Setting maximum pressure?

Quick question, if you were setting up a maximum pressure for an apap after trying it for an open range, would you set the absolute maximum that it reached or set it at the 95% level? The absolute max was 13.7, and the 95% pressure was 11.9. Or leave it open at 8 - 14 cmH2O, which is what I tried last night? I'd like to set a reasonable maximum in the interest of minimum leakage, but don't want it lower than it should be *smile*.

I also ran it at 8 - 12 cmH2O the night before, and the 95% pressure was also 11.9.

Thanks.

I've got mine at 95% + 1.5

I'd set it at the 95% plus a bit more.

You have to look at your data, then, and make sure it's not getting "stuck" at the top of the range for long periods.

IMO...The upper range shouldn't matter. The CPAP will only raise the pressure high enough to stop an Apnea regardless f how high the max is set. You could set the max at 20 and your machine may never go higher than 12 if that's all that is necessary to chase an event

My S9 Autoset will.
I set the max for my titrated pressure, which is from 2-4 cm higher than my 96%.
That way I don't get awakened by the machine, which likes to chase the rare central like a labrador chases a jackrabbit.

Xney wrote:I'd set it at the 95% plus a bit more.

You have to look at your data, then, and make sure it's not getting "stuck" at the top of the range for long periods.

Thanks, that's what I'm thinking...I think I'm going to try the 8 - 12 range for a while and see what happens. When I used that range, it just went up to 12 a few times, didn't stay there for very long. Mostly stayed between 10 and 12. On the other hand, when I used the original 6 - 10 that I was prescribed, it goes to 10 and stays there for long periods of time, which is what eventually got me to think about increasing the maximum. My statistical AHI for the last 9 months is now about 1.4, which is pretty good, but if I can do better, that's fine, too.

I'm really happy to have the data to look at, so I can try things to improve the situation and see what's happening over time.

I wouldn't leave it open, remember that the APAP doesn't start ramping up until an apnea has started. I don't know that it's quite as bad as "chasing" apneas, but it certainly isn't as good as preventing them from even starting with a higher pressure and thus a stronger "splint". As far as I can tell, there are only 2 downsides to higher pressure (though they are very important), one is discomfort (chipmunk cheeks, aerophagia, dry mouth, mask leaks, feel claustrophobic...), and central apneas caused by high expiratory resistance.

If you aren't experiencing either of these, you might as well make your splint as strong as you can to minimize events. I would hypothesize that you'll have a lower AHI if you set it to 10-12 rather than 8. 6-10 certainly doesn't seem right for you! What about starting it at 8.0, and increasing by 0.2 every night so that over 25 nights you creep up to 12.0? Then graph AHI vs. min pressure for that period and see what you see. And of course, if you start finding the high min pressures uncomfortable or generating CAs, then back off and chill at a comfortable pressure for awhile.

RogerSC wrote: Thanks, that's what I'm thinking...I think I'm going to try the 8 - 12 range for a while and see what happens. When I used that range, it just went up to 12 a few times, didn't stay there for very long. Mostly stayed between 10 and 12. On the other hand, when I used the original 6 - 10 that I was prescribed, it goes to 10 and stays there for long periods of time, which is what eventually got me to think about increasing the maximum. My statistical AHI for the last 9 months is now about 1.4, which is pretty good, but if I can do better, that's fine, too.

I'm really happy to have the data to look at, so I can try things to improve the situation and see what's happening over time.

That sounds like a good plan. I wouldn't waste too much effort trying to super dial it in either. At some point, you're doing just fine.

The thing where it was staying at 10 a lot is what you don't want to see. Some people do fine with a completely open range, but machines can also chase events higher and higher, or wake you up when the pressure goes too high, where you really didn't "need" it. They're not perfect. Sometimes on my auto vpap it would just decide to go up to the max range, and then come back down pretty quickly. That wasn't helping, especially since it would wake me up sometimes.

It's one of those things where you have to find out what works for you. Hitting your max range isn't a problem, necessarily. Hitting the max range and staying there, with events then happening because of not enough pressure - that's where the machine having more room would have been good. The other thing is, once in a while everybody has an off night, and you can't get too out of whack with a bad night. You look for consistent or regular patterns, things which happen more than once in a while.

Xney wrote:

RogerSC wrote: Thanks, that's what I'm thinking...I think I'm going to try the 8 - 12 range for a while and see what happens. When I used that range, it just went up to 12 a few times, didn't stay there for very long. Mostly stayed between 10 and 12. On the other hand, when I used the original 6 - 10 that I was prescribed, it goes to 10 and stays there for long periods of time, which is what eventually got me to think about increasing the maximum. My statistical AHI for the last 9 months is now about 1.4, which is pretty good, but if I can do better, that's fine, too.

I'm really happy to have the data to look at, so I can try things to improve the situation and see what's happening over time.

That sounds like a good plan. I wouldn't waste too much effort trying to super dial it in either. At some point, you're doing just fine.

The thing where it was staying at 10 a lot is what you don't want to see. Some people do fine with a completely open range, but machines can also chase events higher and higher, or wake you up when the pressure goes too high, where you really didn't "need" it. They're not perfect. Sometimes on my auto vpap it would just decide to go up to the max range, and then come back down pretty quickly. That wasn't helping, especially since it would wake me up sometimes.

It's one of those things where you have to find out what works for you. Hitting your max range isn't a problem, necessarily. Hitting the max range and staying there, with events then happening because of not enough pressure - that's where the machine having more room would have been good. The other thing is, once in a while everybody has an off night, and you can't get too out of whack with a bad night. You look for consistent or regular patterns, things which happen more than once in a while.

Yes, I agree with you, one night doesn't make a pattern *smile*. I tend to change something and give it some time, at least a week. Both nights where I raised the pressure were better than average nights, so I have some hope that I can get my statistical AHI under 1.0 by doing this. While AHI isn't the whole story by any means, we'll see *smile*.

Many of us leave the maximum at 20, but monitor the data regularly.

Usually, the machine will go up to the pressure you need and not go higher.

For some people it "runs away" and they have to set a maximum pressure.

I have my maximum set at 20. It never gets near 20. However if something unusual goes wrong during the night I want the machine to up the pressure to take care of the apnea. Or the higher pressure might wake me up and give me the chance to deal with the problem without suffering with long events.

As long as your leaks are completely under control, the max should not really matter ...

However, to be on the safe side, I would set min at 2 cm below 95% and max at 2 cm above 95% (set 10 to 14). Try that for a couple of weeks without changing anything else. If 95% remains constant, you bound your 95% by 1 cm on either side and try for another couple of weeks. Eventually you will end up at your optimal "CPAP" pressure at your 95%. If you can handle the pressure, and your AHI is below 1, CPAP mode is the best for you. If 95% pressure causes gas or leaks, go back to APAP mode with min at 2 cm below 95% and max at 1 cm above 95%.