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wildly jagged flow rate curves -- do you see this in your data?
#41
RE: wildly jagged flow rate curves -- do you see this in your data?
The only way you may learn more about this is by video recording or some other form of data. This was probably just a bad night with period of neck kinked due to position on pillow or something along those lines.
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#42
RE: wildly jagged flow rate curves -- do you see this in your data?
I'm thinking about designing some sort of gear to try to measure flow rate without having a cpap machine in the mix. What I'm toying with is to use an F30 mask because it has a large opening in front because the hose connects there. If I put airflow sensors on the mask then I can sleep with it and record data without a cpap machine involved in the loop, and just take straight breathing data.

One thing that I did think of with respect to the "stuttering" breath patterns -- I wonder if there is any possibility that the mask is shifting around and messing up the data collection from the CPAP? Specifically I'm looking at the F30 cushion and seeing that the nose opening is divided into two holes. If the mask were to get pushed over so that the little divider was going across one nostril, then I wonder if air bouncing off the divider -- from both the machine side and from inside the nostril -- is a big enough signal to get detected by the sensors in the machine? That little divider isn't on the other masks I've been wearing over the years when I've seen this signal, so that's not a complete explanation. (My other 3 FFMs are the F10, Amara View, and Dreamwear. I don't trust this data for this purpose when wearing anything other than an FFM, because there is no way to know if air is coming out of my mouth.)
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#43
RE: wildly jagged flow rate curves -- do you see this in your data?
Have you recorded it on camera? That would be much easier and more likely to figure this out.
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#44
RE: wildly jagged flow rate curves -- do you see this in your data?
Yeah, I know... too many projects going on here. Hubs is going to bring home the camera that they were using for some experiments a couple of years ago...
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#45
RE: wildly jagged flow rate curves -- do you see this in your data?
Last night I had 10 minutes of "WTF was that?!?"

   https://www.dropbox.com/s/mgz6cp1001671v...F.png?dl=0

What is striking is that there is quite a bit of leak during this period. Awhile later, some jaggy, but not so totally insane, and no leaks.

   https://www.dropbox.com/s/ehxn27gti10e2s...s.pdf?dl=0

Maybe the leaks are confusing the data collection?

I'm pretty confused by it all...
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#46
RE: wildly jagged flow rate curves -- do you see this in your data?
I now have a second data point which shows that this can happen on the vauto, although it's definitely better on the bipap than the apap. This is a document I made back in September, and it shows a series of two weeks on autoset and then the previous 2 weeks on the vauto.

https://www.dropbox.com/s/4lhoqrbwgleal5...n.pdf?dl=0

The factor that makes this so easy to find -- at least on a ResMed machine -- is that the breathing pattern completely confuses the algorithm as to figuring out whether I'm inhaling or exhaling, and so it reports a ridiculously high respiration rate which sticks out like a sore thumb even in the summary views.

When any level of PS/EPR is running, a view zoomed in enough to see the mask pressure oscillate will show the machine's bewilderment. Here's a comparison of how the two machines react to this breathing:

   https://www.dropbox.com/s/xxy2hgl5r9gisn...P.png?dl=0

(This is why I think that the apap EPR algorithm is implemented with a very high trigger sensitivity. Which makes me shake my head...)

Ok, here's what I saw a couple of days ago. First the whole-night zoom, with a box around the period of weird jagged breathing:
   
   https://www.dropbox.com/s/qpu3wkt49ixgrb...t.png?dl=0

I put the green line in a spot where the measured respiration rate very briefly drops back to something that looks reasonable. I then zoomed in around that spot,
   https://www.dropbox.com/s/s8eftrto6ju4yr...m.png?dl=0
   
and it nicely shows the weird breathing juxtaposed against what's pretty normal breathing for me.

I'm still thinking that this is something positional, in that I usually see movement at the beginnings and ends. The right way to check that out is to set up a camera and see if I can connect it to some body/head position -- or rule it out and return to a state of totally flummoxed!

I think that I can say that my pulse and SpO2 don't show any signs of any particular stress during these episodes, but I do think that I can associate an unpleasant tightness in my throat when I wake up from one.

