NMBAs with LMAs

Specialties CRNA

Published

What are your thoughts/feelings on using neuromuscular blockers during a case with an LMA in place? I know relaxants are not necessary for insertion, but are they contraindicated? I've heard yes and no...personally, I can't think of a reason why it wouldn't be okay to use a NMBA if the surgeon needed relaxation during the case. Others have said it's a big no-no. I've heard that this is done routinely in Europe, as well as mech. ventilation via LMAs (with low PIP)---another topic where there are opposing views in my current rotation.

Thoughts please:)

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Specializes in Cardiac, Pulmonary, Anesthesia.

Airway is secure, so there isn't really a problem doing it. You're also correct that we are one of the few places that doesn't do this.

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So why do people say otherwise?

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Specializes in Cardiac, Pulmonary, Anesthesia.

There could be many arguments, none that hold alot of water since precautions should be taken. One is that it could cause aspiration since sux causes an increase in intragastric pressure. This should be moot in cases where the patient is NPO and typically moot anyway because sux also inreases gastric sphincter tone preventing opening. Other things could be a problem like undiagnosed myotonia dystrophica, blah blah, etc. I'm not saying you can use nmb with an lma on EVERY case, but if you use your noggin it can be done safely.

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That is a good question. I know they do use NMBA with LMA's in Europe as well- heck I've heard they use LMA's with prone cases over there. I was taught the same thing- don't use relaxants with an LMA. If the surgeon needs relaxation- I would just intubate and get a more secure airway. Until the standard changes and people use LMA with relaxants routinely I wouldn't do it.

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Specializes in MICU & SICU.

I am not sure I agree that this is the best practice and I feel that if you need to use relaxants you should just go ahead and place an ETT.

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Specializes in Anesthesia.
Airway is secure, so there isn't really a problem doing it. You're also correct that we are one of the few places that doesn't do this.

Airway is secure with a LMA?

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I am not sure I agree that this is the best practice and I feel that if you need to use relaxants you should just go ahead and place an ETT.

But why is what I want to know? Why do you feel it is unsafe/not the best practice? I agree that you shouldn't need relaxants to place an LMA, but what if you already have one in, and then the surgeon decides he wants the pt relaxed? I have perused my anesthesia texts and can't find any reason why it would be unsafe to use NMBAs with an LMA in place.

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There's no reason to use sux with an LMA unless a pt. has a laryngospasm. It certainly wouldn't provide you long enough duration of action for surgical relaxation. The reason providers in the US don't like to use LMAs for lateral or prone position or w/muscle relaxation, is because they are not a secure airway. An ETT is a secure airway. Can you do it? yes. Would you be able to do cases that way? Often. But if you're needing airway pressures above 20 cm, you're filling the stomach with air & inviting aspiration, among other problems. Lots of people need airway pressures above 20 cm to ventilate, especially the obese. If the pt is prone or lateral & you need to change out the LMA for an ETT, it'd be pretty tough--prone especially. Would YOU want to tell the surgeon the pt needs to be flipped supine onto an open surgical site because you need to intubate? I wouldn't want to explain why I didn't do it up front. And what if things started going bad quickly? Chest wall excursion is limited in the prone position, and obese pts (& others) have little FRC, thus desat quickly. If you want to do it as a student, you're working under the CRNA's license. If you want to do it on your own, you're risking your own. I saw a poster presentation about the use of LMAs for laparoscopic cases. Just because someone else does it & it works for some pts, doesn't make it a good idea or safe practice.

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Thanks for the responses so far. Just to be clear, I don't lie on one side or the other on this topic. In my limited experience as a student, I haven't even used all that many LMAs yet (mostly ETT), so my question was more or less for future reference, and so that this makes sense to me. Of course not for every patient or every case would it be appropriate or safe to give relaxants with an LMA(and not just succs, what I had in mind was a non-depolarizing relaxant) for all of the reasons stated above...but then again for an obese pt or a pt who you suspect would need high inspiratory pressures to ventilate, an LMA would not really be the ideal airway choice for them in the first place.

And I do also have to say...that the idea of using an LMA in a prone or lateral case (or even for a laparascopic case due to the increased probability of needing higher PIP) makes me shudder!! NO way! :)

So.. my hypothetical question was geared towards a healthy pt (no obesity, airway disease, etc).

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A supine healthy patient, I should say!

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Well, you'll soon find that the majority of your patients are not young, healthy & ideal body weight. And that worst-case scenarios drive your practice.

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