Having RG say that she doesn't know much about how how autopaps work MUST go into the Annals of Understatement. That's like telling someone in SouthEast Asia that they're gonna get damp in the face of an on-coming tsunami. I don't know ANYONE who understands better how the various APAPs worh than does RG.rested gal wrote:st3v3k4hn, I'm no expert on the way autopaps work, but I think the machine probably does a lot of behind the scenes sensing that we aren't going to see reflected in the data.
By that I mean... I believe the machine looks at subtle changes in airflow to decide what to do next. It's not just looking at the events you see tick marked, and then taking action. The marked occurrences are the events that actually happened despite the machine working to proactively prevent "events" -- apneas, hypopneas -- as well as flow limitations, snores.
So, if we see pressure rise with no "event" immediately preceding it, and the leak rate is normal (which I think yours was during the area you highlighted on the graph) my bet would be that the machine was seeing enough flow limitation from you that it decided more pressure was needed. Even if the flow limitation was not "limited enough" to warrant a tick mark on the data.
In the middle of the highlighted area, your breathing might have normalized some for awhile, so the machine did start the gradual move down. But apparently during that pressure drop in the center of the highlighted area your breathing showed signs of a problem again, so the pressure moved back up. It moved back up to PREVENT an event from happening. If the event is prevented and doesn't happen, it's not going to be marked. 'Cause...it didn't happen.
In other words, the machine was seeing problems with your breathing during the highlighted time. The problems just didn't get "worse enough" to trigger the official marking of an event. But the problems did warrant keeping the pressure up.
There was almost surely some amount of flow limitations happening in varying degrees all during the highlighted time for the machine to stay up there so long, try to come down, and then say (in effect) -- "Nah, when I try to move the pressure down, the airflow becomes more limited (restricted) again...gotta go back up BEFORE it turns into an official "flow limitation" or worse.
I could be very wrong about any/all of that. I don't know much about the way autopaps go about doing their thing.
So, yes, she is right, that some APAPs, particularly those made by Respironics, do lots "behind the scenes" before an event actually happens. And, Den and others are here are incorrect; Resprionics employs a "probing" algorithm that constantly creates small, step-wise increases in its operating pressure throughout the night to determine whether each increase improves flow-dynamics of your breathing. It will keep doing this until it senses no further improvements, and then will mainitain or back down pressure gradually until it begins a new "probe" cycle.
So, in answer to your question, YES, auto-titrating PAPs made by Respironics will demonstrate small increases and decreases in pressure even if NO events are detected and scored, and will do so throughout the night. If it attempts three such increases in the face of what it scores as flow degradations in your breathing with NO improvements after those three steps it will then score the event as a "non-responsive" event (possibly a central event) and then decrease pressure.
Hope this helps.
Chuck
