AHI & Pressure Settings

[CAAnnieB]

Hi! I'm new here, but not new to CPAP. I took a long break from using my CPAP (was using chin straps with Nasal Pillows & it majorly aggravated my TMJ) & recently decided to get back with it when my son was diagnosed with Sleep Apnea. (He's now on CPAP too.) I have mild OSA, but suffer with chronic pain & Fibromyalgia, so the thought has always been that treating my mild OSA might bring some relief to my long standing pain issues & fatigue. I definitely feel better when using the CPAP. My question is regarding the pressure settings. I have a Respironics Remstar Auto A Flex System One 60 Series machine. I went in today (after using my new machine & mask for a month) for the office to download the info off my card. The therapist told me that compared with my original sleep study years ago; my AHI has INCREASED with treatment from 8 to 11! She wanted to raise my settings by 1 on the lower & upper numbers. I think she said the setting range was originally 5-12 & she wanted to raise it to 6-13. My question is this: Why not open up the upper setting to 20? What harm could come of having the upper limit be set too high? The machine will only go up to the highest pressure needed to eliminate the events, right? I asked her about this & she could not give me an answer other than what she suggested was "following their protocol" & what I suggested was not. Maybe I'm not understanding this AHI & pressure issue, but from reading posts here; I can see the goal is to DECREASE the AHI & hopefully to as close to Zero as possible. Any input/info would be greatly appreciated. Thanks.

[grayghost4]

it is better to keep control of the upper limit .... a noisy leak could be interpreted as snoring and up the pressure beyond what you need and cause discomfort and or wake you up. Then the higher pressure could start compound events .. causing CA's

[LSAT]

In my opinion, for most people the higher limit could be set wide open. In my case, I have my upper limit set at 14. According to Sleepyhead, the highest pressure every night I have checked has never exceeded about 13.5. Changing my upper limit to 20 would not change anything. It's the lower number that is the most important. I have noticed very little change in my average AHI when I have my pressures set at 12/14 or fixed at 12.

[CAAnnieB]

Grayghost4~ What are "CAs"? LSAT~ Yes, it seems to me that the upper setting isn't all that important unless it is set too low. If my mask is working great with no leaking (which I believe is true); why would my AHI be 11?

[JimP]

I lowered my upper pressure because if it goes that high, I was getting air leaks that would awaken me anyway.

It would help if you post your charts. Maybe one of the gurus will see something in them.

[guest1]

Prs1 60 series auto will not run off to 20 in case of a leak. Its algorithm makes sure that if it detects a large leak, it will reduce pressure. I have seen this in my sleepyhead charts. Its also mentioned somewhere in Philips website.

Maybe older gen machines did that and so this idea is still around that upper limit has to be capped. But its no longer the case. IMHO you leave the top end open to 20. And see your reports in sleepyhead software and proceed from there.

[Julie]

CA's = central (or clear airway) apneas.

[Posey]

Hi to everyone. I just logged on to see what I could find on this very topic. SInce it is similar to my situation I'd like to add to it. Is that a faux pas?
Over the last year my AHI (using BiPAP) has steadily increased from <2 to over 6. My leaks are way up and even though I seem to be asleep all night I feel like crap by the afternoon. Hubs says my machine starts blowing like a gale and he sometimes taps me to get me going again. Needless to say it is messing with his rest too. On the last visit my sleep doc was happy with my data so didn't offer any changes. I have anew mask to start using tonight. My current setting is IPAP 13.4 & EPAP 7.8. I was thinking of tweaking it up to 13.8 to see if it makes a difference. Anyone like to comment.

[grayghost4]

Posey : it would be better to start a new thread then poeple can try to help you .... it is hard to comment on two different problems in one thread.
Are you using any software to monitor your progress?

[TyroneShoes]

In my opinion, for most people the higher limit could be set wide open...

I agree with that opinion. But it raises a question why my sleep doc told me to brick my APAP to a straight 8 cm. I am 12 days in to that setting, but it does not seem appreciably different than AHI (under 2) when I had it at 8-14. So I do not see where the wisdom is in that.

Can anyone clarify?

[JimP]

A possibility is that some people are awakened by the changes in pressure so in that case a fixed pressure may work better for them.

