Which gas to use...

[thiloe]

CA-1 here,
just curious, I keep sharing pre-op plans with my attendings and kind of select an anesthesia gas almost at random for the case with a few guiding tenets I list below. I noticed I've developed this feeling that "it doesn't matter which you choose" and I'm uncomfortable I am getting that feeling because I liken that with laziness and ambivalence. I want some better grounds for my choices because currently I find myself just bouncing between sevo and iso, whatever is on the machine at the time. Does it start to make a difference later in more complex anesthesia that I haven't gotten to yet since I'm still pretty early in residency?

Thusfar, my personally developed tenets have been:

Desflurane:
-Expensive so try not to use it unless the attending feels that's the one to use
-No des for pts with reactive airways diseases
-Outpatient ambulatory
-Pungent

Sevo:
-Basically my go-to
-Can do inhaled induction with it
-Gas is fast off-loaded if case is < 2h then it starts to accumulate
-Need to run flows >2 L/min if case is >2h

Iso:
-Cheap (so desireable by the higher ups if we use it) but requires skill to wake up with it alone
-Depots a long time so need to be good about timing
-Pungent

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[waterhammer]

Sounds about right.

Des is not that expensive if you use low flows. Don't usually get tachycardia either, unless you overpressurize.

 

[Pooh & Annie]

The RAD stuff with Des is with high concentrations. Maintenance of anesthesia around a MAC doesn't seem to put them at risk any more than sevo does. Fentanyl has also been shown to blunt the potential for RAD.
That being said, folks with RAD (young ones especially), might have an episode no matter what you give them. Better to not have the Des on board when there are plenty of people who'll spout the dogma to make you look bad.

 

[OB1🤙]

So isoflurane is dirt cheap and lasts a long time, this makes it ideal for cases in which the patient will stay intubated afterward. So cardiac, livers, traumas, etc.

A good anesthesiologist *can* do any case with iso, not that they'd *want* to. Nitrous makes iso wakeups more predictable.

Des vs. sevo- I'm a des guy for these reasons: it is significantly faster off than sevo, and there's no dumb medicolegal issue with running low flows. The reactive airway issue is one of academic concern only- I do all my thoracic cases with des, they're all lifelong smoker/copders, and it just isn't a problem. If someone was in status asthmaticus, maybe then sevo over des.

That said, sevo is a fine gas. It's just slower than des. As you should have been taught, the issue with mandatory 2 lpm flows is all nonsense. Compound A-mediated nephrotoxicity is not a thing in humans. But people do it because lawyers. As has been mentioned, des at 0.5 lpm is not more expensive than sevo at 2 lpm.

Regarding low flow anesthesia- it is well worth your while to go through this presentation on it. We waste a TON of expensive gas on higher flows and it drives me nuts. There is a goldmine of excellent stuff in here.

http://etherweb.bwh.harvard.edu/education/PHILIP/Tech_Block_04/1_LowFlowO2Agt.pdf

 

[epidural man]

My algorithm

Patient A with this and that and that and this = Des
Patient B with that and this, or and this and that = Des
Patient C with also this, and that and that and this = Des
Patient D with.....(well you get my point)
Patient E using an LMA and is a smoker - CONSIDER not using DES
Patient F = needs mask induction ...induce with sevo, likely switch to DES


DES is just as potent bronchodilator as any other volatile anesthetic - but as you mentioned more pungent at initial exposure - know this and work around it.

 

[epidural man]

By the way, MANY people feel VERY dogmatic about what gas they use...they have their anecdotal evidence that for them proves everything. My suggestion is - when your attendings (and folks on this forum) kick and scream and make their dogmatic argument about why this or that gas is better and works just as well, and with talent you can wake anyone up with iso just as quick, etc - smile, agree...and pay attention.

And here is what you need to pay attention to. Most anesthesiologists HAVE NO CLUE about what the patient looks like in the PACU moments after they drop them off - and this is okay. They are busy and they need to move to the next case. It isn't our job to sit around and learn what our work looks like 20 minutes after leaving the PACU.

HOWEVER, as a resident, you have a very unique opportunity when you do your PACU rotation (I hope you get to do it...I loved my month as the PACU resident). PAY ATTENTION!

You will notice something that is as clear as night and day. Patients that come out of anesthesia on Sevo and Iso are extremely groggy for a LONG time...a very LONG time (of course ISO is way worse than SEVO) - and it doesn't matter that the attending was able to wake them up on que with iso. What matters is that 2 hours latter - and I have seen and heard MANY patients complain - the patient will say...."UGH...I feel so tired...I just can't seem to wake up!" ...and it is often very annoying to them.

However, pay attention to the DES patients. within 15 minutes, it is like they didn't even have anesthesia. They are awake and ready to go! If you do my anesthesia, that is what I want. I don't want to feel like crap for 24 hours as the iso slowly leaves the fat behind my eyeballs.

