Sandman Therapy - Reporting Centrals

[spacetoast]

Does anyone have any insights into how Sandman Therapy reports Central apnea events?

I'm wondering how accurate that reporting is because some nights, I get a lot of them when the pressure goes up to around 10 cm.

[jdm2857]

I believe that the Sandman "listens" for the patients heartbeat during apneas. The theory is that if the airway is open, as in a central, the air in the airway will transmit the heartbeat sound, and that the heartbeat will not be transmitted if the airway is obstructed.

I do not know how accurate that technique is.

[spacetoast]

Thanks for the explanation, jdm!

[Mtnviewer]

It might be worth posting the question on the Covedin customer service website. Here is their glossary section for a vague definition: http://www.sandmansleep.com/resources/glossary.cfm

My sleep study doctors told me that PAP machines cannot track true CA's at all, as it can only be done via electrodes on the head as in our sleep study. They also told me that true CA's are not common at all with most people with OSA and on PAP therapy and if it were a concern to an individual, then CA's would show up on a person's sleep study report, and so then one would be advised on treatment. So if no or one or two CA's occurred on your sleep study, then you likely have nothing to worry about regarding CA's.

I'd think that the Sandman machine tracking of CA's is just guessing at "events" that aren't true or complete Obstructive Apneas as per it's algorithm and so it's trying to count these more indefinite events somehow. Perhaps their research indicates that these vague not real OSA events have symptoms something like some CA's in some people, so that's what they're calling them? Only the Sandman people know for sure what their CA events are and how accurate their correlation to anything are and how accurate the machine tracking and their software is.

Ask your doctor about your CA's if you can, but I don't put any reliability into the Sandman CA reports but just view them as not quite full obstruction events but something like snores or some sort of change in my breathing pattern?

Hopefully others have other or more accurate info.

[jdm2857]

Actually, the PSG uses the belt sensors around the chest and abdomen to sense respiratory effort.

The electrodes monitor your EEG and can track the stages of sleep and arousals, but I don't think that the data is capable of detecting the signals for respiration.

[ozij]

I believe that the Sandman "listens" for the patients heartbeat during apneas. The theory is that if the airway is open, as in a central, the air in the airway will transmit the heartbeat sound, and that the heartbeat will not be transmitted if the airway is obstructed.

I do not know how accurate that technique is.

That's not theory it was tested empirically, and it's actually very accurate. When a Sandman senses cardiac oscillation on the airflow, you can be sure its a central apnea. Not all central apneas have cardiogenic oscillations, and the appearance of cardiogenic oscillations in central apneas varies among people -- but if you've got tcardiogenic oscillations, the apneas are central - i.e. open airway apneas.

http://www.chestjournal.org/content/116/3/660.full

http://www.chestjournal.org/content/116 ... nsion.html

http://www.chestjournal.org/content/116 ... nsion.html


O.

[spacetoast]

Thanks for the links and explanations.

I found this old thread that had some really good info in it. Ozij even bumped it three years or so ago:

viewtopic.php?f=1&t=514&st=0&sk=t&sd=a& ... ral+apneas

[jdm2857]

Ozij --

I used the word "theory" in the sense of "Theory of Operation"; not to imply that it only works in theory.

But thanks for the links, anyways.