SH Flow Rate & Resp Rate questions

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Josiah
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SH Flow Rate & Resp Rate questions

Post by Josiah » Sun Feb 18, 2018 10:55 am

When I zoom in on my SH Flow Rate graph what I see is a quite irregular wave but the shape of each individual wave is approximately the same. Am I correct in assuming that the peak of each wave is the conclusion of my inhale and the trough of each wave is the conclusion of my exhale?

What are the units the Resp Rate is measured in? I would presume in breaths per minute but my Resp Rate graph sometimes shows me reaching the top of the graph which would be 50 breaths per minute which seems almost physically impossible.
Josiah

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Re: SH Flow Rate & Resp Rate questions

Post by USMCVet » Sun Feb 18, 2018 11:03 am

I seem to remember someone else showing zoomed in picture of respiratory rate and it had concluded that the machine wasn't counting it right.

Yes i believe the peak and trough of the flow rate is end of inhale and exhale.

Here is a great reference for sleepyhead.
http://www.apneaboard.com/wiki/index.ph ... SleepyHead

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TedVPAP
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Re: SH Flow Rate & Resp Rate questions

Post by TedVPAP » Sun Feb 18, 2018 11:06 am

Both inhalation and exhalation start and stop at zero flow rate. Different from the peaks.

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Re: SH Flow Rate & Resp Rate questions

Post by USMCVet » Sun Feb 18, 2018 11:14 am

Flow Rate graph: A trace of every breath you took

When we use a CPAP, our upper airway is part of a "semi-closed pressurized system" comprising the blower, the tube, the mask, and our upper airway. The system is "semi-closed" because of the intentional leakage built into the mask to prevent re-breathing. A full efficacy data CPAP measures the back pressure at blower end of "system" and uses that data to calculate the air flowing into and out of our lungs all night long. The resulting data is called the Flow Rate data, and the Flow Rate graph provides a trace of very breath you took all night long.

To understand how to read a Flow Rate graph, it helps to zoom in to the point where the individual breaths can be seen:

The y-values are measured in Liters per minute (L/min). When the Flow Rate is positive (above the horizontal line labeled as 0.0), the air flow is going into the lungs and you are inhaling. When the Flow Rate is negative (below the horizontal line labelled as 0.0), the air flow is going out of the lungs and you are exhaling. The farther away from the 0.0 line, the more rapidly the air is moving. So a large positive bump represents a strong, deep inhalation, whereas a large negative bump represents a strong, deep exhalation. The transition between inhalations and exhalations occurs when the Flow Rate graph crosses the 0.0 line. Pauses in breathing show up as flat spots in the Flow Rate at the 0.0 line.

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Josiah
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Re: SH Flow Rate & Resp Rate questions

Post by Josiah » Sun Feb 18, 2018 11:27 am

Thank you both for confirming my understanding of the Flow Rate graph. Since the duration of each breath can be easily seen on the flow rate graph it is relatively easy to compare the resp rate from both the flow rate and the resp rate graphs and they should agree. My experience is that they sometimes don't. I often see quite steep and rapid changes on my resp rate graph that don't correspond at all to very minor fluctuations in the duration of each breath show by the flow rate graph.
Josiah