Let me remind you again....lots of strong feelings about this...but you silently pay attention...take notes...and then practice how YOU would want anesthesia done to you.

 

[OB1🤙]

My algorithm

Patient A with this and that and that and this = Des
Patient B with that and this, or and this and that = Des
Patient C with also this, and that and that and this = Des
Patient D with.....(well you get my point)
Patient E using an LMA and is a smoker - CONSIDER not using DES
Patient F = needs mask induction ...induce with sevo, likely switch to DES


DES is just as potent bronchodilator as any other volatile anesthetic - but as you mentioned more pungent at initial exposure - know this and work around it.

By the way, MANY people feel VERY dogmatic about what gas they use...they have their anecdotal evidence that for them proves everything. My suggestion is - when your attendings (and folks on this forum) kick and scream and make their dogmatic argument about why this or that gas is better and works just as well, and with talent you can wake anyone up with iso just as quick, etc - smile, agree...and pay attention.

And here is what you need to pay attention to. Most anesthesiologists HAVE NO CLUE about what the patient looks like in the PACU moments after they drop them off - and this is okay. They are busy and they need to move to the next case. It isn't our job to sit around and learn what our work looks like 20 minutes after leaving the PACU.

HOWEVER, as a resident, you have a very unique opportunity when you do your PACU rotation (I hope you get to do it...I loved my month as the PACU resident). PAY ATTENTION!

You will notice something that is as clear as night and day. Patients that come out of anesthesia on Sevo and Iso are extremely groggy for a LONG time...a very LONG time (of course ISO is way worse than SEVO) - and it doesn't matter that the attending was able to wake them up on que with iso. What matters is that 2 hours latter - and I have seen and heard MANY patients complain - the patient will say...."UGH...I feel so tired...I just can't seem to wake up!" ...and it is often very annoying to them.

However, pay attention to the DES patients. within 15 minutes, it is like they didn't even have anesthesia. They are awake and ready to go! If you do my anesthesia, that is what I want. I don't want to feel like crap for 24 hours as the iso slowly leaves the fat behind my eyeballs.

Let me remind you again....lots of strong feelings about this...but you silently pay attention...take notes...and then practice how YOU would want anesthesia done to you.

Agree 100%!

 

[Ezekiel2517]

Since you're a CA-1, I'd recommend laying off the Des for the time being. It's sorta idiot proof. Practice using Iso and Sevo for different types of cases and learning how to wake pts up on them. As a resident I'd use Iso with low flows and learned how to wake pts up very quickly on it. Just try different things and learn from them, especially when you're on call and doing those meaningless choles/appys. Also, you may end up going someplace that doesn't have Des so its good to be slick with Sevo/Iso

 

[geauxg8rs]

At the end of the day you are a CA-1 dealing with academic attendings. So you will be wrong a lot(even though the true answer often is it doesn't make a difference). Just suck it up and massage their academic ego!

 

[pgg]

Hawaiian Bruin and epidural man said everything I was going to say.

Desflurane is not more costly and has significant benefits. I use it for nearly everyone I plan to wake up.


Here we are, 2 months into the academic year, and I worked with a CA1 the other day who's never used it. There's still a desflurane dogma stigma out there.


It may be associated with more emergence delirium in kids, because the abrupt wakeup can be disorienting. I don't find it to be any worse than sevo though with a bit of opiate on board, and a parent in PACU right away.

 

[Docuronium]

Regarding low flow anesthesia- it is well worth your while to go through this presentation on it. We waste a TON of expensive gas on higher flows and it drives me nuts. There is a goldmine of excellent stuff in here.

http://etherweb.bwh.harvard.edu/education/PHILIP/Tech_Block_04/1_LowFlowO2Agt.pdf

I appreciate it, but wow that powerpoint is hard to read through---if there's somewhere that the lecture itself is hosted that'd be great.

 

[Planktonmd]

It makes no difference what inhaled agent you use and you can achieve the exact same results with any of them if you know what you are doing. And by the way they are not "Gases", they are vapors.

 

[Pooh & Annie]

Every time we have these kind of discussions we need to start throwing down some cash bets on how long before the mandatory "if you're as good as me you can do anything with anything" response.

 

[dhb]

Des takes 20 years to degrade in the atmosphere so i use Sevo

 

[Planktonmd]

Every time we have these kind of discussions we need to start throwing down some cash bets on how long before the mandatory "if you're as good as me you can do anything with anything" response.

No not if you are as good as me, if you are good at all you should be able to use any vapor !

 

[pgg]

Des takes 20 years to degrade in the atmosphere so i use Sevo

I like warm weather.

