Look at your stats . Check Your 95% number . What that means is this: for 95% of the night, you are at that pressure and under.
The medium pressure number works the same....for 50% of the night you were at that pressure and under.
So when setting a pressure range, we try to look at the 95% number and set the minimum pressure to start approximately 2cm below that number. Most of the time that ends of being almost the same as your medium pressure.
Also, set the EPR at 2, and eventually 1.
(Some people might have fewer CAs if they reduce EPR. EPR at 3 will reduce expiratory pressure by 3 cm-water. That can cause CO2 washout. CO2 is the primary respiratory drive during sleep. )
(Co2 is the primary respiratory drive, awake or asleep. well, actually it's more your blood ph, but co2 makes it more acidic, you breath harder, co2 blows off, you breath less hard. the main thing that happens when you take a bunch of deep breaths then hold your breath isn't a big change in oxygenation, it's a large reduction in co2, and when the co2 builds back up, you get that near uncontrollable desire to gasp for more air. )