Keeping em breathing or using the vent?

[me454555]

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Finally, after lurking w/an occasional post or 2, I've begun my CA-1 year and I actually have a clinical question to contribute to the forum 😱

Let's say you've intubated a patient and he starts breathing on their own but you got another hr or so left in the case. Do you guys like to push the roc and keep em vented or just let em breath their way through the case assuming the surgeon don't have a problem w/it?

I would think there would be some physiologic benfit to keeping the patient breathing on their own w/a CO2 in the 40s or 50s as much as possible. Increased cardiac output b/c you have negative pressure ventilation, better oxygen delivery in the slighlty acidic environment, better brain profusion b/c of autoregulation.

What do the pros think about this? Does it even matter to you?

 

[militarymd]

Finally, after lurking w/an occasional post or 2, I've begun my CA-1 year and I actually have a clinical question to contribute to the forum 😱

Let's say you've intubated a patient and he starts breathing on their own but you got another hr or so left in the case. Do you guys like to push the roc and keep em vented or just let em breath their way through the case assuming the surgeon don't have a problem w/it?

I would think there would be some physiologic benfit to keeping the patient breathing on their own w/a CO2 in the 40s or 50s as much as possible. Increased cardiac output b/c you have negative pressure ventilation, better oxygen delivery in the slighlty acidic environment, better brain profusion b/c of autoregulation.

What do the pros think about this? Does it even matter to you?

I love residents.

 

[Bertelman]

I love residents.

Remember, we get this crap shoved down our throats by academic attendings.

 

[me454555]

I love residents.

So I guess thats your way of saying it doesn't matter?

 

[cchoukal]

A couple thoughts:

1) depends on the surgery. If they're in the abdomen, and the higher respiratory rate or irregular contractions of the diaphragm are making it harder to work, I'd continue paralysis (or deepen the anesthetic, or over-breathe them, or whatever).

2) If the pt was unable to support their oxygenation and ventilation with whatever minute ventilation they could achieve, and if my vent didn't have pressure support, or if they were non-compliant with PS, I'd consider continuing paralysis.

3) there's data to suggest that even short periods of mandatory ventilation (like that administered to a paralyzed patient whose diaphragm is not participating) can have profound atrophic effect on diaphragmatic myocytes, which makes me think spontaneous ventilation in appropriate patients undergoing appropriate surgeries might be the way to go, but the clinical outcomes of such atrophy are uncertain.

Short answer: depends on the patient and the surgery.

 

[pgg]

So I guess thats your way of saying it doesn't matter?

It sort of matters if you let them breathe on their own through a 7 mm straw for a long time and they get atelactatic. Stick an ETT in your mouth sometime and see how long you can comfortably breathe through it. If your vent can do PS you can avoid that extra work and atelectasis.

It might matter if your surgeon "needs" paralysis.

I don't believe any of that oxy-Hb dissociation curve shifting and negative intrathoracic pressure physiologic stuff makes any difference at all, but I'll bet someone out there has written a board question about it.

 

[militarymd]

What cchoukal said.

It does matter, but it's not what you said up there.

It's a gestalt when you're doing the case....

 

[jennyboo]

I usually throw on 5-10 of PEEP and pressure support and let em breathe unless asked for apnea or paralysis by surgeon or attending anesthesiologist. I wouldn't reparalyze or hyperventilate to cause apnea if there's just an hour left (if there's six hours, maybe I would).

No magic formula. Whatever I think will make the wake-up fast.

 

[Mapleson D]

A related question - what *really* happens when you partially close the pop-off valve for a spontaneously breathing patient? One of my attendings said "just dial down the pop-off valve" when I asked if our anesthesia machines had a pressure support setting, but it seems to me like closing the pop-off is really adding PEEP.

 

[jennyboo]

A related question - what *really* happens when you partially close the pop-off valve for a spontaneously breathing patient? One of my attendings said "just dial down the pop-off valve" when I asked if our anesthesia machines had a pressure support setting, but it seems to me like closing the pop-off is really adding PEEP.

Hmm. The old Ohmeda machines had a true pop-off valve where you flip the switch between volume controlled ventilator (which bypasses the reservoir bag) and spontaneous breathing (which goes thru the bag). You could add PEEP by using a PEEP valve to the circuit, or I think if you have a spontaneously breathing patient who is NOT on the vent (pop-off is turned so the bag fills) you can add PEEP by using a PEEP valve OR by dialing down the popoff. But this machine does NOT have a pressure support function.

In newer machines that have pressure support, there is typically a Pressure Support button (next to other options such as Volume Ctrl, Pressure Ctrl, and Manual/Spontaneous). Either your machine doesn't have it or your attending didn't want you to use it and therefore didn't realize you were trying to learn how to turn on the PSV.

 

[deleted50478]

Simv

 

[Arch Guillotti]

A related question - what *really* happens when you partially close the pop-off valve for a spontaneously breathing patient? One of my attendings said "just dial down the pop-off valve" when I asked if our anesthesia machines had a pressure support setting, but it seems to me like closing the pop-off is really adding PEEP.

Sounds like CPAP to me.

 

[Arch Guillotti]

Finally, after lurking w/an occasional post or 2, I've begun my CA-1 year and I actually have a clinical question to contribute to the forum 😱

Let's say you've intubated a patient and he starts breathing on their own but you got another hr or so left in the case. Do you guys like to push the roc and keep em vented or just let em breath their way through the case assuming the surgeon don't have a problem w/it?

I would think there would be some physiologic benfit to keeping the patient breathing on their own w/a CO2 in the 40s or 50s as much as possible. Increased cardiac output b/c you have negative pressure ventilation, better oxygen delivery in the slighlty acidic environment, better brain profusion b/c of autoregulation.

What do the pros think about this? Does it even matter to you?

I am not a pro but I can give you my opinion.

I don't think that it makes that big of a difference. All the physiology stuff MMD is giving you a hard time about probably doesn't make a difference either. My opinion is that whatever you do, STICK WITH IT. Don't keep the them paralyzed w/normal CO2 till the end of the case then flip the vent off and expect them to breath w/reversal. I HATED it when attendings would come in and do that. Blow it off and wait till they wake up. When they wake up flip them over and see what they can do on their own. Or get them breathing on pressure support and titrate in narcotics. I like this method a little better (I think). I think that the wake up is a little smoother. Narcotic titration is ok but not infallible for a smooth comfortable wake up.