Titrating ASV with low AHI

[kevinonasv]

I've been using the ASV for a year+ now. I'm on low pressure settings (5.0 min EPAP, 6.0 PS, 15.0 max IPAP). OSCAR says I have very low AHI (<0.5), but I still often feel very sleepy. 

My daytime sleepiness is also highly volatile, so hard to notice minor improvements. If my AHI is very low, how should I titrate my ASV?

[SarcasticDave94]

Some numbers are missing in your ASV setup. There's either 1 or 2 EPAP, 2 PS numbers, and 2 IPAP numbers. And what mode is this?

PS 6 to start will be pretty high, if that's what that means.

Let's see your recent OSCAR chart with Events, Flow Rate, Pressure, Leaks. Don't zoom in on the chart just yet either.

[kevinonasv]

Thank you! Attaching some images and adding details on my ASV settings.

Mode: ASVAuto
Min EPAP: 4.00 cmH2O
Max EPAP: 5.00 cmH2O
Min IPAP: 4.00 cmH2O
Max IPAP: 11.00 cmH2O
PS Min: 0.00 cmH2O
PS Max: 6.00 cmH2O

Note also that I've turned off ramp, as of last night. I've seen that recommendation on a few threads.

[SarcasticDave94]

First off, note the edit I'll suggest isn't to address events or chart numbers directly but the implied not feeling good for the therapy comment.

I would try 2 things, an edit for EPAP, and another for PS. You can do this as slowly as you want, but I'm thinking both EPAP and PS ranges to be a bit low. We're not going to Max anything out, but add a bit to both.

On EPAP, try Min 5 max 7 or 8. Later, maybe you might want Min 6, with an accompanying max about 3 higher.

PS, I would make Min PS 2 or 3, while Max can stay at 6 or go up slightly.

We're not after zero AHI or individual event types. Again my suggested edits are to address making therapy feel like it's helping you sleep more comfortably.

EPAP increase may help give you a base amount of air. Try the edit and if you don't like it for whatever reason, turn it back down.

A higher than zero PS Min will help exhalation because there's always going to be a differential between EPAP and IPAP. Right now PS Min 0 sometimes takes that differential away. This is probably the first edit, get PS 0 up to about 2 or 3. Then try the EPAP increase.

And keep an eye on your leaks. They're not terrible just yet, but increasing pressures may make it worse. And with ASV, leaks higher than your current will hinder the therapy.

[kevinonasv]

Thank you so much Dave. That's helpful - out of curiosity, the hypothesis is that more air pressure will lead me to sleep better? 

Specifically, air pressure can help reduce flow limitation and ensure I'm getting sufficient air while sleeping? This is counterbalanced by increased leak (and potential discomfort) with higher pressure.

[SarcasticDave94]

I think it might with the "if" thrown in. If we go by the basis most CPAP etc users may feel somewhat air starved at a base minimum below 7, then yes more air, in this case more EPAP Min may help. EPAP Min is the base level air you'll get on ASV.

Second, PS of 0 like I said earlier means your exhale and inhale can at times be the same pressure. This eliminates the leverage PS can afford to assist the exhale breath. That's why I'd think PS Min 2-3 will feel better.

[R750R]

It makes sense that a bit more air pressure could help with flow limitations and overall comfort. I guess I’ll have to see how it feels in practice.

[kevinonasv]

Thank you so much! I will try those settings. Just to clarify, what does "air starved" mean?

[Crimson Nape]

The feeling that you are not getting enough air because of a low pressure setting.
- Red

[SarcasticDave94]

Correct. That's the context I meant.