 

[narcusprince]

Your groggy patients may not be groggy if you do not use versed...... I like to start with sevo and switch to Des. If the case is long and no need to extubate IE free flap case or transplant iso all the way.

 

[OB1🤙]

When I hear the greenhouse gas argument from vegans who either bike or take public transit to work, I respect it.

Otherwise, eh, not so much. The farts from the cows you get your steak or milk from warm the atmosphere one whole hell of a lot more than low flow desflurane does.

 

[CriTICAL]

By the way, MANY people feel VERY dogmatic about what gas they use...they have their anecdotal evidence that for them proves everything. My suggestion is - when your attendings (and folks on this forum) kick and scream and make their dogmatic argument about why this or that gas is better and works just as well, and with talent you can wake anyone up with iso just as quick, etc - smile, agree...and pay attention.

And here is what you need to pay attention to. Most anesthesiologists HAVE NO CLUE about what the patient looks like in the PACU moments after they drop them off - and this is okay. They are busy and they need to move to the next case. It isn't our job to sit around and learn what our work looks like 20 minutes after leaving the PACU.

HOWEVER, as a resident, you have a very unique opportunity when you do your PACU rotation (I hope you get to do it...I loved my month as the PACU resident). PAY ATTENTION!

You will notice something that is as clear as night and day. Patients that come out of anesthesia on Sevo and Iso are extremely groggy for a LONG time...a very LONG time (of course ISO is way worse than SEVO) - and it doesn't matter that the attending was able to wake them up on que with iso. What matters is that 2 hours latter - and I have seen and heard MANY patients complain - the patient will say...."UGH...I feel so tired...I just can't seem to wake up!" ...and it is often very annoying to them.

However, pay attention to the DES patients. within 15 minutes, it is like they didn't even have anesthesia. They are awake and ready to go! If you do my anesthesia, that is what I want. I don't want to feel like crap for 24 hours as the iso slowly leaves the fat behind my eyeballs.

Let me remind you again....lots of strong feelings about this...but you silently pay attention...take notes...and then practice how YOU would want anesthesia done to you.

Agree 100% as well
Another issue is pain control, with Des i feel pts are awake much faster and able to have pain taken care of sooner which likely leads to shorter PACU times whereas with Sevo/Iso pt's are still sleepy for awhile and so takes longer for them to c/o pain and so likely stay in PACU a little longer

My only negative with Des is likely purely anecdotal, I havent noticed increased incidence of bronchospasm with Des, BUT when using an LMA with Des Ive noticed a few cases of laryngospasm and Ive had zero with Sevo so I usually stay away from Des when using an LMA which is fine since you usually use an LMA in short cases anyway so Sevo delaying wake up isnt as much of an issue

 

[pgg]

Your groggy patients may not be groggy if you do not use versed......

+1 to that. The indication for Versed is not surgery.

 

[ph8]

....My only negative with Des is likely purely anecdotal, I havent noticed increased incidence of bronchospasm with Des, BUT when using an LMA with Des Ive noticed a few cases of laryngospasm and Ive had zero with Sevo so I usually stay away from Des when using an LMA which is fine since you usually use an LMA in short cases anyway so Sevo delaying wake up isnt as much of an issue

CriTICAL raises an important point re: Des + LMA. I've seen a couple Des + LMA's lead to laryngospasm and hypoxic arrests in kids.

From the Desflurane product info sheet:

"SUPRANE (desflurane, USP) is not recommended for induction of anesthesia in pediatric patients because of the high incidence of moderate to severe upper airway adverse reactions, including laryngospasm, coughing, breathholding, and secretions, seen in studies of induction of anesthesia in pediatric patients. (see WARNINGS and PRECAUTIONS – Pediatric Use).

SUPRANE is not approved for maintenance of anesthesia in non-intubated pediatric patients due to an increased incidence of respiratory adverse reactions, including coughing, laryngospasm and secretions, seen in one study of maintenance of anesthesia in non-intubated pediatric patients. (see WARNINGS and PRECAUTIONS – Pediatric Use)."

 

[pgg]

Bupivacaine isn't approved for intrathecal use either ...

How do you know it was the desflurane that caused those laryngospasms you saw? We had an overhead anesthesia stat call a couple weeks ago ... patient with an LMA layrngospasmed because he wasn't deep enough at cut time. No one thought to blame the sevoflurane.

I agree that desflurane shouldn't be used for inhalation inductiosn though!

I do see where you're coming from. The package insert says what it says. It's why people run 2 L / min fresh gas flows with sevo. I won't throw stones at conservative practice.

 

[loveumms]

I personally do low flow sevo all the time. Every two hours, I "flush" the system (well, I run 2 liters for a few minutes just so I can document I did so ... ridiculous, yes but I do it none the less).

