Why have prescription maximums (at least initially)?

[MarkWill]

Curious to know what the value is in having a maximum for pressure with a prescription. My prescription is set to 6.0 - 12.0. I can understand the reason for the minimum, but not clear on why my machine would be restricted to 12. I am sure my doctor will be reviewing this data online and looking to adjust in due course but my initial impression on looking at SleepyHead is that I hit max a few times per night. It's not a huge amount but I do hit max.

What would be the disadvantage in setting it higher and letting my body indicate what it actually needs, rather than how my prescription is set (at least in the first few days or which which, I assume, are valuable for assessing how I am doing)?

Thanks.

Mark

[BlackSpinner]

Sometimes high pressures trigger CA's and/or bloating.

Get a manual and change the pressure . It is only air.

[chunkyfrog]

And get Sleepyhead so you know what happens and when.

[MarkWill]

Sometimes high pressures trigger CA's and/or bloating.

Get a manual and change the pressure . It is only air.

Oh I know HOW to change it - but I am just wary of changing anything, as a newbie, without first understanding whether it makes sense to do so. I would imagine newbies could easily mess with all sorts of valuable data just by "tinkering", hence my question.

Sound like I can just ease it up a little and see the results.

Thanks.

Mark

[MarkWill]

And get Sleepyhead so you know what happens and when.

Per my message, it's SleepyHead that made me question why I have the maximum set

[Pugsy]

The maximum setting is really not that big of a deal if the machine never goes there...If your max is set at 12 but you never go past 10 the maximum becomes a moot point. You could set it to 20 and it still wouldn't go past 12.
Just because a machine can go somewhere doesn't mean that it will go there. Heck...if the machine could go to 100 and it never went past 10...it wouldn't matter what the machine was set at.

The maximum setting itself doesn't change anything about how the machine responds unless you reach the max and it wants to go higher but can't.

Now sometimes going higher creates problems...aerophagia, bloating, big changes disturb sleep maybe...or sometimes in rare situations central apneas pop up but most of the time when people get centrals with cpap pressure it's going to happen at any pressure and not just higher pressures. I see pressures over 20 almost every night and I have never had centrals develop because of higher pressures....and I have seen people with a truckload of centrals develop with as little as 6 cm pressure. The ones that do actually develop centrals because of a higher pressure and there's a definite line where above causes centrals and maybe one cm below doesn't...those situations are relatively rare.

Whether you want to limit the max or not...if you don't ever reach it...it doesn't matter what you do with it.
If the changing pressures themselves don't disturb your sleep...it doesn't matter what you do with it.
If you don't blow up like a puffer fish and have a lot of bloating or pain from air in the gut...it doesn't matter what you do with it.
If you don't see many centrals (a few are normal so don't panic if you see them)...it doesn't matter what you do with the max.

As you have already figured out...it's the minimum baseline pressure that is the post critical pressure..it's used to hold the airway open decently for the bulk of the time and allowing the machine to go higher for times where the minimum can't hold it open (supine sleeping, or REM sleep or whatever).

[MarkWill]

The maximum setting is really not that big of a deal if the machine never goes there...If your max is set at 12 but you never go past 10 the maximum becomes a moot point. You could set it to 20 and it still wouldn't go past 12.
Just because a machine can go somewhere doesn't mean that it will go there. Heck...if the machine could go to 100 and it never went past 10...it wouldn't matter what the machine was set at.

The maximum setting itself doesn't change anything about how the machine responds unless you reach the max and it wants to go higher but can't.

Now sometimes going higher creates problems...aerophagia, bloating, big changes disturb sleep maybe...or sometimes in rare situations central apneas pop up but most of the time when people get centrals with cpap pressure it's going to happen at any pressure and not just higher pressures. I see pressures over 20 almost every night and I have never had centrals develop because of higher pressures....and I have seen people with a truckload of centrals develop with as little as 6 cm pressure. The ones that do actually develop centrals because of a higher pressure and there's a definite line where above causes centrals and maybe one cm below doesn't...those situations are relatively rare.

Whether you want to limit the max or not...if you don't ever reach it...it doesn't matter what you do with it.
If the changing pressures themselves don't disturb your sleep...it doesn't matter what you do with it.
If you don't blow up like a puffer fish and have a lot of bloating or pain from air in the gut...it doesn't matter what you do with it.
If you don't see many centrals (a few are normal so don't panic if you see them)...it doesn't matter what you do with the max.

