Adjusting pressure yourself.

Hi all,

I'm quite new to CPAP and hoping to get some tips from experienced users about adjusting the pressure on my machine. I hope this post isn't too long but I'd like to say what's happened already first, then get to the question.

When I first got the machine it was set on auto with the range 5 to 14 cmH20, during this 3 week period my AHI averaged 2.4 so that was a great improvement from AHI 67 on the sleep study. I still felt tired all the time but I was having a lot of problems with the mask so that could have been the reason.

At 3 weeks I had to go back to the equipment supplier so they could see how it was going and they changed the pressure to a fixed pressure of 10.5 and made an appointment for me to see the doctor again in a week. The next 2 nights my AHI was up to 15 and when it looked at the AHI graph in sleepyhead it peaked at about 70 at one stage during the night so I contacted the equipment supplier again and was told that it was the doctor's decision what pressure my machine should be at.

Over the next week with pressure still set at 10.5 my average AHI was 9.37 so when I saw the doctor I told him what I'd seen (but didn't tell him I was looking at the data on sleepyhead) and he suggested increasing the pressure a little bit. I asked him about setting it back on the auto pressure range, instead of fixed, and after some discussion he agreed to set it back on auto, so I was quite pleased with that. However, I noticed the next day that he'd set the max pressure to 12 instead of the 14 it had been at before and he also had disabled the AHI display option on my machine. I had another appointment in a week so I left it to see how it went.

AHI for that week was 4.99 with the highest peak AHI of 56 The doctor looked at the info from the SD card and thought that was OK. Left the pressure the same and arranged a home sleep study for 3 months time.

I still felt really tired all the time and thought that there should not be peak AHI of over 50 so I changed the pressure maximum myself up to 14, assuming that if it had been at 14 before then that is a safe level. Since then my average AHI has been 1.36 with the highest peak AHI on the graph being 11 so that's looking really good.

My concerns now are:
- I'm still tired all the time, though not as tired as I was before starting the therapy.
- So far, the doctor seems to be looking only at averages over a longer period and not really looking in detail at the reports.
- Looking at the pressure graph, it's maxed out at 14 for quite a large part of the night and it's during these times that my AHI goes up.

I wondered if I should increase the maximum pressure a bit more.

I'm a bit scared of doing that because then i'd be increasing it to a higher level than it's ever been at and I don't understand the risks of higher pressures. For example, can too high a pressure harm you?

If you've taken the time to read all that, thanks very much already. If you have opinions about whether I should increase the max pressure a bit more or not then I'd love to hear them.

Thanks guys!

Have you considered downloading (for free) SleepyHead software - see Pugsy's tutorial at top of page - and posting 1-2 nights' results here (use Imgur.com and link to your thread) so we can see what's going on?

OP already has SleepyHead.

Pete, one thing you didn't mention was the event category breakdown of your AHI (obstructive apnea, hypopnea, central (or "clear airway") apnea. Whether you should be making any changes in pressure will depend in part on the AHI categories. How about posting some screenshots of your SH reports?

Thanks for your reply, here's a couple of graphs.

4th December


7th December

Pete, can you post a screenshot like this -- note which graphs are showing on the right, and be sure to include the numbers underneath the pie chart. The calender isn't really necessary but don't worry about it as long as we can see the numbers below the pie chart.

[/quote]

Also post a screenshot of the SH Statistics page including the Change to Prescription settings section of it.

It's kind of you to take an interest, here's the events for the same 2 nights.

4th December
[deleted] - graphs you asked for are posted below

7th December
[deleted] - graphs you asked for are posted below

Thanks again.

oops, sorry, I posted those before I saw what you asked for, I'll post the correct screenshots now...

It took me a bit of time to work out how to display the correct info, hopefully these are right...

4th December


7th December


Statistics

my first thought is that your lower pressure is much too low for much of your needs, so you have events waiting for the machine to get to a higher pressure.

