should i raise my min pressure

so my machine is set from 4-20, and these are my numbers averaged from the last 4 nights. i've been on apap now for about a month and a half, and my pressures have dropped quite a bit.

median = 5.75
95% = 7.75
max = 9.1

HI = 3.25
AI = .175
AHI = 3.43

i know before you guys recommended to raise my lower setting of 4 to something closer to the median, but would you still recommend this with these numbers, and if so, what should i set the lower limit to?

thanks for your help

Aaron

As I understand it, normal breathing even without a mask requires more than 4cms of pressure and most people using a mask feel suffocated at such a low pressure. Looking at your data, you might do better with a min pressure of 8cms and if you're having any leak problems you could lower the max to 12cms. These are only my suggestions but I'm sure some experts will be along to help. Of course if you're working with a good sleep dr, you could discuss it with him/her. Good luck and keep us posted.

Many people can't breathe at 4cm - If you can breathe it's ok. Otherwise maybe 6 minimum and 12 max?

Aaron,

If this was my data, I think I would concur with what Dori has said. If you start at 4, and are hovering around 6, but have a max of 9, that is almost a doubling of pressure that the machine needs to accommodate. What that means is when you do have the occasional event, the machine might not able to ramp up quickly enough to prevent it from happening. I can suggest putting the low number at any setting where you feel comfortable. Many people report that it is hard to breathe at less than 8, so that sounds like a good number to start at. The upper number doesn't matter as much as long as it is higher than what you need. Setting it at 12 would probably work well. The only caveats would be if you are position sensitive (ie, have much worse numbers in certain sleeping positions), or if your sleep study mentioned central events. You might want to run this past your sleep doc or RT, however, if they set the machine for 4 to 20 in the first place, then I'd have concerns about anything that they tell you.

-john-

If the median is 6, there is no way I would set the minimum to greater than that.

First........if your machine is data-capable, get the software so that you can more carefully monitor your progress. You can't manage what you can't measure.

Second...... I suggest that you narrow the pressure range. Something like 7-14 might be good. The machine works better in a narrow range.....and you'll learn from others on this forum that a "wide-open" setting of 4-20 isn't the way to go.

Finally.....understand that "patience" and "experimentation" are the keys to good therapy. Use software to determine how to tweak your system for maximum effectiveness with maximum comfort. Don't get in a hurry......make changes slowly.......after gathering good data.

I don't think there's anything wrong with leaving the max set at 20. Pressure that doesn't need to be used "up there" simply isn't going to be used.

"Narrowing the range" and not having the machine set "wide open"... those phrases to me (in my own personal tweaking) mean adjusting only the minimum pressure upward and leaving the maximum pressure alone for the time being. I don't think a person has to adjust BOTH ends of the range at the same time in order to "narrow the range."

Narrowing the range and not using the machine "wide open" can be accomplished through changing just one thing -- through changing only the minimum pressure.

If a machine has been used at 4 - 20, then changing it to 6 - 20 is "narrowing the range."

If a machine has been used "wide open" at 4 - 20, then changing it to 6 - 20 makes the machine not be "wide open" anymore.

If an autopap has not been using more than a pressure of 10 at any time over a period of several weeks, what could it possibly matter if the machine's maximum pressure is set at 12 or is set at 20?

If 10, at the most, is all the machine ever uses for that person, the machine is not using 11, or 12, or 13, or 14, or 15, 16, 17, 18,19, or 20. Un-used pressure above is...un-used pressure.... whether the max is set for 11 or a hundred. Not that any autopap machine I know of can be set for max 100. LOL!!)

All that said -- sure, there can be reasons to put a leash on the max pressure setting. If a person's machine does use, say 12 at times, but the person gets painful aerophagia on any nights that the machine has used 12, but doesn't get aerophagia when 10 or 11 is as high as the machine went, that person may want to cap the max at 11.

Likewise, if a person is struggling with mask leaks that seem to be driving pressure up, that person might want to set a limit on the max pressure.

If the leak rate is nice and low, and the person is able to see (either on the machine or through software) overnight data about their therapy, and is not being bothered by aerophagia, there's usually no advantage (in my opinion) in lowering the maximum pressure just for the sake of "narrowing the range", or for the sake of not having the machine set "wide open."

Of course, it won't hurt to lower the max, as long as a person keeps it above what's actually needed, as the others in this thread have rightly said.

