Question on Fine Tuning my Pressure

This may be a no-brainer, but I'm just not clicking on it yet.
For past couple of months I have had pretty steady AHI between 1.0 and 1.8 or so, with periodic 2.0 to 2.6 max. My pressure has been set on 10/20 using auto cpap, no flex, and my leaks with Swift LT are pretty steady at 30-33 with mouth taping (should be ~31 with pressure of 10, I think).

Here's what Im puzzling over. On upper right of every details page for the past couple of months, I have shown "Avg 90% CPAP" as 11.0, 11.1, or 11.2, and the "Avg CPAP Pressure" has consistently been 10.3 or 10.4. So I figured that if I bumped up my pressure to 10.5, I'd get a steady average CPAP pressure of 10.5 every night, and achieve the ideal minimum pressure, right? Not.

Surprising to me is that for every one of the nights I've used 10.5 minimum, my Avg 90% CPAP has now been consistently increased to 12.0 and my Avg CPAP Pressure reading has increased to 11.0 to 11.2! There is no change in the numbers showing for any of the NR, FL, OA, H, or VS as compared with my daily reports for the past 2 months. So I don't get it. Seems logical that I should just let well enough alone and set minimum back to 10.0, but I would like to understand this, if some of you can explain....

Sounds "logical" to me......

A couple of things. In the past (at least with the versions I've used), Encore reported pressure settings in round numbers.....so if you have it set for 10.5, it will more than likely report it as 11.0. The other thing is that your nightly pressure needs can/will change, which changes your average and 90% numbers......and usually bumping up the minimum pressure will cause these numbers to change.


Den

You orginal data - Min. 10. average about 10.3 and 90% pressure at about 11 show 2 things:
You're spending 10% of the time above 11 (that's what the 90% number means), an unknown (or unreported) above 10.5, and most of the time between 10 and 11 sometime - when your 90% is 11.3 you even more time at higher perssures. But You don't know how much of your time you spend above 10.5

By jogging the minum up you automatically (mathematically) raise your average - and it would't be 10.5, since that's your minimum, and you still expect to spend some time above it. The only way that would cause your minimum to equal your average would be if you never ever rose above the minumum.

O.

Thanks to both of you. I think I get it! So last question on this is whether there is any reason to keep my pressure at 10.5, or should I just move it back to 10.0 since there seem to be no significant improvements at all with the 10.5? (I was hoping to get AHI's to stay below 1.0 with that increase, and it doesn't seem to be happening).

plr66 wrote:Thanks to both of you. I think I get it! So last question on this is whether there is any reason to keep my pressure at 10.5, or should I just move it back to 10.0 since there seem to be no significant improvements at all with the 10.5? (I was hoping to get AHI's to stay below 1.0 with that increase, and it doesn't seem to be happening).

Without seeing any of your reports, I would say moving your minimum pressure UP would help you more to achieve your goal than moving it back down.

Den

Wulfman wrote:

plr66 wrote:Thanks to both of you. I think I get it! So last question on this is whether there is any reason to keep my pressure at 10.5, or should I just move it back to 10.0 since there seem to be no significant improvements at all with the 10.5? (I was hoping to get AHI's to stay below 1.0 with that increase, and it doesn't seem to be happening).

Without seeing any of your reports, I would say moving your minimum pressure UP would help you more to achieve your goal than moving it back down.
Den

Aacchh! Then I guess I'm not getting it, am I. As I look at all my daily details reports using minimum 10.0----since I was only going above about 11.1 for 10% of the time, and averaging about 10.3 minimum----why am I now needing a higher range of pressure when I bumped the minimum to 10.5? I am so sorry to seem (be) so dense on this. I really thought I got what OziJ was saying....

A lower minimum pressure will allow more events to take place before the machine can respond to them (Autos are "reactive" to events).....consequently a higher AHI.

A higher minimum pressure will preempt more events......consequently (and hopefully) a lower AHI.


Den

plr66 wrote:Thanks to both of you. I think I get it! So last question on this is whether there is any reason to keep my pressure at 10.5, or should I just move it back to 10.0 since there seem to be no significant improvements at all with the 10.5? (I was hoping to get AHI's to stay below 1.0 with that increase, and it doesn't seem to be happening).

plr66

Your logic is actually sound - putting the min back to 10, if the event #'s are consistently the same as when you have the pressure higher, makes sense.

The goal of all cpap therapy is to achieve optimum sleep results at lowest pressure combined with optimum ease of use (minimum leaks & squeaks etc: ) and to be satisfied with your daily alertness.

When you read most literature on pressure settings, 10 is often cited as the point where the majority of users are able to effectively splint the airway open and thus eliminate no-flow apneas. If you were to drop the low setting to 8 you should expect to see a significant deterioration as an increase in events (apneas, flow-lims & hypopneas).

Good luck (but with your considered approach you don't need luck - you have a good inquiring mind & that trumps luck (IMHO) )

OK, now I'm confused too. Wulfman and DSM, are you both disagreeing with each other completely or are you just saying the same thing differently. Isn't the goal to achieve the least events at the lowest pressure? So if the AHI is the same on both the lower or higher min. pressure, then you'd use the lower pressure, yes? Dori

Dori I think actually they are 2 saying completely different things.