See my post here in this thread as part of it applies in this situation...the part about the minimum pressure
viewtopic/t102531/Obstructive-apnea-with-APAP.html

I agree with PR...the minimum is not quite optimal...it's close though.
You are maxing out the pressure at some times during the night but it doesn't seem to be a huge problem. Yeah, the machine wants to go higher but it isn't allowing a truckload of events to slip past the defenses at the current maximum.
You could open up the maximum if you wish...I don't know how much higher it wants to go but if the minimum was more optimally set it might not even want or need to go to that 14 cm or if it did go there it might not stay there as long.

If changing pressures don't seem to be disrupting your sleep...just open max up and see what happens...but I would also increase the minimum just a little to give the machine a little better head start.

OK, that's interesting. I also made the mistake of thinking that the machine would work by trying to stop events while they are happening so knowing a little more about how it works is very useful. Thanks for that.

When you say raising the minimum pressure a little, what min pressure would you try if it was you?

Sleepy Pete wrote:When you say raising the minimum pressure a little, what min pressure would you try if it was you?

Some people will want to use the 90/95% number as a guideline but I don't like to use it myself because I know that it is too easily skewed for it to be something that I want to rely on when determining optimal minimum pressure.

Your AHI isn't horrible as it is now and there isn't any urgent need to change anything. The fact that the machine is hitting the maximum and staying there doesn't mean that there is an urgent need to change the maximum. Now if you were having a truckload of events or snores or Flow limitations happening when the maximum was being reached then yeah...would for sure need a bit more maximum.

If this were my report and I was seeing those little clusters...I would probably just try 1 cm more minimum and see what happens.
I do prefer to do any increasing in stages for 2 reasons. One being that the adjusting is easier and second being sometimes we get lucky and we find that we don't need as much of an increase to clean up the reports as we originally thought we might need.
I would be surprised if you needed more than 2 cm to clean up the clusters. I am usually happy just to see the clusters break up...I don't try for total eradication of all events.
Me..personally...when I was using apap mode I just let it be open at 20 cm but then I never had a problem with wide pressure changes. I slept right through them and I didn't have any aerophagia issues. My OSA was/is worse in REM stage sleep and sleeping position didn't seem to matter. For this reason I decided to let the machine decide to do what it wanted to do and all I did was help it out with a more optimal minimum pressure since I would sometimes see clusters like you are seeing in what would probably be REM stage.

If you want to see what happens with more maximum...you can sure try it and if the changing pressures don't seem to bother you then you can just let it go where it wants to go but if it does bother you then keeping it at 14 isn't really causing a problem in terms of therapy effectiveness. But 1 cm more minimum (maybe 2 cm) might do a little better job breaking up the cluster and there's a good chance that the 14 cm maximum won't be needed as often or for as long if it is needed.

Your therapy results aren't horrible...your AHI is really within acceptable limits. I just don't like to see clusters of anything on a consistent basis. And to better prevent the clusters...just a little more minimum and I would go up in 0.5 cm stages (give it 3 or 4 nights at each setting) then evaluate. Don't ever base a setting on a one night result unless the result is horribly bad.

Not an APAP user so you can toss this out if you want.

But if you were running at 10.5 on straight CPAP and had no issues tolerating that pressure, and since you spend most of the night over 10, I think 10 would be a reasonable starting point.

John

I really appreciate you all taking the time to reply to this thread, especially Pugsy for those long and detailed posts, and I think your suggestion is good too, John.

Following what I've read here, I think I'll start by putting the minimum pressure up and see how that goes for a few days (my experience so far is that it takes me about 3 days to adjust to changes in pressure settings) then look at the maximum if necessary some time after that.

You've got me thinking about how the APAP works too and I have a question about that but I'll create a new thread for it so it's more easily readable for others on the forum.

Thanks again guys, you're a great help!

viewtopic/t94287/viewtopic.php?f=1&t=82 ... 5&#p866535
For people who don't see the new thread asking how the algorithm works...check out the above thread and look for Robysue's response and down near the bottom of her response is how the algorithm works.