Vent - What Doctor Decided

-SWS wrote:Increasing rise time makes for a more gradual pressure-assist slope during inspiration---which in turn marginally diminishes minute ventilation.

So be it,
but decrease the Inspiration Time and marginally increase minute ventilation.
Hence, break-even.

Banned wrote:

-SWS wrote:Increasing rise time makes for a more gradual pressure-assist slope during inspiration---which in turn marginally diminishes minute ventilation.

So be it,
but you decrease the Inspiration Time and marginally increase minute ventilation.
Hence, break-even.

It doesn't work that way, Banned. In the past you mistakenly claimed those two were additive. Rise time is nested inside of Ti. you don't add those two numbers together...

Also I never saw anywhere in this thread where Ti=1.9 seconds was substantiated in any way with technical rationale. Did I miss a post? I probably did...

-SWS wrote:It doesn't work that way, Banned. In the past you mistakenly claimed those two were additive. Rise time is nested inside of Ti. you don't add those two numbers together...

You are correct. In the literature you do not add these two numbers together.

But, let's wait until Madalot actually increases her Rise Time to 4 and decreases her Inspiration Time to 1.9 sec.
It would not be unlikely that she would need to further decrease Inspiration Time to 1.8 sec to accommodate RT 4.
You say not possible, I say quite probable.

-SWS wrote: I never saw anywhere in this thread where Ti=1.9 seconds was substantiated in any way with technical rationale. Did I miss a post? I probably did...

You may have missed this, which she has been repeating daily.

Madalot wrote:There are also times I'm trying to exhale and its pushing air.

My good sir, You really do not want this lady deploying PC AVAPS at Ti 2.0 sec.

I want to remind everyone that at this time, my doctor has decided NO to switching to PC mode. At this stage, she feels that S/T AVAPS is providing me adequate therapy. I have asked that we continue "tweeking" to make the settings more comfortable for me, but at this time, the settings are staying at S/T AVAPS.

Banned wrote: You may have missed this, which she has been repeating daily.

Madalot wrote:There are also times I'm trying to exhale and its pushing air.

Thanks, Banned. I didn't miss that one. However, it's entirely irrelevant to Ti. Recall that shortening Ti works on the timing of the IPAP-to-EPAP transition ("cycling" to EPAP). However, the above is actually a problem with the EPAP-to-IPAP transition instead ("triggering" to IPAP). You don't adjust Ti for that...

For the above problem while in S/T mode, you either lower BPM to allow more time before IPAP's backup rate kicks in, or you adjust "trigger" flow sensing (assuming leaks are already very well-controlled, that is). A great way to experimentally adjust "IPAP trigger" flow sensing (and even compensate for leaks) is to turn on AutoTrak. Madalot's backup rate is already set low at 7 BPM.

Banned wrote:My good sir, You really do not want this lady deploying PC AVAPS at Ti 2.0 sec.

Actually PC mode is so very time-rigid about delivering inspiration that---like Madalot's doctor---I think it's worth trying to avoid if S/T mode can be tweaked to work well. For some patients who cannot tolerate that rigidity, PC and timed modes can sometimes create more problems than they solve. IMHO it really makes sense to try and get S/T mode working first---and that includes seeing if Madalot's own naturally defensive airway reflexes acclimate or become "less argumentative" with the machine. If she can comfortably settle into that machine with S/T mode while SpO2 stays good, that would be superb.

That said, if either PC mode or timed mode becomes a next-logical-step to try, then Ti should really be calculated based on normal spontaneous BPM and measured I:E ratios...

Madalot wrote:I want to remind everyone that at this time, my doctor has decided NO to switching to PC mode. At this stage, she feels that S/T AVAPS is providing me adequate therapy. I have asked that we continue "tweeking" to make the settings more comfortable for me, but at this time, the settings are staying at S/T AVAPS.

I agree with your doctor, Madalot.

So, Madalot deploys Auto-TRAK only during her first trials, but continues to complain of:

Madalot wrote:There are also times I'm trying to exhale and its pushing air.

What then?

Cross that hypothetical bridge when it ceases to be just that...

Good Luck.

Banned, see my very last sentence in this post: Banned's Hypothetical Bridge.

...But screwing around with Ti makes absolutely no sense for any premature IPAP trigger problem. Adjusting Ti makes sense for timeliness-of-cycling to EPAP problems instead.

And this physiologic-adaptation objective can sometimes take a couple or more months:

to try and get S/T mode working first---and that includes seeing if Madalot's own naturally defensive airway reflexes acclimate or become "less argumentative" with the machine. If she can comfortably settle into that machine with S/T mode while SpO2 stays good

Not a fantastic wait for impatient or avid message board readers. Opportunity for physiologic adaptation is probably why Madalot's doctor would like to allow Madalot time to settle in.

