Central apneas can depend on the position?

[kurata]

Hi guys,

My sleep study revealed 47 AHI (40 obstructive, 5 central, 2 mixed).

I started using APAP (resmed s10) a few weeks ago and my AHI went down to the 2-16 range. By using Oscar I can see 99% of my apneas are now central.
Apparently some of them are not real (based on the flow rate graph right before), but most of them are.

A few questions:

a) I noticed that my AHI clearly rises when I sleep on my back. Does this make any sense? Why?

b) Is it possible to have central apneas while asleep? I'm asking this because last night I woke up around 4am and then wasn't able to sleep again (
or, if I slept, it was very superficial). However, Oscar data shows a lot of CAs over this period.

c) Having around central 4 apneas/hour on average is good? Or should i worry about and maybe try to use an ASV?


Thank you!

[Pugsy]

) Is it possible to have central apneas while asleep? I'm asking this because last night I woke up around 4am and then wasn't able to sleep again (
or, if I slept, it was very superficial). However, Oscar data shows a lot of CAs over this period.

If you aren't asleep they don't count. It's fairly common for people to have an increase in central apnea flags because of the irregularity of awake or semi awake breathing. In fact it can also happen in other event categories and isn't limited to just central apnea false positive flags.

These machines only measure air flow. They have zero way to know if we are asleep or not and our awake breathing is very irregular when compared to asleep breathing and these irregularities can cause false positive flags. Go here and watch the videos. It will help you understand the false positive thing. Especially the bottom video.
http://freecpapadvice.com/sleepyhead-free-software

Having around central 4 apneas/hour on average is good? Or should i worry about and maybe try to use an ASV?

You would need at least 5 per hour average and they would need to be for sure asleep flagged events for a doctor to even blink an eye and remotely consider ASV. If any of that 4 per hour average is awake false positive you have to remove it from the evaluation.

[Miss Emerita]

About the AHI while you're on your back: were the events obstructive? If so, that makes sense. Your tongue may be sliding back some, narrowing your airway and making a full bstruction easier. Alternatively, if you use several pillows, or a high pillow, your head may tucking down toward your chest, again narrowing your airway and making obstruction easier.

[TheClerk]

a) I noticed that my AHI clearly rises when I sleep on my back. Does this make any sense? Why?

I can't speak all technical and knowledgeable like the other posters here but, I'm sure it's a big yes!

Although I pretty much never fall asleep while on my back, before CPAP I often reverted to that position while sleeping. Since being on CPAP, I seem to be much more aware of when I do shift in that position and, not long after I do, I can "feel" my airways collapsing (right term?) at the back of my throat. Seeing that I went from an AHI of 34 in my home study, to an average below 1 since almost the day I started CPAP 4 months ago, I would gather that I am now spending the major parts of the nights on my sides.

[chunkyfrog]

The apneas that happen when gravity pulls loose tissues downward would NOT be centrals.
Central apneas happen because the brain stops telling you to breathe.
Like when one has had too much alcohol, or other CNS depressants--or some medical conditions.

[ChicagoGranny]

Seeing that I went from an AHI of 34 in my home study, to an average below 1 since almost the day I started CPAP 4 months ago, I would gather that I am now spending the major parts of the nights on my sides.

... not necessarily. It's more likely that your CPAP process is working well and preventing apneas in all body positions.

[Muse-Inc]

My overnight AHI quadruples when I sleep on my back! So I go to sleep on my side and wake up, it seems to me, in the same position and stiff as a board