As you have already figured out...it's the minimum baseline pressure that is the post critical pressure..it's used to hold the airway open decently for the bulk of the time and allowing the machine to go higher for times where the minimum can't hold it open (supine sleeping, or REM sleep or whatever).

Thanks again. Pugsy. Yes, the reason I am asking is because I am hitting the maximum each night - not much, but every night.

I am going to increase a little each day (wary of the bloating thing and other potential issues) to get a sense of where my body might max out.

Thanks.

Mark

[Pugsy]

When I first started therapy I used a small range but quickly saw that I was hitting the max (I think it was 10 back then) during brief periods during the night which were probably REM stage sleep where it was documented on my sleep study my OSA is much worse.
I think I was using 8 min and 10 max to start with. Sometimes the 8 did a great job but during probable REM it was obvious more than 10 was needed.
I ended up with the max at 20 because sometimes I needed 18 or so...not all the time but enough to leave the machine wide open at 20 and just let the machine sort it out. The pressure changes never disturbed my sleep and I have never had issues with centrals or aerophagia. No reason to not leave it wide open.
I also found out the minimum wasn't quite optimal because when the machine hit 18 I was still having more OAs than I wanted to see in dense clusters. The overall AHI wasn't that bad at around 5.0 because of the time spent in non REM sleep where nothing much happened but the clusters were dense.
I ended up with 10 minimum and 20 max being my apap settings and got the AHI down to below 2.0 most of the time but more importantly the dense clusters were broken up.

If people want to limit the max...and they never reach it anyway I don't say much because it really isn't important. It hurts nothing at all to limit it if that is what they prefer despite the real fact that if the machine doesn't go there anyway and is in reality a moot point. It isn't worth fighting over and we have enough fights here without adding something that isn't worth it.
The older machines in the past would sometimes "chase leaks" and when leaks were present sometimes the machines would try to catch up with more pressure.
With the newer machines today the machine makes a point of not chasing the leaks and in fact will often reduce the pressure in an effort to regain the seal so that old potential issue is no longer a valid issue. The newer machines simply don't/won't go chasing leaks.

[robysue]

I'd like to add my 2 cents to Pugsy's excellent responses.

I happen to use a pretty tight range of pressures. I don't have a problem with CAs, but I do have problems with aerophagia and "spontaneous" arousals that are often tied to my aerophagia. In my case, flow limitations that do not seem to be related to my OSA* drive my IPAP up to wherever I'm willing to set the max IPAP pressure. And that drives the aerophagia, which drives the arousals, which creates more aerophagia and more arousals. And I wake up pretty miserable in the morning.

And my AHI doesn't go down when I increase the max IPAP, and in fact, it can go up if I spend a lot of time semi-dosing between the real wakes caused by the aerophagia.

In my case having a max IPAP pressure is critically important. And my IPAP sits at my max IPAP pressure for long periods of time most nights. And I've learned to just not worry about the fact that I max out my pressure a lot of the time.

So when it comes to the question: Should I increase my max pressure because I'm hitting for <x amount of time> during the night? the answer is: Maybe, Maybe not. It all depends on what you are trying to do with an increased max pressure setting. If you are still having clusters of obstructive events, then, yes, an increase in pressure is worth trying. If you are NOT having clusters of obstructive events, and you don't have aerophagia, but you still don't feel as rested as you think you should, an increase in the max pressure may be worth it. If you are NOT having clusters of obstructive events AND you feel good, there's probably no point in increasing the max pressure. If you are NOT having clusters of obstructive events AND you have serious aerophagia problems OR you have problems with CAs, then there's a real good reason to NOT increase the max pressure.

* What I mean when I say my flow limitations do not seem to be related to my OSA is this: My Flow Limitation Index is pretty stable whether I use a max IPAP = 8 or a max IPAP = 15. My AHI is typically below 2.5 and often below 1.5 regardless of whether my max IPAP = 8 or my max IPAP = 15. The number of RERAs sometimes increases with a higher max IPAP because I'm more likely to arouse or awaken when the IPAP is above 9cm. And the OAs and Hs that get through the BiPAP defenses are typically NOT preceded by any noticeable number of FLs or clear distortion in the shape of my inhalations. Because of all these facts, it seems reasonable to infer that my machine scored FLs are probably NOT closely related to my airway being seriously in danger of starting to collapse.

[PEF]

Robysue, can I ask your opinion on something?

