Recovery of NM fxn in different muscles

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excalibur

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I'm looking at an important graph in Barash, fig 16-14, which shows 7 different muscles and their recovery times after a 0.6 mg/kg dose of rocuronium.

The 7 muscles are divided into a group of 3, 1, and 3. The first group of 3 corresponds to muscles that recover 100% of their twitch height after approximately 25-30 mins. These 3 muscles in order are 1. diaphragm 2. Larynx (laryngeal adductors: vocal cords) 3. Corrugator supercilii (eyebrow).

The next muscle is the 4. abdominal muscles regaining 100% of their twitch height after approximately 35 mins.

The last 3 muscles in order are the 5. orbicularis oculi (eyelid) 6. geniohyoid (upper airway) 7. adductor pollicis (thumb). These muscle regain 100% of their twitch height after apporximately 40 mins.

1. Diaphragm
2. Larynx (laryngeal adductors: vocal cords)
3. Corrugator supercilii (eyebrow)
4. Abdominal muscles
5. Orbicularis oculi (eyelid)
6. Geniohyoid (upper airway)
7. Adductor pollicis (thumb)

The text discusses how monitoring the facial nerve and the eyebrow twitches, which correspond more closely to the vocal cords is a more appropriate monitoring choice for intubation than the thumb. Also, spontaneous respiration is NOT a sign of adequate recovery as the diaphragm is the first muscle to come back. For recovery, monitoring the thumb is optimal since its the last muscle to come back, and corresponds to the geniohyoid and upper airway muscles preventing obstruction upon extubation.

Of note, on the graph, the flexor hallucis (big toe) is not included. It is innervated by the posterior tibial nerve and can be stimulated posterior to the medial malleolus. Barash states that the response of this muscle is comparable to that of the adductor pollicis...hmm...interesting. I guess just think, big toe and thumb are about the same deal.

Comments appreciated.

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We use this info clinically all the time and it is amazing how few are familiar with the level of difference in these responses.


The two common mistakes I see (and have made myself) are using the orbicularis occuli for determining preparedness for reversal and using the abductor pollicis for determining depth of blockade when my surgeons are working in the upper abdomen.

For the longest time, I was arguing with my surgeons during hiatal hernia repairs, whipples etc. They would see diaphragmatic movement and I would have zero abductor pollicis twitches.

Now when I want someone deeply paralyzed for work in the upper abdomen, I will keep 1 corragatur supercillii twitch. About 1 hour before the end of surgery I will switch to monitoring the abductor pollicis to determine appropriate timing for reversal dosing.

My surgeons are much happier with me.

Let me add a warning for anyone who decides to use this technique...
Do not use the corragatur supercilii twitch as an indication of readiness for reversal. You will get burned.

-pod
 
Let me add a warning for anyone who decides to use this technique...
Do not use the corragatur supercilii twitch as an indication of readiness for reversal. You will get burned.

-pod

What's your plan when both arms are tucked?
 
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Issues with nm blockade that can be differentiated with different sites of monitoring have not been an issue since I entered pp.

Most of the cases are done without a monitor....including abdominal cases where academic surgeons ask about twitch levels every 15 minutes.



We use this info clinically all the time and it is amazing how few are familiar with the level of difference in these responses.


The two common mistakes I see (and have made myself) are using the orbicularis occuli for determining preparedness for reversal and using the abductor pollicis for determining depth of blockade when my surgeons are working in the upper abdomen.

For the longest time, I was arguing with my surgeons during hiatal hernia repairs, whipples etc. They would see diaphragmatic movement and I would have zero abductor pollicis twitches.

Now when I want someone deeply paralyzed for work in the upper abdomen, I will keep 1 corragatur supercillii twitch. About 1 hour before the end of surgery I will switch to monitoring the abductor pollicis to determine appropriate timing for reversal dosing.

My surgeons are much happier with me.

Let me add a warning for anyone who decides to use this technique...
Do not use the corragatur supercilii twitch as an indication of readiness for reversal. You will get burned.

-pod
 
I rely on the orbicularis occuli about 99% of the time to determine adequacy for reversal of paralysis and never had a problem.
 
Hello,

As an anesthesiologist who trained in 2 different continents before coming to United States and working as an anesthesiologist, I have to admit never has this specific issue discussed in such detail.

My take-
Now we have a lab value about recovery times, which may not be exact but provide a reasonable guide. However, to determine when one wants to intubate or extubate will depend on a whole set of clinical conditions.

For eg- During Intubation- When am i most concerned about bucking- Neuro cases, head injury, open globe injuries- Here though the corrugator testing might indicate adequate paralysis, wont we be safer by waiting an extra minute to abolish all chances of bucking- ofcourse giving all safety aspects of full stomach etc. So does it really matter where you test as long as you give enough, wait enough and be gentle enough. Surely, i am not saying dont test, but dont be fooled by some numbers.

For extubation- The same rules apply. I have seen a graph in Miller about how if we give more Neostigmine we can reverse quicker. I have never seen this concept in other countries- namely in Uk or Australia. The principle is- If we have 2 twitches - i mean 2 good twitches, not a gentle tweak on the second one, we can safely reverse. Doesnt matter which muscle you test.

So its good to know, for you exams, but clinically- use your judgements, take numbers with a grain of salt- If you actually analyse these studies, you will notice patients outside these measurement values, we cannot safely assume these numbers are the 95% of the values which is mean+/-2SD. Patient might have got excluded, values omitted etc. So there is no one fit all model.

Ga5man
 
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