Pressure range on an APAP?

[teleute]

Just curious - what's the advantage of setting a narrower pressure range than what's possible on an APAP? My husband's on a trial right now, so they've got it set pretty wide open (6-18).

I'm guessing the advantage of moving the lower end up is that when things are under control, it will try to edge back down to 6, and then eventually it might go below the threshold of what works, then there will be events and it'll just have to ramp back up? Just my conjecture - curious to hear if that's the case, or if there are other advantages/disadvantages I'm missing. Also, what about the high end - if he needs a higher pressure, isn't it a good idea to have it available? i.e. if he occasionally has spikes up to 13, setting the max below 13 seems like it might not help him as much as it should, but if you just set it higher than the max, then I don't see the point of restricting it at all.

Feel like I'm missing something here, so very curious to hear from people with experience. Thank you!

[nanwilson]

You are not missing anything, we generally suggest a range of about 6 or 7.. example. if your 90 pressure is 11 then we would suggest you set the minimum at 3 points less (9) and 3 points more (15), thus, your range would be 9 to 15. If the doctor has your testing pressure set at 6 to 18, they are of the opinion for testing that he will not go below 6 and not over 18... few of us can even breath at 6, but that is sometimes needed. Having a wide open range like 6 to 18 is not usually set once you have been titrated at a certain pressure because the machine will have to ramp up from 6 to catch the apnea and suppress it and takes longer to do the job. For example, my 90% pressure is 11, so I have set my machine at 10 to 15 because I find I dont get enough air any lower than 10. Make sure when he gets his own machine that he gets an auto machine that will give ALL the data required to keep track of his therapy. Please read the post on Janknits page entitled maskarrayed... this blog will tell you which machine is preferred and what is a total brick. A brick is a machine that makes the most profit for the supply company but gives you the patient nothing but straight air and NO useful data.
Cheers
Nan

[Wulfman...]

Just curious - what's the advantage of setting a narrower pressure range than what's possible on an APAP? My husband's on a trial right now, so they've got it set pretty wide open (6-18).

I'm guessing the advantage of moving the lower end up is that when things are under control, it will try to edge back down to 6, and then eventually it might go below the threshold of what works, then there will be events and it'll just have to ramp back up? Just my conjecture - curious to hear if that's the case, or if there are other advantages/disadvantages I'm missing. Also, what about the high end - if he needs a higher pressure, isn't it a good idea to have it available? i e if he occasionally has spikes up to 13, setting the max below 13 seems like it might not help him as much as it should, but if you just set it higher than the max, then I don't see the point of restricting it at all.

Feel like I'm missing something here, so very curious to hear from people with experience. Thank you!

It might help to know "why" your husband is on a trial with an APAP. Is he under Kaiser Healthcare or did he fail a sleep study? If he's under Kaiser, they may be attempting to determine which fixed pressure he needs and then will give him a straight-pressure machine.

But, to more directly answer your questions, having the minimum pressure much closer to where it needs to be starting out leaves fewer events untreated. If the pressure has to climb too much, too many events can occur before it gets to where it needs to be.......and then it will drop back down and start all over again.
APAPs increase pressures on Flow Limitations and Snores. If the person has few of either and/or they have "frank" (out of nowhere and without precursor events) apneas, the apneas WILL occur and the machine will not respond to them. APAPs don't typically respond to apneas that are already in progress.

Another thing to consider when determining a range of settings is what is actually causing the pressure increases. Theoretically, you could leave the upper pressure setting open, but if there are things that are causing the pressure increases that are unimportant (like snoring and flow limitations), then I would recommend that the maximum pressure be limited.

Also, keep in mind that the changing pressures CAN be disturbing to one's sleep. When a person goes into a deeper sleep stage or REM their breathing changes. That can trigger pressure increases that could jolt the person out of that much-needed sleep stage........and they then feel unrested because they don't cycle through the sleep stages naturally.


Den

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[teleute]

Nan - Oh, absolutely - I'm an IT professional, so I love having data and graphs to look at. No bricks allowed here. He's currently on the PR 60 series APAP, which we're both liking quite well. We wanted that or the AutoSet for the trial, so was happy when they gave us this one with no prodding.

Den - We're in Canada, so no Kaiser. He did a sleep study that showed AHI in the 50+ range. This APAP trial seems to be what's generally (not always, but most places I talked to - that's a whole different thread...*sigh*) done in our area in lieu of a titration study. Great info - thank you! The pressure increases generally seem to be reacting to hypopneas or obstructive events, but there are also usually snores right in that same region. I'm not initially seeing places where it raises just from snores, but I've got more more data to look through to be sure. Very interesting, though.

[Captain_Midnight]

Nanwilson writes...You are not missing anything, we generally suggest a range of about 6 or 7.. example. if your 90 pressure is 11 then we would suggest you set the minimum at 3 points less (9) and 3 points more (15), thus, your range would be 9 to 15.

