Some graphs blank after turning machine off then on again?

[yaconsult]

First I should mention that I have a wireless sdcard and use sleep master to transfer my data so the sd card stays in the machine so it's not a question of the card being properly inserted or seated.

So when I realized that I was falling asleep, I followed my usual routine of reaching over and turning the machine off and then on again to mark the time that I stopped watching netflix and went to sleep. This morning when I looked at my data, I see that after I turned it back on, some of the waveforms are missing the data from that point on. All of the events seem to have been recorded onto the sd card, but not some of the waveforms. Some of the other charts are blank for the same time period but it looks like pressure, leak, and events were still recorded. Have others seen these missing waveforms before? Is it a glitch with the machine or sleepyhead or something else? Is there a known way to prevent it from happening? Did the machine think that there was no sdcard inserted after I turned it off and then on again? I have followed this same procedure on many other nights and not had the problem. Thanks!

[yaconsult]

Well, I tried a test by taking a nap this afternoon and all of the detailed waveforms for that session are there. I have not touched the memory card at all so I'm kind of confused why some of the waveforms for most of last night are missing.

[robysue]

I have seen this kind of pattern in my own PR System One (series 50) data on some very, very rare occasions. (Like 3 or 4 times in over 4 years of using a PR System One series 50 BiPAP.) The ones I remember right off the top of my head are nights where I believed something happened that scrambled/corrupted part of the SD card.

The one I most clearly remember happened while camping with a battery set up in some pretty cold weather for late May/early June (i.e. temps around freezing), and the battery went "dead" in the middle of the night while the machine was on. I woke up with no air coming through the mask, and tried to turn it off and on before realizing the problem was in the battery. I also tried a couple of different settings on the battery itself without much luck. The next morning I had real trouble loading the data into SleepyHead, but I was far more worried about what to do about the battery and how to use the CPAP for the rest of the camping trip. After borrowing a very, very long extension cord rated for outdoors use from the campsite, I was able to continue using the BiPAP on the trip. After fixing the immediate problem of how to power the CPAP, I turned to figuring out how to rescue as much data as I could from the SD card. It took some computer skills to get the corrupted data to load partway into SH, and once I did get it loaded, the corrupted data looked a lot like the data you posted. The corrupted data affected some, but not all of the sessions on the night where the battery failed. On the subsequent nights, all the data was there.

So if there was any chance of a stray, very short lived power glitch during the night, that *might* explain the problem, even if the power glitch didn't occur right when you turned the machine off and on. If you are really worried about the card, you could simply replace the card with a new and presumably uncorrupted one.

[Pugsy]

I have also seen this happen on my PR S1 on a rare occasion. Never could figure out what happened but you aren't alone. The flow rate graph is from the xxx.005 file and the only thing I can figure out is somehow something happened to get it corrupted. I have even used Encore and still seen where the waveform just goes whacko.

[yaconsult]

Thank you very much, robysue and pugsy! It had me puzzled because it's not what you get if you forget to put the sdcard back in the machine. It started when I turned the machine off and then on again to create a gap in the data marking when I went to sleep.

I guess it's just a rare glitch that happens from time to time. Just knowing that others have seen it is reassuring. Now that I am enjoying the wireless transfer and not having to touch the sdcard any more, I hope it doesn't happen very often.