Scary Charts

This looks like I quit breathing for 15 minutes. Check out the pressure pulses before the flow graph just goes blank. Except the leak chart keeps going just fine and I felt fine this morning and don't remember anything like this. Then things get started again and return to normal. Comments?

Pressure chart is constant throughout the event, but respiration and volume charts all go to zero.

Clearly a spirit of some sort is inhabiting your machine. An exorcist may be in order.

Now the seasoned posters can provide real answers to your question.

This looks like I quit breathing for 15 minutes.

Is it pleasant where you are now?

Or extremely hot?

My DME calls these things "patient disconnects." I don't like that terminology, but I don't have anything better to call them.

The problem is not that you quit breathing or that you took the mask off. The problem is that the machine simply lost track of your breathing. As in the back pressure data that it uses to track your inhalations and exhalations became garbled or "noisy" and the machine could not make sense of it. So it decided that there was not a live human being attached to the other end and it dropped recording the wave flow until the data started to make sense again. If you looked at the data in Encore, you'd have a big "no breathing detected" bar over the leak graph where the "patient disconnect" occurs. The "no breathing detected" bar is a different color than the "Large Leak" bar in Encore. And in Encore's Usage Pattern data, part of the Usage Bar would be Black instead of Green (or Red). And "therapy hours" and "blower hours" would differ by the length of the "patient disconnect."

Why the machine would have problems tracking your breathing is another issue altogether. Sometimes there's a obvious reason: The presence of an official Large Leak on a System One are often associated with "patient disconnects." But in my own data I've seen many "patient disconnects" without an official Large Leak being scored. Sometimes there's a leak that is much larger than normal for me, but that is not large enough to be scored as a large leak. Sometimes there's no evidence of unintentional leaks at all; I haven't been able to come up with a plausible explanation of why a "patient disconnect" would happen when there is little or no unintentional leaking. So I blame the ghosts of Richard Nixon and Rose Mary Woods for deleting the missing wave flow data. I tend to see patient disconnects in my own data when my pillows badly need to be replaced. Usually there are higher than normal leaks just before and during the "patient disconnect"; but sometimes the leak line looks "fine". "Patient disconnects" used to disturb me greatly; I've learned to not worry so much about them any more.

In your case, the Total Leak Rate appears to be about 60 L/min shortly before the "patient disconnect" begins and the wave flow data comes back after the Total Leak Rate declines a bit and the machine manages to NOT lose the wave flow patterns in spite of the next bump in the Total leak graph up to the 60+ L/min range. On Series 60 machines, official Large Leaks are often scored when the Total Leak Rate gets up in the 70+ L/min range and some people start to see Official Large Leaks by the time the Total Leak Rate gets up around 60+ L/min. I suspect that this leak was very close to being large enough for your machine to score it as an official Large Leak. And while this leak was not officially scored as a LL, it was still large enough to create "noisy" back pressure data---i.e. the machine could not distinguish the changes in back pressure due to your breathing because of leak.

Thanks Robysue - if I'd only known the proper search term I might've discovered that. And yeah, it did subtract that time from my sleep hours.

my PR system 1 ASV did almost the exact same thing for 4 hours... it happened right after a midnight trip to the bathroom... it lost all AHI data, pressure. pat triggered breaths and leak rate... and look what it did to tidal volume and minute vent.... it looks like it gets lost and just doesn't know what to do....

Screenshot 2014-07-19 16.46.09 by cowboycasey, on Flickr

Screenshot 2014-07-19 16.50.24 by cowboycasey, on Flickr

Cowboy Casey wrote:my PR system 1 ASV did almost the exact same thing for 4 hours... it happened right after a midnight trip to the bathroom... it lost all AHI data, pressure. pat triggered breaths and leak rate... and look what it did to tidal volume and minute vent.... it looks like it gets lost and just doesn't know what to do....