All these people talking about desflurane and faster wake ups leading to less PACU times, can you point me to the studies that show this. I couldn't find anything and I assume if it was available, then we would all be using desflurane because of this time/money saving feature. I feel like once you learn how to use the agents, you can get the desired wake up with any of them. As a resident, play with them all.

I personally think iso makes for a better wakeup in the right hands because it isn't so abrupt. For my anesthetic, I'll take a TIVA but thats me.

 

[dhb]

When I hear the greenhouse gas argument from vegans who either bike or take public transit to work, I respect it.

Otherwise, eh, not so much. The farts from the cows you get your steak or milk from warm the atmosphere one whole hell of a lot more than low flow desflurane does.

I bike to work

 

[Libertas]

Pretty sure the package insert for des says its contraindicated for use with LMAs in all patients, as well as with non intubated kids, but I don't have a bottle handy to look.

Also, isnt it only the isobaric bupiv that says not for spinal use? The hyperbaric is still approved I think.

 

[pgg]

The only drugs that are FDA approved for intrathecal use are morphine, baclofen, and ziconotide.

That's right. The FDA doesn't approve of spinal anesthesia. Whatever shall we do?!?

 

[vector2]

The only reason your des wakeups are faster is cause you didn't turn your iso off and switch to NO2/ 10-20mg propofol bumps when the resident was closing fascia

 

[ph8]

....How do you know it was the desflurane that caused those laryngospasms you saw? We had an overhead anesthesia stat call a couple weeks ago ... patient with an LMA layrngospasmed because he wasn't deep enough at cut time. No one thought to blame the sevoflurane.

I agree that desflurane shouldn't be used for inhalation inductiosn though!

I do see where you're coming from. The package insert says what it says. It's why people run 2 L / min fresh gas flows with sevo. I won't throw stones at conservative practice.

pgg, you raise a reasonable point; and I cannot say that desflurane was the sole culprit which led to each laryngospasm (granted n = 2 is small, ?secretions/blood on the vocal cords or surgical stimulus despit an etDES of 1+ MAC in each instance). However, once bitten twice shy.

ph8

 

[propadope]

Hmmm. Keeping flows =/>2 lpm for Sevoflurane sounds suspiciously like a way for the manufacturer to get you to make them more money...

Also I believe the issue with desflurane is pungency/UPPER airway reactivity hence the recommendations to avoid with LMA and mask induction. But if a patient is intubated I don't think it matters.

 

[epidural man]

The only reason your des wakeups are faster is cause you didn't turn your iso off and switch to NO2/ 10-20mg propofol bumps when the resident was closing fascia

Two things.

1. The fat:blood, and blood:gas partition coeffecient are really different for the available volatile anesthetics. This isn't made up or theoretical - they actually are really really different. i don't know how to say this in another way except to say - they are very different. I will not explain the implications of this - that is left to the reader to decipher.

2. The wake up time is not the point at all. It is what happens the next 24 hours after this. That is the major and most important point.

 

[vector2]

Two things.

1. The fat:blood, and blood:gas partition coeffecient are really different for the available volatile anesthetics. This isn't made up or theoretical - they actually are really really different. i don't know how to say this in another way except to say - they are very different. I will not explain the implications of this - that is left to the reader to decipher.

Every CA-1 two months in knows this- what's your point? My institution for the past year has very heavily emphasized low flo anesthesia with iso >>>> sevo >des for cases longer than an hour, so I've sat a pretty significant number of iso cases on pts ranging from 9 days old to 95 years old. It's all about knowing your patient.

2. The wake up time is not the point at all. It is what happens the next 24 hours after this. That is the major and most important point.

The next 24 hrs? Ok you've lost me

 

[pgg]

The next 24 hrs? Ok you've lost me

I don't know about the next 24, but it sure matters for the next 1-2. The patient's recovery from anesthesia doesn't end when we walk out of the PACU.

 

[vector2]

I don't know about the next 24, but it sure matters for the next 1-2. The patient's recovery from anesthesia doesn't end when we walk out of the PACU.

Obviously the PACU stay matters, but I've anecdotally never noticed any difference on any inpatients I've post-op'ed the next day that could be attributable to the volatile used.

 

[Colba55o]

Two things.

1. The fat:blood, and blood:gas partition coeffecient are really different for the available volatile anesthetics. This isn't made up or theoretical - they actually are really really different. i don't know how to say this in another way except to say - they are very different. I will not explain the implications of this - that is left to the reader to decipher.

2. The wake up time is not the point at all. It is what happens the next 24 hours after this. That is the major and most important point.

For your ISO patients that your extensive research has shown are so groggy for the next 24 hours, are you controlling for other factors that may lead to oversedation? I don't need to spell out what other agents these people get in the periop period, why blame only the gas?
For a typical case <3 or so hours in a patient that isn't huge, I don't see iso being that much slower than sevo or des.