Do APAP's "learn" from night to night?

mollym · Post by **mollym** » Wed Oct 03, 2007 5:54 pm

I've been on CPAP at 6 for 1-1/2 months and have seen an
improvement, but I'm still tired.
Two days ago I switched to a Remstar M Series Auto Pap
with Cflex 5-20.
The first night my 90% pressure was 6, leakage was
30 (15 over what the book for CL2 says 6 should be) and
my AHI was 2.6 or 4.6 (I don't have it with me).
The second night the 90% pressure was 6.3, leakage and
AHI were the same.

I wanted to give it at least those two nights to see
what the leakage data was. I didn't have leaks when I
was awake, but suspected I did when I was asleep. Unless
someone thinks I need more data (I'm on a 3week trial with
this machine) I plan to add another strap about level with
my eyes around my head to hold it more secure. Shouldn't
need to be very snug at all.

Does an APAP ever "learn" from your 90% pressure or does
it always start at the minimum pressure and you just have
to have the events to bump up? For some reason they set
the minimum on this thing at 5 even though my prescription
was 6. If the minimum is set too low, is there any way
over time for the machine to accumulate enough data to
overcome that and work you down close to an AHI of 0?

After it bumps up 3 times, if you still aren't breathing what does it do?

tillymarigold · Post by **tillymarigold** » Wed Oct 03, 2007 6:18 pm

No, it doesn't learn; you would need to re-program it.

But a minimum setting of 5 if your pressure was titrated at 6 makes perfect sense to me; I have a prescription for each and my CPAP script is for 8 but the APAP script is for 7-11.

90% pressure is a complicated issue, but: remember that the 90% pressure is the pressure that eliminated 90% of all events that were *not* prevented by the minimum pressure and there's no way to know how many events you would have had with no pressure at all because some of them will be prevented before they start.

blarg · Post by **blarg** » Wed Oct 03, 2007 10:18 pm

tillymarigold wrote:No, it doesn't learn; you would need to re-program it.

Yup, that's completely right. It just reacts as it sees events. If you want it to function in a different range, you need to program in that range.

tillymarigold wrote:90% pressure is a complicated issue, but: remember that the 90% pressure is the pressure that eliminated 90% of all events that were *not* prevented by the minimum pressure and there's no way to know how many events you would have had with no pressure at all because some of them will be prevented before they start.

Just wanted to clarify.

90% pressure is the pressure that the machine functioned AT OR BELOW for 90% of the time. It has nothing to do with events, except that obviously, the more events you have, the higher the machine will bump the pressure. That will bring the 90% pressure number up. But they're not directly related.

So if my range is 8-15 and my 90% pressure is 11, that means that for 90% of the time I was using the machine, the machine was cranking out between 8 and 11 cm/h2o.