Clear Airway Apnea

Just wondering what the significance of a clear airway apnea is? Is that a central apnea or are the two different? My AHI is down to 5.3 but I'm having more CAs than OAs.

My understanding is that central apnea and a clear airway apnea are the same thing. The definition of the event is : "A respiratory episode where there is no airflow and no effort to breathe lasting greater than 10 seconds."

The newer machines shoot a pulse of air during an event to check if the airwat is open or blocked, if it is open the event is scored as a CA, if it is blocked the event is scored as an OA.

With my PR 1 machine, I have been seeing a lot of nights with a higher CA index than the H or OA index level. Wonder if it is something with the PR 1 machines.

Dennis

KatyDidAgain wrote:Just wondering what the significance of a clear airway apnea is? Is that a central apnea or are the two different? My AHI is down to 5.3 but I'm having more CAs than OAs.

Funny you should ask. My AHI for last night was 5.3 also. CA was 2.5, OA was 1.0, and H was 1.8.
I've only been on CPAP for just over 5 months but my understanding is that for folks like us with complex sleep apnea ( some OSA's and some CSA'a ), when the titration of the system starts to get the OSA's down, then CSA's start to rise. Not sure why that is but it seems to be that way in my case.

Respironics won't classify a Clear Airway apnea as a Central because the machine doesn't have the abdominal movement / effort reading that would make it perfectly sure - so they call it a Clear Airway Apnea. As a practical matter, it's a central apnea.

I,too, am trying to figure out how to get the OSA's down farther because even a few of them makes my night difficult. At 1.0 and below, I feel pretty good in the morning.

There's some disagreement on the correct terminology, brought about by overly enthusiastic marketeers, IMHO.

On the one hand, Resmed scores all clear airway apneas as Centrals. But that's really just an assumption because without having a connection to the central nervous system via an EMG lead, one can't say definitively whether the cause of an apnea was because the brain did not trigger the diaphragm muscles to breathe, or whether perhaps the cause was feedback from a Hering-Breuer reflex brought on by the stretch receptors in the lungs saying, in effect, "That's enough air. Now Stop." The H-B reflex can be triggered by CPAP therapy, so what Resmed scores as a "central" may actually be an artifact of the very therapy that Resmed's machine is providing. On the other hand, the open airway apnea might be a true central apnea. But there's no way to know without EMG data or effort bands.

The literature put forth by DeVilbiss, on the other hand, and apparently PR as well, refers to open airway apneas as "non-obstructive apneas," (or open airway apneas in the case of P-R) which I think is more intellectually honest than ResMed's rather cavalier assumption that all open airway apneas must be centrals.

My sleep doc is a little put out by Resmed's presuming to be able to score centrals without input from either an EMG or effort bands. I can see his point.

Here's a good resource. See page 4. http://www.devilbissclinicaleducation.c ... nology.pdf