 AutoSet II CPAP Machine

Gary, your profile shows that you have an S8 Autoset II. You missed the fact clearly stated in my posting that my data analyses and conclusion applies to Respironics machines. FYI, Doric's husband uses a Respironics machine not an S8 Autoset II.

lou,

if i may chip in my 2 cents worth, i have the same set-up as you and have apneas ranging from 10, 11, 12,... etc. seconds on up to 25 seconds and everything in between, but nothing less than 10 seconds.

and they seem to come in groups. in other words, i'll go several nights with 0 apneas, then a night or two with 3 or 4. when that happens, sometimes they are clustered together in the early morning (between 4 - 5) when presumably i'm getting REM sleep, but other nights they are spread evenly through the night every other hour.

i'm sure it makes perfect sense to someone, but for now i'm having fun trending the patterns and hopefully will stumble on a pattern and ways to make improvements.

cinco777 wrote:GaryG wrote

This matches my results. I show many apneas from my Resmed software over the past few months, and none of my reported Apneas are less than a value of 10. (No disrepect meant to Cinco, but just sayin...)

_________________
Machine: S8 AutoSet II CPAP Machine

Gary, your profile shows that you have an S8 Autoset II. You missed the fact clearly stated in my posting that my data analyses and conclusion applies to Respironics machines. FYI, Doric's husband uses a Respironics machine not an S8 Autoset II.

And Lou's comment was specifically about his data and he has the ResMed Auto Set II (and is struggling along with me to figure out the ResScan v3.7 software on the s8 autoset. And frankly your comment totally confused me. But we're all friends here (I hope). Sorry for any confusion. I do a lot of that, er uh confusion.

fishhead wrote:lou,

if i may chip in my 2 cents worth, i have the same set-up as you and have apneas ranging from 10, 11, 12,... etc. seconds on up to 25 seconds and everything in between, but nothing less than 10 seconds.

and they seem to come in groups. in other words, i'll go several nights with 0 apneas, then a night or two with 3 or 4. when that happens, sometimes they are clustered together in the early morning (between 4 - 5) when presumably i'm getting REM sleep, but other nights they are spread evenly through the night every other hour.

i'm sure it makes perfect sense to someone, but for now i'm having fun trending the patterns and hopefully will stumble on a pattern and ways to make improvements.

Having the same probs myself trying to figure out patterns, now that I've got my leakage #'s down. If you figure anything out, PLEASE let us know.

garyc - i'm not sure if this is what you're looking for but i just found some great reading in this thread:

viewtopic/t45793/resmed-respironics-AHI-and-facts.html

pugsy makes a great explanation of how the software helped her recognize that her worst apneas were occurring during REM sleep. so while her averages looked good, she wasn't getting good sleep and had to make some adjustments to see improvement.

well, i'll let you read it for yourself so i don't misquote her. plus, she explains it much better than i can. anyway, it's given me something to work on now.

so, if you see this... thanks pugsy! and thanks to all the others that contributed to that thread.

fishhead, reread Pugsy's comments and actually with my less than 3 months experience, I kinda disagreed with Pugsy. Now I have no scientific evidence but I don't necessarily agree the directly correlating sleep study numbers with CPAP machine numbers, but otherwise she has good points and is usually very knowledgeable. I hope she doesn't get mad at me.

The AI stands for apnea per hour. When calculating apneas per hour, you divide the number of apneas by the number of hours.

12 apneas in 8 hours is gives an Apnea Index of 12/8 gives and AI of 1.5.

Respironics math has been proved to be highly original in many ways - much of it being the result of rounding. And then they do averages.

Rescan flags the length of each apnea it reports, separately -- and you can even stretch the charts out to focus on 10 second intervals. A 10 seconds breathing cessation is the minimum length for the interruption to be reported as an apnea by Resmed. A Resmed will report 11 second apneas too -- I've seen those in my data, so rounding in that measure -- if it exists at all - is negligible.

Shorter apneas are better.

O.