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how do our machines know CA from OA?
#11
I thought I'd add this graphic from an Airsense 10 Autoset with EPR at 3 showing what happens during an OA event. Note the flow limitation in the preceeding breath and the recovery breath.  The forced oscillation technique FOT is the bumpy line beginning after 4 seconds of apnea.  We are showing the flow line and mask pressure here. Notice the auto pressure is increasing before the event as the algorithm anticipates the obstruction.

[Image: wxNRuZuh.png]
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#12
(03-02-2017, 10:48 AM)Leemax Wrote:
(03-01-2017, 08:44 PM)eseedhouse Wrote: Well, it's sorta kinda true depending on what you mean by "difference".  Your machine cannot technically tell if an apnea is Central or not.  All they can do is determine that the apnea occurred while your airway was not blocked.  That does not prove that the apnea meets the clinical definition of "central apnea".  The machine also can't tell if you are awake or asleep, and if you are awake it's reports are pretty well meaningless so far as the severity of your sleep apnea is concerned.

But it can give you enough information for your own purposes.  If an apnea occurs while your airway is not closed, then it's pretty well got to be a central, but the technical definition requires an actual measurement of your brain waves, which your machine cannot do.

I had some time to think about this for over an hour this morning (starting about 2:00). When I came back to bed after getting up to go to the bathroom, I would start drifting off to sleep and have a transitional clear airway event, which happens a lot to me. What woke me more than the apnea, which I might have passed through and gone to sleep, were the "forced oscillations" of my machine to see if my airway was open or closed. Anyhow, while it's true that our machines can't tell if we're actually asleep, if we look at our analysis in the morning and see that we had, say, 13 seconds of no breathing, an open airway, and no big inhalation right before the apnea, we were almost certainly asleep (or heading that way) and not just holding our breath as we turned around in bed. When we have fifteen events of over 10 seconds duration, in the space of about 26 minutes, ( as I did on the 27th between 0406 and 0432), it seems that it's a pretty safe bet that sleep, or an attempt thereof, is happening. Is that an accurate analysis or just something that my 0200 brain came up with? Shy

Aside from all that it's pretty frustrating to be awakened by the FOT every few minutes. I wish there were a way to temporarily bypass that feature.

(I would have uploaded the screenshot, but I haven't really learned how to do that. I was looking at the tutorial that's reference here on the board, and it's too early to try to follow all of those instructions. I confess that I'm somewhat of a Luddite when it comes to doing stuff like that.)

Have you tried turning the "Ramp" feature on on your ResMed machine so it builds pressure slowly after you've taken a bathroom break?

Bill
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#13
I also find that the forced occilations tend to awaken me more than any other aspect of the therapy.

When it happens, I tend to be just about asleep when I am then awakened by it. I typically don't think I was asleep and don't recall not breathing so it took me the longest time to figure out what was actually happening.

About two weeks ago I discovered that when I am on my back and the occilations occur, they sometimes make my chest vibrate up and down from the occilating pressure which in turn has already caused the entire mattress to start shaking. Before I realized what was going on, I thought we were having an earth tremor or some such thing! Needless to say, that wakes me up.

I haven't tried the ramp feature as I tend to be most comfortable with the full pressure I am used to and it doesn't happen frequently enough to be that much of a bother to me.
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#14
(03-02-2017, 04:22 PM)RichardVT Wrote: About two weeks ago I discovered that when I am on my back and the occilations occur, they sometimes make my chest vibrate up and down from the occilating pressure which in turn has already caused the entire mattress to start shaking.  Before I realized what was going on, I thought we were having an earth tremor or some such thing!  Needless to say, that wakes me up.

I haven't tried the ramp feature as I tend to be most comfortable with the full pressure I am used to and it doesn't happen frequently enough to be that much of a bother to me.

The mattress is shaking?!?! That must be some crazy-strong oscillations! Smile  I can just barely feel mine, but it's enough to wake me up. I'm glad I'm not alone in that. I set the ramp on mine for 30 minutes, so we'll see if that makes a difference.
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#15
Actually, I can make it happen when on my back if I keep an open throat and stop the airflow in just the right position. The occilations begin and it kind of starts to set up a harmonic kind of reverberation with my lungs and chest. Kind of strange!

Lol!
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#16
My mind's eye is conjuring up a really weird picture. Yikes! IF I ever tried that I would make sure my wife wasn't around. She would think I was having a seizure. (BTW, I have no plans to try that!) Smile
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#17
CORRECTION

I had it happen several times and after I was awakened by it, I made it happen again about a week ago.

I just went to bed and tried to make it happen again, it's not the occilation that gets my chest going but rather it seems to be when holding my breath just right with a bit of effort keeping my lungs expanded a bit the machine seems to want to blow to fill my lungs then lets off a bit for the exhaust pressure relief then seems to get a bit stuck between blowing and reliefing rapidly which is a lot more pressure differential than the occilation by itself (which I just discovered is barely noticeable with an open throat but is a bit noticeable with a closed throat where it can be felt more in the mask vibrating).

Sorry for any confusion.
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