[TyroneShoes]

A possibility is that some people are awakened by the changes in pressure so in that case a fixed pressure may work better for them.

Well, that makes sense, and is exactly why I brought mine down from 20 to 14. And that does not seem like a therapeutic reason, more of a comfort reason. But the sleep doc's change to straight 8 was not based on anything I ever mentioned to him regarding any of that, so I still don't get the logic in him doing that.

Last night I got unusually high clusters of events that seemed to be grouped during 4 REM sessions, something I never saw during APAP. Would it not have been better to have APAP mode invoked to prevent that?

[Pugsy]

Last night I got unusually high clusters of events that seemed to be grouped during 4 REM sessions, something I never saw during APAP. Would it not have been better to have APAP mode invoked to prevent that?

That's why I always preferred APAP mode because I would rather have the machine use a higher pressure for part of the night than to have to use a higher pressure all night (to handle just the REM stage events).
If someone is using cpap mode and seeing clusters of anything (assuming obstructive in nature) then they are going to have to use a higher cpap fixed pressure all night if they want to prevent REM stage sleep clusters.
In my case the difference needed was at times rather huge...sometimes I would need 18 cm for those REM stage events and I didn't want to use 18 cm all night just to deal with the times in REM stage sleep. The rest of the night I could get by with 10 to 12 cm pressure doing a good job..duh...let's see use 18 cm all night or use apap mode 10 to 20 and let the machine go to 18 maybe for 10 minutes a couple times a night...guess which one I chose to do?

[TyroneShoes]

OK, so why is Pugsy apparently a lot smarter than my sleep doc? Or most people's?

That is great info.

I was at 5-20 initially, and he said "go to straight 8". OK, but I never knew why. I agreed that raising the lower limit was a good idea, but I did not understand lowering the high limit, at all. I asked him if that was to prevent inducing centrals, but I did not really get an answer.

OK, so I cheated and went to 8-14, because that upper limit seemed to be under the threshold of what would wake me up, which happened very rarely. But the logic here is that I had a machine capable of being something other than a brick, and while maybe a brick is all I need, those raises in pressure that the machine decides to make on its own, are made because of some probably good reason, right? So why limit the machine if it is making good decisions dynamically, about pressure?

AHI went down. 30 days later I went to straight 8, and had 10 days of that prior to the sleep doc getting a download. AHI remained about the same, but I think 8-14 would have handled last night's clusters a little better, so I may go to 9-14 and see where things go. I have no comfort issue with 8; no ramp, so I think I could easily tolerate a higher low pressure limit.

But what I want to avoid is my sleep doc just going through the motions with me once he realizes I have gone rogue on him again and decided to take the therapy into my own hands. Doing that might be smart, but the risk you run is that the doc just bails out because he thinks I'm not listening to him anyway. He does not have a huge ego like most docs, but I want to be careful of that anyway. Maybe that is a whole other discussion.

But I still want everyone's input regarding these thoughts, so TIA.

[Pugsy]

I suspect that most docs look at overall AHI (if they even look at anything past hours of use) and if the AHI is less than 5.0 they don't go any further. Technically I suppose it probably isn't needed but technically doesn't always satisfy me and my inquiring mind.
Technically 8 cm fixed pressure will probably give you an "acceptable" AHI and if someone didn't see the details they wouldn't know about the clusters or if they did notice the cluster they might be thinking that they aren't bad enough to do anything about them.
I quit trying to figure out the inner workings of most doctors' minds long ago when I was working with them.

When I presented my own findings about my REM clusters to my NP and showed my reasoning for my settings she totally agreed with me. In fact she told me to just leave the maximum wide open since I was almost going there on occasion (and I didn't have any issues with centrals or aerophagia or changing pressures disturbing my sleep) anyway and the machine wouldn't go there without a good reason.

If a doctor won't listen to reason and logic and instead takes a "I walk on water" attitude towards me and doesn't value my input...that doctor will no longer be working for me.
Most docs won't even notice a change in pressure if you don't point it out to them anyway. They tend to look at hours of use and maybe AHI. They look at summary usage numbers and really don't spend all that much time evaluating nightly detailed reports unless they have to.