What exactly does "blowing back" at an ASV reset?

[Utah Desert Rat]

Last night I got the distinct impression my Aircurve 10 ASV wasn't working right -- it seemed "sluggish" and its response to breath-holding tests were anemic to non-existent. This morning's Oscar looked normal, even though my experience was different.

Before I go into any settings details here, I want to just try blowing at it a few times to see if that makes a difference. But first I'd like to understand exactly what that does, technically. Can someone help me out with that? TIA!

[Sleeprider]

This is a really simple technique to get the machine out of supplying large pressure support by showing you are spontaneously breathing. It is literally a purposeful exhale and inhale that causes the machine to back off supplied breaths. You don't really need to blow, but showing you are in control very quickly gets the machine to reset to minimum PS.

[SarcasticDave94]

Yes that's correct what Sleeprider had posted. To me when I did blowback on my ASV, it was to signify to the ASV that I was breathing as I should and not having a CA. It should reset the ASV downward to lower PS and EPAP for a short time, hopefully enough to drift off to sleep.

As for holding your breath to test the ASV, your results will likely vary and not show you anything of value in my opinion. To me, testing the ASV by fake centrals proved little evidence that was any value other than proving a breath hold can be accomplished.

Someone looking on at this will probably translate it to be nothing more than an adult throwing a tantrum and holding their breath to get their way.

And your ASV will likely be bewildered a bit as it was trying to serve faithfully and keep you from holding your breath. But alas it failed you.

Only you can prevent breath holds.

[Utah Desert Rat]

And your ASV will likely be bewildered a bit as it was trying to serve faithfully and keep you from holding your breath. But alas it failed you.

I can imagine!    Usually I'd get a pretty good "puff" out of it, but sounds like that's not always the case.

Thanks for the info, folks. Good to know what that does and when to use it. Obviously it doesn't apply to not enough pressure.

I'll boost the settings tonite to goose pressure a bit. Maybe I was just getting used to it!

[SarcasticDave94]

What is your current pressure set? Include mode, EPAP, PS please.

[Sleeprider]

With the Resmed ASV, it uses your minute vent and breathing rate from the prior 90 seconds to set its backup rate and pressure support to maintain minute vent. There are several disadvantages to this approach. If you mask up while still breathing hard from the exertion of going to the bathroom and preparing for bed, it remembers that high breathing rate as what it should maintain, and as a result, you will feel pushed hard by the machine as you slip into a more relaxed state and would normally lower breathing rate and volume. The solution is to settle down before masking up. The other disadvantage is to individuals with pulmonary diseases or impairments that gradually give the machine lower and lower targets to maintain. Eventually so low that it is insufficient to maintain good oxygenation. That is why this machine is expressly not recommended for COPD, neuromuscular disorders and other pulmonary diseases and the ST-A with iVAPS is used instead where minimum respiratory volume and rate targets can be set. Ask Sarcastic Dave about that one. The ASV is for individuals with central or complex apnea that normally maintain an appropriate breathing rate and volume spontaneously. When you feel "pushed" by the machine, you can push back simply by breathing normally. That is harder than it sounds because when you think about your breathing, you suddenly start breathing deeper and slower. Try to understand how this machine works, and it will make it easier for you to live with its weaknesses and its strengths. Avoid masking up too soon while your heart rate and breathing are elevated, and this will eliminate most of the problems you have described.

[Utah Desert Rat]

This is the setup I've been using for the past few weeks, Dave. I've been doing really well on it (comfortable, and over half my nights are 0.00 AHI), but it seemed last night I felt a tad "air starved", like it wasn't pushing quite enough air. It also didn't seem nearly as "agressive" as it usually is when responding to the slow-downs I always have when I'm starting to drift off. Maybe it's my imagination (kinda like hearing that "funny little noise" in the car engine!)

[Utah Desert Rat]

The ASV is for individuals with central or complex apnea that normally maintain an appropriate breathing rate and volume spontaneously.

That's me. My diagnosis is opioid induced central sleep apnea (AHI 37, sleep study is posted here). From all indications, the machine is working perfectly for that. I love it. But I'm still in the fine-tuning stage!

[SarcasticDave94]

OK copy. Despite being on ASV Auto mode, it's an EPAP of 4-4 and PS 0-5 currently.

If you would like a bit more air, 1 of 2 ways you can try. IMO they'll feel different so consider trying both, but not together. Whichever you do, include the OSCAR shot and tell us how you felt.

The 2 directions, add 1 or 2 to EPAP, or to PS Min. Since EPAP is static 4, you may have to increase the range maybe 4-6. Call this choice 1. Choice 2 would be adding 1 or 2 to PS Min. One of the 2 will feel better to you.

Choose one setting change are a time to determine the effects.

For a baseline, what does the top of the left panel show, events, AHI, etc? This way we see what changed.

[Utah Desert Rat]

Since EPAP is static 4, you may have to increase the range maybe 4-6.

Sooo, that translates to setting EPAP Max to 6? 

Top part of the left panel attached. As you can see, I have a lot of desats. I'd like to get those down, but not sure if that's possible. At least my average is up to 94% Sp02 now (up from 89).

Thanks ever so much for the invaluable help!