Vent - What Doctor Decided

General Discussion on any topic relating to CPAP and/or Sleep Apnea.
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Banned
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Re: Vent - What Doctor Decided

Post by Banned » Fri Apr 02, 2010 8:11 am

Madalot wrote:The problem I'm experiencing now is when I DON'T inhale on my own and the machine kicks in a breath. That's when we sometimes "argue." My breathing has slowed down enough that the machine kicks one in for me. So, it's pushing air and in the midst of that, I try to inhale on my own. That seems to be when the arguments occur.
Maybe SWS has a thought on that..
Madalot wrote:Last night was bad. And it DID seem that it was forcing air on me more often when I was trying to exhale.
I understand 2 sec IS much better compared to 1 sec. Why not give yourself a trial night at 1.9 sec? Or, maybe it just takes adapting, as people say. I still think you can tame this system.

The reason I keep harping on the small adjustments is that in the real world of AVAPS, a tenth of a second (.1 second) does make allot of difference.

I have some understanding what .1 second can do for your Inspiration Time. It's huge.
And I did get AHi 0, with a manual Breath Rate, manual Inspiration Time, and manual Rise Time in PC AVAPS mode.
AVAPS: PC AVAPS, EPAP 15, IPAP Min 19, IPAP Max 25, Vt 520ml, BPM 10, Ti 1.8sec, RT 2 (Garage)
BiPAP Auto SV: EPAP 9, IPAP Min 14, IPAP Max 25, BPM 10, Ti 2sec, RT 2 (Travel Machine)
VPAP Adapt SV: EEP 10.4, Min PS 4.4 (Every Day)
Mask: Quattro
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-SWS
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Re: Vent - What Doctor Decided

Post by -SWS » Fri Apr 02, 2010 9:17 am

Madalot wrote:My experience the last few nights seems to indicate that the Inspiration Time IS 2 seconds, but if I try to exhale before that, the machine usually lets me without much problem.
That part's good, Madalot. That says Ti, while running in S/T mode, is behaving only as an upper time limit or cap---as it should. So at least you no longer have the earlier problem whereby the machine prematurely cycles from IPAP to EPAP. Lengthening Ti gave you the latitude to inhale for longer than just a second. That's supposedly what patients with restrictive diseases most often need...

However, you still have this altogether different problem to solve:
Madalot wrote: And it DID seem that it was forcing air on me more often when I was trying to exhale.
That problem is not solved by Ti in any mode: Ti while running in S/T mode is about limiting inspiration time; and Ti while running in PC mode specifies a constant or fixed time value for IPAP. Again, adjusting Ti in either S/T or PC modes will not solve the problem of IPAP beginning too early, since Ti affects the post-trigger length of IPAP...

Now we need to look more closely at the machine parameters and usage scenarios that might cause IPAP to trigger prematurely. And somewhere among these scattered threads Madalot included her preliminary set values for machine trigger sensitivity...

P.S. Poll... Pole... clever, RG!
Last edited by -SWS on Fri Apr 02, 2010 9:24 am, edited 1 time in total.
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Banned
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Re: Vent - What Doctor Decided

Post by Banned » Fri Apr 02, 2010 9:21 am

Madalot wrote:
Dual Prescription: OFF
Mode: S/T
AVAPS: ON
Tidal Volume: 400 ml
IPAP Maximum Pressure: 23.0 cm H20
IPAP Minimum Pressure: 14.0 cm H20
EPAP: 6.0 cm H20
Breath Rate: 7 BPM
Inspiratory Time: 1.0 seconds
Trigger Type: Flow Trigger
Flow Trigger Sensitivity: 4.0 l/min
Flow Cycle Sensitivity: 20%
Rise Time: 2
Ramp Length: OFF
Circuit Disconnect: OFF
All Alarms (I'm not going to bother listing them all): OFF
AVAPS: PC AVAPS, EPAP 15, IPAP Min 19, IPAP Max 25, Vt 520ml, BPM 10, Ti 1.8sec, RT 2 (Garage)
BiPAP Auto SV: EPAP 9, IPAP Min 14, IPAP Max 25, BPM 10, Ti 2sec, RT 2 (Travel Machine)
VPAP Adapt SV: EEP 10.4, Min PS 4.4 (Every Day)
Mask: Quattro
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-SWS
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Re: Vent - What Doctor Decided

Post by -SWS » Fri Apr 02, 2010 9:28 am

Thanks much, Banned!

