NMB and spine surgery

[caligas]

Assuming a dose of 0.6mg/kg provides 0/4 twitches, what does should provide complete elimination of all localized twitching triggered by bovie in spine exposure? Or is that not achievable?

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[pgg]

Not exactly sure what you're asking. Direct Bovie-to-muscle contact will make the muscle contract regardless of how much NMBD you use.

 

[nimbus]

Even if you eliminate all neuromuscular transmission, some of the muscle twitching is from direct depolarization of the muscle cell membrane by bovie current. While you can reduce muscle twitching with nmb but you cannot eliminate it.

 

[caligas]

Even if you eliminate all neuromuscular transmission, some of the muscle twitching is from direct depolarization of the muscle cell membrane by bovie current. While you can reduce muscle twitching with nmb but you cannot eliminate it.

Fair enough, it cant be eliminated. But, if you have no twitches at the hand is the localized twitching maximally optimized, or can it possibly be reduced by giving additional relaxant?

 

[Idiopathic]

so im not sure what the appropriate dose is but if you are referring to electrical stimulation in the spinal area causing hand twitching then that would not be direct muscle stimulation and should be ablated by fairly low dose nmb.

i dont appreciate the context...was this a case where neuromonitoring was involved and did not work correctely? or perhaps a surgeon wanted to know if the patient was relaxed because he saw twitching even though you had 0/4 at the monitor?

 

[caligas]

so im not sure what the appropriate dose is but if you are referring to electrical stimulation in the spinal area causing hand twitching then that would not be direct muscle stimulation and should be ablated by fairly low dose nmb.

i dont appreciate the context...was this a case where neuromonitoring was involved and did not work correctely? or perhaps a surgeon wanted to know if the patient was relaxed because he saw twitching even though you had 0/4 at the monitor?

The latter. Im talking about small local muscle stimulation at the spine from the bovie. Surgeon insistant that 0 twitches does not preclude giving more roc to reduce the muscle movement. He also knows that we often pretend to give more and dont. I gave more and it did seem that there was less local twitching. Twitch monitor was working fine, confirmed by neuromonitoring tech.

 

[Mman]

The latter. Im talking about small local muscle stimulation at the spine from the bovie. Surgeon insistant that 0 twitches does not preclude giving more roc to reduce the muscle movement. He also knows that we often pretend to give more and dont. I gave more and it did seem that there was less local twitching. Twitch monitor was working fine, confirmed by neuromonitoring tech.

Well then surgeon must understand that doing so increases risk of postop respiratory failure in his patient. The relationship between increased doses of NMBs and increased incidence of respiratory failure is pretty clear.

 

[caligas]

Well then surgeon must understand that doing so increases risk of postop respiratory failure in his patient. The relationship between increased doses of NMBs and increased incidence of respiratory failure is pretty clear.

Yes, of course. But what I am asking is from a physiological standpoint does 0 twitches on a TOF equate to maximal reduction in bovie stimulated local muscle activity. Assume you are 1 hour into a 8 hour fusion if that helps reduce postop ventilation concerns.

 

[nap$ter]

Yes, of course. But what I am asking is from a physiological standpoint does 0 twitches on a TOF equate to maximal reduction in bovie stimulated local muscle activity. Assume you are 1 hour into a 8 hour fusion if that helps reduce postop ventilation concerns.

neuromuscular blockers work at the junction - they absolutely do not affect direct stimulation of the muscle from the bovie - at all.

if the bovie is stimulating small motor neurons leading to twitch of muscles - that is affected by NMB's, but that is almost certainly not what your surgeon was complaining about.

if you have 0/4 twitches, you have >/=95% receptor occupancy. so - theoretically giving more drug could occupy that last 5% of receptors, and if the twitching is secondary to stimulation of motor neurons with the bovie it could lead to less twitching - theoretically.

but - that is not what was happening, and that last 5% of receptors is not worth going after, and is not causing the twitching. that's horse- s - h - i - t. the reduction of movement you and your surgeon thought you saw is likely placebo+bias.

don't lie to surgeons - this guy sounds like he's been lied to in the past and trusts his own knowledge about our specialty more than ours.

i wouldn't give more nmb in this situation - tell the surgeon why, if he wants to know. but i would make sure i didn't have double burst or tetany first (although your neurotech confirmed it) - tof is an imperfect test.

step up to the mike. this is our specialty, and nmb's are our domain.

 

[Mman]

Yes, of course. But what I am asking is from a physiological standpoint does 0 twitches on a TOF equate to maximal reduction in bovie stimulated local muscle activity. Assume you are 1 hour into a 8 hour fusion if that helps reduce postop ventilation concerns.

The surgeon wants to know if the patient is relaxed. My answer is yes and please resume operating so we can finish this in less than 8 hours.

 

[Idiopathic]

Yes, of course. But what I am asking is from a physiological standpoint does 0 twitches on a TOF equate to maximal reduction in bovie stimulated local muscle activity. Assume you are 1 hour into a 8 hour fusion if that helps reduce postop ventilation concerns.

you can always give more but you will probably never be able to totally eliminate this response and you will overdose on NMB to get there. after you double check your monitors and dosages, reassure the surgeon that this is not a problem. occasionally they will have difficulty exposing and will attribute it to muscle spasm...you may also be able to augment your relaxation with volatile anesthetic.

 

[Planktonmd]

When you give extra medications that the surgeon imagined he needs, this has a placebo effect on the surgeon and they will imagine that it made a difference.
Surgeons love it when you do what they tell you to do even if it made zero sense.
If you are a nurse then you have no choice and you should do what they told you, but if you are a physician then you should be able to formulate a logical argument and suggest a better solution to the problem.

 

[Idiopathic]

Unfortunately in this situation the solution is either "tolerate that" or "dont bovie so much"

It can be challenging

 

[EdPierce]

just give NS and lie to him yet again, if he doesnt like getting lied to dont ask for stupid stuff, or give 20 of ppfl. his argument does not make scientific sense. his extent of knowledge of NMBDs is that "the more they give the better" and "sometimes they lie about giving it". probably doesnt understand it will delay wake up, need to be reversed which can have HD consequences, prolong exposure to anesthesia, not add anything to his surgery.