Obstructive or Central?

[Arik]

Hi Guys,

I made an experiment, holding my breath for about 20 seconds while having my CPAP and mask on me. The software reported Obstructive Apnea. Is it correct?
 
Thanks,
Arik  

[Sleepster]

It depends on how you held your breath and how well the machine interprets it. If your airway is blocked the machine is supposed to register an obstructive apnea. If your airway is unblocked the machine is supposed to report a clear airway apnea (also called a central apnea.

When you draw in the air you plan to hold, one way to hold is to block your airway. But I believe it's also possible to hold the air in instead using your diaphragm.

[mesenteria]

I agree.  If you prevent air from entering or leaving your lungs, but don't close off your airway by using your mouth, tongue, or the pharynges, the machine will get a different sensation when it attempts to pulse because your airway is still open. It's just that you are controlling your diaphragm, which is akin to your brain not inducing breathing during a central.  If the machine attempts to pulse against the lips, pharynges, or your tongue, it will detect a blockage much more proximal to the machine, and call it an obstructon.

Or, so it seems to me to be the reasonable explanation for what you have found.  I don't know if it would be related to time, backpressure, or what.

I'll keep reading hoping to learn of another explanation.

[Arik]

So if I repeat the test using a nasal pillow mask, it is definitely central?

Thanks,
Arik

[Reznik]

Hi Guys,

I made an experiment, holding my breath for about 20 seconds while having my CPAP and mask on me. The software reported Obstructive Apnea. Is it correct?
 
Thanks,
Arik  

Here's what you need to know:  The machines use pressure pulses in an attempt to guess at whether an apnea is obstructive or central.  Their detection methodology is poor.  If it reports obstructive, it is more likely right than wrong.  If the machine reports central, it's 50/50 as you've noticed.

This fact is very frustrating for me because (1) doctors assume that the machines are 100% accurate and (2) the pulses can be disruptive to the sleep of some users, and they may not even know it.  

I am hopeful that, in the future, ResMed and Respironics will use analysis of the breathing waveforms in order to flag apneas as central vs. obstructive, as F&P does in its latest model.  They also should make it more widely known to doctors that the only way to be absolutely sure is with the use of a chest strap.  At one time, there was some technology that would scan your body using radio waves to determine if your chest was moving.  ResMed put that technology into a sleep quality device, but never added that to it's CPAP machines, and the sleep quality device has since been abandoned.

[Arik]

There is an application called "Sleep Score" by Resmed, with the same idea using your smartphone. It supposes to monitor your chest moving. Don't know how accurate it is.

[Reznik]

There is an application called "Sleep Score" by Resmed, with the same idea using your smartphone. It supposes to monitor your chest moving. Don't know how accurate it is.

I'm almost certain that this is the commercial version of ApneaApp, which was developed by the University of Washington...

https://apnea.cs.washington.edu/apneaapp.pdf

Hopefully, Resmed will add this technology, which uses sound pulses that are inaudible to the human ear, to detect central/obstructive events in the future instead of FOT pulses...

[Reznik]

Disregard.  Posted in wrong thread.