Quotes are from the post on the other thread. The data posted on the other thread looks like this:
(04-22-2016 01:36 PM)tmoody Wrote: I do wonder why my maximum IPAP in a given night seldom goes much higher than about 12, even though the EPAPmax value is 23.
I am not an ASV expert by any means. But it looks like there is some kind of algorithm programed into the machine that dynamically determines a reasonable "local max IPAP" value that is based on both the current EPAP value and parameters that are determined by the shape of the inhalations in the flow rate graph. It looks as though the machine wants to use as little extra IPAP pressure as needed when it starts triggering inhalations. If a little extra IPAP doesn't work to stabilize the breathing OR if the breathing gets ragged in some specific way, it looks like the "max IPAP" algorithm kicks in and increases the local max IPAP so that the machine can add more extra IPAP when it needs to trigger inhalations. Clearly, the local max IPAP only reaches the max IPAP setting when the machine is finding the need to trigger lots and lots of inhalations---i.e. the machine's noninvasive ventilator properties are being used at their max capability to trigger the inhalations.
Quote:Last night's maximum [EPAP] was 9.5, but I still had 26 hypos during the night. From my reading on this forum and in the manual (I still don't pretend to have a clear understanding), the whole point of having a variable EPAP with a fairly high maximum is to have enough "ceiling" to increase EPAP pressure to get rid of OAs and HAs.
You are using a PR System One ASV. I am not sure if the "Auto EPAP" algorithm used by your machine is similar to the "Auto BiPAP" algorithm used by the simpler PR System One BiPAP Auto machine. But it looks like it might be.
In the PR Auto BiPAP's "Auto" algorithm, EPAP is increased for clusters of OAs, clusters of OAs mixed with Hs, and snoring. Clusters of Hs result in an increased IPAP, not an increased EPAP.
In your data, there's a distinct cluster of just Hs right before 1:30. It's clear that the EPAP did not increase in response to those Hs. It's less clear, but it appears that the actual IPAP was increased during the cluster and then was lowered after the cluster of Hs appears to clear up. It would be useful to zoom in on the time frame of 1:15 to 1:45 to see exactly what is happening to the IPAP during and right after that cluster of Hs.
Quote:I'm not complaining. 26 HAs is still about half of what I was getting on APAP. I'm just curious about why the ASV doesn't bump EPAP pressure a bit higher on those HAs. I guess this question is a bit OT for this thread.
It looks like the PR ASV "auto EPAP" algorithm is similar to the PR BiPAP Auto's "auto" algorithm. See my comments above.