OSCAR: cannot change AHI/hour Time Window

[PurchanceToDream]

Changing this setting is disabled in preferences and there does not seem to be a checkbox or some such to enable changes.

Since clinical diagnosis requires a 2 hours window, it seems to me that 2 hrs would make more sense. Also this is long enough to encompass a typical sleep-cycle plus some padding, so it can give better idea of whether you are getting through entire sleep cycles (all stages of sleep) with low AHI.

The tooltip strongly recommends against changing the time window and keeping it at 60 minutes.

Is there a justification for why 60 minutes is preferred over any other time window. In particular why would 60 minutes be better than 120 minutes?

Is there a way to enable changing this parameter?

Maybe I am just unaware of some recent research or clinical definitions/standards.

[A KLERK]

AFAIK the Indexes are defined as incidents per hour. OSCAR shows the final AHI as the arithmetic mean over the total hours, but also has a "sliding" average graph at the bottom of the daily page.
Can you give a reference for that 2 hours time period?

[GuyScharf]

Are you referring to the "AHI/Hour Graph Window" on the File/Preferences/CPAP page?  That value affects only the AHI graph, which is usually seen only when you scroll down to the last of the graphs. It does not affect any index calculations.

Most people think this graph is not very useful.

However, if you really want to see what this graph looks like with a different value for this variable, you will need to edit the profile.xml file in the folder for your profile (OSCAR_Data/Profiles/your profile).  Search for the line that says "<AHIWindow type="double">60</AHIWindow>" and change the number to 120 (or whatever number you like as long as it is larger than 30).

[PurchanceToDream]

Are you referring to the "AHI/Hour Graph Window" on the File/Preferences/CPAP page?  That value affects only the AHI graph, which is usually seen only when you scroll down to the last of the graphs. It does not affect any index calculations.

Most people think this graph is not very useful.

However, if you really want to see what this graph looks like with a different value for this variable, you will need to edit the profile.xml file in the folder for your profile (OSCAR_Data/Profiles/your profile).  Search for the line that says "<AHIWindow type="double">60</AHIWindow>" and change the number to 120 (or whatever number you like as long as it is larger than 30).

Yes, that is the preference setting I am talking about.

I have a lot of waking/transition apneas, so the overall session AHI is not helpful.

The graph is more useful to see at a glance what kind of AHI I was getting over all possible time windows (of a given size).

Thanks for the tip on the .ini file.

I still wonder why the setting is shown but disabled in the preferences window, and why the tooltip so strongly recommends against changing it from the 60 minutes setting.

[GuyScharf]

I still wonder why the setting is shown but disabled in the preferences window, and why the tooltip so strongly recommends against changing it from the 60 minutes setting.

I don't know the history. I suspect that at one time SleepyHead either enabled this option or intended to do so in the future. But it was disabled as it is now when OSCAR was forked from SleepyHead.

[A KLERK]

I still wonder where the 2hour window comes from. Who uses that?

[Sleeprider]

These are just rolling averages, and is a pretty simple concept. As Guy says, most people don't find it particularly useful, but it was originally conceived by Palerider to help see variability of AHI through the night. I think it was never fully developed and refined. Anyway Palerider could probably speak best to what the vision for this was.

[A KLERK]

Changing this setting is disabled in preferences and there does not seem to be a checkbox or some such to enable changes.

Since clinical diagnosis requires a 2 hours window, it seems to me that 2 hrs would make more sense. Also this is long enough to encompass a typical sleep-cycle plus some padding, so it can give better idea of whether you are getting through entire sleep cycles (all stages of sleep) with low AHI.

The tooltip strongly recommends against changing the time window and keeping it at 60 minutes.

Is there a justification for why 60 minutes is preferred over any other time window. In particular why would 60 minutes be better than 120 minutes?

Is there a way to enable changing this parameter?

Maybe I am just unaware of some recent research or clinical definitions/standards.

I still wonder where you have seen this:  clinical diagnosis requires a 2 hours window ?

[PurchanceToDream]

I still wonder where you have seen this:  clinical diagnosis requires a 2 hours window ?

I just recall reading it some years ago, I think in the context of insurance requirements to receive treatment.

Googling for it now, the references I find to "2 hours" all have something to do with a split study -- you need 2 hours of qualifying AHI in the first part of the study before switching to titration. Maybe back in the day I misread something that was also referring to this.

I'm interested in 2 hours because it is a large enough span to encompass a full sleep cycle plus some "padding".

[A KLERK]

Good enough, as you already saw that the possibility to change the timespan is already in a settings file...
But I would like to emphasize that it's not so much the timespan, but in the end the oxygen desaturation that ruins people's health. So I always suggest to look for clusters and high-rising AHI over a short time span. 
Best of all is a continuous pulse saturation measurement after all...
Just my two Eurocents...