Why doesn't APAP respond to apneas?

Sorry, but for us num-nuts who are desperately tyring to follow the conversation but are failing miserably , could we ask one of you educate fellers to do another small summary post? Specifically, what the auto-BPM functionality do, and why does snoredog want to turn it off (sorry if i missed it in one of the previous posts!!) ? thanks

Echo, BPM is the machine's backup rate in Breaths Per Minute. When that backup rate or BPM is in auto mode, the machine will automatically maintain that value based on running averages of the patient's own spontaneous breaths.

Turning BPM from auto to manual means that you need to know not only the correct spontaneous breath rate, but just as importantly the correct pulse width or time that should be spent in inspiration. We can see on Bev's Encore charts a larger than acceptable spread between manual backup BPM of 10 and Bev's spontaneous machine-affected breath rate of 16.1 (now higher than before). We have absolutely no way of knowing how counterproductive the manual inspiratory time setting of 1.2 happens to be.... it's a blind guess also for lack of PSG instrumentation. And to continue making adjustments to manual BPM and manual IT short of a PSG simply flounders around in blind pilot mode IMO.

Snoredog's rationale, so far, for turning auto BPM off has been to get at that alluring but mysterious inspiratory setting of 1.2 seconds. He's not sure specifically why it shows up in literature so much, but the fact that it does apparently lends a measure of promise. The PSG titration charts recommend IT of 1.2 as a starting point for routine manual titration by clinicians who have PSG equipment to closely follow all the effects of manual titration changes. Snoredog's been wanting to try that alluring and mystical 1.2 second IT setting ever since he first laid eyes on it.

I think these experiments might have been better controlled if they were baselined and incremental. The more I think about it, the more I think shotgun changes are not the way to go. PSG certainly is the way to go. I would personally at least like to see those CPAP and BiLevel baseline measurements that should have been the experimental front-end before introducing small controlled deltas.

So, tonight I do your original night 1 from yesterday?
EPAP 14
IPAP Min 14
IPAP Max 14
When I do that, there is no BPM, TI or Rise Time. Correct?

Bev

That's correct, Bev. That gets us a measured CPAP baseline. Thanks.

I'm sure you meant that in the beginning. I was confused by the straight CPAP =14, and thought that meant back to the Auto in CPAP. Duh! See what foggy brain does to a person?

Bev

Bev, if CPAP@14 feels no worse than APAP@14-17, would you mind collecting CPAP@14 cm autoSV data until next weekend?

Specifically I would like to see how much night-to-night variability there is in your spontaneous breath rate and volumes. That data run thus gives us a much better idea of your spontaneous breath rates and volumes when not dysregulated (short of any unanticipated spikes in OSA) as well as measuring basic variability itself. I would also like to see if, during that week, you ever happen to machine-score PB, which I doubt.

If CPAP@14 feels less restorative than APAP at 14-17 then I suggest that you don't bother collecting a week's worth of data.

Sure, I can do that.

Bev, Are you starting to feel like a cpap experiment with dueling docs. The more I read the more confused I get lol. Hope you are understanding this stuff. lol It is good to get all the input if you can figure it out. But it sounds like you are on the right track. Good to know if I have a really hard time these folks sure can help me out. Melinda

Thanks -SWS! Every little bit of explanation helps

I'm confident that in the end we will find the right solution and I'm so grateful that these folks are willing to work with me. If it wasn't for this board, I would have been one of those folks who tried it for 30 days, if it didn't work, would have abandoned it.

I want to get this straight before I introduce another variable: Lyrica (unless, SWS,SAG, you think it would be okay to go ahead and start that)

Bev

Bev, if it were me I think I'd probably grab four nights or so baselining CPAP@14cm without Lyrica. Then I'd add the Lyrica for another three or four nights of CPAP@14cm while baselining.

I'd be looking with an eye toward night-to-night variability itself, including episodic spikes. I'd also be looking for a better established/measured spontaneous BPM and running nightly average volumes. The longer those two baselines are collected, the more reliable the data becomes related to general variability and episodic SDB spikes, if any.

I see no reason to wait, and would go back to your original settings (APAP 14 - 17 cmH2O), because:

1. I don't think prolonged time at 14 cmH2O is the correct choice because you'll end up leaving those persistent events (which my guess are REM-related obstructive apneas)(of course, you would need NPSG to confirm this) on the table.
2. I think you already have plenty of data on those baseline settings. That AHI is to die for.
3, I really don't see anything interesting coming out of prolonged monitoring in terms of respiratory values.
4. That data would be academic anyway because I think it's quite clear what your settings should be.
5. There is a school of thought that says that CSDB will resolve with acclimatization, and if that's the case, then these aggressive approaches may destabilize this (although I'll admit that the 14 cmH2O across on the SV proposed now is benign).
6. I really like what the pregabalin might do for the awakenings (Hindmarch 2005 showed 9.18 awakenings on pregabalin vs 27.10 on withdrawal night), and that's what I'm curious to see.
7. However, if the pregabalin does not improve sleep quality, then you run risk of compounding the sleepiness and/or fatigue. So my guess is that results (either positive or negative) should appear quickly.
8. And boy, you have a lot of N. symptoms, so I'm also really hatin' dial wingin' in this case just trying to pick up 1.2 AHI.

SAG

http://www.medicinenet.com/pregabalin_l ... rticle.htm

Generic name Pregabalin
Brand name = Lyrica.

Good luck, Bev.

O.

-SWS wrote: Snoredog, I disagree entirely about turning Auto BPM off that early.

that's easy to say after the fact,

-there was no Periodic Breathing in last night's report,
-Avg. Patient triggered breathing went from 85% to 98%, she also didn't stay very long in backup mode,
-so those fixed backup settings resolved the event that sent her there pretty quickly.
-Increase in HI was expected when you limit IPAP Max, that is the pressure that eliminates those.

My last suggestion is she go back on Aflex, she clearly did a lot better there.

Are you guys telling me that I just bought a real expensive door stop?

Bev