Madalot, when you get a chance in the upcoming days, would you mind sharing with us exactly what your manual says about these parameters:
Banned wrote:
Madalot wrote: Trigger Type: Flow Trigger
Flow Trigger Sensitivity: 4.0 l/min
Flow Cycle Sensitivity: 20%
We might be able to come up with some useful thoughts that you can discuss with your doctor and RT... In the meantime I'll revert to reading the non-Trilogy manuals that I happen to have on hand.
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Madalot
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Re: Vent - What Doctor Decided

Post by Madalot » Fri Apr 02, 2010 9:42 am

-SWS wrote:Thanks much, Banned!

Madalot, when you get a chance in the upcoming days, would you mind sharing with us exactly what your manual says about these parameters:
Banned wrote:
Madalot wrote: Trigger Type: Flow Trigger
Flow Trigger Sensitivity: 4.0 l/min
Flow Cycle Sensitivity: 20%
We might be able to come up with some useful thoughts that you can discuss with your doctor and RT... In the meantime I'll revert to reading the non-Trilogy manuals that I happen to have on hand.
Yes, I'll do that. Give me a while and I'll try to copy the information on these settings directly out of the manual.

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Madalot
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Re: Vent - What Doctor Decided

Post by Madalot » Fri Apr 02, 2010 10:51 am

Okay -- Here is the information on those 3 settings:

Trigger Type: The device can be set to trigger breaths based on automatic flow thresholds or specific flow settings. You can select either Auto-Trak or Flow Trigger as the Trigger Type. When Auto-Trak is selected, the Auto-Trak trigger initiates based on automatic flow thresholds. When Trigger Type is set to Flow Trigger, Flow Trigger Sensitivity and Flow Cycle Sensitivty become active and the trigger initiates based on the Flow Trigger Sensitivity Setting.

Flow Trigger Sensitivity: Flow Trigger is the initiation of inspiration when the patient's inspiratory effort causes flow to increase by the Flow Trigger Sensitivity Setting. If you set the Trigger Type to Flow Trigger, the Flow Trigger Sensitivity Setting displays. You can increase or decrease the setting from 1 to 9 l/min in 1 l/min increments. A flow trigger occurs when this value is set to any setting from 1 to 9, the ventilator is in exhalation phase, the minimum exhalation time has expired and the flow increases by the Flow Trigger Sensitivity Setting.

Flow Cycle Sensitivity: If you set the Trigger Type to Flow Trigger, the Flow Cycle Sensitivity setting displays. You can increase or decrease the setting from 10 to 40 percent (%) in 1% increments.

I pulled this directly out of the manual. Now you'll have to excuse me while I shake the cobwebs out of my brain after copying this. It doesn't make any sense to me!!

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ozij
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Re: Vent - What Doctor Decided

Post by ozij » Fri Apr 02, 2010 11:18 am

Madalot wrote:Okay -- Here is the information on those 3 settings:
Flow Trigger Sensitivity: Flow Trigger is the initiation of inspiration when the patient's inspiratory effort causes flow to increase by the Flow Trigger Sensitivity Setting. If you set the Trigger Type to Flow Trigger, the Flow Trigger Sensitivity Setting displays. You can increase or decrease the setting from 1 to 9 l/min in 1 l/min increments. A flow trigger occurs when this value is set to any setting from 1 to 9, the ventilator is in exhalation phase, the minimum exhalation time has expired and the flow increases by the Flow Trigger Sensitivity Setting.
If I understand this correctly, then your machine is slightly trigger happy some of the time, and responds at the merest whiff of change, when you're actually not ready to inhale yet. You're exhaling, the minimum time has passed, and there's a change in your exhalation making the machine revert to inhale pressure, even though that change does not indicate you're back to inhaling. Hence the argument.
Flow Cycle Sensitivity: If you set the Trigger Type to Flow Trigger, the Flow Cycle Sensitivity setting displays. You can increase or decrease the setting from 10 to 40 percent (%) in 1% increments.
This one is beyond me.

