Pressure - 95th Percentile

Folks: I just received my first report out since getting my Resmed Autoset S9. Under the Pressure (cm H2O) header it records a 95th % reading. At the bottom of the report it refers to the 95th percentile. This reading is anywhere from 11.6 thru 15.3 with an average of 14.0. Does this mean this was my cm H2O pressure reading 95% of the hours I slept? My auto set settings are 11-18.

Thanks for your help, Sheriff

Percentile pressure numbers just mean that for 95% of the time you were AT OR BELOW that stated pressure.

ResMed uses 95 % , Respironics uses 90 %.

Percentile pressure numbers just mean that for 95% of the time you were AT OR BELOW that stated pressure.

ResMed uses 95 % , Respironics uses 90 %

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Pugsy: if my lower setting is 11 and my 95 percentile is a 14, should I bump the lower number up, or leave it? Would I be buying anything?

Sheriff

Sheriff Buford wrote: Pugsy: if my lower setting is 11 and my 95 percentile is a 14, should I bump the lower number up, or leave it? Would I be buying anything?

I would leave it alone with what I have seen you reporting in your AHI numbers.

One of the advantages to APAP is the variables. I use APAP. I sometimes have very little pressure increase and sometimes it will nearly max out at 20. My minimum pressure is 10 cm. Some nights I have 90 % showing 11 or 12 but sometimes it is 16 and up. I could set minimum to 15 and pretty much guarantee event free nights but I see no sense in that because it is over kill in my book.

Yeah, if you were wanting to use straight CPAP maybe set it closer to that 95% number but why use a higher pressure all the time when a higher pressure part of the time works just as good? My feelings about it anyway. Pressure changes have never bothered me. If they don't bother you.. then leave things are they are and let the machine do the job it is designed for. Now if your AHI wasn't good, different discussion but from what you have said, pretty much can't get any better.

I wouldn't change things one bit if I were you and feeling good.

Sheriff Buford wrote: Pugsy: if my lower setting is 11 and my 95 percentile is a 14, should I bump the lower number up, or leave it? Would I be buying anything? Sheriff

Some of us folks set their lower range to the 95th and upper add 2 or 3 for their upper range. In your case that would mean 14-16 or 14-17. It also depends on your EPR settings. You can tweak your apap range to see what happens. Start at say 13-16 for a week and see what happens and then zero in on a tighter range.

I usually get 11.2 to 11.4 as my 95th and my apap is set at 10.6 to 13, with EPR at 1 -- it's been like this for the past 9 months and I get fairly good results. Each individual is different.

There you go, now dtsm has offered what some of the others do in regards to their 95 percentile numbers. I expected someone to offer that way of looking at it.

2 completely different ways of looking at things.

Given your reported AHI numbers I don't see what would be gained by changing. Plus I have never felt that the percentile numbers are the holy grail as to where settings should be made. They are too easily skewed by other factors.
Now if pressure variations disturbed your sleep, yeah tighten the range, if AHI was bouncing all over the place, yeah tighten the range. If you were having some clusters of events, then yeah tighten the range a bit.

Your choice though. Besides do you know what happens when you set that minimum closer to the now 95%? You get a new higher 95% number just because of the law of numbers. I have tried minimum of 11 and 12, just to see what happens. AHI was unchanged. I felt the same, didn't make me feel any better than my 10 min. Your mileage may vary though. Again, I just see no sense in using more pressure unless there is an apparent need when less gets the job done.

I have some great examples of variations in my 90 % numbers. If you would like to see them, let me know. I think you would then understand why it might not be the holy grail of numbers for everyone. It might be for some but certainly not for all.

Sherriff Buford,
I ended up posting in my bragging rights thread an example of a good night and a bad night where the 90 % pressure numbers are hugely different and I think you will see why I don't put much emphasis on that particular number. Why would I want to use 16.5 cm pressure when I can use much lower and get great results?
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Pugsy wrote:Sherriff Buford,
I ended up posting in my bragging rights thread

Now I know how you got to 3500 posts in such a short period of time

dtsm wrote:Now I know how you got to 3500 posts in such a short period of time

Well its been 2 years now and I am female and I do talk a lot.

I could have posted same comment here but thought the other thread was better spot since it lets newbies know that even old timers have bad nights. I didn't want to hijack this thread with my reports. Other thread has lots of different discussion.

