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wildly jagged flow rate curves -- do you see this in your data?
RE: wildly jagged flow rate curves -- do you see this in your data?
You keep theorizing. Start testing/proving this. Go back and look at your old autoset data. Look through say a weeks worth of data at each EPR setting you used. Calculate the time spent in this breathing and divide it by total time slept during that period. Based on the data you have posted I expect the percentage of time spent in this breathing to be higher for lower EPR values unless the data you have posted isn't indicative of average night.

There are only two possible reasons this is lower on vauto. One is higher PS. The other is a lower trigger sensitivity. The ability to use higher EPR/PS and tweak the pressure wave form using timing controls are the only differences between these machines. Its the same blower motor operating at approximately the same pressures with approximately the same waveforms (minus what you tweak with timing controls).

These machines are much more basic then you give them credit for. They don't care nor take into account your chipmunk cheeks etc. Mask pressure and flow rate are simple calculations done at the machines. What you are questioning the accuracy of is flow rate as this is the data where you are seeing these fluctuations. Flow rate is calculated by the machine using some combination of sensors and I assume a vfd driven blower. Put on your mask, turn on the machine and place a hand near the inlet filter and breath in (you can feel air being sucked into machine) then breath out (you can feel air being pushed out). It is that flow through the machine that is being calculated/recorded and as far as I know could be as simple as recording the blower positioning. What is happening in your mouth, lungs etc does not matter, all that does is affect what pressures/flows are seen and recorded at the machine.

As a mechanical engineer I have been blown away by the accuracy of the flow rate data recorded by these machines. When I use my camera I can see a visible explanation for almost every odd breath I see in my OSCAR data. To review my camera data I literally look at the time of an odd shaped breath in OSCAR and then look at that time on the video. There is no point in watching the full 8+ hrs of video because most of it is me sleeping normally and almost every movement, odd breath or arousal shows up in my OSCAR flow rate data. I know because I did watch almost every minute of my first few videos when first comparing to OSCAR.

These flow rate charts are so accurate you can literally determine your heart rate from them by calculating the spacing between the extremely minor exhalations caused by expanding blood vessels in your lungs (aka determining the spacing of cardiogenic oscillations). This blew my mind and it wasn't until I saw my recent CT images that I was able to better understand why we can see these cardiogenic oscillations in our data. You can see something similar by clicking axial or coronal lung window in the viewer at this link and then scrolling up/down through images to see the blood vessel structures throughout the lungs and realizing that the vessels take up a fair amount of space. Cardiogenic oscillations in data are physical flow changes being measured at the machine, crazy accurate measurement ability. 


Now stop and think about this for a bit. You have seen this on multiple machines, it is not a calculation error. We know these flow rate data charts are extremely accurate and it is something real being caused by something your body is physically doing. The big kicker is that this is not a little blip like a cardiogenic oscillation, your body is creating rapid, large amplitude air flow direction changes at the machine. I've already recommended video recording this multiple times but will do so again. Once you catch this on video it will be blatantly obvious what is happening (although maybe not blatantly obvious what is causing it), if it isn't obvious I will be very surprised.
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RE: wildly jagged flow rate curves -- do you see this in your data?
Gonna second the video recording. I got a cheap IR capable Wyze Cam V2 and an SDcard for it. It sits on the table next to my bed and watches me sleep every night. I even figured out how to automatically start and stop it recording so I don't forget anymore! It's not the greatest of interfaces, but it works, and watching myself is how I figured out that those nights where the machine reported something that looked odd and I could check. Where I could verify that I wasn't, in fact, breathing for over a minute... where I was shifting, or scratching my nose... and also where I figured out that I rub my fingers together IN MY SLEEP... Or the time I woke myself up with such a big leg jerk that I knocked the table, and I had no idea what had woken me up so suddenly. I just had to glance at the time (though it was obvious on the data in OSCAR LOL) and check around then on the video. I spent less than £30 and it's been invaluable.
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RE: wildly jagged flow rate curves -- do you see this in your data?
Yeah there are lots of cheap infrared camera options. The key is to find one that records to an SD card and saves them in a format you can access/use (first one I tried did not).

I use a Nooie outdoor version but their indoor or 360 version may be easier to use. You have to use their app to operate it but it isn't too bad if you have the right wifi connection type. The only downside is that it saves the video in 5 minute intervals so you end up with a ton of files for a night.

