Configuring an AVAPS

[jbsix]

The other unit to look at is the Resmed Aircurve 10 ASV. For the System One SV advanced, the backup rate is called BPM or breaths per minute. By default, I'd suggest 14, but you may be able to look at your CPAP data and get something about 2-BPM less than your normal mean. The setup is pretty simple. This device offers up to 25 cm maximum pressure. You can set the max not to exceed any pressure, but for you, probably 20 cm. EPAPmin and needs to be set high enough to prevent most OA. For you, I think EPAPmin 8.0 and EPAPmax 11.0. PSmin 2.0, PSmax 8.0.

With these settings you will start at 10/8.0 to 13/11 for normal spontaneous breathing, and will see up to 16/8.0 to 19/11 in the presense of CA. The machine will detect reductions in volume and insufficient breaths per minute and will provide pressure support on a breath by breath basis to maintain your respiratory volume and rate.

Other settings have to do with inspiration time, BiFlex or rise time, ramp, humidity etc. The PRS1 960P is a full automatic ASV and has many settings that can be tweaked to increase comfort and synchronization with your breathing. An optional heated hose is available for this unit for about $75, and you can add it at any time.

Thank you! This clarifies things immensely. I'll check out the Resmed too if it's cheaper.

About the bpm-
1. should i use the best night on my cpap as a data point? I have one that's fairly recent and AHI 3.09. Or perhaps it would be better to run the machine for an hour or so whilst awake.
2. Were you referring to the median value of resp rate in sleepyhead rather than mean? or weighted average?

[Sleeprider]

You can set the preferences in Sleepyhead to report median or average. Both statistics are relevant, but I usually use the average. The breaths per minute are normally set at 2-less than your sleeping average BPM. It seems to result in a more natural feeling and keeps the machine from taking over when you are spontaneously breathing. In Sleepyhead, just click on File/Preferences, and under CPAP tab, set middle calculations to Normal Average, and upper percentile to 90%. I think that is more useful than the defaults.

The Resmed Aircurve ASV is not at all inexpensive, and getting a discounted price will be difficult. Its users report a more natural feeling respiration where the machine follows their natural pattern so well, they are almost unaware of the machine assisted breaths. The Philips seems to be more adjustable, but it takes some time to dial in the finer settings to where they feel completely natural. You are much more likely to find a PRS1 Model 960 at a good price.

[jbsix]

Thanks, I couldn't find it anywhere. Choosing mean over median makes more sense to me too. And wow, aircurve sure is expensive! I don't mind tweaking as long as I'm sleeping well

[jbsix]

I got the PRS1 ASV and am having a little trouble fine-tuning it.

For day 1, I thought I'd replicate my APAP settings (8-12) except I'd add more exhalation pressure relief since that was my biggest complaint on APAP.

These are my settings:

Code:

EPAP min = 4.0
EPAP max = 8.0
PS min = 4.0
PS max= 4.0 ; for an effective IPAP range of 8-12
bpm = 14 ; Resp. Rate mean on APAP = 16.56
Ti = 2.0 ; Insp Time mean on APAP = 2.18
Bi-Flex = 2 (and therefore no rise time set)

I switch on therapy and inhale, IPAP=8.0; good.
I exhale, EPAP=4.0; excellent.

But after about 1.5-2 seconds of exhalation, it switches over to IPAP prematurely even though I'm still exhaling. This results in the mask inflating as I'm still exhaling.

If I perform the world's longest exhalation here, the machine will switch back to EPAP after ~2s and then back to IPAP after ~2s and so on; completely ignoring my breathing cues.

I suspect it is due to one of the last three settings (most likely Ti), but could use some input.

[Sleeprider]

Take BPM down to 12 BPM and see if that solves your problem.

[jbsix]

Had to take bpm down to 8 before it was at least feasible to put it on for the night. But there's still interference where it tries to force ipap while i'm still exhaling or epap while I'm still inhaling.

How is bpm calculated/put into effect?

If I set Ti to 3.0, the max bpm i can set is 10. So from what I can extrapolate, this would mean 10x3s inhalations per minute (30s), leaving another 30s for exhalation which is why it is trying to force change pressure type. Am I correct?

If so, then I could play around with it to get a better inhalation to exhalation ratio of 1:2.

[Sleeprider]

I would not exceed 2.0-2.2 on Ti. 8.0 is the low end of normal for BPM, 14 would be high. You want to find what works, but at some point that backup rate will kick in if you're not breathing. This is one of the thing the Resmed ASV does pretty well automatically is to sync with the user when they are spontaneously breathing. I've never heard a complaint that the machine cuts off exhalation.

We have a number of members that use this class of machine, and I'm hoping they will kick-in their opinions.

[jbsix]

Could you elaborate on why 2.2 Ti shouldn't be exceeded?

The thread title saying AVAPS probably doesn't help with exposure...

[Sleeprider]

The inspiration time default is 1.8, and many of us have increased that. There is no hard rule you can't go more than 2.2, but give it a try before you increase beyond that. If you have a normal I:E ratio, then 2-seconds of inhalation and 3-sceonds of exhale will give you about 12 breaths per minute. Increasing Ti to 3 seconds would result in less than 10 BPM. It may be necessary for severe COPD in order to get the needed volume, but I would approach that kind of unusual inspiration time methodically and slowly, rather than all at once.

A procedure for setting Ti would be to set Ti at 1.8 (minimum). If the machine feels like it is switching from IPAP to EPAP too fast, than increase Ti in .1 increments. Don't increase Ti unless you get that "I wasn't done yet" sensations.

[PaytonA]

I would not exceed 2.0-2.2 on Ti. 8.0 is the low end of normal for BPM, 14 would be high. You want to find what works, but at some point that backup rate will kick in if you're not breathing. This is one of the thing the Resmed ASV does pretty well automatically is to sync with the user when they are spontaneously breathing. I've never heard a complaint that the machine cuts off exhalation.

We have a number of members that use this class of machine, and I'm hoping they will kick-in their opinions.

From what I get from reading through this thread again is that jbsix has a Philips Respironics ASV not a Resmed but maybe I have missed something.

Best Regards,

PaytonA