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Flow Limitation Time - jdavidstark - 09-27-2022
In OSCAR, is there some way to see or calculate the total time for a given day for which there is some flow limitation recorded?
I have an Airsense 10 Autoset in AutoCPAP mode. And I see the flow limitation graph on the Daily page and how that graph indicates how much flow limitation I had at each point over the course of the night. But I'm looking for some way to tell for how long I had flow limitation during the night.
I have an upcoming visit with my sleep medicine provider, and the duration of flow limitation as a percentage of sleep time is one of the diagnostic criteria for UARS. So, if it's possible to get that time frame out of OSCAR, that would (potentially) help me in the conversation about possible changes to my treatment even though my sleep apnea now regularly falls in the "normal" AHI range.
Thanks so much for your help (and I apologize if I'm simply overlooking this answer in the existing documentation or misunderstanding what that's telling me about what I'm seeing)!
RE: Flow Limitation Time - multicast - 09-28-2022
Don't give too much on FL, i.e., what the machine shows in the graph. It's a kind of golden calf, don't dance too much around it. What is shown by the machine is *not* a physical flow limitation per se, but a *grading* of your breathing (0 corresponds to A, 1 to F) -- no more, no less.
A physical FL -- the "real thing" -- is a non-linearity between pressure and breathing-flow during inspiration. In short: the breathing effort does not linearly correspond to the flow of breathing. This non-linearity is measured by comparing the flow of breathing with the (negative) oesophageal pressure during the breathing (these scientists found out that the breathing effort is proportional to the oesophageal pressure) -- which can only be done in a lab, either by swallowing some probe or with some belts around your abdomen.
In short (again): our machines can by no means detect "the real thing". And even human beings can't be sure what exactly is happening only by looking at the flow rate -- but their guesses are more educated.
Nevertheless a very clever algorithm analyses the flow rate and grades the quality of breathing, in a way. Now the machine's crystal ball gives some coaching by raising pressure in case the grading worsens. Please have in mind that the machines grading may or may not correspond to a physical flow limitation.
Astonishingly enough this works in most cases! Who heals is right ...
What matters is how you feel with the therapy. Don't care too much about the machines grading: it's pointless.