inhalation induction for potential difficult ventilation scenario?

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gasman7k

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I am confused why this isn't used more often. If you keep patient spontaneously breathing, they will auto regulate their depth of anesthesia and maintain SV. Once they are asleep and spontaneously ventilating, you can intubate.

This seems like a legit alternative to awake intubation in situations such as tamponade, mediastinal mass, etc...

I am assuming I am missing something...

1. Will patients actually become apniec (and the neg-feedback scenario of SV during inhalation induction more theoretical than real life)?
2. Will the patient not be deep enough for intubation?

thanks all,
CA-2

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The patient won't autoregulate their anesthesia depth. Consider : if you dial in 3% sevo vs 8% sevo, will the patient change their resp rate to adjust?

A nice dose of sevo will cause some relaxation. Could easily crap out your anterior mediastinal mass if there is obstruction by the mass. Similarly, you'll get some sympathectomy from a sevo induction and your PeripVR and preload will drop which will not go well for tamponade. There are board answers to these scenarios for a reason.
 
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I like a spontaneously ventilating technique when you are concerned that the patient may not tolerate positive pressure ventilation like with a mediastinal mass. It's nice to be able to apply some positive pressure through the mask and see if there hemodynamics will tolerate it and/or if you can ventilate.
 
I am confused why this isn't used more often. If you keep patient spontaneously breathing, they will auto regulate their depth of anesthesia and maintain SV. Once they are asleep and spontaneously ventilating, you can intubate.

This seems like a legit alternative to awake intubation in situations such as tamponade, mediastinal mass, etc...

I am assuming I am missing something...

1. Will patients actually become apniec (and the neg-feedback scenario of SV during inhalation induction more theoretical than real life)?
2. Will the patient not be deep enough for intubation?

thanks all,
CA-2

Awake FO intubations are less necessary today than they were before the advent of reliable VL, so when it is chosen as a technique, it's for a specifically identified issue with the airway or surrounding structures . A mediastinal mass is a sub glottic issue that is distinct from an upper airway or anatomical problem.

All that said, it isn't at all just a matter of spontaneous ventilation. With the tissue/ muscular architectural changes with GA, you have no guarantee that the airway of the awake patient will be the same when he's asleep.

The greatest advantage of AFOI is the cooperation from the patient.
 
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How many out there have tried doing an inhalation induction in an adult? Did one during residency and it seemed to take forever
 
How many out there have tried doing an inhalation induction in an adult? Did one during residency and it seemed to take forever

My go to with a mediastinal mass that's significant enough for symtoms. The younger patient needs to be well secured to the table, however
 
How many out there have tried doing an inhalation induction in an adult? Did one during residency and it seemed to take forever

I do it a few times a year. Usually in the cyst room on a frail old patient. Slip in the LMA with nothing given but oxygen and sevo.
 
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How many out there have tried doing an inhalation induction in an adult? Did one during residency and it seemed to take forever
We actually do a dozen or so of these a week. We have podiatrists that do shock waves for plantar fasciitis, with the device running for seven minutes per site (most patients are a single site, we do a few bilateral each week). We choose our patients carefully, but usually do inhalation induction and mask volatile maintenance for the brief procedure. Sometimes, we give a little fentanyl or a little propofol, but the majority are straight volatile cases.

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I was in ICU couple years ago and the OR did one in the middle of the night for an ant med mass they thought was a low thyroid.

Patient went apneic, couldnt pass 6.0 ETT,thoracic surgeon tried to rigid bronch, ripped open trachea >> tension ptx, decompressed >> emergent sternotomy to directly intubate bronchus below tear. Sats below 20 for awhile.

Guy was awake and neuro intact the next morning when I came in.
 
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I was in ICU couple years ago and the OR did one in the middle of the night for an ant med mass they thought was a low thyroid.

Patient went apneic, couldnt pass 6.0 ETT,thoracic surgeon tried to rigid bronch, ripped open trachea >> tension ptx, decompressed >> emergent sternotomy to directly intubate bronchus below tear. Sats below 20 for awhile.

Guy was awake and neuro intact the next morning when I came in.
Probably shaved a few years off of your life though.
 
main problem with gas induction for difficult airways is losing the airway during your induction due to the loss of muscle tone.
at that point you can't deepen them with more gas, and you can't lighten them because you can't blow off the gas

like many things, they can work well - if done skilfully.
do you really want to do a technique you've done "a few times" in a patient that has a difficult airway.