Perhaps I just should have sent Sheriff a private message to that thread but honestly didn't think about it till just now.
Second thought, perhaps I should have sent this message to you privately...but I will leave it here. Not trying to change your mind about how you look at things. Only trying to explain why I look at it differently. Not saying you are wrong and I am right. Only saying that in some situations it might work differently for others and it all comes down to personal choice and what works best for that person. Before I suggest to anyone that they increase pressure I would hope that I could give valid reasons based on overall data and not just one item that may not give accurate description of the whole picture. Given options, people can then make informed decisions base on their own reports.

Pugsy wrote:

dtsm wrote: Given options, people can then make informed decisions base on their own reports.

EXACTLY, which is why in my post I started with: "some folks", and ended it with: "each individual is different"

I looked at my detailed data, and found the pressure it never seemed to go below (the "5% number" (not reported anywhere)) and set my minimum to just above that.

Sheriff Buford wrote:... my first report out since getting my Resmed Autoset S9. Under the Pressure (cm H2O) header it records a 95th % reading. At the bottom of the report it refers to the 95th percentile. This reading is anywhere from 11.6 thru 15.3 with an average of 14.0. Does this mean this was my cm H2O pressure reading 95% of the hours I slept? My auto set settings are 11-18.

Maybe the following explanation can be helpful to you:
- if you were to plot the distribution of machine generated air pressures (relative to atmospheric) throughout the night's recorded time, you'd get a bell-shaped statistical distribution; rather than providing the entire curve, the program reduces it to 3 numbers: the median or average, the 95% value (a measure of its spread), and the highest value reached (tells you whether you hit the top limit of 18); that's like plotting SA patients' Body Mass Index and rating you as average, elevated, severe, or low on that scale
- the lowest and 5% values may not be of interest for this application; still I expected you to say that the lowest matched the starting value of 11, or even lower if you use an initial pressure ramp; in my case the range is 6 cmH2O, just above and below the critical airway pressures needed in two body positions; and if I manage to stay in side position for the night, then the pressure curve hugs the lower limit
- rather than AHIs and summaries, I prefer to look at the pressure and flow curves instead: it may show me that at a particular time of night the ResMed algorithm bumped the pressure up to account for a flow limitation (maybe REM sleep or changing body position), a mask leak, or some other event (like a Texas barbecue + drink + desert coming back to haunt you in the middle of the night with stomach acid reflux); the deviation from normal sleep flow pattern is the interesting part (sleep fragmentation, or interruption of "good sleep"), if you know how to get to it
- some sleep doctors use the home CPAP results as additional information to adjust the pressure range

I'm probably the only one one who looks at my medians and adjusts based on my HI and recent medians. The median is the number exactly where half the numbers were lower and rest higher, so if it's consistently close to my low setting and my HI is OK, in my mind no tweaking. When my median rises and my HI increases, I watch to see if it's a trend; if it is, then I increase the low pressure.

When I had to sleep on back (injured shoulder) this is what happened:

• My medians, 95thcentile, & HI went up several numbers
• I started showing AIs
• I started leaking enough to trigger my 'mask off' alarm several times/night
• My sleep was lousy from pain as well as frequent wakeups

I had to do something to compensate! I finally figured out my jaw was dropping pulling my mask and creating those leaks, so I bought a small soft foam cervical collar which stopped my jaw from dropping -- fixed the leaks. I kept increasing my low pressure until my HIs started to reduce and my median was close to my low pressure. I reached a place where my AHI stabilized and then reduced a bit. Wasn't until I could go back to sleeping at least part of the night on my side that I could reduce my low pressure; it still isn't where it was before I injured my shoulder but then I gained some wt during all that mess and still haven't lost much of it.

For what it worth I got my best numbers by setting the machine wide open for several nights. Then set the max to the 90 or 95 % level. and the min at 1 cm under the median. I think the small jumps above 95 % disrupts my sleep. and the min close to the median keeps the pressure level more constant, I end up at 15 to 17 setting. my tritrations was at 8 and i suffered for years keeping the max limit to 12 to 15. Otherwise I am in good health and should not have been scared of higher pressure or the doctor knows best. I do think the S9 will ramp a little higher than needed if not resicted. Any wider ranges and I get higher AHI and feel not as good.