mitigating flow limit awakenings with asv therapy

Hello, Thanks to everyone helping on this board. I switched from cpap to asv due to central apneas and largely mitgated my apneas and hypopneas. I am however experiencing lots of flow limits. I seem to wake up about an hour after I fall asleep and again around 4 am. I would be pleased with my results if they didnt actually wake up at these two times each night. I set my ps to the max and am still have these flow limit events. I am in my infancy in understanding all of these metrics as they relate to therapy. Thsi will be my first imgur attachment. Any suggestions that you my have on my situation and posting would be appreciated. Specifically, I am interessted and getting rid of as many flow limitations as possible. I am also wondering if a bi-pap might be better than an asv in my situation. A specific example of one of my awakening events is exactly around 1:05 am.





I have an aircurve asv with a f20 full face mask.

fastandthecurious wrote: ↑

Wed May 10, 2023 8:46 am

I am also wondering if a bi-pap might be better than an asv in my situation.

Are you aware that the ASV model machine is a bilevel machine?
BTW...the term bipap is really a marketing label for Respironics bilevel machine?
ASV is a bilevel machine with a back up rate and variable PS to deal with central apneas.
Regular bilevel machines don't have a back up rate available.

As for your flow limitation graph...ASV machines are notorious for making mountains out of FL mole hills anyway.

Also it is normal to wake up after the completion of a REM sleep stage. How can you know for sure that FLs are causing the wake ups?

At any rate you can make your ASV function like a regular bilevel machine with a little tweaking of the PS settings if you want to try regular bilevel....or "bipap".

I did not know any of the information that you just shared with me. Thank you! Looks like I will be digging into the manuals. If it is showing high flow limits during my wake up periods consistently, what other possibilities exist for me to research to stop that from occuring. It seems to occur out of a dream state. so it does appear to be related to my sleep cycles. I just dont know the best way to progress forward to optimize my sleep architecture.

fastandthecurious wrote: ↑

Wed May 10, 2023 8:46 am

I am however experiencing lots of flow limits.

Resmed bilevel subtype ASV machines tend to report crazy looking FLs, for some reason, leading us to be very suspicious of those charts.

fastandthecurious wrote: ↑

Wed May 10, 2023 8:46 am

I seem to wake up about an hour after I fall asleep and again around 4 am.

How quickly do you fall back to sleep? A few awakenings per night are normal. It's only a problem when you can't go back to sleep.

Even normal sleep architecture can include a wake-up or two at the appropriate time.
The key is how you feel upon awakening, and if you are able to get to sleep after.

You should ignore the flow limitation reading on an ASV machine:

https://www.apneaboard.com/wiki/index.p ... PS_and_ASV

Flow limitation is a common characteristic of pressure support induced inspiration. When you don't make the spontaneous effort to breathe, the ASV pressure support does ensure a volume of air is inspired; however as the lung fills, resistance increases, and this gives the appearance of flow limitation. This is not upper airway resistance, but a function of resistance in the lung itself. We see this on nearly every individual that has posted close-ups of the respiratory flow wave during ASV and ST non-invasive ventilation intervention. We don't try to treat this form of flow limitation, but rather accept that it is a common result of non-invasive ventilation.