* kids are completely different
 
I was in ICU couple years ago and the OR did one in the middle of the night for an ant med mass they thought was a low thyroid.

Patient went apneic, couldnt pass 6.0 ETT,thoracic surgeon tried to rigid bronch, ripped open trachea >> tension ptx, decompressed >> emergent sternotomy to directly intubate bronchus below tear. Sats below 20 for awhile.

Guy was awake and neuro intact the next morning when I came in.
And that my friends is why the answer to this question is awake FOB.
 
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Kinda on a tangent, but what the worse that can happen with a awake FOB (keeping in mind the reasons we would be doing a awake FOB in the first place)? what do you do if they larygospasm? Don't have much experience in this regard, and texts are not always clear about it.
 
Not the original question but I've found inhalation inductions are the most hemodynamically stable induction technique with wide applications. Cardiac cripples/vasculopaths, septic shock, severe volume depletion. Train tracks. Great thing to gain some comfort with in residency if attendings are on board.

As many stated above, I would question the use in difficult airways. Good oral boards answer however (after the obligatory AFOI of course).
 
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Kinda on a tangent, but what the worse that can happen with a awake FOB (keeping in mind the reasons we would be doing a awake FOB in the first place)? what do you do if they larygospasm? Don't have much experience in this regard, and texts are not always clear about it.
Awake patients don't laryngospasm.

There are lots of "worst" things that can happen with awake intubations, but the most common worst thing is probably that the patient gets too much sedation and isn't awake any more. Usually this is when a patient gets a little bit of sedation, and then someone blames restlessness/uncooperation on inadequate sedation (when it's really due to hypoxia & hypercarbia), gives more sedation, and now they've got a semi-induced, unrelaxed patient and the worst possible intubating conditions in a hypoxic patient with a bad airway. And the neck gets cut, or worse, doesn't get cut.

Also, something that deserves to be explicitly stated in this thread - the need for spontaneous ventilation and awake intubation are independent issues. There are reasons to maintain spontaneous ventilation that have nothing to do with the difficulty of an airway (e.g. a tamponade patient with an easy airway who might not tolerate PPV), and there are reasons to do awake intubation where the instant the tube is in place you can slam in an IV induction drug and paralytic (e.g. hx of head/neck radiation).
 
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I am confused why this isn't used more often. If you keep patient spontaneously breathing, they will auto regulate their depth of anesthesia and maintain SV. Once they are asleep and spontaneously ventilating, you can intubate.

This seems like a legit alternative to awake intubation in situations such as tamponade, mediastinal mass, etc...

I am assuming I am missing something...

1. Will patients actually become apniec (and the neg-feedback scenario of SV during inhalation induction more theoretical than real life)?
2. Will the patient not be deep enough for intubation?

thanks all,
CA-2

WHy do they have to be awake for the FOB why cant they just be spontaneously breathing but asleep on sevo? I think the adult inhalational induction plus glidescope is a great approach to the difficult airway.

In my experience no they never get apneic as long as you open their airway, and yes they can be very deep to the point they are hypotensive.

Its easy to do this induciton wrong and just take over squeezing the bag because you cant open the airway adequately, but when done right its a beautiful thing... No PPV, No apena inducing meds, No waiting to come back breathing, Great HD stability...
 
I was in ICU couple years ago and the OR did one in the middle of the night for an ant med mass they thought was a low thyroid.

Patient went apneic, couldnt pass 6.0 ETT,thoracic surgeon tried to rigid bronch, ripped open trachea >> tension ptx, decompressed >> emergent sternotomy to directly intubate bronchus below tear. Sats below 20 for awhile.

Guy was awake and neuro intact the next morning when I came in.

You think sevo cause apnea?
 
You think sevo cause apnea?
Sevo doesn't directly cause it, but if you mask induce a kid on 8% sevo for 5 minutes they will go apneic or have extremely shallow breathing after hyperventilating themselves in stage 2.
 
A) it takes forever
B) patients will stage 2 like crazy
C) necessarily inferior to AFOI bc you still have to intubate

A good (keyword is "good") single breath induction is probably as fast as propofol. Though, I wouldn't instrument an airway after just one breath of sevo, they are induced pretty quickly. Sometimes I do inhalation inductions for quick procedures where I'll either mask through it or slip in an LMA.

My last couple of awake intubations have been awake glidescopes. After good topicalization, patients tolerate an awake glidescope pretty well. Obviously with head and neck cancer stuff you may need the fiberoptic, but the glidescope is a nice first try option.

