Differentiating between obstructive and central apnea events

[DannyCPAP]

I am quoting from the “CPAP and insomnia blog by RobySue”
http://adventures-in-hosehead-land.blog ... -test.html
“An obstructive apnea is an apnea where there is still evidence that you are trying to breath… The belts the tech puts around your chest and stomach are used to measure the effort to breathe”
“A central apnea is an apnea where there is no evidence (from the belts) that you are making an effort to breathe”
Therefore, if the sleep lab needs a belt on the stomach to differentiate between the two, how reliably can SleepyHead and the ResMed software do the determination without it?

[-SWS]

Resmed claims 95% accuracy:
http://www.resmed.com/us/assets/documen ... -paper.pdf

I personally think that manufacturer's 95% accuracy claim is high:
viewtopic.php?f=1&t=77372&p=712549&#p712549

[DannyCPAP]

Resmed claims 95% accuracy:

My ResMed S9 Elite CPAP shows zero or one obstractive events a night (pressure is 7). I do have central events, measured usually 3 AHI a night. Is an APAP machine better suitable than CPAP in this case? My sleep doctor does not believe in the accuracy of the home machine so he dismisses any discussion about its measurements.

[Julie]

A regular cpap machine such as you have will not catch or report centrals. Period. If you have the odd one, even every night when falling asleep, that doesn't mean you have central apnea, but if you've been diagnosed by pros as having it, then you absolutely need to do two things, get an appropriate machine (like a bipap, Vpap, or ASV), and change doctors!!

[robysue]

A regular cpap machine such as you have will not catch or report centrals. Period.

The OP is using an S9 Elite. It most certainly will detect and report centrals using the same FOT algorithm that the S9 AutoSet uses. Indeed, the Elite records all the same data that the S9 AutoSet records; it just has no APAP mode.

[-SWS]

My ResMed S9 Elite CPAP shows zero or one obstractive events a night (pressure is 7). I do have central events, measured usually 3 AHI a night. Is an APAP machine better suitable than CPAP in this case?

Probably not. An ordinary "current generation" APAP machine is designed to: a) treat obstructive apneas, snores, and flow limitations, and to b) refrain from pressure increases in response to central apneas. Your fixed-pressure is already low, and it seems to treat your obstructive apneas/hypopneas quite well.

My sleep doctor does not believe in the accuracy of the home machine so he dismisses any discussion about its measurements.

Well, if he were a doctor who believed in CPAP machine measurements, he'd probably point out that your residual AHI is pretty good. Any AHI below 5 is considered subclinical, with around 3 being good.

Bear in mind a few central apneas and even a little periodic breathing occurs in the "normal" (non-apnea) population. By numeric definition, your CPAP treatment is considered successful. That said, you MIGHT spot a pattern whereby your central apneas tend to happen a little more during sleep/wake and wake/sleep transitions. Even that happens a bit in the "normal" (non-apnea) population. I would also add that your central apneas might even reduce in numbers a bit as you become more and more adapted to sleeping with CPAP.

If you're looking for sleep improvements toward more daytime zest, consider researching the term "sleep hygiene".
https://www.google.com/#hl=en&sclient=p ... 43&bih=600

BTW, welcome to this board. Feel free to ask just as many questions about CPAP or sleep as you can think of. This message board is an awesome group of well-informed hoseheads.

[Slartybartfast]

Maybe it's a fine point, but contrary to the hype from ResMed's marketing department, all the S9 series machines can really do is to infer from the data that a central has occurred. Without abdominal belts or an EMG lead connected, centrals can't be identified with certainty. They can only be inferred. Resmed says they are 95% accurate in their identification. Perhaps that's true, in the study that they sponsored, but real or phantom centrals aren't really of concern to most of us. We all sigh during our sleep. Following the sigh the elevated oxygen level imparted by the sigh is usually followed by a delay before the next breath is drawn. A central apnea. It's the obstructive apneas that will get you!

My doc, too, doesn't believe in automatic machines. Says the claims made by the manufacturers are over-reaching and careless, and he doesn't believe any data from automatic machines, either. I show him my printouts and he usually checks the 95% pressure and compares it to my titrated pressure from the lab and sniffs that it's pretty close. I disagreed enough with him that I bought my own machine out of pocket when he prescribed an S9 Elite.

[mikewithe]

Maybe it's a fine point, but contrary to the hype from ResMed's marketing department, all the S9 series machines can really do is to infer from the data that a central has occurred. Without abdominal belts or an EMG lead connected, centrals can't be identified with certainty. They can only be inferred. Resmed says they are 95% accurate in their identification. Perhaps that's true, in the study that they sponsored, but real or phantom centrals aren't really of concern to most of us. We all sigh during our sleep. Following the sigh the elevated oxygen level imparted by the sigh is usually followed by a delay before the next breath is drawn. A central apnea. It's the obstructive apneas that will get you!

My doc, too, doesn't believe in automatic machines. Says the claims made by the manufacturers are over-reaching and careless, and he doesn't believe any data from automatic machines, either. I show him my printouts and he usually checks the 95% pressure and compares it to my titrated pressure from the lab and sniffs that it's pretty close. I disagreed enough with him that I bought my own machine out of pocket when he prescribed an S9 Elite.

Off topic, I know, but I love your name. And congratulations on your award for the coastline of Norway!

[archangle]

Technically, a CPAP machine can't definitively detect ANY apnea without an EEG or O2 sensor. They can't definitively distinguish a central from an obstructive without a chest effort belt.

Even trained sleep techs with full PSG data will sometimes give different scores for events.

If you have a "real" central apnea, it's possible your airway is closed during the central apnea, and even a "perfect" clear airway detector would rate it as "obstructive."

Despite the above concerns, the numbers are still useful. If you don't record any events, you probably aren't having severe apneas. Most of the uncertainty in categorization is for "borderline" events.

I think it's important to look at the actual events. How long did the event last, how much did your breathing decrease, how close together are the events, did you breathe heavily before and after the event, etc.?