Why set a max pressure with Apap?

[AMK]

When I had the top end maxed out, the pressure would go berserk several times a night.
Each time, I woke up, most unpleasantly.
Setting the max to a bit above my 95% gives ME the best results--(lets me SLEEP.)
After all, that's what I'm there for.
I do not recommend others use my settings--find your own, and embrace your own inner Goldilocks.

Chunkyfrog, are you using the "for her" on your machine or regular apap?

[SnoringInOregon]

Because of advice I received here, especially from palerider, I switched my Airsense from the "for her" mode to regular apap so that the pressure can go as high as it needs to. I had the max pressure set at 16 and I see that last night 16 was not high enough; I had a run of OAs and the machine needed to go higher. So I'm going to set it higher, of course, but I was wondering, then, why have a cap on the max pressure at all? Why not leave that at 20 and just pay attention to the min pressure?

Given that you saw OAs at 16, you probably need a higher max. I will give you a counter-example. It's what happened to me.

My DME set up my machine at (7,20). After using SleepyHead for 3 months and paying careful attention, I changed to (8,15). I wanted to see if I could reduce RERAs, that's why I raised min. That did help RERAs a lot. I never saw machine go to max greater than 12.8 (and that was mostly in very early days) so I lowered max.

A few months passed uneventfully. Then we had horrible air pollution from wildfires. Haze in the air, red red sun, etc. One night shortly after I go to bed, machine sees VS and shortly later another VS. Machine changes pressure 8 -> 10. Machine sees another VS and an FL and goes to 13.5. A few more VSs and machine goes to 15.

That's when things go totally crazy. I experience a number of CAs (which I rarely see). My flow rate looks a lot like CSR in spots, but machine doesn't flag it as such. I keep waking up briefly, thinking "why do I have air in my mouth?".

Thru it all, the machine was like the Honey Badger. Honey Badger don't care. Honey Badger don't give a shit. In other words, machine just kept pressure at 15 for nearly 2 hours. Until I finally woke up enough to turn the machine off briefly. When the machine started again it was happy to stay at 8.

Long story short, sometimes the machine can't cope if it has too broad a range to work with.

I can't imagine how bad things would have gotten if machine was still "wide open" at max of 20 as set by DME and not at max of 15 that I had changed it to.

I immediately changed to (8,12.5) and machine hasn't hit that new maximum yet.

[yrnkrn]

High pressure may result in annoying leak that wakes you up.
If the high pressure is really needed to solve obstructive events this must be solved, but if it's just due a flow limitation you may prefer to sleep through rather than wake up.

[AMK]

Given that you saw OAs at 16, you probably need a higher max. I will give you a counter-example. It's what happened to me.

My DME set up my machine at (7,20). After using SleepyHead for 3 months and paying careful attention, I changed to (8,15). I wanted to see if I could reduce RERAs, that's why I raised min. That did help RERAs a lot. I never saw machine go to max greater than 12.8 (and that was mostly in very early days) so I lowered max.

A few months passed uneventfully. Then we had horrible air pollution from wildfires. Haze in the air, red red sun, etc. One night shortly after I go to bed, machine sees VS and shortly later another VS. Machine changes pressure 8 -> 10. Machine sees another VS and an FL and goes to 13.5. A few more VSs and machine goes to 15.

That's when things go totally crazy. I experience a number of CAs (which I rarely see). My flow rate looks a lot like CSR in spots, but machine doesn't flag it as such. I keep waking up briefly, thinking "why do I have air in my mouth?".

Thru it all, the machine was like the Honey Badger. Honey Badger don't care. Honey Badger don't give a shit. In other words, machine just kept pressure at 15 for nearly 2 hours. Until I finally woke up enough to turn the machine off briefly. When the machine started again it was happy to stay at 8.

Long story short, sometimes the machine can't cope if it has too broad a range to work with.

I can't imagine how bad things would have gotten if machine was still "wide open" at max of 20 as set by DME and not at max of 15 that I had changed it to.

I immediately changed to (8,12.5) and machine hasn't hit that new maximum yet.

I'm not sure of your terms. I don't know what VS or CSR means. I agree that higher pressure can bring on the CAs (I do know that term ). I seem to go two weeks with pressure needing to go no higher than 12.5 and then apropos of nothing I'll have a bad night where if the pressure can't go high enough I'll go an hour with an AHI of around 70. Frankly, on nights when things are bad like that I would rather have the high pressure wake me up and I'll turn the machine off and on and start over rather than sleep through an AHI of 70.

[Pugsy]

I'm not sure of your terms. I don't know what VS or CSR means. I agree that higher pressure can bring on the CAs (I do know that term ). I seem to go two weeks with pressure needing to go no higher than 12.5 and then apropos of nothing I'll have a bad night where if the pressure can't go high enough I'll go an hour with an AHI of around 70. Frankly, on nights when things are bad like that I would rather have the high pressure wake me up and I'll turn the machine off and on and start over rather than sleep through an AHI of 70.

