Flow Limitation

[MMcG]

A quick question about flow limitation events. I just watched a youtube video recommended by someone here which explains all the common respiratory sleep events, including flow limitation. The video specifically referred to a "chair like" shape to the breathing pattern during a flow limitation event. My Devilbiss/Intellipap machine show me having frequent flow limitations but the wave pattern is nothing like the chair shape. Below are two screenshots, the first a detail from my Oscar data last night, the second from the video. I strongly suspect that my CPAP machine is flagging false flow limitation events. Any thoughts please?

[BlueDragon]

Your OSCAR chart shows typical flow limitations -- the inhalation portion of your breath has a flat top, suggesting that inhalation rate was limited. "Normal" breath pattern shows a rounded top.

The "chair" diagram seems to be less common, at least in my experience. It suggests that inhalation started at full volume and then was restricted. I think usually it is restricted in the first place so you don't get the "back of the chair" part.

[Miss Emerita]

MMcG, the images aren't there. Could you try again? Meanwhile, here are images of flow limited inspiration:

Flow images for FL.jpg

On the far left is a normal trace; then we see the variety of flow-limited breaths. I think of them as various combinations of dents, humps, and plateaus. My machine will also sometimes flag small-sized inhalations as flow-limited.

[Dog Slobber]

When asking for comments related to some other resource (video, webpage, post, etc) you're better off linking to the resource so we can also see exactly what was said, the context and the credibility of the resource.

While a chair-like trace is a classic look for flow limited breathing, it's *not* the only pattern. A flattened top instead of a rounded peak is also an indicator of flow limitations.

I would not consider your flow limitations to be false positives.

[Miss Emerita]

Apologies: Pugsy pointed out she could see the attachments, plus a comment from Blue Dragon. I looked again, and there there were! Plus now a comment from DS.

[MMcG]

When asking for comments related to some other resource (video, webpage, post, etc) you're better off linking to the resource so we can also see exactly what was said, the context and the credibility of the resource.

While a chair-like trace is a classic look for flow limited breathing, it's *not* the only pattern. A flattened top instead of a rounded peak is also an indicator of flow limitations.

I would not consider your flow limitations to be false positives.

Thank you. Maybe I should look at increasing my minimum pressure then? Pugsy here in reply to someone recommended the youtube video. Here's the link:- https://www.youtube.com/watch?v=-gie2dhqP2c

[MMcG]

Your OSCAR chart shows typical flow limitations -- the inhalation portion of your breath has a flat top, suggesting that inhalation rate was limited. "Normal" breath pattern shows a rounded top.

The "chair" diagram seems to be less common, at least in my experience. It suggests that inhalation started at full volume and then was restricted. I think usually it is restricted in the first place so you don't get the "back of the chair" part.

Looks like I need to try to limit them then. Thanks.

[MMcG]

MMcG, the images aren't there. Could you try again? Meanwhile, here are images of flow limited inspiration:


Flow images for FL.jpg


On the far left is a normal trace; then we see the variety of flow-limited breaths. I think of them as various combinations of dents, humps, and plateaus. My machine will also sometimes flag small-sized inhalations as flow-limited.

Looks like mine are of the far right type. Thanks.

[BlueDragon]

DeVilbiss BLUE machines report flow limits at three levels: Mild, Moderate, and Severe. Flow limits classified as "severe" are flagged as events and show up in your Events graph. OSCAR graphs all three levels of flow limits in the Flow Limits graph. So you should see a FL event only when the graph shows a Severe flow limit. (Mild, moderate, and severe flow limits have graph values of 1, 2, or 3 respectively.)

[Dog Slobber]

When asking for comments related to some other resource (video, webpage, post, etc) you're better off linking to the resource so we can also see exactly what was said, the context and the credibility of the resource.

While a chair-like trace is a classic look for flow limited breathing, it's *not* the only pattern. A flattened top instead of a rounded peak is also an indicator of flow limitations.

I would not consider your flow limitations to be false positives.

Thank you. Maybe I should look at increasing my minimum pressure then? Pugsy here in reply to someone recommended the youtube video. Here's the link:- https://www.youtube.com/watch?v=-gie2dhqP2c

I'm familiar with the video.

And yes, you interpretted it incorrectly. The video did reference a Chair-Like shape, but also referenced a flattening. You can't interpret that as, it must or always is chair-like.

[dataq1]

When asking for comments related to some other resource (video, webpage, post, etc) you're better off linking to the resource so we can also see exactly what was said, the context and the credibility of the resource.

The image presented by Miss Emerita is found in the article at: https://www.sciencedirect.com/science/a ... 516#bbib30

[dataq1]

A quick question about flow limitation events.

Another source to consider is:
http://www.apneaboard.com/wiki/index.ph ... mitations authored by the OSCAR team.
The Expiratory mouth breathing with normal inspiratory flow looks like the reverse chair trace.
I'm going to go out on a limb here but I'd bet that the expiratory mouth breathing with normal inspiration is what might expect if the patient were inhaling thru the nose and exhaling thru the mouth while using a nasal mask

[dataq1]

See the thread I started on Oct 19 2021 titled "Pressure Response on AirSense 11"
about half way down the page we get into a discussion of flow limitations.

I've also sent you a new private message

[MMcG]

See the thread I started on Oct 19 2021 titled "Pressure Response on AirSense 11"
about half way down the page we get into a discussion of flow limitations.

I've also sent you a new private message

Will do. Thanks.

[MMcG]

A quick question about flow limitation events.

Another source to consider is:
http://www.apneaboard.com/wiki/index.ph ... mitations authored by the OSCAR team.
The Expiratory mouth breathing with normal inspiratory flow looks like the reverse chair trace.
I'm going to go out on a limb here but I'd bet that the expiratory mouth breathing with normal inspiration is what might expect if the patient were inhaling thru the nose and exhaling thru the mouth while using a nasal mask

Yes, I use a nasal pillow and I know from the wave pattern that I am breathing in through the nose and exhaling through the mouth. This varies a lot. Some nights it can only be for a few minutes in total, but on other occasions I've kept up for forty-five minutes or more and done that more than once during the night. I have EPR on my Devilbiss/Intellipap machine but my sleep technician has recommended against using it. I think his logic is that if I can adapt and outgrow the exhale puffing (I am doing a lot less of it after 7-8 weeks on CPAP therapy), it will be better in the long run than to become reliant on EPR. I can see logically how it might discourage exhale puffing, but in the example on "apnea board", it suggests it also helps with flow limitation too. I'm not clear as the why this would be so, because surely EPR does nothing for inhaling? If I knew why it might solve both problems, I'd discuss it with my technician and give it a try.