Understanding APAP Pressure Ranges

[upsman]

I understand that even though a PAP machine is using auto mode, there still needs to be a set range of pressure...min and max. The machine will react to flow limitations and increase pressure as needed. I realize that a wide-open range of 4cm-20cm is generally not the most effective setting. 

Increasing the min pressure is the most effective way to clear obstructive apneas, but not necessarily centrals. What part does the max pressure setting play in auto mode? The minimum pressure is what treats the events, right? Generally, isn't the 20cm setting for max pressure OK? What indicators would show the max pressure needed to be lowered, or that the range should be tighter?

Also, am I correct in thinking that the minimum pressure should be as high as necessary to treat the apneas, but not so high as to be uncomfortable. I see so many new patients under the impression that it's OK to leave the default, wide-open setting at 4-20 because the machine is automatic and will adjust on its own. My understanding is that if the machine determines a need for say 9cm pressure to stop an event, then the drastic sudden increase from 4-9 could be unsettling and lead a new patient to feel the pressure is too high. 

Help me sort this out a little better. 

[staceyburke]

In the ResMed pressure is increased when flow limits go up (FL are smaller apnea) to stop them from becoming H and OA events. The pressures continue to rise as long as there are flow limits.  We set the max below 20 to stop runaway pressures. If your OA is controlled at say 15 you don’t need max more than 16. If not it can go up to 20 causing sleep disturbances and added mask leakage.

[upsman]

 If your OA is controlled at say 15 you don’t need max more than 16. If not it can go up to 20 causing sleep disturbances and added mask leakage.

Ahhh, OK. 
So the max pressure ideally should be just slightly higher than what's needed to treat the events. 

[Gideon]

My Max is 25 but I never go anywhere near there. In my case, and from I've seen in your case so far, you can set max to the machine max. Should you sho the runaways mentioned above then move it down.

EPAP (min pressure) manages OA events and if not enough EPR/PS also hypopnea, RERAs, UARS, and Flow Limits
EPR/PS manages hypopnea, RERAs, UARS, and Flow Limits

This machine cannot treat centrals! For centrals we avoid them as much as possible. We decrease flushing of CO2 by lowering EPR/PS then by lowering Pressure variation (minimizing range) then by lowering pressure (Min and Max) . Note that these actions are the polar opposite of the above so managing centrals becomes a balancing act between obstructive and central events.

[quiescence at last]

This is a good point that G. makes. If you get through an initial 'body gets used to APAP' period of say 30 days, and at that point still have very high (I'll arbitrarily say 10/hr) or even increasing CA counts, then you likely have to play a balancing game until you can get physician to validate need for a machine that will treat both central and obstructive apnea.

Good luck as you chart your course.

QAL