I now have 2 machines. For a year, I used my Resmed S9 Autoset. My AHI is usually below 1. Right now I have min pressure set to 6.4 and max pressure set to 7.4. On those Sleepyhead reports, I do see a lot of pressure bumped against the ceiling for most of the night. So I am gradually raising pressure .2 at a time. Very slowly because I had a lot of trouble with aerophagia and mouth leaks whenever I raise pressure. But I was pretty much satisfied and was not going to raise pressure much.

But things got more complicated when I got my PR Dreamstation. At the same pressure as the Resmed, my AHI ran between 5 and 7 consistently, 50 to 70% hypoapneas, 5% OA's, 1% CA, and RERA 15% to 25% and same for FL's roughly. These are rough averages. The thing that stands out is a whole lot of hypoapneas.

So after talking to Pugsy and PR, I raised the Dreamstation pressures, first a little which did not help much. I kept a log and it turns out that I needed to have min pressure at 7.5 and max pressure at 8.5 just to get my AHI down to 2.99. I gave up on the machine at that point because I could not tolerate the amount of pressure I needed to get my AHI to below 1. My guess is that I would need max pressure around 11 or 12. I had terrible problems with the pressure increases and woke up all night due to aerophagia and mouth leaks.Slept badly.

Do you think I should just give up on the Dreamstation? or do you think the Resmed is missing events? I know the algos are different, but I guess I need to make some sense of what the 2 machines are telling me? Is my apnea treated or not? The dreamstation says no and the Resmed says yes.

[Pugsy]

PEF...I am betting Robysue is going to ask about how you feel your sleep quality is and how you feel during the day with the 2 machines and AHI relationship.
You might as well try to explain it now and save some time. I don't think she knows your whole story.

There's more to effective OSA treatment than just the AHI all by itself. Numbers don't guarantee anything except a good math score.

Everyone wants to target the AHI as the end all measuring tool for what constitutes optimal OSA therapy but they forget that the other stuff matters..and maybe matters even more than the AHI.

[robysue]

Pugsy's pretty much predicted what I'm going to say.

Robysue, can I ask your opinion on something?

I now have 2 machines. For a year, I used my Resmed S9 Autoset. My AHI is usually below 1. Right now I have min pressure set to 6.4 and max pressure set to 7.4. On those Sleepyhead reports, I do see a lot of pressure bumped against the ceiling for most of the night. So I am gradually raising pressure .2 at a time. Very slowly because I had a lot of trouble with aerophagia and mouth leaks whenever I raise pressure. But I was pretty much satisfied and was not going to raise pressure much.

Why are you raising the pressure if your AHI is already below 1 AND you have lots of trouble with both aerophagia and mouth leaks when you raise the pressure?

What do you think raising the pressure will accomplish? It's not going to substantially reduce your already admirably low AHI. And it sounds like it is going to increase your discomfort at night, and hence adversely affect the quality of your sleep and life.

Back when I was a newbie who was struggling mightily with just trying to sleep with this dang thing on my nose blowing air down my gut, NotMuffy (later to be known as Sludge) asked me (and many others) these important questions:

What do you think a 0.0 AHI will do for you?
What is your short term goal for using xPAP?
What is your long term goal for using xPAP?

So since Sludge is no longer around to ask you those questions, I'll ask you to answer them. They're important questions for you to think about and they are important questions for you to answer if you want quality help from us in figuring out the best way for you to get high quality sleep.

But things got more complicated when I got my PR Dreamstation. At the same pressure as the Resmed, my AHI ran between 5 and 7 consistently, 50 to 70% hypoapneas, 5% OA's, 1% CA, and RERA 15% to 25% and same for FL's roughly. These are rough averages. The thing that stands out is a whole lot of hypoapneas.

Different machines with VERY different algorithms, both for increasing the pressure and for scoring events lead to differences in machine scored AHIs. That said, are you counting either the RERAs or FLs in your AHI? If so, you're comparing apples to pineapples instead of the more usual apples to oranges comparison.

It may be that your body responds better to the Resmed algorithm.

I'll add: When I went from a Resmed S9 AutoSet to a PR System One BiPAP, my AHI did go up from "always below 1.5 and usually below 1.0" to "usually between 1.0 and 2.0 and almost always between 1.0 and 3.5". The distribution of events didn't change much (mostly OAs even though my diagnostic sleep tests showed my problem is almost exclusively "hypopneas with arousal".) But my comfort level went up and in time my ability to sleep with the machine started to increase and I slowly started to feel better.