O.

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-SWS
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Re: Vent - What Doctor Decided

Post by -SWS » Fri Apr 02, 2010 11:35 am

Trilogy Manual wrote: When Auto-Trak is selected [that's the 1st trigger type], the Auto-Trak trigger initiates based on automatic flow thresholds. When Trigger Type is set to Flow Trigger [that's the second trigger type available], Flow Trigger Sensitivity and Flow Cycle Sensitivty become active and the trigger initiates based on the Flow Trigger Sensitivity Setting.
Madalot wrote:And it DID seem that it was forcing air on me more often when I was trying to exhale.
Flow-trigger sensitivity is the very first parameter that clinicians must select to make sure the machine transitions or triggers from EPAP to IPAP just right---not prematurely nor too late. That threshold flow value needs to be set just right---especially amidst leaks. And, as the name implies, the algorithm senses HOW MUCH patient-sourced flow needs to be present in order to correctly trigger that EPAP-to-IPAP machine transition that's currently not working very well.

Here's the bearing leaks have regarding false/premature triggering from EPAP to IPAP: no mask leaks mean that the 4.0l/min flow value really was patient-sourced (the trigger over to IPAP was thus warranted); however mask leaks that happen to exceed expiratory patient flow by 4.0l/min or greater, will falsely trigger IPAP when the machine happens to be set to that manual threshold value of 4.0l/min.

However, Auto-Trak is the OTHER flow-trigger type available. And rather than pinning that threshold down to a manually-set 4.0l/min threshold, the Auto-Trak algorithm will try to determine the best sensitivity threshold amidst leaks and patient variability. However, Auto-Trak can compensate for patient variability and leaks only within reasonable limits.

Regardless, the first thing I would try is setting flow trigger to Auto-Trak rather than a manual setting. There's a chance the Auto-Trak algorithm might match your natural cycles and leak tendencies better than a manual hard-coded threshold of 4.0l/min. We can also discuss the manual subordinate parameters a bit. But I'd personally be very inclined to see how the machine triggers and cycles when you allow the algorithm to do its job by selecting Auto-Trak instead...

If Auto-Trak proved inadequate, THEN I would turn on manual Flow Trigger mode once again, and consider making necessary manual sensitivity adjustments.
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Re: Vent - What Doctor Decided

Post by jnk » Fri Apr 02, 2010 12:15 pm

Madalot,

As I understand it, "trigger" means "starting the breathe-in pressure" and "cycle," in this context, might mean "starting the breath-out pressure." So I read those instructions mostly to mean the following: 'In order for the machine to know when a patient has started a breath, you can EITHER let the machine figure out how best to do that OR simply specify a certain amount of change in air movement the machine has to sense before it increases pressure. Then specify how much of a change in air movement the machine needs to sense before it decreases the pressure.' That is likely a gross oversimplification that hopefully -SWS or Ozij will correct if I am too far off.

jeff
Last edited by jnk on Fri Apr 02, 2010 12:20 pm, edited 1 time in total.
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-SWS
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Re: Vent - What Doctor Decided

Post by -SWS » Fri Apr 02, 2010 12:20 pm

Well, Jeff is right regarding how Respironics uses the terms "trigger" and "cycle":
AVAPS Manual wrote:Cycle- The transition from inspiration to expiration
Trigger- The transition from expiration to inspiration
And here we can see how Respironics employs that same "trigger" and "cycle" usage:
Trilogy Manual wrote: Flow Trigger is the initiation of inspiration when the patient's inspiratory effort causes flow to increase by the Flow Trigger Sensitivity Setting.