You can also use any type of camera if you leave lights on and wear a blindfold. I did that the first couple times.
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RE: wildly jagged flow rate curves -- do you see this in your data?
The Wyze, if you use the SD Card, records everything in standard video format, one minute long videos, so that when it runs out of space, you only lose it minute by minute as it overwrites the old files. You can scan manually, or use their phone app. To be honest, before I got the Wyze, I used OBS and the crappy webcam built into my laptop. Wearing my eye mask and turning down the brightness gave enough light to record my sleep without overly disturbing me. LOL
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RE: wildly jagged flow rate curves -- do you see this in your data?
Ok, I'm convinced that you guys are right. I set up my overview screen in such a way that I can see that there IS a relationship between EPR/PS and the "jaggies".

This view is everything from Day 0 for me:

(A recap... The 3-month gap from mid-Decmeber 2020 to mid-March 2021 is because I had a sleep study in Nov 2020 and Dr Pompous ruled that I didn't have apnea and I should stop using the machine. Then I started up again with back sleeping and chin tucking, and had an in-person appointment with Dr Pompous, which got me another sleep study last April. Between when the study was ordered and I had it, the brilliant people here educated me on EPR and flow limits, and positional apnea and cervical collars. So by April I was educated enough to produce an AHI of 18 on demand, LOL. Before 2021 I spent 6+ years running with crappy parameters -- the typical apnea patient given a sleep study and a prescription and abandoned to figure things out for myself. I decided at the beginning that the "comfort features" were a crock and so I turned off ramp and  EPR. While I was right about ramp, the EPR decision was dead wrong and I suffered continuous flow limits whenever I was asleep.

Here's just 2020:
You can tell the difference between autoset and vauto because the autoset pressure barcharts are yellow and green where the vauto are only yellow. Over that time I was experimenting with different things.)

There IS a strong correlation between lots of jaggy breathing and lack of pressure support, but it's not black and white. I've got two nights where I got jaggy breathing with the vauto and PS of 4, trigger medium -- two nights where I ran all the same settings on the vauto as dozens and dozens of nights where it looked MUCH better than those two nights. With the autoset, EPR turned off is systematically worse than EPR=3, but I've still got a bunch of EPR=3 nights that look worse than a bunch of no-EPR nights. As well as noting that every night where I've got periods of dramatically weird jagged breathing those periods will be interleaved with periods where everything looks great. This is what makes me sure that there is another factor that matters -- maybe positional, or something like that.

The camera that the hubs brought home was bought to monitor plant growth as part of some student research projects, so isn't infrared. But he says we can buy an infrared, and we'll just sleep with the lights on until then. (I am married to a man whose grad school roommate pointed out that he's the perfect grad student. Doesn't sleep, drinks coffee continuously - Dielaughing - so the lights on won't bother him!)
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RE: wildly jagged flow rate curves -- do you see this in your data?
The key is always to look at averages especially in cases like yours where your data can fluctuate significantly night to night and because you know there is a positional apnea aspect that is better/worse some nights (and depending on how you treat it).

How often does this breathing happen at 0 EPR? If it is a nightly occurrence then I would use autoset at 0 EPR (or PS 0 on your vauto) for a night to get this on tape. Right now we are just trying to understand/confirm the mechanism behind this pattern so there is no point affecting multiple nights sleeping with lights on etc at current settings (in case that was your idea). Hopefully a few minutes of this on tape will make it obvious what is happening and then we can start coming up with more theories and potential treatments etc.
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RE: wildly jagged flow rate curves -- do you see this in your data?
I know it's so easy to tug on the ends trying to figure out the weird results, but averages are definitely the way to go.

Your hubby is a good man LOL sleeping with the light on for you! Hopefully the camera will help figure out what's going on.
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RE: wildly jagged flow rate curves -- do you see this in your data?
(01-04-2022, 05:46 AM)Ratchick Wrote: Your hubby is a good man LOL sleeping with the light on for you! Hopefully the camera will help figure out what's going on.

The first day of class the hubs always shows the students this video https://youtu.be/zC8vMA58U7M He tells them that their data is THAT IMPORTANT!!!!!
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RE: wildly jagged flow rate curves -- do you see this in your data?
LMAO well THAT'S enough to get your blood pumping. Goodness!
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