So after talking to Pugsy and PR, I raised the Dreamstation pressures, first a little which did not help much. I kept a log and it turns out that I needed to have min pressure at 7.5 and max pressure at 8.5 just to get my AHI down to 2.99. I gave up on the machine at that point because I could not tolerate the amount of pressure I needed to get my AHI to below 1.

Again, why do you think you need to get (and keep) your machine scored AHI to less than 1.0?

When did you feel the best---or the "least worst" if you've never felt good on PAP:

• When you were using the S9 AutoSet with an AHI < 1.0, or
• When you were using the Dreamstation with an AHI = 3.0.

If you felt about the same on the two machines, it doesn't make much difference which you use. But if you felt much better (or "much LESS awful" on one of the two machines, you have an answer as to which machine (and which settings) to use.

My guess is that I would need max pressure around 11 or 12.

Why? Again, your AHI is already less than 1.0 on the Resmed S9 when you have the max pressure set at 7.4. And your AHI was less than 3.0 when you had max pressure on the Dreamstation set 8.5. There is no good reason to believe that you need a max pressure up around 11 or 12. Particularly since you add:

I had terrible problems with the pressure increases and woke up all night due to aerophagia and mouth leaks.Slept badly.

What max pressure were you using when you woke up all night due to aerophagia and mouth leaks?

Do you think I should just give up on the Dreamstation? or do you think the Resmed is missing events? I know the algos are different, but I guess I need to make some sense of what the 2 machines are telling me? Is my apnea treated or not? The dreamstation says no and the Resmed says yes.

I think the following:

1) You need to quit chasing a 0.0 AHI.
Seriously. If the Resmed shows your AHI < 1.0 night after night, it is unlikely that it is missing so many events as to make your CPAP therapy somehow ineffective. If the PR Dreamstation needs a bit more pressure to reduce the AHI to around 3.0, that's likely because the PR Auto algorithm is much less aggressive in terms of pressure increases. So more events can get through if the min pressure is set "too low" The Resmed machine may be less aggressive at scoring Hs than the PR machine, so there's also that. But again, the point in using either machine is NOT to chase a superb, extra low AHI night after night when doing so makes it impossible to sleep.

The point of using the machine is to make it possible to get enough quality sleep each night to get through your day feeling pretty decent to pretty good under most ordinary circumstances in your life. There will ALWAYS be the occasional bad night or even string of bad nights when life throws you a curve ball and your sleep is simply bad. And some of those 'bad" nights may just be nights where you had a lot more events than normal scored by the machine because Pugsy's infernal aliens decided to pay you a visit during the night.

2) You need to quit worrying about whether your OSA is being effectively treated.
Both machine's data are showing that with the correct settings for that machine, your OSA is treated effectively. Perhaps not perfectly, but certainly effectively: If the Dreamstation reports an AHI = 3 when you are using a pressure range of 7.5-8.5, then the Dreamstation agrees with the Resmed S9 that your OSA is being effectively treated. You are using a pressure range of 6.4-7.4 on the S9. That's only a 1.1cm difference in pressure, which is negligible. And for most people a 1cm difference in pressure when you are close to "the correct setting" is not going to make that big of a difference in terms of AHI. And if, by chance, you are adding the RERAs and FL on the Dreamstation to the AHI count, then as I said before, you're comparing apples and pineapples rather than just comparing apples and oranges.

3) You need to focus on comfort issues and learning how to sleep well with your machine---regardless of which machine you decide to use.
Seriously: Regardless of which machine you choose to use, you need to focus on the aerophagia and the mouth leak problems. They're doing far more to cause your sleep to be bad sleep than any residual events that are getting through the xPAP defenses at this point. Anything you can do to minimize the aerophagia and mouth leak problems will do far more to improve your sleep in the long run than worrying about how to get your already good-to-great AHI even lower.

4) You haven't said anything about the Flex and EPR settings on the two machines.
Flex and EPR both can affect aerophagia, and how they affect aerophagia can differ from person to person. And if you happen to have EPR turned OFF or only set to 1, but you have Flex turned on (at *any* of its settings), that could be enough to explain why you need a bit more pressure with the DreamStation. That said, I'm more interested in the Flex and EPR settings in terms of your bad aerophagia rather than how they might (or might not) affect the machine scored AHI.

[PEF]

WOW, this is a lot to digest. Thanks to both of you, Pugsy and Robysue. You 2 are so amazing.

I will start with the 3 questions Sludge asked you about your therapy: That will also explain about the quality of my sleep.

