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Flow Rate Interpretation
#1
Here is a sample screenshot for my flow rate for Nov.11. This what my flow rate usually looks like when I am sleeping.
[attachment=2972]

Here is a sample screenshot for my flow rate for Nov. 12 while I am sleeping. This is the first time that my flow rate looked like this . What is the difference between the two ? Is it just that I was breathing more deeply on Nov. 12 ?.[attachment=2973]
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#2
nadprok,

Both snippets of breathing look like pretty normal sleep breathing.

It is actually HARD to directly compare the 11/11 data and the 11/12 data because the y-axis scale on the two plots is not the same.

To make what I'm saying a bit clearer:
  • On 11/11 the y-axis goes from -150 L/min to +150 L/min, which is a difference of 300 L/min for the whole vertical distance.

  • On 11/12 the y-axis goes from -100 L/min to +100 L/min, which is a difference of 200 L/min for the whole vertical distance.
And the two graphs take up the exact same amount of room on the computer screen. Hence a peak at roughly 25 L/min is going to look bigger on the 11/12 data because it takes up more of the space on the vertical axis. Likewise a peak exhalation rate of -35 L/min is going to look bigger on the 11/12 data because it takes up more space.

When we carefully analyze the max's and min's on both sets of data while paying careful attention to the scales on the vertical axes, we see that:
  • On 11/11 it looks like your inhalations are maxing out at about 25 L/min and the exhalations reach a min of about -35 L/min.

  • On 11/12 it looks like your inhalations are maxing out at about 25 L/min and the exhalations reach a min of about -35 to -40 L/min.
So my guess is that there is no actual statistically significant difference between the size of the inhalations on 11/12 vs those on 11/11. Same thing with the exhalations.

Finally I'll add: The change in the vertical axis scaling is enough to change the visual shape of the individual breaths in the wave form. Were you to change the vertical scaling on both graphs to be the same, my guess is that the two wave forms would look much more similar to each other than they do in these screen shots.

If you are interested in trying to rescale the y-axis, you can right click on the title bar area of the graph, select y-axis and then select "override" and set the top and bottom values where you want them to be for the graph. To go back to the original graph, right click on the title bar area of the graph, select y-axis and then select "auto-fill"
Questions about SleepyHead?
See my Guide to SleepyHead
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#3
Thank you very much robysue. I didn't know that there was a change in the vertical axis scaling. I don't know how that happened. I followed your instructions and now the y-axis are the same for both dates. The flow rate is now similar for both dates.
You experienced people on the forum are a wonderful help to those of us that are still struggling to digest everything we need to know.

Thank you
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