My inspiratory time is higher than expiratory on Auto S Bipap

[Stubert]

I changed recently from cpap to Bipap and have dialed in settings that work a lot better and at a lower pressure. My flow limitations have also got much better.
I see that my ventilation is on the high side and inspiratory time higher than expiratory, which in the perfect world would be 1:3. I am 190cm and 100kg (starting AHI 66 nov. 2022).
Please see data from last night.
Do I need to increase PS to have a longer expiratory, to clear the lungs?
I am afraid a higher PS will then increase my ventilation?
I still get some arousal, can that be due to not clearing the lungs and building up Co2?
I am running in Auto S mode, on the Prisma 25S, and cannot set any manuel settings other than min. Epap, max Ipap and PS range.
Thank you.

[Sleeprider]

Your Lowenstein bilevel is capable of variable PS. To improve inspiration time we would want a higher minimum PS. I will recommend changing PS min to 4.0 and to be honest, the maximum PS to 4.0 as well. I don't see any issues in your chart or zoomed image with the lower PS, and I have no real experience with this bilevel machine, however based on your zoomed image, your inspiration/expiration times are normal and not accurately reported. This is a fairly common problem with different machines that they do not accurately report the I:E crossover correctly and count the low or zero flow ahead of inspiration as part of the inspiration time rather than as part of expiration which would be correct.

[Stubert]

Thanks SR!
It's been a week trying settings out again. I find it best not to increase PS, as my tidal volume gets quite high and I feel like over ventilated and heavy head, when fixed at 4.
This night was pretty good, eventhough a fixed PS of only 1.5.
I am not sure I am in the clear Bipap category, but CPAP or APAP does not do the job. When on APAP, the löwenstein softpap/EPR works differently than Resmed, meaning that the pressure drops 1-3, but returns back to normal pressure during exhale and does not "wait" until you take a new breath. It does not work well for me - then the Bipap is better and shoots a little harder pressure, and Ipap waits to increase until new breath is started.

Back to this night, please see chart. Night felt good, not as often awake as usual. Remember about 3 times and awake from 05:55 till end.

Also data from O2 ring, rarely this good O2, but still a lot of movement.

My concern is the med minute ventilation, its 9.38. Is it on the high side? Any comments on this matter? I think my med tidal volume is quite all right.

BTW, changed mask to F&P Evora from Resmed F30i.

[Sleeprider]

Your choice looks a lot like the Resmed Airsense CPAP with EPR which is in reality a bilevel pressure with differences of 1 to 3 cm, just as you describe. Our goal is comfortable treatment and as good sleep quality as we can get, so you seem to have accomplished that with low PS. Thanks for the explanation of how soft PAP works in your machine and how it differs from the bilevel delivery.