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Resmed A10 Pressure runup without apparent cause
#11
I'm still new at this, and I use straight CPAP, so I don't get a flow limitation graph in my own data, but here's the definition from the Apnea Board Definitions Wiki: "Flow Limitation - Partial closure of the upper airway, which impedes the flow of air into the lungs."

and here is a chart from Beginner's Guide to SleepyHead with different abnormal breathing (flow) waveforms and what each means.

My understanding is that flow limitation indicates that there's resistance in the airway that isn't severe enough to cause an apnea or hypopnea. Not sure that's correct.





(04-03-2016, 07:16 PM)Ed1101 Wrote: Seems trying to add a chart , I inadvertently posted twice and I cannot delete. One should not be logged in on iPad and then add image on computer without logout on iPad first. See post #9 for chart and reply.

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#12
(04-03-2016, 06:35 PM)Ed1101 Wrote: I understand that higher is worse. How high would one expect it go if no air is flowing and what is the meaning of the "flat tops" on the flow rate graph? I do not understand the scale on the flow limitation chart.

Thanks for the explanation Vsheline, but I do not see a positive and negative on the flow limitation graph only what appears to be positive?

your "no air is flowing" is not applicable to flow limitations.

look at the tops of the airflow when the flow limitation graph is high, and compare that to the tops of the airflow when the flow limitation graph is low.

normal breath inhalation is a smooth humped curve, when the airway narrows and there is flow limitation then the tops of the curve is chopped off to a varying degree, the more it's flattened, the worse the flow limitation is.

instead of my trying to post a tiny subset here, go to 'images.google.com' and searching for 'flow limitation' and you'll see plenty of examples, as well as what to look for in your flow graph.
(04-03-2016, 07:47 PM)green wings Wrote: My understanding is that flow limitation indicates that there's resistance in the airway that isn't severe enough to cause an apnea or hypopnea. Not sure that's correct.


that's not correct, you can have flow limitations all night long without an apnea or a hypopnea...

flow limitations do make it harder to breath, and thus require more effort and can cause sleep disruption because of that.
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#13
Thanks palerider. Your answer helped me to understand better a very confusing topic - "flow Limitation" and the flow limitation graph and its relationship to the flow rate graph.

It appears that the flow limitation graph is not a empirical graph and microanalysing it is probably not a good idea. I think that the flow limitation graph is best used for purposes of trending and heuristically/visually comparing FL severity from one night to the next. Thinking-about Perhaps it does help explain why the pressure increases occur without a corresponding flagged event. That is probably why the ResMed graph shows only a shape representation (rounded, flat top, chair shape of flow rate waveform) and not a numeric scale. The SH flow limitation scale was the source of my confusion in that it has a numeric scale to which I attempted to attach more significance than an indication of increased flow limitation reflected in the flow rate graph waveform shape.

It does not matter how slowly you go as long as you do not stop. --Confucius
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