CPAPtalk.com

Central apnea means you aren't breathing, and you aren't trying to breathe as measured by a chest effort belt or something similar. It also only "counts" if you're asleep.

At best a CPAP machine can tell that you aren't breathing and that your airway is open.

A CPAP machine can't tell if you're asleep, so it may count a "wake apnea," which doesn't "count."

You may have a central apnea, but also have a closed airway. Your brain "forgets to breathe" and your body is not trying to breath, and your airway also collapses. A CPAP machine will count this as an obstructive apnea even though it's actually a central.

The machine may not correctly figure out whether you have a clear airway or not. It is trying to determine what is happening while "looking" through the humidifier, 6 feet of hose, your mask, and your nose. It could make a mistake.

From what I understand, I think that if the machine detects a "clear airway" apnea, it is probably a central apnea, as long as you're asleep. You may have some true central apneas that the machine will call an obstructive apnea.

You should also realize that you may be "awake" in some sense and not remember being awake. A slight disturbance may wake you up enough to cause some disturbed breathing without you being fully conscious. That's one of the reasons they put EEG leads on you for an in-lab sleep test.

My guess is that most people are overwhelmed to start with. Even a small sample of definitions adds to the pile, and many have no clue how to do more than power up and down. If you're to the point where you want LOTS of info, it's assumed that you should be competent enough to find it, or have some ideas HOW to find it.

Just a guess on how the minds of others work. Mine is much simpler.

Bear in mind that manufacturers legally protect "their" terminology,
---forcing their competitors to expand the lexicon.
It's a bad situation, because in medical matters, it is very bad to be confused.

When I look at the data in sleepyhead, it shows up as a clear airway flag. I figured out how to reconfigure my machine to show more information and it finally separates out AHI into obstructed and central apneas. I think, like stated above, it's a matter of who is interpreting the data and just what they call it.

It's interesting to note that the machine will separate out how many central apneas (usually 2.5-2.9 per hour) from the obstructed apneas (mostly around .5 per hour) which very seldom adds up to the total apneas. Which means I have to do math to figure the hypopneas....

In my sleep study, I had significantly less central apneas (but still had them). Could therapy be making these worse? I'm on a steady pressure of 8 after my ramp. Or could it be a function of how the machine is coding the data without all the input that happens in a sleep study? I guess I should be grateful I don't have to hook up to an EEG every night, just my machine.

lynbarnes wrote:In my sleep study, I had significantly less central apneas (but still had them). Could therapy be making these worse? I'm on a steady pressure of 8 after my ramp. Or could it be a function of how the machine is coding the data without all the input that happens in a sleep study? I guess I should be grateful I don't have to hook up to an EEG every night, just my machine.

It depends.

If you are spending time in bed hooked up with the mask and NOT sleeping or only very lightly dozing, a lot of the machine scored central (clear airway) apneas may be so-called sleep-wake-junk (SWJ) and/or transitional events that would NOT be scored on an in-lab sleep test because you weren't actually asleep when they occured. (Your machine presumes that if you are using it, you are asleep.)

But some people do have problems with pressure-induced central apneas. In other words some people do have a real and potentially clinically significant increase in CAs once they start PAP therapy. Usually the sleep docs will be a bit cautious about treating a small increase in machine scored CAs in a new PAPer; the reason why is two fold. First, for a lot of new PAPers, the number of pressure induced centrals are not very numerous (the CAI stays below 5.0 and the overall AHI stays below 5.0) AND as the newbie adjusts to PAP therapy, the numbrer of machine scored CAs decreases with time. Second, the ASV machines needed to treat real central sleep apnea and real complex sleep apnea are both far more expensive than a regular CPAP/APAP or even a run of the mill bilevel machine AND the ASV machines are also more difficult to get used to sleeping with. Hence it makes a lot of sense to take a wait and see attitude towards a small number of machine scored CAs in a newbie's CPAP data.