Cowboy Casey,

Your problem is NOT the same as sc0ttt's: Your machine continues to record the flow rate data just fine. Your question is not, "Why does the machine think I'm not breathing?" Your question is, "Why did the machine drop the AHI data, the pressure data, the leak data, and the patient triggered breaths data even though it still was tracking my breathing just fine?"

For the AHI data, it's worth zooming in and scrolling through four hours of flow rate data using about a 5-10 minute window and looking for "obvious" events that were not scored. It could be that there weren't any. Or it could be there are some and the AHI flagging was indeed dropped.

For the rest of the data? That's a real toughie.

One thing I'd try if I were you is to look at the same night in Encore. If Encore shows AHI data, the pressure data, the leak data, and the patient triggered breaths data for that four hour period, then it's likely the problem is a SleepyHead bug. If Encore is also missing the AHI data, the pressure data, the leak data, and the patient triggered breaths data for that four hour period, then it's time to report the problem to the DME and see what they have to say about it. Unfortunately there's no way to look at the flow rate data in Encore since the night this happened was July 1, and Encore only downloads the last night (or two) of flow rate data.

robysue wrote: In your case, the Total Leak Rate appears to be about 60 L/min shortly before the "patient disconnect" begins and the wave flow data comes back after the Total Leak Rate declines a bit and the machine manages to NOT lose the wave flow patterns in spite of the next bump in the Total leak graph up to the 60+ L/min range. On Series 60 machines, official Large Leaks are often scored when the Total Leak Rate gets up in the 70+ L/min range and some people start to see Official Large Leaks by the time the Total Leak Rate gets up around 60+ L/min. I suspect that this leak was very close to being large enough for your machine to score it as an official Large Leak. And while this leak was not officially scored as a LL, it was still large enough to create "noisy" back pressure data---i.e. the machine could not distinguish the changes in back pressure due to your breathing because of leak.

Hmmm, the shape of my leak line is a little unusual, but Sleep Mapper gave me a 100% mask fit score for last night. I do think you're probably right; I'm kind of surprised my machine didn't turn itself off with that much funky data.

sc0ttt wrote:
Hmmm, the shape of my leak line is a little unusual, but Sleep Mapper gave me a 100% mask fit score for last night. I do think you're probably right; I'm kind of surprised my machine didn't turn itself off with that much funky data.

I think pugsy's aliens came and abducted you last night....

do you feel like you've been probed?

If you had quit breathing for 15 minutes you wouldn't be posting on cpaptalk. Com and telling us all about it

Thanks Robysue, That was the only night that it happened so I figured it was almost the same... Interesting... I will keep an eye on it and see if it happens again... I think it just got confused..

robysue wrote:

Cowboy Casey wrote:my PR system 1 ASV did almost the exact same thing for 4 hours... it happened right after a midnight trip to the bathroom... it lost all AHI data, pressure. pat triggered breaths and leak rate... and look what it did to tidal volume and minute vent.... it looks like it gets lost and just doesn't know what to do....

Cowboy Casey,

Your problem is NOT the same as sc0ttt's: Your machine continues to record the flow rate data just fine. Your question is not, "Why does the machine think I'm not breathing?" Your question is, "Why did the machine drop the AHI data, the pressure data, the leak data, and the patient triggered breaths data even though it still was tracking my breathing just fine?"

For the AHI data, it's worth zooming in and scrolling through four hours of flow rate data using about a 5-10 minute window and looking for "obvious" events that were not scored. It could be that there weren't any. Or it could be there are some and the AHI flagging was indeed dropped.

For the rest of the data? That's a real toughie.

One thing I'd try if I were you is to look at the same night in Encore. If Encore shows AHI data, the pressure data, the leak data, and the patient triggered breaths data for that four hour period, then it's likely the problem is a SleepyHead bug. If Encore is also missing the AHI data, the pressure data, the leak data, and the patient triggered breaths data for that four hour period, then it's time to report the problem to the DME and see what they have to say about it. Unfortunately there's no way to look at the flow rate data in Encore since the night this happened was July 1, and Encore only downloads the last night (or two) of flow rate data.