In general, I’d recommend against doing exactly what I’ve done. However, my recent journey into tracking sleep stats provided me with information that I used to determine, on my own, what might be a better pressure range.
While reviewing data from 17 nights I realized that on 14 of those nights the average pressure used was above 9. In addition, in cpaptalk.com forums I read some accounts in which several individuals suggested that lower minimum pressure settings can be a problem for some people.
Specifically, the idea is that if a pressure of 9 is needed to clear the airway, but the minimum starting pressure is 6, then it may be taking the CPAP too long to detect that a higher pressure is needed. By the time the unit ramps up the pressure the apnea or hypopnea event may already be over due to the body’s automatic response.
I’ve used this range two nights in a row and I do seem to have experienced an improvement in my sleep.
Updated 10/12/2011: My opinion regarding exercising the ability to change machine settings has changed slightly. Visit my page on living with a CPAP for more information.