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Judging Mask Leaks
#11
That interests me! Eager to see it!
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#12
Sorry, I am having trouble locating the figure I put together. For now, here is some text on the same thing.

Previous post.

"I initiated a previous thread concerning the difference between my maximum leak rate on Rescan versus Sleepyhead. Since then I have been watching this and have found that it occurs all of the time. It is just the statistics. The graphs look identical. I have also noted that the 95% leak rate suffers from the same difference.

I have not methodically scrutinized the respective leak rate graphs for comparison but they look identical. So why the difference in statistics? I have an idea which is what I want to present.

First the leak rate is calculated based on an offset of the exhalation curve from expected. In order to provide the expectation the software uses some number of curves to set up a zero line and then compares the actual measured curves to the zero line. The offset is the unintentional leak rate.

As a result, it seems to me, that if one is breathing very regularly and then suddenly takes a deep breath that will show up as a spike in the leak rate graph. I imagine that I am simplifying this somewhat but this train of thought made me curious. I started looking at the spikes in my leak rate chart and noticed that for many of these spikes there was also simultaneously a spike in my flow chart.

I also did a small test with my CPAP. After I had awakened in the morning, I stayed in bed for an extra 20 minutes and breathed with different tidal volume and timing. At the same time, I was carefully checking for unintentional leakage all around the mask. I can usually feel leakage but I also checked for leakage using my hands. There was no leakage. When looking at my leakage graphs, there were leaks recorded through that whole 20 minutes. Not large leaks but spiky and higher than previous leakage rates. Made me feel like I was definitely on the right track

Here is what I think may be going on with the statistics. I think that Resmed recognized this and set up an algorithm that ignores these for statistical purposes. Therefore the Rescan 95% and maximum leak rate statistics are always lower than the equivalent Sleepyhead statistics."

Best Regards,

PaytonA
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#13
I do think you are on to something. At the moment, however, what really matters to me is that Sleepyhead records every leak, large or small. and in whatever pattern. This alone is sufficient to relieve my previous anxiety re large leaks, and how they relate to the apneas. But you have given me a whole new area of concern, and I'm grateful for the input. Jim
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#14
I think that I found the image I was looking for and hopefully I can get it to display in this post.

[Image: 7InrGHN.png]

Hopefully I got it right. If so, I have installed lines between the leak spike and the flow rate spike to show the relationship.

It did not come out the way I wanted but at least you should be able to get to it and see it.

Best Regards,

PaytonA
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#15
Your 0 leaks graph resembles one of mine, although on a given night I might have a half-dozen clusters. I would like to post a graph, but the current situation doesn't allow for it. My son's laptop uses MS, while my unit has a Linux OS.

A few months back, in an older OS, I had Sleepyhead installed through a Wine setup, but my new OS is not there yet.

All best, Jim
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