Machine changes

[speppers]

Hi everyone,

Quick question! I recently went from using a Resmed S9 Autoset that I was renting, to a different Resmed S9 Autoset that I now own (purchased gently used - 77 hours). All the settings on the new machine are exactly the same as the old machine - same minimum pressure, same maximum pressure, same EPR, etc. The only difference is that I'm using the Climateline tube instead of the Slimline.

With all variables the same, why would my AHI have increased a bit on the machine that I own? I have only been using it for 3 days now, so I was wondering if the algorithm takes time to "learn" about my apneas or something like that. For instance, on these particular pressure settings, my AHI on my previous machine was about a 0.79. For the past three days, I've had the following AHI's: 0.3, 2.2, and 1.8.

Any thoughts?

Thank you guys!

[Pugsy]

AHI numbers can and will vary from night to night even without changing anything at all. The changes you are seeing are statistically unimportant. Those are small changes.

Also...always when you evaluate your AHI be sure to look at the event category breakdown. Remember that centrals (Clear airway events in SleepyHead) we have to sort of ignore because they won't/can't respond to pressure. Also it's normal to have a few of them anyway and the number can and will vary.
When you look at the nights with the little higher AHI....what is the breakdown into event categories compared to the prior nights with less AHI?

[speppers]

Thanks Pugsy! I got a couple of numbers wrong in my previous post - I was going off memory - but here are the actual numbers:

Aug 23: AHI 0.69 (Obstructive: 0.69)
Aug 24: AHI 2.25 (Obstructive: 0.99; CA: 1.27)
Aug 25: AHI 1.85 (Obstructive: 1.00; CA: 0.85)

I have also been sleeping a bit deeper for the past couple of days, so that is probably related. I am trying to find a minimum pressure that reduces obstructive apneas without causing too many central apneas. For the last couple of weeks, I thought that this would be the right pressure (minimum set to 6.8; 95% pressure is ~10). However, now I am not sure! I guess I just want to be sure that it's not the new machine that is causing issues.

[Pugsy]

You know if you have been sleeping a little deeper then you may have been getting a little more REM stage sleep than you had in the past.
It's common to have our OSA to be worse when in REM stage sleep and also when sleeping supine ...or maybe even a little of both.

Statistically those small differences don't mean anything unless you maybe a a big ugly cluster giving you that average.

We don't sleep the same every night...we might move around between side sleeping and sleeping on our back...and the sleep stages sure go through their cycles. Some nights more so than others for any number of reasons.

Your numbers are well within acceptable limits. If you are seeing maybe little clusters of OAs or hyponeas then maybe a tiny tweak in that minimum pressure but nothing urgent.
The important thing is are you sleeping well and feeling decent and not getting a perfect math score.

Don't go chasing numbers all by themselves. They are elusive and it will drive you crazy because they can change every night even if you don't change anything.

[speppers]

Okay, thanks Pugsy!