My advice is to still evaluate and compare how well/poorly Auto-Trak might be able to automatically match your triggers, cycles, and leaks, Madalot. But if you revert or stay with manual "Flow Trigger" (instead of using Auto-Trak) then let's work out the details of those subordinate parameters toward avoiding as many premature EPAP-to-IPAP transitions as possible...

on edit: I just had to straighten out my own wrong definitions and quotes...

P.S. Thanks, Jeff!
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Re: Vent - What Doctor Decided

Post by jnk » Fri Apr 02, 2010 12:41 pm

Seems to me that the definitions can sometimes change a bit, depending on whether they are talking about machine-controlled breathing or patient-controlled breathing. All I know is that it ain't exactly English. RT-Speak and Manufacturer-Speak often sound like two different obscure dialects of Klingon.
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Re: Vent - What Doctor Decided

Post by -SWS » Fri Apr 02, 2010 12:50 pm

-SWS wrote:Regardless, the first thing I would try is setting flow trigger to Auto-Trak rather than a manual setting.
Madalot, I think there's something I would double check even before asking the doctor and RT for permission to try Auto-Trak...

I would double check that the Trilogy's LCD set-up menu happens to agree with the type of exhalation port my RT installed in the machine's hardware. If the clinician installed a passive port, then the LCD set-up menu needs to agree with that passive "Circuit Type". Conversely, if the clinician installed an active port instead (unlikely and unwarranted), then the LCD menu would reflect an active "Circuit Type":
http://trilogy100.respironics.com/pdf/T ... tGuide.pdf


Awe, Jeff... Klingons aren't so bad.... at least not since the alliance treaty. Now those Romulan bastards, on the other hand....
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Madalot
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Re: Vent - What Doctor Decided

Post by Madalot » Fri Apr 02, 2010 6:13 pm

-SWS wrote:
-SWS wrote:Regardless, the first thing I would try is setting flow trigger to Auto-Trak rather than a manual setting.
Madalot, I think there's something I would double check even before asking the doctor and RT for permission to try Auto-Trak...

I would double check that the Trilogy's LCD set-up menu happens to agree with the type of exhalation port my RT installed in the machine's hardware. If the clinician installed a passive port, then the LCD set-up menu needs to agree with that passive "Circuit Type". Conversely, if the clinician installed an active port instead (unlikely and unwarranted), then the LCD menu would reflect an active "Circuit Type":
http://trilogy100.respironics.com/pdf/T ... tGuide.pdf


Awe, Jeff... Klingons aren't so bad.... at least not since the alliance treaty. Now those Romulan bastards, on the other hand....
I had to look at the documentation on this link because I couldn't find where it listed this. Now I see why!! I'll access it tomorrow to check the setting.

I've been messing with my van today. We purchased a modified mini van last year (for my powerchair) and it's malfunctioning badly. I've been on the phone all day today trying to figure out how to get it back to the dealer to get it fixed. LONG story, but I haven't had time to mess with the ventilator. And now, I'm bushed.

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Re: Vent - What Doctor Decided

Post by Madalot » Sat Apr 03, 2010 4:03 pm

-SWS wrote:
-SWS wrote:Regardless, the first thing I would try is setting flow trigger to Auto-Trak rather than a manual setting.
Madalot, I think there's something I would double check even before asking the doctor and RT for permission to try Auto-Trak...

I would double check that the Trilogy's LCD set-up menu happens to agree with the type of exhalation port my RT installed in the machine's hardware. If the clinician installed a passive port, then the LCD set-up menu needs to agree with that passive "Circuit Type". Conversely, if the clinician installed an active port instead (unlikely and unwarranted), then the LCD menu would reflect an active "Circuit Type":
http://trilogy100.respironics.com/pdf/T ... tGuide.pdf
-SWS --

Sorry it took me so long to do this. I just checked and it's definitely Passive.

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Re: Vent - What Doctor Decided

Post by newhosehead » Sat Apr 03, 2010 6:31 pm

Kathy,
Any progress with getting your van fixed?
Jeanette
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