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Strange flow rates. Can anyone help me figure out what this is? - Printable Version

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Strange flow rates. Can anyone help me figure out what this is? - Kobalt - 10-22-2021

Hi all,

I'm reviewing my Oscar data and finding that there are strange patterns with my flow rates. I've attached an image below and highlighted what I'm talking about in red. Can anyone help me determine what these are and what to do about it?

Thanks!

RE: Strange flow rates. Can anyone help me figure out what this is? - 2SleepBetta - 10-22-2021

Some call that "cardiogenic", others "cardio ballistic", effect. In the quiet seconds before inspiration begins, the beating of our heart gives us, in a manner of speaking, a little CPR-like compressions internally. Those are common. I show a lot of it. When doing work to analyze our sleep, their presence in the data is a bother. Makes it hard to reliably determine the start of a true inspiration when you have so many little "mini breaths" before inspiration starts. It is no problem for me or those who who show it here at AB, as far as I know.

I'd only be concerned if they were a sudden marked change. If you've long been without them, and know that, and they suddenly began showing up, then ask your MD about them. I am not sure about urgency in that latter case.

RE: Strange flow rates. Can anyone help me figure out what this is? - Kobalt - 10-22-2021

(10-22-2021, 02:39 PM)2SleepBetta Wrote: Some call that "cardiogenic", others "cardio ballistic", effect. In the quiet seconds before inspiration begins, the beating of our heart gives us, in a manner of speaking, a little CPR-like compressions internally. Those are common. I show a lot of it. When doing work to analyze our sleep, their presence in the data is a bother. Makes it hard to reliably determine the start of a true inspiration when you have so many little "mini breaths" before inspiration starts. It is no problem for me or those who who show it here at AB, as far as I know.

I'd only be concerned if they were a sudden marked change. If you've long been without them, and know that, and they suddenly began showing up, then ask your MD about them. I am not sure about urgency in that latter case.

Great, thank you!

RE: Strange flow rates. Can anyone help me figure out what this is? - cathyf - 10-22-2021

I believe that they are measurement artifacts from the way that the machine probes for central apneas. Go find a CA in your data and look at the mask pressure curve, and you'll see a "trill" of tiny fast pressure probes. Also at least my CAs are in the context of a whole run of breaths with little 1-2-3-second breaks at the end of the exhale, and then the CA looks like I had a little pause that got a little longer and if it's at least 10 seconds then it's a CA. But if you look at the CA you see that the machine starts the trill as soon as you pause at the end of an exhale, and then if the pause lasts for 10 seconds it has the information to rule it a central.

So as soon as you pause, the machine starts probing -- is there a bounce? is there a bounce? is there a bounce? is there a bounce? is there a bounce? is there a bounce?... If it gets to the end of 10 seconds and you are still not breathing, it looks and decides that if there were bounces then you are in OA for ten seconds already and counting. If there haven't been any bounces back, it decides that have been in CA for ten seconds already and counting. If you start another breath before the 10 seconds are up, then the machine says "oh never mind."

RE: Strange flow rates. Can anyone help me figure out what this is? - quiescence at last - 10-22-2021

the fact that you pause after exhale is one of the major signs that you are sleeping.  the awake body and brain tries to control the inhale and the exhale.  the asleep body acts totally differently - the nor the body or brain attempts to control the exhale.  the mechanism that is in play is a signal to inhale, and once inhale is over, the balloon that was filled just deflates on it's own.  this shows up as air flow pattern of "in-out-pause".  the lungs monitor the buildup of CO2 and signals the brain of that (each and every breath), the brain responds with a direction to muscles to initiate inhale.

[Image: btZIMzUl.png]

the above is a case where the machine really is trying to measure your flow resistance to breathing, and this only occurs after about 5 seconds.  It doesn't do that on the previous breaths that still have the pause.  the machine does that to decide whether to count the pause as obstructive (OA) or not (CA).

your breathing pattern is not concerning at all to me.

QAL

RE: Strange flow rates. Can anyone help me figure out what this is? - Geer1 - 10-22-2021

100% cardiogenic oscillations. They are caused by the pulmonary blood flow and superimpose on flow rate chart at end of exhale because respiratory muscles are relaxed. 

Some people are more prone to these because of a longer relaxed time between breaths and some have larger amplitude due to higher blood flow. 

https://www.sciencedirect.com/science/article/abs/pii/S1569904809001360?via%3Dihub

RE: Strange flow rates. Can anyone help me figure out what this is? - SevereApnea - 10-23-2021

Hi Kobalt

your flow rate graph looks very pixelated to me.

This might be from your image capture software (MS Paint/image viewer etc) or maybe graphics processor, no matter.


There does seem to be some Cardiogenic Oscillation (Cardiogenic Oscillations) in there and perhaps some FOT 

Go to this page PAP technology and search the page for FOT.

I can sometimes see 2 such COs in my own charts, one large one small one large one small etc depending on certain conditions.

[attachment=36588]


Thanks for the link Geer1  

I always thought it was simply because of cardiac pulsations transmitted from the heart to the airways directly, but this abstract hints this is not so.
I look forward to reading the full article.

It might also be somewhat more complicated than that: Collier & MRI

"However, it is worth noting that certain experimental and physiological conditions, such as low flow rates, hyperinflated lungs (13), higher cardiac output per beat, and lower heartbeat frequencies, are more favorable for the observation of cardiogenic oscillations"

All really rather academic and of no real benefit to our therapy but interesting digression.

and another interesting read: rogue capno waves

I often wondered if the CO were related to BMI. I exhibit lots of CO with BMI of 23 - 24, and am more aware of my heart beating depending on PS or EPR, mask selection and pressures.

{{Looking into the future.....
Now, if our SD cards could read out a Cardiac Oscillation Index that would be fun to look at.
Particularly if we have the ability to record if we were supine or side sleeping.}}