I think all residents should take a week or two and do only inhalation inductions on adults. Do single vital capacity breath inductions and gradual inductions. It's more fun than prop/roc/tube anyway.
 
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WHy do they have to be awake for the FOB why cant they just be spontaneously breathing but asleep on sevo? I think the adult inhalational induction plus glidescope is a great approach to the difficult airway.

In my experience no they never get apneic as long as you open their airway, and yes they can be very deep to the point they are hypotensive.

What if your mediastinal mass compresses as the patients gets relaxed from the sevo and you get some tracheal compression?

As for the tamponade patient, potent inhalation agents will lower your SVR. Your preload drops, and that doesn't go well. You don't need an awake FOB. A ketamine induction would should do just fine.

But in neither case would I recommend a mask induction. Just seems like a bad idea in both scenarios.
 
I am confused why this isn't used more often. If you keep patient spontaneously breathing, they will auto regulate their depth of anesthesia and maintain SV. Once they are asleep and spontaneously ventilating, you can intubate.

This seems like a legit alternative to awake intubation in situations such as tamponade, mediastinal mass, etc...

I am assuming I am missing something...

1. Will patients actually become apniec (and the neg-feedback scenario of SV during inhalation induction more theoretical than real life)?
2. Will the patient not be deep enough for intubation?

thanks all,
CA-2

I think it's doubtful you can reliably get them deep enough to tolerate laryngoscopy. Inhalational induction is an "old-school" technique for difficult intubation, but I have never heard of it described for suspected difficult ventilation.

Awake intubation may be used for cardiac tamponade in order to keep the patient spontaneously ventilating, not typically because there is a concern for difficult ventilation. The concern is that positive pressure ventilation will cause hemodynamic collapse.
 
I am confused why this isn't used more often. If you keep patient spontaneously breathing, they will auto regulate their depth of anesthesia and maintain SV. Once they are asleep and spontaneously ventilating, you can intubate.

This seems like a legit alternative to awake intubation in situations such as tamponade, mediastinal mass, etc...

I am assuming I am missing something...

1. Will patients actually become apniec (and the neg-feedback scenario of SV during inhalation induction more theoretical than real life)?
2. Will the patient not be deep enough for intubation?

thanks all,
CA-2
Difficult airway + non cooperative pt + emergent/urgent case
Best choice in this crappy situation
Been there
Not fun

Either that or hold them down for awake trach which is pretty brutal
 
A good (keyword is "good") single breath induction is probably as fast as propofol. Though, I wouldn't instrument an airway after just one breath of sevo

Nor would you after 0.5-1 mg/kg propofol. Just because they close their eyes doesn't mean they're induced.
 
Difficult airway + non cooperative pt + emergent/urgent case
Best choice in this crappy situation
Been there
Not fun

Either that or hold them down for awake trach which is pretty brutal

Inhalation or titrate some ketamine. Both are underutilized for these situations.
 
Mask induction in an adult with a potential for difficult ventialtion is a very bad idea because by the time you get to an anesthetic level sufficient to manipulate the airway all the soft tissue would have collapsed and you will have complete airway obstruction.
Anticipated difficult ventilation should always make you think about awake techniques.
 
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Mask induction in an adult with a potential for difficult ventialtion is a very bad idea because by the time you get to an anesthetic level sufficient to manipulate the airway all the soft tissue would have collapsed and you will have complete airway obstruction.
Anticipated difficult ventilation should always make you think about awake techniques.
I used it for a skiny patient in which an oral cannula would easily solve an airway obstruction. I wouldn't use this technique for a fat patient.
 
That's the key. Inhalation inductions can be nice for those in whom you would like to maintain spontaneous ventilation, hemodynamic stability, or who may be difficult intubations, but not good for those with potential for difficult ventilation.
 
Sevo doesn't directly cause it, but if you mask induce a kid on 8% sevo for 5 minutes they will go apneic or have extremely shallow breathing after hyperventilating themselves in stage 2.

strongly disagree. I have done this and that is not true. It takes a good technique to open the airway in a SV kid. Those who "go apneic" just need better mask manipulation to open their airway, head to the side, mouth open, possible nasal. You get through stage 2 smoothly every time... then intubate at 5%+ sevo. Agree its not for fatties
 
What if your mediastinal mass compresses as the patients gets relaxed from the sevo and you get some tracheal compression?

As for the tamponade patient, potent inhalation agents will lower your SVR. Your preload drops, and that doesn't go well. You don't need an awake FOB. A ketamine induction would should do just fine.