VS is vibratory snores...shows up on Respironics event graphs.
CSR is Cheyne Stokes Respiration which is a very specific form of Periodic Breathing. There are many forms of Periodic Breathing and CSR is just one. If someone sees a LOT of CSR along with a LOT of central apnea they need to be evaluated by their doctor. Just to rule out potential cardiac issues and maybe a need for a different machine.

When people can go long periods of time without a dramatic change in pressure needs and then wham...they get episodes of really high pressures the 2 most common culprits are
Supine sleeping (rolling over on your back)
or
REM stage sleep.
or maybe someone has a little of both...REM while on their back.

If it is supine sleeping then maybe doing something to make sure one stays off their back is enough...if it is REM sleep there's not much we can do about it except maybe increase the minimum pressure so the machine can get to the higher pressures faster and also with a higher baseline pressure the airway is hopefully held open better to start with and less chance of it collapsing so dramatically requiring those higher pressures.

I prefer to just have the minimum pressure high enough to do whatever job the machine needs to do and sleep in any position I want because my OSA is worse in REM and I can't do anything about REM. So I figure just let the machine sort it out.
If you have a copy of your sleep study it should give you some clues as to whether your OSA is worse on your back or during REM...either is quite common.

If you are unlucky enough to have aerophagia pop up with the higher pressures that are needed sometimes...then you re-evaluate where the line might be where you don't have aerophagia problems and limit the machine so it doesn't cross that line.
Sometimes we have to make compromises when using higher pressures create significant problems of some sort.

[AMK]

Oh my OSA is definitely primarily in REM, and I assume it's worse when I'm on my back which I would never consciously be. I didn't have any trouble with the pressure going up to 16. Thanks Pugsy for explaining VS and CSR!

[AMK]

To update my post, I've been using my machine set at regular apap with a max pressure of 16. 16 wasn't high enough so I set it at 17. 17 wasn't high enough so I've set it to 20. My pattern seems to be of having 3 weeks of nights where the pressure doesn't go any higher than 11-13 and I do pretty well, and then I'll have a night like the one in my original post here, where the machine just can't go high enough and I end up going for a period of time with one OA after the next. So now I'm waiting to find out how high the machine actually has to go on those nights. I don't think I need to adjust the min pressure right now. If the machine goes to 20 and wakes me up, that's fine, I can just turn the machine off and back on since this happens so infrequently. I would rather wake up than go for an hour with severe OA. I have not been able to identify a variable responsible for these occasional bad nights, and as Pugsy said, it could be that for whatever reason once in a while I end up on my back. My only fear is that 20 may not be high enough, but time will tell.

[Guest]

To update my post, I've been using my machine set at regular apap with a max pressure of 16. 16 wasn't high enough so I set it at 17. 17 wasn't high enough so I've set it to 20. My pattern seems to be of having 3 weeks of nights where the pressure doesn't go any higher than 11-13 and I do pretty well, and then I'll have a night like the one in my original post here, where the machine just can't go high enough and I end up going for a period of time with one OA after the next. So now I'm waiting to find out how high the machine actually has to go on those nights. I don't think I need to adjust the min pressure right now. If the machine goes to 20 and wakes me up, that's fine, I can just turn the machine off and back on since this happens so infrequently. I would rather wake up than go for an hour with severe OA. I have not been able to identify a variable responsible for these occasional bad nights, and as Pugsy said, it could be that for whatever reason once in a while I end up on my back. My only fear is that 20 may not be high enough, but time will tell.

What IS your minimum pressure? I can't see that you've stated it in your previous posts.
And, from your reports, what is causing your pressures to increase? Snores or flow limitations? It's usually one or the other or both.
Are you actually having any apneas or hypopneas or is your pressure just increasing?
If you have nasal congestion, do you have some routine before bedtime to clear out as much of it as possible?
Do you have the humidification cranked up? Sometimes too much humidity can actually cause more nasal congestion because it can increase the swelling in the nasal passages. Sometimes, going in the opposite direction with the humidity setting works better.
Lots of factors can affect the snores or flow limitations.

[Goofproof]

Because you don't know better, do you drive your car in the store parking lot full throtle.... No Brainer, use the software to set it right. Want to know it, 2 cm under and 2 cm over your best treatment pressure or 1 cm under and 2 cm. Why give the machine free rein to go crazy. Jim

[Pugsy]

What IS your minimum pressure? I can't see that you've stated it in your previous posts.
And, from your reports, what is causing your pressures to increase? Snores or flow limitations? It's usually one or the other or both.
Are you actually having any apneas or hypopneas or is your pressure just increasing?
If you have nasal congestion, do you have some routine before bedtime to clear out as much of it as possible?
Do you have the humidification cranked up? Sometimes too much humidity can actually cause more nasal congestion because it can increase the swelling in the nasal passages. Sometimes, going in the opposite direction with the humidity setting works better.
Lots of factors can affect the snores or flow limitations.

