Curious, why limit range on APAP?

[ExactlyAmy]

I'm curious why limiting the pressure range on an APAP helps?

In my mind, what makes logical sense is that since my Airsense11 has a range available of 5-20, if a person left the range wide open then you could get the best benefit, or most accurate.  Because it should sense what a person needs and then adjust to any pressure in the full range as needed.

But instead, we move both ends of that for our personal range.  And that seems to be better for some reason.

In my case, 3 weeks into CPAP therapy, I've landed on 8-18 giving me the best sleep (as in, most rested feeling in the morning, with good numbers).

So I'm curious why a 5-20 isn't best?  Or even when I tried 8-20?  Those were 'okay', but 8-18 works way better.

 

[jdougc]

7 cm is the minimum pressure for an adult.
Large pressure swings can cause arousals to some people.
Many recommend the wide pressures to "zero in" to an effective range.
The machines will ramp up after an event and then fall down for comfort until the next event.
Once the effective range or constant pressure is figure out,  people  can use cpap or constant mode with no delays for ramping up to an effective pressure.
Similarly a tight range can be effective with little delay to get to the needed pressure

[staceyburke]

Ill give it a try.  The top number is the highest the machine can go.  If you have reasons for the machine to reach 20 you may have quite a few centrals or H events.  How you need to work with those are different.  The least amount of pressure makes for better sleep.  So you may not have a bad AHI but the constant raising and lowering of the pressure will cause you not to ever get into deep sleep.

The same thing goes with lower pressure if it is zooming back up to stop events you are not getter restful sleep.  Many people complain that the AHI is low but I feel terrible.  Again, you want your pressure low enough you can fall asleep and stay asleep with the lowest number you need.

[jsmit86]

While some have the school of thought to "let the machine go as high as it wants to", that often does not deliver the best results.


I was originally prescribed 8-12 range.
I was doing OK, with AHIs under 5.
I posted using OSCAR on another CPAP board, and got some good advice that improved my results somewhat.
If I remember correctly they suggest 10-20, with EPR 1.
That improved me to 1-2 AHI for the most part.


After I got my Airsense 11, I posted to Sleep HQ.
I did find using sleep HQ to be easier than OSCAR, and the data format was easier for me to understand.
I did have some arousals with the mask blowing out from time to time waking me up.
The suggestion I got from the Sleep HQ forum, was to change to 11-17 initially, and then a tweak to go to 12-17, with EPR revised to 3.
After that, My AHIs are almost always less than 0.5, and often at 0.0.  My sleep is good, which is the most important thing.
(I don't necessarily chase 0.0, but I do celebrate it.)
The EPR setting drove a big change in my results, which was a suprise to me. It's not just about comfort.


Bottom line, letting the pressure go to 20 can sometimes be counter productive.
It's a good idea to get your data reviewed, and see if you can improve not just your AHI, but your quality of sleep.
I'm pretty dialed in at the moment, so I am not going deep into the data again unless something changes.
I do use My Air to at least monitor leak, and AHIs.

[jdougc]

jsmit86,
Glad your sleep is good.
What did EPR change, your Flow Limits?
Can you post a good night?
Thanks.

[super7pilot]

jsmit86, exactlyamy:

Not sure why so many newbies and even a few experienced users seem over wrought about a hi max setting and not so worried about the low setting. It does not go to that max unless it is needed and can help in that if one does have a big leak that doesn't wake them. So I don't believe for a moment that a hi max setting is counter productive. They will have some extra room to effect continued therapy with that leak if they have a hi max.

It is the low setting and EPR that is far more important to therapy.

But I'm always willing to learn. So I would like to hear as to why you feel a hi max is counter productive. Maybe there is something I have missed.

[Dormeo]

One good reason to cap the maximum pressure is that the machines (especially ResMed) will increase pressure in response to flow limitations. The idea behind the algorithm is that the FLs portend OAs, so the higher pressure will head off those future OAs.

But often FLs don't portend OAs, and increases in pressure often don't help with the FLs themselves. (EPR is usually the better tool for FLs.) If these FL-related pressure increases wake people up, either directly or via leaks, then capping can make complete sense.

[jsmit86]

jsmit86,
Glad your sleep is good.
What did EPR change, your Flow Limits?
Can you post a good night?
Thanks.

I don't recall the exact details, but it may have had to do with flow limits.
I don't currently have an SD card in my machine to post current results.
I was signed up to Sleep HQ on a trial, but I did not subscribe to the paid version once I was dialed in.


When I posted on another board using OSCAR it was probably in 2017 or 2018.
At that time the reply on the board suggested raising the minimum pressure, and adding EPR.
I had a definite improvment in sleep, and reported AHI events.

I got a new Airsense 11 machine in 2021, and I went ahead and posted the results on Sleep HQ at that time.
The first tweak was to raise the min pressure to 11 IIRC, and to limit the MAX pressure to 17, and to change the EPR to 2.

I posted results after that and they suggested changing EPR to 3, and raising the min to 12.
I did that and the results were great.
Less waking up, and AHIs almost always less than 1, and typically less than 0.5.

I have not bothered to go deep into the data since then because the results have stayed excellent.

Regarding the other comment about MAX pressure, I know that some think letting the machine go to 20 is a good idea, but in my case capping the max to 17 definitely improved the results. Not sure I rember the specific reason, but I have seen many posts supporting capping the max, and also many that claim 20 is the way to go. In my case the results convinced me to use 12-17 with EPR 3.

Bottom line, for some users capping the max produces better results, so I let that be my guide.

[greatunclebill]

simply put you set the high pressure a little above the highest it goes for you at wide open. you set the low number at the highest you can tolerate comfortably . the lower you make it the more it has to work to get where its needed.

[ExactlyAmy]

Thanks everyone for your responses!
Definitely helped me look at it all from other perspectives, and understand some of the reasons why it might matter, and might make a difference!