Do you lower your max pressure?

Desperate to stop these constant leaks, I was watching a video by "CPAP Reviews" on YouTube yesterday. One of the things he said was to lower your max pressure when using an APAP machine, so long as your AHI stayed at 5 or less. Basically he was saying the higher pressure tends to break the seal of the mask and to experiment to get the lowest pressures you could so long as your AHI stayed in the "controlled" range.

The concept makes me a bit nervous that the machine will not be able to force open my airway if I am having an obstructive apnea because its "firepower" is artificially capped.

Curious what others think of this concept of setting a max pressure on an APAP. Do you do it?

tisket wrote: ↑

Wed May 26, 2021 5:01 pm

The concept makes me a bit nervous that the machine will not be able to force open my airway if I am having an obstructive apnea because its "firepower" is artificially capped.

Did you know that the machine never "forces the airway open" anyway???
Did you know that when an obstructive apnea is actually happening the machine won't/can't/doesn't increase the pressure at all during the actual event?
The job of the pressure is to hold the airway open to prevent the airway from collapsing....not to force past obstructions caused by collapsing soft tissues during the event.
It can't generate enough pressure even at max 20 or 25 cm to force the tissues open....so it does nothing during the event itself.

All that said.... you can try limiting the max and see if it helps with leak control or not and THEN decide if limiting the max allows too many apnea events to happen because the machine isn't able to hold the airway open and prevent the collapse.

But if you were thinking that the machine actual does anything during the actual apnea event.....you were thinking wrong.
None of the auto adjusting pressure machines (apaps) will do anything during the actual event. What they do is sit there and twiddle their little thumbs and then try to figure out how to best prevent the next collapse from happening based on what is going on and how many collapses you have had recently . Pressures are changed ONLY after the airway has opened back up and the event is resolved.
Nothing happens during the event.

Interesting Pugsy. Looking at these sudden surges in pressure I see in Oscar I assumed it detected a closed airway and was responding, since they seem to surge up rapidly and then trail off.

If you actually zoom in on the pressure line you will see that the machine never does anything in the blink of an eye or "surge" or change anything one way or the other rapidly. Any changes take place over maybe a few minutes.
Looks faster response time due to the scale of the graphs. Zoomed in the changes are much, much slower and during the actual flagged event there won't be any changes at all. It's always been this way with the auto adjusting algorithms on apaps.

Even if the machine could increase rapidly and go to the max...it isn't enough to blow the airway tissues out of the way and force the airway open.
Because the machine can't go high enough...it doesn't even try.
I don't know what might be needed to actually move soft tissue blocking the airway but I suspect upwards of 100 cm or more and that for sure would wake someone up to get blasted like that in the blink of an eye.

tisket wrote: ↑

Wed May 26, 2021 5:01 pm

Desperate to stop these constant leaks, I was watching a video by "CPAP Reviews" on YouTube yesterday. One of the things he said was to lower your max pressure when using an APAP machine, so long as your AHI stayed at 5 or less.

An AHI of 5 is pretty terrible sleep, it's like someone sitting by your bedside and poking you with a sharp stick every 12 minutes, all night long.

This is bad advice.

If the leaks aren't waking you up (or disturbing a bed partner), and they're not over 24lpm, then ignore them.

If they are waking you up, then maybe you need another mask (I'd suggest mask liners, but I don't know if there are any for your mask.

tisket wrote: ↑

Wed May 26, 2021 5:43 pm

Interesting Pugsy. Looking at these sudden surges in pressure I see in Oscar I assumed it detected a closed airway and was responding, since they seem to surge up rapidly and then trail off.

The surges aren't sudden, not if you zoom in so you can see the night on a minute by minute basis.

Whenever the pressure jumps up and trails off, it's just *reacting* after the fact, to breathing events, If that's happening a lot, then your minimum pressure is too low.

Pugsy is right, the machine always, always, waits till *after* the event is over before it increases pressure.

Interesting thanks.

Yes when I say "leaks" I mean 25% of the night being spent in large leak territory. And it does not wake me up. Using nasal pillows and mouth tape.

I lowered the minimum pressure and also readjusted my mask after reading the instructions again. It's the Aloha and I thought (I started using it years ago) that when adjusting the cushion you were supposed to start with it all the way out on the prongs, but it turns out you're supposed to start with the prongs all the way in, and adjust from there. I put the prongs all the way in and between that and the lower pressure, the last two nights I've had large leaks of 2.7% and 0% so I am hoping I have finally found an answer to these large leaks. I haven't lowered the max pressure.

tisket wrote: ↑

Thu May 27, 2021 5:11 am

I lowered the minimum pressure

You probably want to*raise* the minimum pressure.

Since my AHI is like 1.2, and my problem is leaks, I don't know why I would want to raise the minimum pressure. I raised it several times in the past, and it just seems to be leading to more and more large leaks.

The best way to make changes is in very small increments.
That gives your body plenty of time to adapt without feeling uncomfortable.

tisket wrote: ↑

Thu May 27, 2021 9:14 pm

Since my AHI is like 1.2, and my problem is leaks, I don't know why I would want to raise the minimum pressure. I raised it several times in the past, and it just seems to be leading to more and more large leaks.

You want to raise your minimum pressure to address potential apneas from occurring at all. This often results in reducing the need for the machine to go to higher pressures.

Assuming your leaks are pressure driven, they are probably not occuring when at the lower end, increasing your minimum and therefore reducing the time at higher pressures can reduce leaks.