basic question about the process of inducing and intubating

[Colba55o]

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I'm almost too embarrassed to admit that I don't know this, so what better place to ask than an anonymous forum😀

Is a typical sequence of events for a routine case: induction, mask ventilate, paralytic, intubate? I know that omitting the mask ventilating step would be an RSI.
Or am I incorrect and that the sequence is REALLY: induction, paralytic, mask ventilate, then intubate?
I know that the use of a paralytic is dependent on the type of surgery, but it's also used to faciliate intubation, correct? What would happen if you tried to intubate without using a paralytic?
Also, I read that after you induce, by mask ventilating you are essentially "preoxygenating". How is this different from preoxygenating when the patient is awake and breathing 100% O2?
I guess I don't really understand why you mask ventilate at all? Why not just attempt to intubate as soon as the patient is induced? If you are unable to bag mask, does that mean you shouldnt try to intubate?

Perhaps ultimately what would help me understand this is if someone posted a simplified sequence of steps that are carried out, with an explanation of each step.
I feel like a REAL idiot for not getting this

 

[Bertelman]

Induce, paralyze, mask ventilate, intubate.

Some academic types demand you demonstrate the ability to ventilate before paralyzing. That just means one breath with the mask.

If you intubate an adult w/o paralyzing, you risk regurgitation of gastric contents and vocal cord movement and coughing.

Technically, once you've paralyzed and begun mask ventilating, you are no longer pre-oxygenating. You are merely oxygenating, buying time until the paralytic has found it's home. Depending on the paralytic used, this takes anywhere from 1-3 minutes before you can predict adequate intubating conditions in most patients.

 

[pgg]

Is a typical sequence of events for a routine case: induction, mask ventilate, paralytic, intubate? I know that omitting the mask ventilating step would be an RSI.

That's a reasonably common sequence. Omitting the mask vent step doesn't necessarily make it an RSI though.

A classic RSI is a technique by which you give fast acting induction agent and paralytic (usually succinylcholine, but maybe 1.2 mg/kg rocuronium), usually with cricoid pressure, without mask ventilation, with the intent of securing the airway with an ETT as rapidly as possible.

Some people will induce, mask ventilate to "prove" the airway, then give the muscle relaxant, wait for it, then intubate. Others think "proving" the airway before giving muscle relaxant to someone with a reassuring airway exam is unnecessary, or even ridiculous.

Or am I incorrect and that the sequence is REALLY: induction, paralytic, mask ventilate, then intubate?

There is no one correct sequence. An appropriate sequence is whatever accomplishes the induction goals for that particular patient under the particular circumstances of the case.

I know that the use of a paralytic is dependent on the type of surgery, but it's also used to faciliate intubation, correct? What would happen if you tried to intubate without using a paralytic?

Intubating without a muscle relaxant may carry an increased aspiration risk, and it's generally not as easy to intubate. That doesn't necessarily make it difficult or impossible though. Most anesthesiologists will give a paralytic prior to intubating adults, most of the time. Kids are another issue.

Whether or not a paralytic is helpful or "needed" for the surgical procedure is unrelated to intubation.

Also, I read that after you induce, by mask ventilating you are essentially "preoxygenating". How is this different from preoxygenating when the patient is awake and breathing 100% O2?

Mask ventilating after induction isn't preoxygenation. The purpose of preoxygenation is to give yourself more time before an apneic patient desaturates. It lengthens your safety margin if you unexpectedly have difficulty mask ventilating or intubating a patient who is no longer spontaneously breathing.

I guess I don't really understand why you mask ventilate at all? Why not just attempt to intubate as soon as the patient is induced?

Because muscle relaxants, even succinylcholine, all take time to work. Optimum intubating conditions might not be present for 30 seconds, a minute, or longer after induction. If there's no reason to not mask ventilate the patient during that period, most people do.

In some circumstances, it may be helpful or reassuring to prove to yourself that you can mask ventilate that particular patient.

If you are unable to bag mask, does that mean you shouldnt try to intubate?

No. Usually if you have trouble mask ventilating +/- oral/nasopharyngeal airways, the right thing to do is just stick the tube in. There are some occasions when if you've only given the induction agent (ie no paralytic) it may be safer to let the patient wake up.

 

[RedAnesthesia]

Induce, paralyze, mask ventilate, intubate.

Some academic types demand you demonstrate the ability to ventilate before paralyzing. That just means one breath with the mask.

