Whats the purpose of setting ipap on bpap?

[OSAsucks]

Maybe I'm confused, but what's the purpose of setting IPAP values on a vauto bpap system? I've seen people say to narrow the range but won't the system just go up to the EPAP + PS value? Why not just leave IPAP at 25 cm h2o? 

My avg pressure for the last 6 months and year is around 11.6. My settings are 7 epap, 25 ipap and ps of 4. Trigger is very high and cycle is med. Timax is 3 and min is 0.3. I usually get less than 1 ahi every night and my FL are almost completely resolved but I still feel fatigued all the time. I'm just trying to understand why ipap should be lowered as some people recommend here. Or maybe I'm misunderstanding somethings.

[SarcasticDave94]

On the VAuto, IPAP generically is the inhale pressure. But this setting is Max IPAP, telling the VAuto this is your maximum pressure. Does it just go with EPAP plus PS? Somewhat, but it does increase above that based on event.

EPAP Min defines the minimum pressure overall. IPAP Max defines the maximum pressure overall as well. PS is setting the definite differential between EPAP exhale and IPAP inhale. Suppose you have these settings, EPAP Min 5, PS 4, IPAP Max 20. EPAP must be a minimum 5, but it will increase if there's a need to. So at exhale 5, you inhale, PS adds 4 so you're at a minimum 9. But during an event, EPAP might have gone to 7, add PS 4, your IPAP is now 11. And so on for increases up to the IPAP Max 20 in this example.

[OSAsucks]

Ah I see, thanks