The answers to the bulk of your questions can be found by searching AMK other threads.

She was having some really ugly OA clustering...very sporadic though and fairly brief. Not every night. Not even once a week.
Flow limitations weren't the problem...full grown OAs were the problem.

[AMK]

The answers to the bulk of your questions can be found by searching AMK other threads.

She was having some really ugly OA clustering...very sporadic though and fairly brief. Not every night. Not even once a week.
Flow limitations weren't the problem...full grown OAs were the problem.

Thanks, Pugsy. I did not give my minimum pressure in this thread because it had nothing to do with the issue I asked about in this post. Since most nights things look good, I would rather not risk adding more centrals into the mix by raising the min pressure. I like to focus on one issue at a time and finding the correct max pressure is it right now. If 17 isn't high enough then why not try 20?

[Pugsy]

If 17 isn't high enough then why not try 20?

No reason not to try 20 and just leave it at 20 and let the machine sort it out unless it goes higher and happens to trigger a visit from the aerophagia monster and if he hasn't stopped by yet I doubt he will.

Same thing about your concern about triggering centrals. If you aren't getting them at 17 I doubt that raising your minimum 1 or 2 cm will trigger them. Higher pressures don't always trigger centrals and in fact when they do it's relatively rare. I used to see pressures over 20 with my bilevel on occasion and never had one more central than a normal random central.
There are many people using pressures over 20 all night long and never have more than a random centrals.

The thing is though...it's the minimum pressure that is the most critical pressure setting. It does the bulk of the job holding the airway open and the maximum is reserved for the special cases...like REM needs or supine needs.
Often when the minimum is more optimal the maximum pressure reached will actually reduce because the machine doesn't have to go trying to fix something after it has happened...it prevents it in the first place with a more optimal minimum where the machine can go a bot higher more quickly and better prevent the airway from collapsing and thus maybe not need as much on the higher end.

For reducing AHI that is either OA or hyponea...more minimum is the key...not having a higher max that the machine may or may not go to.

But to answer your question...there's no reason to not raise the minimum and just leave it there unless it goes higher and causes problems like aerophagia or centrals which I really doubt you will have central issues. If you haven't had them pop up with pressures of 17...highly unlikely they will pop up with either the max of 20 or increasing the minimum 1 or 2 cm.
Now having a rather wide range of pressures going on can make leak management a bit more of a challenge...you have to fit the mask at the higher pressures if you are having leaks at higher pressures and sometimes the wide pressure changes will disturb sleep but you might be like me...I saw pressures over 20 nearly every night when I was on bilevel and I slept right through it all and never knew it happened until I saw the report and leaks weren't any more of an issue that at single digit pressures.

[AMK]

Thanks again, Pugsy, lots to think about there. I had a night in August where I only had 9 events the whole night but they were all centrals. Most nights I have at least 2-3 centrals. The centrals don't come when the pressure is at its highest...they come randomly. I don't think that changing my max pressure has affected the CA count. I did raise my min pressure from 7.4 to 7.6 a month or so ago and I've been thinking about getting that up to 8 to see what happens. I am grateful that aerophagia is not an issue for me, probably because of how I rig my face up with tape and a chin strap. Once in a while I form a mouthful of air but it's rare.

Two nights now with the max pressure set at 20 and the machine hasn't needed to go higher than 12. But that's typical. Eventually I'll get one of those bad nights and I'll see how high it needs to go.

[ChicagoGranny]

You still miss it. You said 120 MPG when you meant 120 MPH

ah, yes, old eyes!

Fat fingers. G and H are side by side.

[Pugsy]

Remember that having a few centrals get flagged is normal...like a sleep onset central..those are normal and not cause for alarm.
Sleep stage transition centrals..it's normal to wake up after REM stage. Now we may or may not (usually not) remember waking up but we do and when you do you go back to sleep and another chance for a sleep onset central to happen. We have multiple REM stages during the night so multiple chances for a sleep onset central.

Also we have Sleep/Wake/Junk centrals...or centrals getting flagged during an arousal. Turn over in bed and hold your breath central...quite common but we don't realize we are pausing our breathing but the machine might flag it because it only measures air flow.

So don't get all in a panic over a few centrals here or there....it's normal for one thing and another is a few might be SWJ and those don't count anyway.

Now if you started seeing 4 or 5 centrals every hour...every night all night long...then we have a talk about centrals but the number you are having...even if every one of them were real...isn't enough for concern.