Flow Limitation

palerider · Post by **palerider** » Thu Nov 04, 2021 11:13 pm

dataq1 wrote: ↑
Thu Nov 04, 2021 9:49 pm

palerider wrote: ↑
Thu Nov 04, 2021 9:21 pm

So I looked at your parts list and realized that you were mis-identifying parts. Sensirion SDP is NOT a flow meter.
Inaccuracy plus snark is not a contributor I want to deal with or respond to in the future

You see? this is why people give up on trying to educate you, you're arrogant and ignorant, which isn't a good combination.

I'll try *ONE MORE TIME* then I write you off as an idiot.

Read this page:

https://www.sensirion.com/en/about-us/n ... in-bypass/

That explains how the flow sensors work in CPAPs, (at least, all the ones I've disassembled).

BlueDragon · Post by **BlueDragon** » Thu Nov 04, 2021 11:55 pm

dataq1 wrote: ↑
Thu Nov 04, 2021 10:23 pm
However, flow limitations or abnormalities (such as that displayed by the apneaboard wiki (shown above) suggest that a significant volume that has to exhaled eventually is not being captured by the device (at least not within scope of the graphics time scale).

I have no reason to believe that is the case. The flat top on the graph represents the flow rate, not the flow volume. Volume is the sum under the curve. If you want the same volume with a flow-limited breath, the breath just has to be a slight bit longer to achieve the same volume.

dataq1 wrote: ↑
Thu Nov 04, 2021 10:23 pm
What concerns me is that a flow pattern, like that shown in the apneaboard wiki graphic, would be graded as a flow limitation and subsequently an increase in pressure would be ordered in a APAP machine.

[UPDATE TO CORRECT ERROR] Most machines increase pressure in response to flow limits. Some older DeVilbiss machines may not. (Thanks to palerider for the correction.)

dataq1 · Post by **dataq1** » Fri Nov 05, 2021 8:04 am

BlueDragon wrote: ↑
Thu Nov 04, 2021 11:55 pm
I have no reason to believe that is the case. The flat top on the graph represents the flow rate.....

I think you are referring to a different graphic than I. When I said " flow limitations or abnormalities (such as that displayed by the apneaboard wiki (shown above)" ,I was specifically referring to this graphic in the apneaboard wiki on flow limitations:

: Expiratory mouth breathing.jpg (15.88 KiB) Viewed 704 times

But I definitely concur with you that "Volume is the sum under the curve" (albeit that I say it is represented by the area under the curve..... same notion yes?)

dataq1 · Post by **dataq1** » Fri Nov 05, 2021 8:09 am

palerider wrote: ↑
Thu Nov 04, 2021 11:13 pm

It is clear that you are intent on making this personal.

BlueDragon · Post by **BlueDragon** » Fri Nov 05, 2021 8:33 am

dataq1 wrote: ↑
Thu Nov 04, 2021 10:23 pm
[What concerns me is that a flow pattern, like that shown in the apneaboard wiki graphic, would be graded as a flow limitation and subsequently an increase in pressure would be ordered in a APAP machine.

ok, now I think I understand the question you are asking: you are asking if expiratory mouth leaks will result in the CPAP machine misidentifying the situation and raising pressure.

I don't know the innards of CPAP machine programming, so don't know the answer. The graph you referred to has "normal inspiratory flow morphology" so I don't know why a machine would classify it as a flow limitation.

MMcG · Post by **MMcG** » Fri Nov 05, 2021 10:56 am

dataq1 wrote: ↑
Fri Nov 05, 2021 8:04 am

BlueDragon wrote: ↑
Thu Nov 04, 2021 11:55 pm
I have no reason to believe that is the case. The flat top on the graph represents the flow rate.....
I think you are referring to a different graphic than I. When I said " flow limitations or abnormalities (such as that displayed by the apneaboard wiki (shown above)" ,I was specifically referring to this graphic in the apneaboard wiki on flow limitations:
Expiratory mouth breathing.jpg

But I definitely concur with you that "Volume is the sum under the curve" (albeit that I say it is represented by the area under the curve..... same notion yes?)
[/quote

This is the exact pattern my Devilbiss/Intellipap machine records as "Expiratory Puffs". There are not seen as flow limitations however and, accordingly, the machine doesn't respond to them in any way.

palerider · Post by **palerider** » Fri Nov 05, 2021 12:32 pm

dataq1 wrote: ↑
Fri Nov 05, 2021 8:09 am

palerider wrote: ↑
Thu Nov 04, 2021 11:13 pm

It is clear that you are intent on making this personal.

You're welcome to stop arguing with everything anybody posts to you any time you wish.

dataq1 · Post by **dataq1** » Fri Nov 05, 2021 1:21 pm

For the benefit of MMcG;

: Flowrate-tidal volume.jpg (74.41 KiB) Viewed 667 times

palerider · Post by **palerider** » Fri Nov 05, 2021 3:04 pm

dataq1 wrote: ↑
Fri Nov 05, 2021 1:21 pm
For the benefit of MMcG;
Flowrate-tidal volume.jpg

If you're going to be posting screen shots of flow, make them more meaningful by turning on the zero line.

Flow Limitation

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