some breathing events not flagged

[echo]

Hi guys, hope everyone is well, I haven't been on here in forever! Miss you all!

I've been feeling pretty crappy lately, and it only ocurred to me today to check my cpap data. Although AHI and other parameters look good, the software doesn't seem to be flagging all breathing events. For example, in the Sleepyhead screenshot below, there appear to be 2 events where the flow rate = 0 (approx 5 and 10 seconds each) but they aren't flagged as anything. Any idea why?

And what is the little red square between time 11:09 and 11:10?

Thanks for any help!

[Pugsy]

Remember that all events that are flagged have to meet certain minimum requirements...so much reduction in flow and at least 10 seconds in duration. I imagine that the one that appears to be maybe 10 seconds was really 9 seconds in the eyes of the machine.

I think the box may be a pressure pulse test which is what the machine uses to help decide if a flow reduction is central or obstructive in nature. Check to see if you have a pressure pulse noted in your events tab at about that time frame. Pressure pulses may or may not be seen next to flagged events because the machine may end up deciding the reduction in flow didn't meet the minimum criteria to earn a flag.

[echo]

Thanks Pugsy, that makes sense!

Yes, you're right, those are pressure pulses (never noticed that before in the Events tab)!

What happens in response to the pressure pulse if the event is central vs obstructive?

[Pugsy]

If the pressure pulse tells the machine that the reduced air flow is central in nature the machine says "oh, it's a central and I don't respond to centrals at all"....if it decides the reduced air flow is from airway tissues sagging and partially/fully blocking the airway and is thus obstructive in nature then it thinks "hmmm, obstructive maybe (or maybe not) I need to increase the pressure to help hold the airway open better".
I don't think the machine will respond to one lone event unless there is something else going on like maybe a snore or flow limitation that we don't see so easily on the graphs.
It used the pressure pulse to help it decide what to do should certain other criteria needs are met.
Don't ask me the exact criteria for pressure increase response as I don't file that away in my brain storage. I think it's a combination of things and I never really worried to much about why something gets done...I just want it done and I trust the machine to do its thing.

In your situation above both flow reduction events didn't earn a flag and there doesn't seem to be anything else going on around them so I would suspect that nothing was done even if it was obstructive in nature.