How to you compute your 90% pressure?

Hi,

I have seen the term 90% pressure, and don't know what it means. Could someone please tell me? Many thanks, MoonBear

MoonBear wrote:Hi,

I have seen the term 90% pressure, and don't know what it means. Could someone please tell me? Many thanks, MoonBear

The 90% pressure level is reported by the PR System One Auto machines, if I recall correctly. It's the pressure level that the machine was running AT or BELOW for 90% of the time the machine was running for the reporting period. It also means that the machine was running AT or ABOVE the 90% pressure level for 10% of the reporting period.

So for example, if your 7-day average 90% pressure level is 12.4cm and if your machine was running for a grand total of 50 hours during the last seven days (a bit more than 7 hours per night), that means that for a total of .9 x 50 = 45 hours during the week, your machine was running AT or BELOW a pressure of 12.4cm. And for 5 hours during the week, the pressure was AT or ABOVE 12.4cm.

But MoonBear, your signature indicates you're using a ResMed S9 Elite, which is a fixed pressure CPAP machine. If you look at pressure data in ResScan or if there's any pressure data on the Elite's LCD, the median pressure, the 95% pressure (which is what ResMed uses), and the max pressure should all equal your set pressure, which presumably is the pressure that was determined during your titration sleep study.

There are folks around here who will say that if you have a chance to do an auto-titration for a week or so, that your fixed pressure can or should be set rather close to the 90% or the 95% pressure level reported by the autotitrating machine during the week since that's usually high enough to take care of most of the apneas and hypopneas and low enough to not cause problems with tolerating the pressure.

HI Robysue,

As ever, a brilliant explanation that is so helpful. my machine starts at a 4 and my max level is 14. My doc read ny card for the first week and I have gone from 101 apneas an hour to less than 1! Needless to say, I am thrilled. But that was before I woke hearing a bit of a hiss coming from the lower part of my mask, which started AFTER I got to sleep with this clear, very soft gel-like patch only nose. The Quattro leaves the worsening mark and bump every night. The patch seems to reduce soreness, but not redness.

Today, I feel more tired than I have although that may have nothing to do with this leak issue. Seems odd that therre could be a leak that I cannot feel anywhere, but can only hear or is this typical?

Many thanks for your help as ever.

Namaste,
MoonBear