Clinical Management
Neuromuscular blockers are mainly used to facilitate tracheal
intubation and provide surgical relaxation. The required intensity of neuromuscular
blockade varies with the surgical procedure. In practice, important safety issues
with neuromuscular blockers are cardiovascular and respiratory side effects and the
adequacy of recovery to normal neuromuscular function.
Several clinical alternatives to neuromuscular blockers are available
to provide adequate surgical relaxation. It is important to keep them all in mind
to avoid relying only on neuromuscular blockade to achieve a desired degree of relaxation.
These options include adjustment of the depth of general anesthesia, regional anesthesia,
proper positioning of the patient on the operating table, and proper adjustment of
the depth of neuromuscular blockade. The choice of one or several of these options
is determined by the estimated remaining duration of surgery, the anesthetic technique,
and the surgical maneuver required.
TABLE 13-7 -- Guide to nondepolarizing relaxant dosage (mg/kg) under different anesthetic
techniques
*
|
|
|
|
Dosage for Relaxation |
|
ED95
under N2
O/O2
|
Dose for Intubation |
Supplemental Dose after Intubation |
N2
O |
Volatile Anesthetic
†
|
|
Long Acting |
|
Pancuronium |
0.07 |
0.08–0.12 |
0.02 |
0.05 |
0.03 |
|
Metocurine |
0.28 |
0.3–0.4 |
0.05 |
0.2 |
0.1 |
|
d-Tubocurarine |
0.5 |
0.5–0.6 |
0.1 |
0.3 |
0.15 |
|
Gallamine |
3.0 |
4.0–6.0 |
0.5 |
2.0 |
1.0 |
|
Alcuronium |
0.25 |
0.3 |
0.05 |
0.2 |
0.08 |
|
Doxacurium |
0.025 |
0.05–0.08 |
0.005–0.01 |
0.025 |
0.02 |
|
Pipecuronium |
0.05 |
0.08–0.1 |
0.01–0.015 |
0.04 |
0.03 |
|
Intermediate Acting |
|
Vecuronium |
0.05 |
0.1–0.2 |
0.02 |
0.05 |
0.03 |
|
Atracurium |
0.23 |
0.5–0.6 |
0.1 |
0.3 |
0.15 |
|
Cisatracurium |
0.05 |
0.15–0.2 |
0.02 |
0.05 |
0.04 |
|
Rocuronium |
0.3 |
0.6–1.0 |
0.1 |
0.3 |
0.15 |
|
Short Acting |
|
Mivacurium |
0.08 |
0.2–0.25 |
0.05 |
0.1 |
0.08 |
|
Continuous infusions (µg/kg/min)
required to maintain 90%–95% twitch inhibition under N2
O/O2
with intravenous agents |
|
Mivacurium |
3–15 |
|
|
|
|
|
Atracurium |
4–12 |
|
|
|
|
|
Cisatracurium |
1–2 |
|
|
|
|
|
Vecuronium |
0.8–1 |
|
|
|
|
|
Rocuronium |
9–12 |
|
|
|
|
*Suggested dosages provide
good intubating conditions under light anesthesia. Satisfactory abdominal relaxation
may be achieved at the dosages listed after intubation without a relaxant or with
succinylcholine. This table is intended as a general guide to dosage. Individual
relaxant requirements should be confirmed with a peripheral nerve stimulator.
†Potentiation
of nondepolarizing relaxants by different volatile anesthetics has been reported
to vary 20% to 50%. Recent data suggest, however, that this variation may be much
less, particularly in the case of intermediate- and short-acting relaxants. Therefore,
for the sake of simplicity, this table assumes a potentiation of 40% in the case
of all volatile anesthetics.