1. I am not after 0 AHI, but I would like it to be below 5 on both machines. But I do believe you that the numbers on both machines are good. I do think that my OSA is treated, but I am not sure about my UARS. That is such a complicated subject. that is why I wonder so much about RERA's and FL's.

(Sorry, I did not make it clear that I was describing the pie chart, not AHI, when I told you the breakdown of events. the AHI, I assume, just includes OA's and H's.)

2. What is my short term goal? My goal was to stop certain symptoms that were happening to me while I slept at night and would often wake me up: weird incidents of LPR. Waking up in the morning with a sore throat, stuffed nose or asthma symptoms. I had read in Dr. Steven Park's book "Sleep Interrupted", that UARS can cause these symptoms. I also woke up with headaches, had to use the bathroom several times at night, etc. THIS GOAL HAS BEEN ACCOMPLISHED. CPAP has taken most of these symptoms away. I am so happy about that.

3. My long term goal is to get better quality sleep. This has been only partly accomplished. I have some great nights, but still a lot of bad nights. I can't seem to get into a pattern where I have consistent ok nights and I am really not sure why. It may be that I am expecting too much from my therapy. I am determined to get as much out of it as I can.

It cannot fix insomnia. My sleep onset insomnia has continued to be worse since I started CPAP. I don't know why because the mask and tape are very comfortable. I guess my brain just uses it as an excuse to do what it wants: to stay awake. I read Dr. Krakow's book and got a lot out of it. But it made me realize that I am not a normal person when it comes to sleep. For example, I just don't get sleepy at night. It takes medication to do that. In the morning, I never remember falling asleep. And if I do get sleepy, it only lasts a few minutes at most.

I think the leak problem happens when the insomnia is bad and it takes me 3 or 4 hours to get to sleep, or more. I fall into a DEAD sleep, often grinding my face into the pillow and somehow rolling around on my hose (even with the hanger). My mouth will be dry in the morning and I will be vaguely aware of struggling a few times to keep my mask on and in place. On these nights I get about 4 to 5 hours at most. I usually don't feel great in the morning, but better that I would feel, pre-cpap. It is just frustrating to have a really good night with minimal leaks and the next spending 20% of the night in large leak territory.

When I can get to sleep within an hour, my mask stays in place, mouth leaks are minimal and I wake up feeling really good.

I have been obsessed with raising the pressure, I know that. I am bothered by the pressure graph hugging the top for most of the night. I made the graph look better by raising the pressure to max 10 one night, but did not sleep well, lots of leaks and stomach air. So I will just leave the pressure where I am most comfortable. I agree that comfort is most important.

To answer question #4, I have both Flex and EPR turned off. I did some experimenting, but noticed no difference in comfort. Do you have any specific advice?

Ok, so I now feel pretty certain that my CPAP therapy is maxed out, after asking 3 experts over and over. My husband tells me I tend to want to tinker with things and I guess he is right. My other sleep issues are not related to CPAP therapy.

I am very pleased that my original goal for starting CPAP, getting rid of very disabling, mysterious symptoms, that greatly puzzled my doctors, have been addressed. For that, I am eternally grateful.

I am going to keep reading over your answers because sooner or later, I will get the irrational idea that I can solve the rest of my sleep issue with more pressure. I do get it this time, I promise!

Pugsy, I hope you don't think I doubted you, I did not, I was just obsessed with the idea of more pressure.

I am in the process of designing a sleep log, based on Robysue's recommendations. It is not as easy as I thought it would be. I hope it will be worth the effort.

Thanks again!

[PEF]

You asked a question I did not answer, about how I felt using the different machines.

The machines FELT very different. I don't know what it was. I used the Dreamstation for maybe a total of one month, split into about 2 weeks each. Both times, I could not get used to it and did not sleep well. My brain cried out for the Resmed. I felt the Resmed was "with" me, sort of "knew" me. I felt a strange sense that the Dreamstation was not in sync with my mind.

It was like there was communication between my brain and the machine and, when the machine changed, my brain just did not like it. In the morning after using the Dreamstation, which I was not used to, I had been having a struggle all night.

I suspect it is all about what I was used to. I don't think I can use the Dreamstation, but it probably could have been the other way around, if I had started on that one first.

[Pugsy]

RobySue..PEF has some ugly looking FL graphs on the ResMed machine...and I am fairly sure that is the reason the machine wants to go higher but can't because if she lets it then she pays for it with aerophagia issues.
They weren't as ugly on the DreamStation...don't know why.

PEF....I don't mind at all if you want RobySue's thoughts. It's always good to have another set of eyes evaluating the data.