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Question about ResMed 10 AirSense pressures
#1
Question about ResMed 10 AirSense pressures
I have a somewhat technical question. I have been looking at the machine treatment data from my new ResMed 10 AirSense AutoSet. The flow strip chart often shows a flow fluctuation at about one cycle per second, about 5 per 4 seconds. I don't know if this is my breathing, or if it is an artifact of the machine. (I'll try to add the first attached image here. It's a three min strip showing some small, regular, variations of my breathing flow. Many, but not all, of the flow charts that have been recorded show this about one cycle per second fluctuation on/in my respiration flow.)

   

I think that I saw somewhere that the AirSense uses four cycle per second pressure pulses to determine airway compliance. I've noticed on flow charts that there is often fluctuations like that during pauses in respiration. In the next attachment i've circled the four per second fluctuations in red, and I've circled the about one cycle per second fluctuations in green.

   

(If the inserting attachments has worked...) My question is; is the about one cycle per sec flow fluctuation an artifact, or is it likely to be real?

Thank you,
Jim

(edited to add more)

Here is a enlargement of the mask pressure strip chart showing the fluctuations.

   

Thank you!
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#2
RE: Question about ResMed 10 AirSense pressures
The first graph looks like some kind of snoring -- something in the airway is vibrating.

The circled red in the second screen shot and the last screen show shows ResMed's FOT (Forced Oscillation Test?) where the CPAP machine is attempting to determine whether the apnea is Obstructive or Central.
Useful links
Download OSCAR (current version is 1.5.1)
Best way to organize charts
How to attach charts to your post

Apnea Board Monitors are members who help oversee the smooth functioning of the Board. They are also members of the Advisory Committee which helps shape Apnea Board's rules & policies. Membership in the Advisory Members group does not imply medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.
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#3
RE: Question about ResMed 10 AirSense pressures
It could be cardiogenic, 130bpm, a bit fast.
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#4
RE: Question about ResMed 10 AirSense pressures
My heart rate, from pulse-ox, was about 80, and that's a close match for the fluctuations. (I counted again) So that seems to be the likely cause of the fluctuations.

Thank you, for seeing that.

It makes me wonder if seeing cardiac activity on the CPAP flow and pressure traces is not unusual, or if it is significantly unusual?

Thank you!
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#5
RE: Question about ResMed 10 AirSense pressures
Similar chart traces have appeared for some other Apnea Board members. I don't recall the circumstances, but at least I can confirm these exist.
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#6
RE: Question about ResMed 10 AirSense pressures
Thank you, Dave

that is reassuring
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#7
RE: Question about ResMed 10 AirSense pressures
Yup cardiogenic oscillations (another name is cardioballistic artifacts). I have them myself.

I have read that the amplitude is primarily effected by volume of pulmonary blood flow but I haven't been able to figure out if there is any clinical relevancy. You primarily see them at rest between exhale/inhale because muscles are relaxed at that point.
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#8
RE: Question about ResMed 10 AirSense pressures
What is the mechanism by which cardiac issues affect the flow rate?
Useful links
Download OSCAR (current version is 1.5.1)
Best way to organize charts
How to attach charts to your post

Apnea Board Monitors are members who help oversee the smooth functioning of the Board. They are also members of the Advisory Committee which helps shape Apnea Board's rules & policies. Membership in the Advisory Members group does not imply medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.
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#9
RE: Question about ResMed 10 AirSense pressures
(05-27-2021, 12:26 AM)GuyScharf Wrote: What is the mechanism by which cardiac issues affect the flow rate?

My understanding is it is most affected by pulmonary flow rate/pulses (blood flow through the lungs). There are some studies that determined this using patients on bypass so they could adjust the flow rates etc. 

I imagine the pulse from heart beat expands arteries/veins in lungs which increases pressure and creates minor exhalation then vice versa when pressure drops in arteries/veins it does so in lungs as well. What I don't understand is why some people have these artifacts and why some people don't. Does having them mean you have more pliable veins/arteries so their sizes change more with blood pressure? Do are hearts beat slightly differently? I haven't had luck finding good info on this. Nothing that makes me think it is anything to worry about anyways.
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#10
RE: Question about ResMed 10 AirSense pressures
Maybe FOT around 6:35:20.
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