If you intubate an adult w/o paralyzing, you risk regurgitation of gastric contents and vocal cord movement and coughing.

Technically, once you've paralyzed and begun mask ventilating, you are no longer pre-oxygenating. You are merely oxygenating, buying time until the paralytic has found it's home. Depending on the paralytic used, this takes anywhere from 1-3 minutes before you can predict adequate intubating conditions in most patients.

I was always taught induce, mask ventilate, paralyze then intubate. If you paralyze the patient before proving you can ventilate then are unable to intubate the patient you are up **** creek, right?

 

[Planktonmd]

I was always taught induce, mask ventilate, paralyze then intubate. If you paralyze the patient before proving you can ventilate then are unable to intubate the patient you are up **** creek, right?

No,
The fact that you can ventilate by mask before giving a muscle relaxant, does not guarantee that you can ventilate by mask after you give a muscle relaxant, and many times when you have difficulty ventilating with mask giving a muscle relaxant actually improves the situation.
So, this whole thing about proving ability to ventilate (usually in academia) before giving a muscle relaxant is anecdotal and based on superstition.
But since you are a medical student, at this point in the game I would do whatever the attending or the resident say, if they say ventialte with mask first then that would be the right answer.

 

[pgg]

I was always taught induce, mask ventilate, paralyze then intubate. If you paralyze the patient before proving you can ventilate then are unable to intubate the patient you are up **** creek, right?

This is one of those areas where academic dogma doesn't seem to stand up to the way anesthesia is done elsewhere by logical, safe anesthesiologists.

The problem is that the patient changes when you give the muscle relaxant. Just because you can ventilate him before paralysis doesn't mean you can after. Usually, mask ventilation gets easier with paralysis.

Mask ventilation can also get harder after paralysis. Fat lotta good "proving" the airway did now.


The bottom line is this - if you're worried about an airway, do it awake. If you're not worried enough to do it awake, but there's a hint of heebie-jeebies poking the back of your mind, use succ rather than roc.

If the airway is reassuring, just induce, give the paralytic, stick the tube in, and get on with the case.

We have LMAs and video laryngoscopes these days. The risk of finding yourself in a can't-ventilate/can't-intubate situation in a routine case with a reassuring airway is just about zero. And it's not a risk that I believe can be appreciably reduced with some superstitious airway proving.

 

[Sergio99]

Bertelman and pgg explained it very well.

We all know how difficult it is to intubate without a relaxant because at one time or another we forgot to give it and tried to intubate with the mouth hard to open, the tongue getting in the way, the patient swallowing, the vocal cords closing, etc., the same way as when you try to intubate an awake patient in the ER or in the ICU.

When you induce a patient, he usually stops breathing, the airways close, the alveoli begin to collapse and become atelectatic. The oxygen saturation quickly drops. If you are not ventilating, you may not have time to intubate before the patient suffers hypoxic damage to the brain or the heart. That is why RSI is always a stressful situation.

In the cases that you cannot ventilate and the patient is getting blue, if you cannot intubate quickly, you may have to do a cricothyrotomy. Whether to give relaxants before you can ventilate or not, is hard to decide, because sometimes you cannot ventilate due to laryngospasm, and a litlle bit of a relaxant solves the problem, but you burn the bridge of being able to wake the patient up in a hurry. However, if you cannot ventilate anyway, you may not be able to afford the time it will take to wake him up and may have to do the cricothyrotomy. I agree with Planktonmd regarding muscle relaxants.

Airway problems are scary. You always want to have the best possible conditions to ventilate and intubate.

 

[Mman]

When you induce a patient, he usually stops breathing, the airways close, the alveoli begin to collapse and become atelectatic. The oxygen saturation quickly drops. If you are not ventilating, you may not have time to intubate before the patient suffers hypoxic damage to the brain or the heart. That is why RSI is always a stressful situation.

Really? In a patient that does not have significant cardiopulmonary disease, good preoxygenation goes a long ways and gives us a nice margin of safety. Even if you only get a patient to maybe 90% of their vital capacity oxygenated, that's still roughly 3500-4000 mls of oxygen in their lungs. Considering they only use roughly 250 ml/min of oxygen, that's well over 10 minutes of oxygen they have stored in their lungs. Of course pCO2 and pH will be fighting against you over time, but there is zero reason for RSI to be a stressful situation.

It's obese patients and sick patients that can make it more stressful, but RSI by itself is nothing special.

 

[jwk]

Bertelman and pgg explained it very well.