Nan, I would be interested to know why you would recommend 3 inches LESS than the 90% range.

I do not make recommendations. I am, however, interested in the rationale for folks' selecting pressure ranges. I recall advice hereabouts (a few years back) that recommended that the lower range be set at (or a half-inch above) the titrated cpap level, and the upper range an extremely tight 2 or 3 inches above that. This is what I did (with the consent of my doc), and my ahi has consistently averaged 0.2-0.3 for the years since.

One suspects that any pressure range that is lower than the 95% pressure is simply inviting apneic events, and accompanying "issues". (Contrary opinions invited.)

Again, I do not offer recommendations, just analysis and discussion.

.

[flyingwithoutwings]

So, if my average pressure is 9.4 should my APAP be set at 8.9 - 11.5??

[bavinck]

I am, however, interested in the rationale for folks' selecting pressure ranges. I recall advice hereabouts (a few years back) that recommended that the lower range be set at (or a half-inch above) the titrated cpap level, and the upper range an extremely tight 2 or 3 inches above that. This is what I did (with the consent of my doc), and my ahi has consistently averaged 0.2-0.3 for the years since.

One suspects that any pressure range that is lower than the 95% pressure is simply inviting apneic events, and accompanying "issues". (Contrary opinions invited.)

s

I am interested in this too. What is written above seems good logic to me, given the 95% pressure data.

[BlackSpinner]

It depends on when you need your pressure. Some people need much higher pressure during REM sleep then regular sleep. Some can sleep comfortably at 8 during non REM while they need 12 or more during REM. Since most of the night is spent in non-REM, spending the rest of the time at lower pressures help which swallowing the air problems.

[Goofproof]

I'd use 8 to 11 cm for a few nights and then reevaluate and see if you need farther adjustment. Total mask leaks over 40 lpm can affect data. Jim

[RestedRebel]

Just curious - what's the advantage of setting a narrower pressure range than what's possible on an APAP? My husband's on a trial right now, so they've got it set pretty wide open (6-18).

I'm guessing the advantage of moving the lower end up is that when things are under control, it will try to edge back down to 6, and then eventually it might go below the threshold of what works, then there will be events and it'll just have to ramp back up? Just my conjecture - curious to hear if that's the case, or if there are other advantages/disadvantages I'm missing. Also, what about the high end - if he needs a higher pressure, isn't it a good idea to have it available? i.e. if he occasionally has spikes up to 13, setting the max below 13 seems like it might not help him as much as it should, but if you just set it higher than the max, then I don't see the point of restricting it at all.

Feel like I'm missing something here, so very curious to hear from people with experience. Thank you!

My machine is set from level 7 to level 20. I usually average around 10, with an occasional night at 14.

[penuel]

If my prescribed therapeutic pressure on CPAP was 14.5 cm then I would start the APAP pressures on 14.5cm max and 11.0 cm min. Next, I would spend a night with this setting and get a pressure graph on ResScan (b/c I have a Resmed machine). The graph would show the pressure curve plus the two limit lines. Next, I would start adjusting the set-up on the APAP so that the pressure curve only "kisses" those limit lines. The reasons: I don’t want the machine to suddenly boost the pressure needlessly and give me emergent central apneas (Complex Sleep Apnea) and also cause more leaks b/c of the higher pressure. As to the low pressure limit I set it so to have the machine respond more quickly to events.

[flyingwithoutwings]

I'd use 8 to 11 cm for a few nights and then reevaluate and see if you need farther adjustment. Total mask leaks over 40 lpm can affect data. Jim

Thanks. My prescribed pressure is 7 and when my machine was set at straight 7 my AHI's were always between 7 - 10. Then I turned off Ramp and raised the pressure and my AHI's have remained <5 with 95% pressure of 9.4. Leaks are very minimal if at all.

[Goofproof]

I'd use 8 to 11 cm for a few nights and then reevaluate and see if you need farther adjustment. Total mask leaks over 40 lpm can affect data. Jim

Thanks. My prescribed pressure is 7 and when my machine was set at straight 7 my AHI's were always between 7 - 10. Then I turned off Ramp and raised the pressure and my AHI's have remained <5 with 95% pressure of 9.4. Leaks are very minimal if at all.

In my opinion the ramp is like training wheels, I'm a get on and ride guy!

The ramp keeps you from having the treatment to stop apneas, until it effects are off. A narrow pressure range on APAP, allows the machine more of a chance to correct events quickly. By setting a lower upper limit you prevent a pressure runaway. High pressure is like a dog chasing it's tail. More pressure, more leaks, more leaks more apnea, the machine calls for more oressure, even more leaks, results not good.

Looks you are on the right road! Jim