But my point is that lowering the max down from 20 usually is NOT what causes improvement in an AHI when the minimum pressure setting is being raised at the same time.

The improvement in AHI when both ends of the pressure range are being adjusted at the same time is almost always because of one thing, in my opinion...the improvement was because the minimum pressure was raised. Not because the minimum was raised AND the maximum was lowered at the same time. The improvement had nothing to do with an un-used max of 20 being lowered to an un-used max of 12.

It's usually only the MINIMUM pressure that is the important one to consider or tweak, imho. If a person's autotitrating treatment needs tweaking at all.

Aaron, from your numbers, you seem to be doing fine at 4 - 20. With your nice low AI and HI, and the fact you have no complaints about breathing at 4 cm, it doesn't look like there's any compelling reason to tweak your pressure settings at all. But if you want to experiment simply to see what raising the minimum pressure would do (and you probably would see an even lower AHI, not that that's necessary...yours is already quite low) then setting the range any of these ways should be ok:

6-20
7-20
8-20

Aaron, I agree with bigk about this:

bigk wrote:4cm - If you can breathe it's ok.

Snore data, or complete charts might be helpful to see why pressures adjust upward. That said, I'd probably set the minimum at 6.5. But then Rested Gal just about said the same thing. In adjusting pressure, my goal has been to set minimum pressure above the threshold for apnea triggering events. At the same time, I don't leave the top wide open, but leave room for any adjustments in up to the maximum pressure used in auto. In your case the minimum and maximum would be a range between 6.5 and 11, and could be a little tighter if you find that comfortable. If you feel good, no change is needed. If you feel your sleep is disturbed or not restful, make adjustments as needed. In spite of the science and numbers, that is really the bottom line.

When I adjusted my pressure, I had a few week's data to look at and saw that I never went below 10cmH20 so that is what I picked for my minimum pressure. The Resmed clinic I attended - the doctor there - said that they set the max at 15 so the machine doesn't "go crazy" and out of control - LOL. Complete rubbish I guess but as I never went higher than 15, I selected that as my upper pressure - I used 10-15 and still use that today. I did find on the S8II that occasionally in recent days I did hit 15 so I may have to adjust that up however with the S9 I have been below 15 (only 2 nights so far) and my AHI is 0.00 which I never believed possible - so I won't be making any changes in a hurry.

i agree with restedgal on the max, though i'm not expert it just makes logical sense. it should not matter if the max is set at 20 or 15, if you never go above say 12.
i do want to try and adjust my minimum settings though. my DME recommended not to change them only because he goes on the notion of "if it's not broke, don't fix it" but being the way i am, i always like to achieve the best results if possible even if my results are already great.

also, i'm kind of confused why someone would have trouble breathing at 4 cm, even if the machine was set at 1 cm, wouldn't that be pushing more air to you than if you were not using cpap at all and therefore making breathing easier?

i think i'm going to try and set the min at 6 for now and see how that goes.

thanks for all the responses.

so i set the machine min at 6.....so far so good, ahi for first two nights is now down to 1.7 from on average around 4 or so.

asylvia wrote:also, i'm kind of confused why someone would have trouble breathing at 4 cm, even if the machine was set at 1 cm, wouldn't that be pushing more air to you than if you were not using cpap at all and therefore making breathing easier?

Nope. As I said - *I* and many people don't get enough air at 4cmH20 to breathe comfortably. If you do that is great.

bigk wrote:

asylvia wrote:also, i'm kind of confused why someone would have trouble breathing at 4 cm, even if the machine was set at 1 cm, wouldn't that be pushing more air to you than if you were not using cpap at all and therefore making breathing easier?

Nope. As I said - *I* and many people don't get enough air at 4cmH20 to breathe comfortably. If you do that is great.

I'm the same way. even 5 and 6 feel too low.

I think it may have to do with the speed that you want to draw the air in. the 4 cm is just slower than you could draw free standing air into your lungs when just breathing normally without a mask and hose. Or at least thats how it feels to me. I also feel like its not expelling my exhaled air from my mask fast enough to clear it all out of my mask before I started drawing air in again.

that may be, and i'm quite sure when i put my machine on when it was set to 4, that it did not stay at 4 for long (i'd get up and look at the screen and seconds after i put it on it would read five point something) so maybe that is why i never noticed having a problem with it set to 4.

nobody ever answered the question " why would you set the minimum higher the the mean?"