We all know how difficult it is to intubate without a relaxant because at one time or another we forgot to give it and tried to intubate with the mouth hard to open, the tongue getting in the way, the patient swallowing, the vocal cords closing, etc., the same way as when you try to intubate an awake patient in the ER or in the ICU.

When you induce a patient, he usually stops breathing, the airways close, the alveoli begin to collapse and become atelectatic. The oxygen saturation quickly drops. If you are not ventilating, you may not have time to intubate before the patient suffers hypoxic damage to the brain or the heart. That is why RSI is always a stressful situation.

In the cases that you cannot ventilate and the patient is getting blue, if you cannot intubate quickly, you may have to do a cricothyrotomy. Whether to give relaxants before you can ventilate or not, is hard to decide, because sometimes you cannot ventilate due to laryngospasm, and a litlle bit of a relaxant solves the problem, but you burn the bridge of being able to wake the patient up in a hurry. However, if you cannot ventilate anyway, you may not be able to afford the time it will take to wake him up and may have to do the cricothyrotomy. I agree with Planktonmd regarding muscle relaxants.

Airway problems are scary. You always want to have the best possible conditions to ventilate and intubate.

I've never seen a cricothyrotomy done in 30 years of anesthesia. I know they're done occasionally, and I think the vast majority are by non-anesthesia personnel in the ER or pre-hospital with poor airway and intubation skills to begin with, and who mess up the airway with traumatic intubation attempts that leave them with little choice but to do a cric. I've seen exactly one "can't intubate/can't ventilate" in all these years, and that was due to a huge neck hematoma caused by a Swan introducer placed in the carotid and then removed. That patient got an emergency trach from the surgeon who walked in about the time we lost the airway.

In MOST cases, RSI's are really no more stressful than any other induction, just a different sequence. I worry FAR more about surgical complications and events that are beyond my control (laparoscopic trocars in aortas for example, or surprise placenta accretas in women with poor pre-natal care) than I do my own airway management skillset.

As far as giving a muscle relaxant for laryngospasm - 10mg of sux will usually break the spasm, the patient keeps right on breathing, and emergence is not delayed. If you're burning bridges and delaying emergence with muscle relaxants for laryngospasm, you're giving too much.

 

[Arch Guillotti]

As far as giving a muscle relaxant for laryngospasm - 10mg of sux will usually break the spasm, the patient keeps right on breathing, and emergence is not delayed. If you're burning bridges and delaying emergence with muscle relaxants for laryngospasm, you're giving too much.

The exception would be kids that spasm and desaturate who don't have an IV. When giving IM sux to a peds you need to give a pretty hefty dose and it may take some time to wake up from this.

 

[Sergio99]

...I've never seen a cricothyrotomy done in 30 years of anesthesia...

I have never seen one, either, in 34 years of anesthesia, but every airway course, textbook, and residency program teach that it is the thing to do.

...I've seen exactly one "can't intubate/can't ventilate" in all these years...

You have seen one more than I have seen in 34 years.

...In MOST cases, RSI's are really no more stressful than any other induction, just a different sequence...

I see that you have a good idea of what you are saying, because you emphasized the operative word "MOST." Yes, you are right in that they usually go smooth and you sail through them uneventfully. The problem is that you don't know which one is the one that is going to be rough. It is the uncertainty of the situation what I meant by stressful. In everything else I agree with you, except that I wouldn't minimize so much its dangers.

 

[Hamhock]

Disclaimer: Originally, I am EM-trained. I am certainly not looking to instigate an anesthesia vs. EM crash-airway battle. I am honestly - truly - innocently asking:

1. What kind of training do anesthesiologists have with crics or emergent trachs?

2. How many crics have senior residents or attendings done? (probably not too many in the OR, but what about the ED?)

3. Is it a requirement for completion of residency?

Most sincerely, HH

 

[doctor712]

The exception would be kids that spasm and desaturate who don't have an IV. When giving IM sux to a peds you need to give a pretty hefty dose and it may take some time to wake up from this.

This is a GREAT thread if only because it's at the level of what I've been taught over and over during shadowing. And it's VERY interesting to hear pp guys explaining the mask ventilation before paralytic reality and dogma deal. I've been told by 2-3 attendings: anesthesia is all about mask ventilating first. (not preoxygenating) but making sure you can ventilate. because, as they always say, "if you can't ventilate, why paralyze?" i think, as plankton said, that's not always the path to success, or a question that makes sense, but as he also said, until your attending says otherwise... however, hearing the explanation here is really priceless.

