Strange Night - Runaway Pressure Pulses?

Very strange night - am not sure what to make of it.

I slept well and comfortably; AHI was 0.09. But I have a clear memory of awakening at some point in the night to a strong, rapid succession of huge pressure pulses, like a gale force wind that forced my mouth open. I remember reaching over and tapping the controls on the machine to reset the pressure by turning it off (I thought) and then starting over with ramp - but the machine's data viewed through Sleepyhead shows none of this! It doesn't show two sessions, and it doesn't show a burst of pressure pulses anywhere.

The machine believes that I had one single OA of 20 seconds, and a few clusters of RERAs, and that is all. There was only one leak of any consequence, and that was 33 - smaller than I'd expect if I did open my mouth. The leak did immediately follow the OA so I guess that is the most likely candidate, but the flow curve is really unremarkable. I'm at a straight 12 pressure setting, and no deviations from that are shown either.

I find nothing in the user's manual about anything like this. Has anyone else experienced anything like this? I suppose it is possible that I dreamed it...

If it weren't for the lack of ramp-related deviation from 12, I would have suggested that you check one of SleepyHead's settings. SleepyHead can be configured to merge nearby sessions, where nearby can be user-defined. I think the current version defaults to merging, but I tend not to use the officially released versions.

There would most likely have been a burst, for some definition of burst, of pressure pulses associated with the 20 second OA. I have only seen my machine log an apnea without a pressure pulse once. Probably on the order of three to five would be expected for your duration, spaced around five seconds apart. These are indicated on the flow graph with a small square, either bright red or dark red (dark red is newer versions), and in the events tab. As for effects on the flow graph beyond the coloured square, I typically see a wibble during the pulses during CA events, but not OA.