NMB 101: 13 Lucky Reminders
for use of NeuroMuscular Blocking Agents
Rob Morrison MD February 2012
1) Laryngeal mask anesthesia has changed expectations in the OR and
PACU. Endotracheal anesthetics can't be rushed. LMA anesthetics
require no paralysis and permit fast "extubations" => PACU
transfers => hand-offs. Endotracheal anesthetics need time for pre and
post extubation assessments.
2) EXTUBATION IS A PROCEDURE. It deserves a checklist with "hard
stops" and a procedure note on the anesthesia record. What's more,
not all patients can or should be extubated before the PACU phase.
|3) We often intubate with larger doses of
Vecuronium, Rocuronium and Cisatracurium than are necessary. Learn the
ED95s (Effective Dose for 95% depression of T1 twitch height).
For short, elective cases lower NMBD doses plus propofol plus inhalation
agent results in excellent Intubating conditions in 4-5 minutes.
|NMBD ED95 ( 15% less with
|Vecuronium 0.05 mg/kg (50 mcg/k) Example: 80kg
= 4.0 mg
||Up to 0.02 mg/kg
|Rocuronium 0.30 mg/kg
From table 29-6, Miller's "Anesthesia"
4) We often "top-up" with more NMBD than is necessary. It's
safest to maintain ~2 twitches and use small top up doses (see table
above). Avoid top-ups in the last ~45 min before giving Neostigmine.
Instead of top-up NMBDs use incremental propofol, opiates, IV lidocaine,
and, when necessary, tell the surgeon that you can't safely give any more
5) Neostigmine is an ANTAGONIST not a "reversal." The
only true reversal out there is Suggamadex and the FDA won't let us have
it. (At ~$80 a pop it's even too costly for the Europeans.)
6) "Blind Paralysis" is common. Traditional methods of
assessing NMB recovery (vigorous bucking, full tidal volumes, head lift,
hand grip, NIF, visually observed TOF, 5 sec 50hz tetanus, etc) result in
unrecognized residual paralysis. Since the introduction of quantitative
nerve stims, multiple studies have documented very high rates of residual
paralysis in the PACU. Rates as high as 40% if neostigmine was given, and
60% if neostigmine was omitted.
|7) Residual paralysis results in unwanted critical
respiratory events including reintubations in PACU. This is fact, not
speculation. (Murphy et al, Anesth Analg 2008;107:130-137) Patients at
highest risk: Renal dz, Hepatic dz, obesity, diabetes, circulatory
deficiency, age>70, pulmonary disease, hypothermia.
8) Neostigmine & glycopyrrolate does NOT increase the risk of
nausea and vomiting. (Cheng, Sessler, Apfel, Anesth Analg.(2005); 101:
1349-1355. Joshi et al, Anesth Analg (1999); 89:628-31, Hovorka et al,
Anesth Analg (1997); 85:1359-61) Even if it did, safety demands minimizing
the risk of residual paralysis.
9) Neostigmine is an effective antagonist only when given with TOFs of
3 or 4. If given to reverse vecuronium with a TOF of 1-2 there will be
~22-30 minutes of continued weakness. This is the same as if you waited
10-15 min for a 3rd twitch to appear before giving neostigmine. (see page
||Effective Neostigmine dose
BTW, the duration of neostigmine action is only ~30
minutes following a 70mcg/kg dose. Another reason not to use it too early.
|10) Using the facial nerve as a monitoring site is
often necessary but recovery at this site occurs earlier (~17 min if
vecuronium is used) than at the ulnar nerve. Also remember to confirm
recovery at the ulnar nerve because the pharyngeal muscles needed for
airway support and swallowing recover in synchrony with the thumb muscles
not the facial muscles.
11) NEVER mix "steroidal" and "quinolinium" NMBDs.
You will be unable to predict NMB effect or recovery.
12) ALWAYS give neostigmine even if the TOF count has been 4 for
>50 min. As Ronald Miller wrote in a July, 2010 editorial (Anesth Analg;
111:3-5): "If a decision is made not to give neostigmine, then
specific reasons must be recorded." For us this means ALWAYS give
neostigmine and glycopyrrolate. If and when you ever use a quantitative
neuromuscular tester and you can document a TOFR >0.9, then you can
13) Lastly, there still is no true substitute for
succinylcholine. Use it when risks (full stomach, difficult airway)
justify it. And if vecuronium is used after sux, remember to use the ED95
dose (0.05 mg/kg) NOT the intubating dose.