False events

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
hardball
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Joined: Tue Apr 18, 2017 6:53 pm

False events

Post by hardball » Tue Apr 18, 2017 6:55 pm

I've been using a CPAP machine now for 4 weeks - a ResMed Autosense 10, with a ResMed large nasal pillow. My range is set to 10-20. My problem is, it usually takes me about an hour to fall asleep, and while waiting to fall asleep, I will have several deep yawns, which take longer than 10 seconds to complete. When I yawn, I'll have to open my mouth, but still keeping the pressure in my nose. However, the ResMed interprets this as an 'event', and flags it. I usually have to take 3-5 deep yawns before I fall asleep, and these false events skew my AHI rating. Is there a way to keep the machine from flagging these events?

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Julie
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Re: False events

Post by Julie » Tue Apr 18, 2017 7:18 pm

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Last edited by Julie on Tue Apr 18, 2017 9:11 pm, edited 1 time in total.

Guest

Re: False events

Post by Guest » Tue Apr 18, 2017 7:36 pm

hardball wrote: these false events skew my AHI rating.
Can you give an example of the skewing?

hardball
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Re: False events

Post by hardball » Tue Apr 18, 2017 7:45 pm

Guest wrote:
hardball wrote: these false events skew my AHI rating.
Can you give an example of the skewing?
Well, it counts as 'events' things that are really just me trying to yawn. So, I have 3 or 4 'events' that aren't apnea events. These get added into the calculation of AHI, and give me a higher rating than I should have.

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chunkyfrog
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Re: False events

Post by chunkyfrog » Thu Apr 20, 2017 12:30 pm

If you actually need to yawn, then it is a real event. Do not sweat it.
Just let it be.
It does not really matter.

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LSAT
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Re: False events

Post by LSAT » Thu Apr 20, 2017 2:20 pm

hardball wrote:
Guest wrote:
hardball wrote: these false events skew my AHI rating.
Can you give an example of the skewing?
Well, it counts as 'events' things that are really just me trying to yawn. So, I have 3 or 4 'events' that aren't apnea events. These get added into the calculation of AHI, and give me a higher rating than I should have.
You are the only one looking at the score. Ignore the CA's since they are what is called sleep/awake junk. The computer doesn't know if you are awake, sleeping, yawning etc. It just knows there was a lull in the breathing for 10+ seconds.

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robysue
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Re: False events

Post by robysue » Thu Apr 20, 2017 7:03 pm

hardball wrote:I've been using a CPAP machine now for 4 weeks - a ResMed Autosense 10, with a ResMed large nasal pillow. My range is set to 10-20. My problem is, it usually takes me about an hour to fall asleep, and while waiting to fall asleep, I will have several deep yawns, which take longer than 10 seconds to complete. When I yawn, I'll have to open my mouth, but still keeping the pressure in my nose. However, the ResMed interprets this as an 'event', and flags it. I usually have to take 3-5 deep yawns before I fall asleep, and these false events skew my AHI rating. Is there a way to keep the machine from flagging these events?
Don't stress out over the 3-5 "events" caused by yawns that happen before you are actually asleep. In the grand scheme of things, they're not affecting the recorded AHI as much as you might think they are. And also keep in mind that the fact that you are using the machine for about an hour before falling asleep also skews the data, although in the opposite direction.

To illustrate what I mean, let's look an example with some made up data.

Let's suppose that you use the mask for 8.5 hours, but during that first hour of usage you are actually awake. So your real sleep time is actually 7.5 hours.

Now let's suppose that during the 7.5 hours of real sleep you have 14 real events scored. So your real AHI would be 14/7.5 = 1.87.

Now lets add 4 "false events" caused by the yawns in that first hour of usage before you fell asleep: The machine assumes your sleep time is 8.5 hours and that the number of events is 18 = 14 real + 4 fake events. So the machine calculated AHI = 18/8.5 = 2.11.

The difference between the true AHI = 1.87 and the machine calculated AHI = 2.11 is not statistically significant, and it's certainly not enough to worry about.

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kteague
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Re: False events

Post by kteague » Thu Apr 20, 2017 8:23 pm

It may be different for your machine, I'm not up on the newer ones, but that's the only reason I use the ramp feature for a few minutes so I can get most of the yawning, coughing and throat clearing out of the way before the data counts it in the reports. If that ramp for a few minutes became a problem for any reason, I would just know to ignore the extra "events". But then again, I haven't had a sleep doctor monitoring my data for about 6 years.

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