What Does 95% Mean?

[kgriggs]

I'm looking at Sleepyhead Statistics.

What does 95% mean, in this context?

Channel .. Min .... Med ... 95% ... Max
... EPAP 15.50 . 16.50 . 21.40 . 22.10

[surferdude2]

It means 95% of the events happened below that number. It also means 5% of the events happened above that number.

In your case, it's referring to the expiratory pressure of your therapy.

[kgriggs]

Thanks SD2

So, if I'm wondering whether I need to change change my EPAP, what specific data addresses this question?

[surferdude2]

That depends on what difficulty/insufficiency you are trying to correct. The 95% figure is often used to determine if the current settings are correct to give you proper therapy most of the time. It doesn't tell the whole story since you are taking it out of context as to all aspects of the therapy and your ability to tolerate it.

[kgriggs]

Current EPAP setting has been untouched for 4 days, and AHI is 4.01%

You think I should just leave it alone, or tweak it some more?

[PaulaO2]

If it has only been 4 days, leave it alone. You need to collect more data so you can see more of a trend.

There are a lot of variables that go into the quality of sleep. So just 4 nights is nothing. You want at least 10 days, hopefully more.

[PaytonA]

I agree. The median being 16.5 means that half of the night was spent between there and 15.5

[vsheline]

It means 95% of the events happened below that number. It also means 5% of the events happened above that number.

More precisely, a 95% pressure of 21.4 means the pressure was 21.4 or lower during AT LEAST 95% of the time, and that the pressure was 21.4 or higher during AT LEAST 5% of the time.

An extreme example would be for a fixed-pressure CPAP machine, where the Min and Median and 95% and Max pressures could all be the same number.

[archangle]

It means 95% of the events happened below that number. It also means 5% of the events happened above that number.

No, that's wrong.

It means that the pressure was below that pressure for 95% of the time. Events have nothing to do with it.

https://en.wikipedia.org/wiki/Percentile

For instance, if your machine was running for 100 minutes, the pressure was at or below that pressure for 95 of those minutes.

"Med" is median, which is the 50th percentile. It's not the average pressure.
BTW, it's percentile, not "percent", despite the "%" symbol, which matters in some cases.

In this case, assuming 100 minutes of therapy.

Channel .. Min .... Med ... 95% ... Max
... EPAP 15.50 . 16.50 . 21.40 . 22.10

The pressure was always above 15.50 (minimum)
It was at or below 16.50 for 50 minutes (median)
It spent 95 minutes below 21.40 (95th percentile.)
Always below 22.10 (maximum)

In CPAP therapy, the 95th percentile number is often used as sort of a rule of thumb as a "good enough" number. If you wanted to go back to manual pressure, you might set the pressure at the 95 number. If you wanted to reduce the pressure range your auto blows at, you might start a few points below the 95 number.