Question: Arch, or anyone, (more dogma maybe), you mention Sux for peds. Isn't sux contraindicated in peds because of potential for hyperkalemia? Or is that more of the same "airway dogma kinda" talk...?

Great thread!

D712

 

[jwk]

I have never seen one, either, in 34 years of anesthesia, but every airway course, textbook, and residency program teach that it is the thing to do.

Absolutely agree.

We're in the middle of our annual "difficult airway checkoff". Every person in our department, MD, CRNA, and AA, does the same checkoff sheet. (lucky me - I get to do the invasive skills checkoff for my entire department) Just to make sure everyone is on the same page, everyone does a series of GlideScopes, lightwands, and bougies on actual patients. (most of us become dependent on one of these three techniques and forget about the other two). We also have a couple of airway mannequins that we go through and perform Melker crics, retrograde wire intubations, LMA FastTrach, the combitube, ventilating tube-exchange catheters, and our jet ventilator setup - all things we rarely (if ever) use. We also review the contents of our difficult airway carts, since we have a collection of somewhat obscure toys in there as well (an old Claris stylet for example). FOB's are primarily a doc procedure at our place, and are used fairly frequently so there is not a line item for them on our checklist.

 

[gasaddict54]

This is a GREAT thread if only because it's at the level of what I've been taught over and over during shadowing. And it's VERY interesting to hear pp guys explaining the mask ventilation before paralytic reality and dogma deal. I've been told by 2-3 attendings: anesthesia is all about mask ventilating first. (not preoxygenating) but making sure you can ventilate. because, as they always say, "if you can't ventilate, why paralyze?" i think, as plankton said, that's not always the path to success, or a question that makes sense, but as he also said, until your attending says otherwise... however, hearing the explanation here is really priceless.

Question: Arch, or anyone, (more dogma maybe), you mention Sux for peds. Isn't sux contraindicated in peds because of potential for hyperkalemia? Or is that more of the same "airway dogma kinda" talk...?

Great thread!

D712

Sux is controversial primarly bc of fear of MH, K only going to rise about 0.5 unless u have some preexisting anomalies going on ex paralyzed within last year, burn victims etc ec

 

[pgg]

Isn't sux contraindicated in peds because of potential for hyperkalemia?

Sux is controversial primarly bc of fear of MH, K only going to rise about 0.5 unless u have some preexisting anomalies going on ex paralyzed within last year, burn victims etc ec

The fear isn't MH, but rather undiagnosed muscular dystrophies in young males. If there's an indication for an RSI in a child, it's a judgment call - you can and sometimes should use succ. High dose roc is an alternative.

 

[Bertelman]

Disclaimer: Originally, I am EM-trained. I am certainly not looking to instigate an anesthesia vs. EM crash-airway battle. I am honestly - truly - innocently asking:

1. What kind of training do anesthesiologists have with crics or emergent trachs?

2. How many crics have senior residents or attendings done? (probably not too many in the OR, but what about the ED?)

3. Is it a requirement for completion of residency?

Most sincerely, HH

1) Almost none

2) probably none

3) no

 

[Arch Guillotti]

1. What kind of training do anesthesiologists have with crics or emergent trachs?

Not much, though a lot of us have seen an emergent trach at some point.

We are very good at securing the airway and we are also very good at coming up with alternative plans to secure the airway if we suspect there is going to be a problem.

Unfortunately, sometimes we also get sucked into problems that we have not created ourselves.

Most of us that have been through residency recently did a fair amount of awake intubations. For a lot of these I did a transtracheal block. Unless the pt. has no neck, surgical scarring, etc - i feel like I could pretty easily palpate the right spot to do a cric. Not something I ever plan on doing but probably eventually will have to at some point.

 

[Sergio99]

Disclaimer: Originally, I am EM-trained. I am certainly not looking to instigate an anesthesia vs. EM crash-airway battle. I am honestly - truly - innocently asking:

1. What kind of training do anesthesiologists have with crics or emergent trachs?

2. How many crics have senior residents or attendings done? (probably not too many in the OR, but what about the ED?)

3. Is it a requirement for completion of residency?

Most sincerely, HH

You are right, Hamhock, I can answer exactly he same as Bertelman:

1) None
2) None
3) No

The only time I did a tracheostomy by myself was over 35 years ago, when I was an internist/intensivist, before I ever considered to apply for anesthesia residency, and that trach was not because of difficult airway, but because the patient's attending neurologist wanted one.