why is 90% auto cpap at max pressure

The "90%" pressure means that you spent 90 percent of the time AT that pressure AND at pressures BELOW that pressure.

I had written this...which is incorrect. "It also means that you spent 10 percent of the time at pressures above that pressure."

Here's the correct skinny on the 10% above the 90%, thanks to Jules:

jules wrote:You can't say 10 % of the time you are above that cut off. It is 10 % of the time you are AT or above that cutoff.

The 90% pressure doesn't mean that you spent 90 percent of the time up AT that one pressure. Although that's possible if a person has their autopap set for same minimum and maximum pressure.

With a range of pressure set (like 5 - 15) you might have spent most of the time at pressures way below the "90%" pressure, and a very short time actually using the 90% pressure.

What range is your autopap set for?

(Edited to correct a number typo to "10 percent")
(edited a second time -- correcting an incorrect statement I had made in this post, to a correct statement, thanks to Jules. :D )

My REMSTAR AUTO M SERIES IS SET for a max pressure of 15 cm H2O, and on somenights the 90% AUTO CPAP is at 15 cm H2O, and the AUTOCPAP is at 12 cm H2O, I am concerned that my 90% AUTO PRESSURE IS at my max presure, which is not good.

Yes, you are right. The top of your range should be at least 1-2 cm above your 90% pressure (but *don't* keep bumping up your bottom pressure if your numbers are OK, otherwise you'll make the 90% pressure look like it's higher than it is).

OK

tillymarigold, the RT suggested to rasiepressure by 2 cm H2O since my 90% Auto CPAP was at the max Pressure for most of the nights, now I like to know why, what is going on, if you could share more info on this subject, the RT does not seem to have a real good knowlegde on this subject, thanks.

I know I am really digging deep on this 90% stuff, but if my 90% number is at my max pressure, then how can the other 10% be higher.

suppose you stayed at the same pressure all night - what would your 90 % ile pressure be then?

if you divide the night up into a bunch of pieces and make a long list of the pressures at each time and sort them in order, you got what the software is starting to do. Then you look at the list and determine where the top 10 % of your data is at. The cut off for that top 10 % of the data is the 90 %ile number. It can very well be all the numbers in that top 10 % of the data are the same as that cut off number or it might be there are data values above the cut off.

You can't say 10 % of the time you are above that cut off. It is 10 % of the time you are AT or above that cutoff.

The 90% pressure number must then be used to adjust pressure or verify that the max pressure setting is correct. What is the purpose of this information. On a 23 day period my 90% auto cpap pressure was at 15 cm H2O which is the same as my max pressure for 14 day. Just looking for an explanation from someone who has clinical experience for this information. Respironics encore pro must include this 90% auto cpap for determining something.

jules wrote:You can't say 10 % of the time you are above that cut off. It is 10 % of the time you are AT or above that cutoff.

Thanks, Jules! I'll edit in a correction to where I had stated the 10 % thing incorrectly. (me and math.... )