Our disparity lies in your belief that Madalot has only a premature IPAP trigger problem.

I believe Madalot has a 1) premature IPAP trigger problem, a 2) timeliness-of-cycle to EPAP problem, and a 3) Rise Time problem.

If Madalot could cure all her ills with Auto-TRAK, I would be very happy.

Banned wrote:Our disparity lies in your belief that Madalot has only a premature IPAP trigger problem.

I believe Madalot has a 1) premature IPAP trigger problem, a 2) timeliness-of-cycle to EPAP problem, and a 3) Rise Time problem.

Actually that's not the case at all, Banned. You cited premature IPAP trigger when I asked you why you wanted to decrease Ti. My ensuing comments were merely relevant to explaining why those two didn't go together after all.

I suspect Madalot has additional patient/machine synchronization issues. And that is why I asked her to try to better discern sequencing in the last paragraph here: viewtopic.php?f=1&t=50789&start=60#p469107

If Madalot could cure all her ills with Auto-TRAK, I would be very happy.

Well, as it turns out AutoTrak attempts to manage flow sensitivity for BOTH transitions: 1) "triggering" to IPAP, and 2) "cycling" to EPAP. So it's a darn good thing to try next IMHO. The good news is that AutoTrak works well for most people. The bad news is that AutoTrak works poorly for others such as myself. I normally use APAP. But when I tried M-Series auto BiPAP, the AutoTrak algorithm in spontaneous mode read me poorly. I don't exactly view it as a respiratory panacea... But it really makes sense to try under these circumstances IMHO...

...Because I have been reminded by Banned that Madalot "daily" reports a premature IPAP triggering problem.

Banned wrote:

-SWS wrote: I never saw anywhere in this thread where Ti=1.9 seconds was substantiated in any way with technical rationale. Did I miss a post? I probably did...

You may have missed this, which she has been repeating daily.

Madalot wrote:There are also times I'm trying to exhale and its pushing air.

-SWS wrote: . . . The good news is that AutoTrak works well for most people. The bad news is that AutoTrak works poorly for others such as myself. I normally use APAP. But when I tried M-Series auto BiPAP, the AutoTrak algorithm in spontaneous mode read me poorly. . . .

Interestingly, I believe Madalot's first post to this board described a similar experience with the same machine. ( viewtopic.php?f=1&t=48795&p=445871#p445871 ) But I agree that trying AutoTrak may be a logical thing to do, now that she has a backup rate.

jeff

jnk wrote:

-SWS wrote: . . . The good news is that AutoTrak works well for most people. The bad news is that AutoTrak works poorly for others such as myself. I normally use APAP. But when I tried M-Series auto BiPAP, the AutoTrak algorithm in spontaneous mode read me poorly. . . .

Interestingly, I believe Madalot's first post to this board described a similar experience with the same machine. ( viewtopic.php?f=1&t=48795&p=445871#p445871 ) But I agree that trying AutoTrak may be a logical thing to do, now that she has a backup rate.

jeff

Coincidence... I have also been thinking about that aspect of Madalot's spontaneous BiLevel experience a lot lately.

As a side note, my own breathing failure with AutoTrak was the opposite of what Madalot described in that early thread. Mine was a bizarre case of over triggering---let alone in spontaneous mode ---while Madalot's was initially a case of not triggering. But she now has a backup rate to counter her moments of not triggering IPAP as you well point out, Jeff.

IMHO now would be a great time to see if AutoTrak can automatically maintain trigger and cycle sensitivity thresholds for her, so that she does not continue to over-trigger or over-cycle as she seems to be doing lately with those manual flow-based sensitivity settings. I suspect her RT bypassed Trilogy AutoTrak simply because Madalot did not effectively trigger her first spontaneous-mode machine. However, the challenge with throwing multiple experimental respiratory changes or deltas into the pot all at once, is how hard any "catch all" or "multiple change" method can be to discern the desirable/adverse effects of any one implemented change...

Popping in here for a minute -- still haven't heard from my doctor or RT yet. Technically, my RT has about another 15 minutes to call me to ahere to the "24-hour window" she's supposed to return my calls in. But I digress.....

I have to be honest here and say that a lot of the last few posts have been so over my head that my head is spinning and my eyes are popping out of their sockets!!

As I've said, I think there are so many variables and options. And I think there could be arguments for all the "scenarios" mentioned here as valid. We'll just have to wait and see what my RT & doctor think and decide.

Last night wasn't bad at all. I don't recall any "arguments." Go figure. I think this is one of the things that makes this so frustrating. Just like my muscle weakness in my arms and legs, the breathing issue can be (and is) variable from night to night, thus making treatment options difficult to pin down.

Madalot wrote:We'll just have to wait and see what my RT & doctor think and decide.

Always, Madalot. Always.