AHI varies between 1.5 and 6 from night to night - back sleeping?

[luke1081]

Hi there. Have been using CPAP since mid-February and for the most part have not struggled with using the Resmed and a full face mask. However, my AHI seems to vary up and down from night to night. Sometimes it'll be 2, other times it's around 6. I have a suspicion it's down to back sleeping vs side sleeping but I know you can't tell if it's positional on the Sleepyhead software. I have attached the last couple of nights as an example and am wondering if there's anything I can do/change to ensure a more consistent AHI from night to night? Thank you!

[Pugsy]

On the night with AHI of 6 nearly 4 of that was central/clear airway flagged events.
How was your sleep quality that night? Sleep soundly for the most part or a lot of wake ups and fragmented sleep and considerable time spent with mask and machine on?

Usually when it is side sleeping vs supine sleeping the apnea events are obstructive in nature (OAs and hyponeas) and not centrals.
If when you see a higher AHI night and it's primarily central...I doubt it is related to sleeping position.
Watch the videos here so you can learn how to distinguish awake flagged events (which don't count) and asleep flagged events.
http://freecpapadvice.com/sleepyhead-free-software

Now when we see clustering of obstructive in nature events we often think supine sleeping but it can also be REM stage sleep. Both of which are known to make OSA worse. The fix for those is more minimum pressure.

But when the AHI is primarily central apneas more pressure won't necessarily fix those type of events.

[luke1081]

Thanks Pugsy, this is useful information.
Yes, it was a restless night and when I woke several times, I found myself lying on my back which led me to the belief it was positional.

Now I getting into using Sleepyhead, I look back through the last month or so, my obstructive apneas, on average, tend to be around 0.1 or 0.2 (with lots of 0.0s); while my central/clear airway apneas are around 2.0 on average. I am guessing that my sleep apnea, thus, is most caused mainly by central apneas - which, I am guessing, means my airway is not necessarily closing down at night? As way of information, I scored 21.0 on my sleep test, I am a 37 year old male, not overweight, a non-drinker and non-smoker. I have a deviated septum and permenant rhinitis.

[Pugsy]

An occasional real central apnea is normal and nothing to be alarmed about or do anything about.
Real as in you were asleep...and sleep onset or sleep stage transitional central apneas are normal.

Then there are the awake/semi awake false positive flagged events...and if we aren't really asleep they simply don't count.
Not long ago I had a night where my AHI was 3.4 which is unusually high for me and it wasn't just centrals either. It was a nice combination of centrals, OAs and hyponeas. I decided to take the time to zoom in on each flagged event just to see if I was asleep or not and every single one of those flagged events were arousal related. I wasn't asleep. Didn't surprise me much though because I knew that I just had a crappy night's sleep that night. Lots of tossing and turning and remembered wake ups (not to mention the wake ups I don't remember) due to a bad night with the old back pain stuff.

When you see a lot of those sort of nights when the bulk of the events are arousal/awake related flags you have to look at whatever is causing the poor sleep and try to fix that. The cpap machine doesn't know if you are awake or not. It only measures air flow and our awake breathing is often very irregular compared to asleep breathing and those irregularities can cause the machine to flag events that simply aren't real.

Now it wouldn't be impossible to have a cluster of real OAs/hyponeas cause a wake up...and then you get some false positive flagging happening because of the wake up. So that's why we zoom in and try to figure out if what we are seeing flagged is real or not.

When you see a lot of awake flagged stuff and not much asleep flagged stuff then those events aren't the cause of the bad sleep but instead they are a by product of the bad sleep.