Lower average pressure with AirSense 11 Autoset

Starting four nights ago I replaced my aging AirSense 10 Autoset with the newer 11. The prescribing professional and I did everything we could to keep all the settings the same, including max and min pressure, ramp, EPR, etc. I did not accidently pick the "for Her" algorithm or the "soft" version of the standard one. Subjectively, I felt little change, and my therapeutic results have been comparable. I'm accustomed to an AHI of around 1 (a little less in recent months after losing weight), and sure enough I've averaged about .75 with the new machine, almost all of it HI. So far business as usual, and that's good.

There has been a big change in pressure, however. My min and max settlings are 10.0 and 15.0 cmh2o. Up until now, I averaged about 13.25. I inevitably hit 15 multiple times, and quite a bit of the night was spent up in the 14 to 15 band. Most nights my pressure distribution graph in OSCAR looked like a boa constrictor who just swallowed an elephant and hadn't moved it very far. But last night (and this has been typical of the last four), I averaged 11.0 and maxed out at 12.75. Graphs show the algorithm being clearly responsive to events, pushing the pressure up after a couple of early hypopneas, for example, but allowing pressure to slowly drift down without ever getting close to 15. The other difference, which I presume is a consequence of lower pressure, is that I have fewer large leaks. I do have a new mask, and maybe that has helped my seal, but it is the same model (the F20) I've been using for ages.

So what do you suppose is happening? As I recall, one of the big stories about the 11 was how little the fundamentals changed, and in particular, that the auto-adjustment algorithm remained the same. Have others had this experience? Was my old machine perhaps on the fritz? I'm very happy with all this, of course. It may be too early to tell, but I think I feel like less air is getting pushed through my digestive tract. Fewer leaks also mean fewer squealy noises to disturb my better half. So all is well, but I'm curious about the change and invite insights.

Both set to FF mask? Some Oscar plots between the two might help here. The AS10 has a bigger motor than the 11... no idea if this matters here. I love both my AS10s and don't want an 11 from what I hear.

PST wrote: ↑

Mon Mar 25, 2024 10:51 am

Starting four nights ago I replaced my aging AirSense 10 Autoset with the newer 11.

.

I do have a new mask, and maybe that has helped my seal, but it is the same model (the F20) I've been using for ages.

4 days, new mask - how about running for 4 days with the old mask and no other changes?

vandownbytheriver wrote: ↑

Mon Mar 25, 2024 9:52 pm

Both set to FF mask? Some Oscar plots between the two might help here. The AS10 has a bigger motor than the 11... no idea if this matters here.

Both set to FF. I didn't know about the difference in blower motors. Perhaps that has something to do with it.

I appreciate the suggestion of going back to the old mask for a few nights to see if that makes a difference. If I were rigorously scientific and not so lazy I would, but I have updated my F20, its cushion, and my headgear many times over the years and it never resulted in this kind of systemic drop in pressure.

I don't know if this will have any bearing on this, but the AS11 has 3 mode settings...CPAP, AUTOSET and AUTOSET FOR HER. The AS10 had only 2. Make sure you are not set to AUTOSET FOR HER.

Same thing for me, average pressure drop with no discernible change in results. I have a graph, but the board seems to be too full for attachments.

PST wrote: ↑

Tue Mar 26, 2024 8:00 am

vandownbytheriver wrote: ↑

Mon Mar 25, 2024 9:52 pm

Both set to FF mask? Some Oscar plots between the two might help here. The AS10 has a bigger motor than the 11... no idea if this matters here.

Both set to FF. I didn't know about the difference in blower motors. Perhaps that has something to do with it.
(snip)

We're definitely going to need to see some pressure/flow charts to determine what's going on. An Oscar picture would also include all the settings. If you could load two Oscar profiles, one with the old machine and one with the new, then post picture links here, we'd be in business here. Otherwise it's just tossing rocks in a puddle, guessing.

www.sleepfiles.com/oscar

edfreeman wrote: ↑

Tue Mar 26, 2024 6:01 pm

Same thing for me, average pressure drop with no discernible change in results. I have a graph, but the board seems to be too full for attachments.

please see this regarding the full attachments issue and how to post images here-

viewtopic/t183806/Attachment-storage-is ... MENTS.html

Ok, just so folks can see what the OP is talking about. This is a screenshot from Resscan, since OSCAR displays the maximum settting instead of the maximum observed pressure
in its summary/overview graphs. Ignore the AHI spikes, it was the holidays and there might have been food and (especially) beverages that tend to disrupt peaceful sleep. I rarely have an AHI over 1, and it is usually 0.5 or less.
You can tell clearly where the AS11 was put into service in Dec 19, 2022. I have an AS10 still in service at my mother's house when I visit, and I can show you where I always see a pressure "spike" to my maximum of 13 on those overnights with it. This is one of those things that is real, an improvement IMHO in how the machine behaves to get the same results, but not sure how much it really matters as both machines provide good treatment.

Having introduced this topic, I now find that it isn't as big a mystery as I thought, at least in my case. I was curious because my trusty 10 had been bumping against my 15 cmH2O ceiling much of the night with a pretty high average pressure, whereas the new 11 seldom got close to 15 and averaged almost 2 cmH2O lower than its predecessor. I was going to post some graphs, but in the process I looked back at my last five years, not just the last year, and found that the consistently high pressure was a recent phenomenon. The new machine is actually more of a return to my old normal. That improves the odds that what jumped out at me has to do with something wearing out or getting obsolete on the old equipment. Subjectively, I feel like I'm getting better sleep in the last week. I'm skeptical of subjective impressions, but I actually got more than 8 hours of sleep last night, which is mighty unusual, and I feel swell. So I think I'll just get comfortable with what is turning out to be a good thing and add a thumbs up for the AirSense 11.