What is the exact criteria for SleepyHead apnea and other events and is it same sleep clinics use??

Just curious, I put some custom events to track on my sleepyhead playing with flow limit and duration. But I can't find anywhere what airsense 10 or sleepyhead tracks by default for apnea, hypopnea, etc? Like is it 25% FL for 10 seconds? or 50% FL or what? And is there anyway to put more than 2 custom events? I've been on CPAP a while and have never been able to get past feeling just "ok". Despite low AHI. Pretty sure I wake up before I have an event, because I still spend a lot of time awake.

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sventory wrote: ↑

Thu Jun 21, 2018 1:58 pm

Just curious, I put some custom events to track on my sleepyhead playing with flow limit and duration. But I can't find anywhere what airsense 10 or sleepyhead tracks by default for apnea, hypopnea, etc? Like is it 25% FL for 10 seconds? or 50% FL or what? And is there anyway to put more than 2 custom events? I've been on CPAP a while and have never been able to get past feeling just "ok". Despite low AHI. Pretty sure I wake up before I have an event, because I still spend a lot of time awake.

'FL" is 'flow limitation', which doesn't directly have anything to do with apneas or hypopneas. Apneas and hypopneas are scored with a reduction in tidal volume, something like >50% for 10 or more seconds for a hypo and > 90% for 10 or more seconds for a apnea.

Flow limitations don't necessarily result in a lower volume, rather they result in a lower flow rate.

Hmm but that's what the sleepyhead info provides you for when setting up custom events. It mentions FL and duration, not tidal volume. Wouldn't the flow be limited if the tidal volume is down?

sventory wrote: ↑

Thu Jun 21, 2018 1:58 pm

. . . I can't find anywhere what airsense 10 . . . tracks by default for apnea, hypopnea . . . ?

The manual for your machine says:

The ResMed dudes wrote:An apnea is when the respiratory flow decreases by more than 75% for at least 10 sec. A hypopnea is when the respiratory flow decreases to 50% for at least 10 sec. . . . The AirSense 10 recognizes and treats traditional as well as less common flow-limited breath wave forms. . . . -- https://www.respshop.com/manuals/ResMed ... %20her.pdf

The ResScan Interpretation Guide gives further information on their take on flow limitation as used for informing the algorithm when to react:

The ResMed dudes wrote:Flow Limitation -- A measure of partial upper airway obstruction. This measure is based on the shape of the inspiratory flow–time curve. A flattening of the inspiratory flow–time curve suggests upper airway obstruction. A normal inspiratory curve would be round shaped. . . . - Shape of the curve is key (rounded vs. flattened) - Device recognizes changes in the flow curve as flow limitation and will respond with changes in pressure. -- http://www.apneaboard.com/ResScan_Inter ... -Guide.pdf

sventory wrote: ↑

Thu Jun 21, 2018 1:58 pm

. . . Is the exact criteria [the] same sleep clinics use??

No, the definitions used by machine manufacturers and home-use software differ from the definitions sleep clinics/centers use, since clinics/centers collect other signal data for interpretation of flow data. Home-treatment-machine info is calculated using proprietary algorithms, and the AHI reports provided by home-treatment-machines are designed only to be used for trending purposes, not so much in comparison to PSG information or information from other machine manufacturers.

sventory wrote: ↑

Fri Jun 22, 2018 12:47 pm

Hmm but that's what the sleepyhead info provides you for when setting up custom events. It mentions FL and duration, not tidal volume. Wouldn't the flow be limited if the tidal volume is down?

What do you mean by "FL"?

Regardless what you're seeing, an apnea and hypopnea are a reduction in air volume respired.

Flow limitations do not necessarily result in a lower volume. Try breathing through a small straw, you can still take a full breath, it just takes longer because the small tube causes a flow limitation.

Perhaps this will help. https://www.youtube.com/watch?v=-gie2dhqP2c

Wow great information! I didn't think to check the manual (which I lost long ago heh). This all makes sense.

No, the definitions used by machine manufacturers and home-use software differ from the definitions sleep clinics/centers use

That seems awfully weird, I know you need a EEG to detect RERAs accurately, but are you telling me what was marked as an apnea or hypopnea on my PSG may or may not have been picked up by my CPAP and visa versa? That seems just strange for data consistency and pattern recognition.

Perhaps this will help. https://www.youtube.com/watch?v=-gie2dhqP2c

This video is awesome! I get it now.

So if I still sleep so bad with CPAP but have very low AHIs I should be trying to ad custsom flags for maybe 30-40% for 10 seconds or any kind of flow decreases under 10 seconds really I Guess. So if I have 75% decreases for 9 seconds, it won't be marked as any event right? I'm pretty sure something like that is happening.

sventory wrote: ↑

Fri Jun 29, 2018 10:19 am

So if I have 75% decreases for 9 seconds, it won't be marked as any event right?

Correct. All OAs, central apneas, hyponeas must have a duration of at least 10 seconds to earn a flag.
The amount of flow reduction that lasts for at least 10 seconds dictates the category....but anything less than 10 seconds doesn't earn a flag. Even 100 % reduction that lasts only 9 seconds. Conversely a flow reduction of 25% that lasts a minute...no flag either.

Up to you if you want to do the custom user flag thing. You can easily drive yourself bonkers with this stuff because just because you see something doesn't mean it means much in the grand scheme of things.
What you might also do if you have the presence of mind when you wake up during the night is reach over and turn your machine off and then right back on again. This way you will have a break in therapy and you can then zoom in on the time frame right before you turned the machine off and back on again to see if maybe something shows up that might explain the wake up. Maybe there was a 9 second something or other happen a minute before you turned the machine off...maybe not but you will have a better idea where to look if you have a known marker for awake time. It's impossible to try to remember the times and we don't really want clock watching or doing anything that might make it take longer to get back to sleep.

If you do decide to play with custom user flags you will also likely need to do the "rebuild your data" thing in SleepyHead for SH to know to start looking.

sventory wrote: ↑

Fri Jun 29, 2018 10:19 am

No, the definitions used by machine manufacturers and home-use software differ from the definitions sleep clinics/centers use

That seems awfully weird, I know you need a EEG to detect RERAs accurately, but are you telling me what was marked as an apnea or hypopnea on my PSG may or may not have been picked up by my CPAP and visa versa? That seems just strange for data consistency and pattern recognition.

If your home machine could give you the same quality info as a sleep lab/center, there would be no sleep labs/centers.

Home machines are very good at finding 10-second pauses of a certain percentage of flow in breathing, since that only takes one channel (flow) to find consistently. Everything else, unlike a lab/center test, is an estimate/extrapolation/approximation for trending purposes, which is extremely valuable, but does not compare to the diagnostic and titration value of full-multichannel-using labs/centers. The way events are reported by each method of evaluation is customized according to the technology or technologies being used to gather data on the events. For example:

Labs/centers are able to tell if a 10-second pause was damaging to sleep. Home machines can't even tell if you ARE asleep.

Labs/centers can use effort belts to tell pretty well how much effort you are putting into breathing and whether your breathing is in sync. Home machines use only the status of the airway to make educated guesses to differentiate the mostly-central events from the mostly-obstructive events.

Never discount the usefulness of home-machine data, but never consider it truly comparable to labs/centers as to what it reports and how accurately it reports. Getting full value from any technology requires a full comprehension of the technology's limitations and the limits of how it is being applied and reported.

Apples and oranges are both tasty and nutritious, but they aren't exactly the same.