Airsense 11 not flagging obvious events

[APAPpy]

My sleep study determined I had an AHI of 17, which I was told is moderate sleep apnea and might benefit from CPAP therapy.

I purchased an Airsense 11 and thought I was responding well with an AHI below 5 every night. But then I discovered OSCAR and started zooming in on the waveforms and it seems some events are going unflagged.

Can someone tell me if it's normal for the Airsense 11 to not flag flatline events like the one highlighted in the attached image, and therefore not respond to them? How accurate can AHI be if it's missing obvious events like that?

[sptrout]

The ResMed Autosense Products are notorious for missing obvious SA events (other brands may be similar). The best way to find your true AHI is to slowly scan through the events section and count them yourself. You will almost certainly find more "hits", maybe a lot more. To make matters worse your machine counts your total sleep time as from the moment you start the machine until you stop it. I do not know about you, but I never fall asleep when I start the machine and unusually am awake long before I turn it off. 

Therefore, your machine is undercounting SA events and over estimating the time asleep. Your actual AHI will be more, to much more, that what your machine calculates. The formula for calculating AHI is the total number of SA times (10 seconds or more) divided by the time asleep in minutes. Converting the time asleep to minutes can be confusing, so be careful when calculating this number. If your final calculated results far exceed your machines displayed results then work to improve your results using you calculations.

Normally, these conflicting results are not a big issue unless a person's asleep time is much less than the machines "on" time. 

Bottomline, flatlines are not normal and should have been counted as a SA event. Also, you may want to change your pressures to a low of 7 and a high of 12. Your 95% pressure is 9.36 so no reason to set your max pressure to higher than 10. (Remember those percentages are the time that the pressure is below 95/99.5 percent of the total time.) Kind of trying different settings and see what changes if anything. Another idea is to go to CPAP Mode with a constant pressure of around 9-10). Not much to lose by trying different settings.

[super7pilot]

I would differ in that having some headroom above your median used pressure is wise. As you might need it. I would however have the 'minimum' pressure set rather close to that median or even 95% pressure with the EPR for expiatory relief. With the current setting of 6CM and an EPR 3. Your min pressure is at 3cm, But the AS11 can only go to 4CM. So your EPR is actually at 2cm. And that low a pressure is more appropriate for a child. Most adults can feel air starved at 6-7.

In addition, That group of OA's at around 1:40 AM look like they could be positional OA's. I.E. tucking your chin towards your chest. That type of OA CAN NOT be fixed via pressure. But can be helped very much by a soft cervical collar and or a flatter pillow.

It is also helpful to post the whole nights chart. Not just a zoomed section. Also, are you just starting XPAP?

[APAPpy]

Thanks for the tips, sptrout

Those pressures were set by my sleep clinic and you're right, I should up the min to 7 if only because I get the feeling of being out of breath and chasing air before falling asleep.


Concerning the events Airsense 11 is ignoring, it definitely seems like a decision by Resmed. The device is obviously capable of sensing these minor events, after all it sees and records them. Maybe it's a reliability issue, Resmed only counts events above/below certain thresholds where reliability can be assured.

[APAPpy]

Thanks super7pilot,[url=https://www.apneaboard.com/forums/User-super7pilot][/url]

I'm a little over 2 months into therapy and still learning the basics but coming from the tech world I'm learning quickly.

[super7pilot]

Thanks super7pilot,[url=https://www.apneaboard.com/forums/User-super7pilot][/url]

I'm a little over 2 months into therapy and still learning the basics but coming from the tech world I'm learning quickly.

I was told by my sleep Dr. and many of the very helpful folks on this forum to gauge ones success on how they feel after getting used to the therapy and dialed in using the OSCAR data. My Dr. also told me that I will have bad nights and good nights. Just like those that are not on CPAP. 

The first month was hellish even though my events dropped from my studies 22ahi down to 1-2 very quickly. So I wasn't having apnea's, But the breathing of pressurized air was disrupting my sleep.  Now I'm at .3 to 1.5 AHI and I feel much better.

Also. The reason that an AHI of less than 5 isn't usually treated is because we humans do not have perfect sinewave sleep breathing patterns. We are amazing bio-mechanical beings, But what we are NOT is perfect.

As a "tech" person. You might be mindful to not try to micro analyze your OSCAR data. It's a guide. I don't even bother to look at mine everyday now. The screen info on the AS11 is fine once you use OSCAR to get dialed in and start feeling better.

[APAPpy]

As a "tech" person. You might be mindful to not try to micro analyze your OSCAR data.

Yeah, that would be me 

I'll remind myself of that one going forward.

[super7pilot]

Yeah, that would be me 

I'll remind myself of that one going forward.

As I once worked on ICBM nuclear missiles. Being detailed was a good thing. But I tried and was pretty successful in leaving that at work. Now I'm retired and couldn't care less about being a pedant.

[APAPpy]

I had an excellent night's sleep with the min pressure upped to 7cm @sptrout and in fact it's the longest I've slept since starting CPAP therapy a few months ago. I didn't feel like I was starved for air once 




Here, again, are a few flatlines from last night that Resmed ignored. I think I'll send them a bureaucratic email about it to see if they dare an explanation 













Thank you to everyone on here who are passionate about CPAP therapy, I'm learning so much reading you all 

[super7pilot]

Glad you had a better nights sleep. Do remember that for an event to be flagged. It has to last longer than 10 seconds.

Your OA’s that are clustered are very likely positional from chin tucking. So, try a flatter bed pillow and or a soft cervical collar.