1. In general, on APAP, a higher minimum pressure will prevent more obstructive apneas, therefore resulting in a lower AHI.
2. However, if you get the same AHI at two different minimum pressures, then in theory the lower one will work just as well for you as the higher one. Therefore, the lower one could be the pressure of choice.

BUT a lower minimum AHI could also cause more snores, which might be precursors to apnea's, and then you might be better off using the higher pressure.

You're right though, I think that in the end the goal is to have a minimum pressure that's just high enough to prevent most or all apnea's and hypopnea's, not too high, not too low, but juuuuust right.

That's why it's important to track your data for a week or more, at a particular pressure, in order to see the overall trend.

DoriC wrote:OK, now I'm confused too. Wulfman and DSM, are you both disagreeing with each other completely or are you just saying the same thing differently. Isn't the goal to achieve the least events at the lowest pressure? So if the AHI is the same on both the lower or higher min. pressure, then you'd use the lower pressure, yes? Dori

DoriC

I corrected my posting as I meant to include the words 'at the lowest pressure'

I believe we are talking the same sorts of things but emphasizing different points. Wulfman is consistently right about the points he makes so any misunderstanding is usually the emphasis rather than a missed point.

MY post was supporting lowering the pressure back to 10 as that fits the description of a lowest pressure achieving consistent results.

Den, correctly emphasized that raising pressure has always been the way to improve results - the issue of it being set at 10 or 11 is a valid point as follows

Argument 1 - go for the lowest consistent pressure
Argument 2 - if 11 is comfortable, stay there as it provides added insurance

Point being that back at 10 CMs increases the 'probability' of more events, but this is something that can be tested (as our parent poster was doing). If 10 is as consistent as 11 over time, then go for 10.

Hope this clarifies

DSM

Well thank you, Dori, for asking that question. I have to admit that I was scratching my head with the dilemma, but it seems as usual that I may have been "over-thinking" it. I appreciate the clarification from both DSM and Echo, and hear no dissent from either Den or OziJ.

As it happens, the jury is now still out and I'm going to need to give this another week or so to figure out, as I had a "runaway" at the increased pressure last night that I don't understand. Got up to the bathroom, and after that, the pressure shows that it hit the max on & off for the next 2 hours. I always shut off the machine before getting up at night (2 minutes), and hook up before turning it back on. Believe me, I was fully awake and suffering for the entire 2 hours, and the mask did not feel like it was leaking---and I have no idea what brought on that runaway. Unfortunately, I didn't have ramp set up since I never use it. Result was the 2nd highest AHI I've had since starting this--at 5.4--and OA's at 3.9 I think (usually less than .5). Whew! Another aberration? By the way, this has all been on my Remstar as listed below.

plr66 wrote:Well thank you, Dori, for asking that question. I have to admit that I was scratching my head with the dilemma, but it seems as usual that I may have been "over-thinking" it. I appreciate the clarification from both DSM and Echo, and hear no dissent from either Den or OziJ.

As it happens, the jury is now still out and I'm going to need to give this another week or so to figure out, as I had a "runaway" at the increased pressure last night that I don't understand. Got up to the bathroom, and after that, the pressure shows that it hit the max on & off for the next 2 hours. I always shut off the machine before getting up at night (2 minutes), and hook up before turning it back on. Believe me, I was fully awake and suffering for the entire 2 hours, and the mask did not feel like it was leaking---and I have no idea what brought on that runaway. Unfortunately, I didn't have ramp set up since I never use it. Result was the 2nd highest AHI I've had since starting this--at 5.4--and OA's at 3.9 I think (usually less than .5). Whew! Another aberration? By the way, this has all been on my Remstar as listed below.

I get away from the forum for a day and ya start talkin' 'bout me again.

I think you need to do something about THIS:

plr66 wrote:My pressure has been set on 10/20 using auto cpap,.....

There are usually some "reasons" for an Auto to increase pressures.....and not all of them are valid, either. That's why I'm not normally an advocate of wide open pressure settings.
In these cases, I think one needs to determine just what is a "reasonable" maximum pressure that's needed. As I said before, Autos are "reactive"......and take too long to respond to Hypopneas and Apneas but are very responsive to leaks and snores. If one is prone to the last two, you need to keep a very narrow band of pressure or go to your best single pressure.

Den

[quote="plr66"]Well thank you, Dori, for asking that question. I have to admit that I was scratching my head with the dilemma, but it seems as usual that I may have been "over-thinking" it. I appreciate the clarification from both DSM and Echo, and hear no dissent from either Den or OziJ.

I know what you mean by "over-thinking". That's my middle name, but these great folks here have patience beyond measure and they will make sure we get the answers we need no matter what. Who knows, I may be asking the same question again tomorrow even though tonight I'm sure I understand it. We can do this! Dori

I obviously did something wrong with the "quote" option. Can someone explain how that works so that it's shaded. Thanks.