But in neither case would I recommend a mask induction. Just seems like a bad idea in both scenarios.

Don't always assume that ketamine is going to maintain cardiac output. Ketamine has some direct negative inotropic effects and it's ability to maintain cardiac output is often from sympathetic stimulation. A patient is acute tamponade may already have exhaustion of their sympathetic outflow, and those negative inotropic effects of ketamine may show themselves.

Ketamine and sevoflurane can both be used effectively in cardiac tamponade in order to maintain spontaneous ventilation so long as you are prepared to maintain optimal hemodynamics by other means if necessary.
 
Ketamine and sevoflurane can both be used effectively in cardiac tamponade in order to maintain spontaneous ventilation so long as you are prepared to maintain optimal hemodynamics by other means if necessary.
Ketamine maintains preload far better than Sevo. You're right that Ketamine may depress CO in sympathetically spent patient. But that's still going to go far better than giving Sevo to the same patient.
 
Ketamine maintains preload far better than Sevo. You're right that Ketamine may depress CO in sympathetically spent patient. But that's still going to go far better than giving Sevo to the same patient.

I have to disagree here. I find that a bolus of ketamine will tank hemodynamics in a marginal patient much more significantly than a gradual sevo induction. I suppose it depends how much you are bolusing but in my hands 1mg/kg will tank a patient while a sevo induction is stable in that same patient. I don't give opiates on top of either of these techniques bc that is a death blow in these patients. Anyway, that's my experience. I appreciate if yours is different.

Hard to generalize across all sick patients in various scenarios but inhalation induction is my preference for maintaining hemodynamics.
 
Ketamine 1mg/kg is still a hefty dose. Half that won't disrupt hemodynamics nearly as much, and can be enough to induce a marginal patient. If not enough, you can still slowly titrate in some sevo/iso, and get by with less of both. This is one of my common techniques for ****ty hearts with good airways.
 
strongly disagree. I have done this and that is not true. It takes a good technique to open the airway in a SV kid. Those who "go apneic" just need better mask manipulation to open their airway, head to the side, mouth open, possible nasal. You get through stage 2 smoothly every time... then intubate at 5%+ sevo. Agree its not for fatties

Sorry you are incorrect. You can definitely make a kid apneic off 8% sevo. Have done it frequently. Unless you think I can't tell the difference between apnea and obstruction...
 
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Great thread. Why is the textbook answer for intubating a patient with epiglottis, who could be a very difficult mask ventilation, to do an inhalation induction with sevo?
 
Great thread. Why is the textbook answer for intubating a patient with epiglottis, who could be a very difficult mask ventilation, to do an inhalation induction with sevo?

Because it works and you can reverse course. I did this recently on a middle aged woman. Prior to induction she looked terrible, anxious, sitting upright, salivating and stridorous. As soon as she fell asleep, I starting assisting with ppv and knew I was golden when I gave the first breath. It turned out to be remarkably easy to ventilate her. Her airway was better asleep than awake. Glidescope showed an red angry swollen epiglottis but the airway was still widely patent.
 
Sorry you are incorrect. You can definitely make a kid apneic off 8% sevo. Have done it frequently. Unless you think I can't tell the difference between apnea and obstruction...

Yep, leave a kid breathing 8% sevo too long and they will become apneic (and hypotensive). there are limits to kids robustness too.
 
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Yep, leave a kid breathing 8% sevo too long and they will become apneic (and hypotensive). there are limits to kids robustness too.

maybe at 8. i dont usually target 8 i target 3-4, but i turn it on 8 and get them super deep through a quick stage 2 and land them on 3-4. They breathe spontaneously without PPV assistance the whole time. Often they are at 5%+ and are intubable with nothing else
 
How many out there have tried doing an inhalation induction in an adult? Did one during residency and it seemed to take forever
46 adult inhalation inductions in the first month of CA-1, and pretty much any time I worked with the PD after that. Got good with mask control and finger positioning, something I still harp on when I teach residents/students.

I have done a few in the last year or so of general practice. Frail types like Dr. Doze mentioned.
 
I was in ICU couple years ago and the OR did one in the middle of the night for an ant med mass they thought was a low thyroid.

Patient went apneic, couldnt pass 6.0 ETT,thoracic surgeon tried to rigid bronch, ripped open trachea >> tension ptx, decompressed >> emergent sternotomy to directly intubate bronchus below tear. Sats below 20 for awhile.

Guy was awake and neuro intact the next morning when I came in.

Did you ever publish it?
 
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