Air Curve 10 ASV Back-up Rate

[TSVanwinkle]

   
I have been using the Air Curve 10 ASV since April 2019.  For the most part, after going through the initial acclimation to ASV and going through numerous masks and positional adjustments, no one would throw rocks at having an ASI rate on most nights usually at zero to 1.  However, its still a bit of a love hate relationship and that has to do with the built in backup rate.  Any time it senses the need to provide breath by breath therapy it does so at a significantly lower rate than my normal breathing pattern.  Normal is 14-15.  ASV BPM is 7 - 9 and my body and the ASV seem to battle one another and at times, it wakes me.  The lower BPM also drops my minute vent rate.   My understanding, from having read many of the threads on this forum, including publications from Resmed, is that in ASV Auto, which is how my machine was setup, it is supposed to sample my normal breathing pattern and closely match it when breath therapy is needed.   I have also read that a backup rate less than 15 is not recommended for machines that have adjustable BPM. During a recent visit with my pulmonary doc, I brought this question up and he had no answer.   I asked if they had any contacts at Resmed that might be able to inform us if this was normal--or if my machine is malfunctioning.  I was informed, they have no contacts at all with Resmed.  Oh.  . . . .  I called Resmed customer service and was informed they could not discuss this with me and referred me back to the pulmonary doc or the DM supplier.  So, I am looking for some guidance in regard to whether this is just how the "normal" algorithm works or if my machine may have an issue.  

Many thanks, as always.

[Sleeprider]

I can't see the unassisted breath rate well enough to count it, but it looks high. I see 15-16 bpm during the period of assisted breaths. You may need to zoom in further and include no more than 4-minutes. Also include a full night so we can see the variation of respiration rate tidal volume, minute vent and pressure. The machine maintained minute vent and gave you the opportunity for spontaneous breathing. If you arouse durng this kind of episode, you can use the blow-back method to retake control of the pace and volume.

[SarcasticDave94]

It appears to me that it might be fine. However, it seems like your ASV might be choosing a little too low backup rate. But it's not a setting that can be edited. If your backup breath rate matched or exceeded your normal spontaneous breath rate, it kicks in to early and easily. I've read somewhere the backup rate should be at least 2 under your spontaneous breath rate, which is what I selected when I borrowed a ResMed ST-A. It appears my spontaneous rate was 12, so I chose 10 on the ST-A and was fine.

[TSVanwinkle]

Thanks for the reply   Here are the two snapshots you requested; full night and 4 minute expansion.

[SarcasticDave94]

I could be way off base, but is it possible your reported high respiration rate at about 15 may be based on the PS Min maybe needs to go up a bit to about 3 and this has you otherwise work extra? With a bit higher PS Min maybe things level out, to give you a touch more pressure differential.

Secondly I'd take Ramp out of the equation.

[TSVanwinkle]

Thanks Dave.  Here's the story on the ramp.  Until recently, I had not used it upon advice from the forum.  However, getting to sleep was a little tough, because ASV would start pumping me, just as I was beginning to drift off.  During the first five minutes or so, my breathing rate naturally tappers off as I go from active to resting.  One of the things I've observed through use of Oscar, is that the ASV algorithm interprets that BPM dropping slope  as the need to kick in--even though I am awake and not obstructed.  So . . . . . I set the ramp to give me five minutes to settle in before ASV becomes active.  Doing so has allowed me to get to sleep easily and rapidly.   I've also spent time looking at the triggers, prior to ASV kicking in.  Many of them happen after I've taken a quick and deep breath.  That gets interpreted as an interruption even though there was no obstruction or central occurring.  Interesting. 

One of the surprising and disappointing things I am discovering about Resmed; for as good as their product is-- they seem not to be interested in receiving clinical feedback from those who use their product or have questions.   (example was my pulmonary doc not having any working relationship with Resmed) In my perhaps naive way of thinking, I have always believed that user feedback is invaluable for a company that strives to improve their product.  Resmed's "My Air" deems my therapy as a success--but as I have experienced; a low AHI doesn't necessarily translate into a restful night's sleep--especially when machine and body seem to fight each other.  

I will also note here, that I sleep with a foam cervical collar.  I count it as being at least 50% of the therapy because it pretty well stops the chin tucking obstructive apnea.

[Sleeprider]

Well, this is unchanged from what we discussed in your other therapy thread. http://www.apneaboard.com/forums/Thread-...-years-use Pressure support increases your tidal volume, so the machine slows the respiration rate to maintain its primary target, the minute vent. It's not even clear to me that you needed the pressure support. What happens if you cut back pressure support from 1.0 to 15.0 to 1.0 to 6.0? This is the smallest ASV pressure support option possible. Willing to try?

[Geer1]

Yeah try lowering PSmax, it will reduce the volume of those breaths which will force spontaneous respiration rate to increase and take over sooner.

The only reason to use a high PSmax is if it is required to battle central apnea and this example doesn't show that as being an issue. Your breaths appear very responsive to the backup rate (it is hard to tell if this even is backup rate or just slow spontaneous breathing) and your max PS used in this example is only 9.5 so limiting it down to 6 probably won't cause any significant issues.

If unsure of going all the way down to 6 to start you could try doing it in stages (10, 8, 6).

[SarcasticDave94]

The way you described the starting issue is likely where Blowback could be used. That's what I needed to get to sleep better as the ASV kicked as I transitioned to sleep. So I blew back to get it to back off.

Zero to 5 will be the lowest PS you can get, if that's helpful.

[TSVanwinkle]

re changing PS max to 6 from 15,  here are the graphs from last night.  Not as peaceful possibly because I seem to have more mask leaks than normal.  I'll leave the settings as is for one more night for comparisson purposes, unless advised otherwise?