If anybody (elliotg?) has any thoughts, maybe we can figure out something more as to what this means?
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#47
RE: wildly jagged flow rate curves -- do you see this in your data?
The more data you share the more I am certain this is asynchronicity due to whatever causes your pointy, high amplitude cardiogenic oscillation like features in flow rate.

The one downside of the vauto in this case is the timing control setting Timin. It holds a pressure increase for set length of time even if that pressure increase was initiated at the wrong time. For an example look at the breath at 5:27:30. You can see how the oscillation or whatever you want to call it triggers an early pressure rise and that is ultimately what gets the machine out of sync with your spontaneous breathing and triggers the following episode of this odd shaped breathing.

To help avoid this you should turn Timin as low as possible (I think lowest setting is 0.1 sec) and you can try lower trigger sensitivities (think you might already be doing that) to avoid premature triggers.

Have you ever tried PS higher than 4? In your case I believe it is warranted to try going higher (I would go up to 5 in one or two steps for a while at each step). Your flow rate charts still indicate some restriction and breathing effort that could be improved with higher PS.
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#48
RE: wildly jagged flow rate curves -- do you see this in your data?
I have not followed this for a while, and what Geer1 suggests makes sense. Also, what is your trigger sensitivity setting. You can avoid the machine triggering IPAP with the slight cardiogenic artifacts by lowering sensitivity.
Sleeprider
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#49
RE: wildly jagged flow rate curves -- do you see this in your data?
I'm still not convinced that there is any kind of causal relationship with EPR/PS and the jagged breathing, because I used the machine for 6 years with EPR turned off and I've got these episodes scattered all through my data. The recording of the impossibly high respiration rate is just showing how confused I've made the machine. Once I turned EPR on last spring, then looking at the mask pressure bouncing all over made it more graphic how confused the machine gets as to whether I'm inhaling or exhaling. If EPR is simply turned off (my state for the first 6+ years of cpap use) then trigger can't matter.

I'm also not totally convinced that this isn't some weird measurement artifact. I don't really understand how the machine can measure mask pressure from the other end of what is a pretty long hose. When the airflow path is a straight line from windpipe to nose, that's a reasonably simple model. But once cheeks can inflate/deflate completely out of sync with breathing, and my mouth can open up and air can circle around nose and mouth and that can also be completely out of sync with the flow in and out of my windpipe -- well when I start thinking about that I'm pretty skeptical that the sensors down in the machine can really know all of that data to the precision that a cpap engineer claims. And over the 7 years I've been doing this I've been through a lot of masks -- F10, Amara View, Dreamwear FFM, F30, Dreamwear Nasal, N30i, P30i, F30i -- in various sizes. It's hard to believe that a particular signal out of an F10 must always represent the same airflow behavior as when that signal comes out of an F30i -- and all the machine knows is that I'm wearing a full-face mask.

The machine records a tremendous amount of data at very high precision, and this nagging voice in the back of my head keeps saying "there's no way a couple of pressure sensors at the other end of the hose can REALLY see all that." (Not to mention that the skeptic who sleeps on the other side of the bed actually teaches computational fluid dynamics and has said on more than one occasion that he totally does not believe the data.)
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#50
RE: wildly jagged flow rate curves -- do you see this in your data?
Can't really comment on your data and weird results (though apparently during what I am guessing is REM sleep, my resp rate can apparently triple sometimes, and the FLs shoot up so...)

But with regard to the F30i, your concern about the mask shifting and blocking the nose is EXACTLY why I can't use this mask, as much as I would love to. It ends up shifting just enough to partially (or sometimes completely) obstruct one or even both nostrils... and that sure wakes me up with a gasp. I considered even cutting out the middle strip but figured that might just ruin a perfectly good mask insert... and as I paid for it myself, I'm somewhat loathe to try. So it sits beside my bed, for the times I can't cope with pillows but my nose is too sore at the bridge for a FFM. *Touch wood* that won't be for a while now I have a routine in place, though!
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