Neuromuscular effects of rocuronium on the diaphragm and adductor pollicis muscles in anesthetized patients.
BACKGROUND
Rocuronium has properties that may make it suitable for rapid-sequence intubation. However, its neuromuscular effects have been studied only on the adductor pollicis. This study compares the neuromuscular effect of rocuronium on the diaphragm and adductor pollicis in humans.


METHODS
The forces generated by the diaphragm and the adductor pollicis during supramaximal single-twitch stimulation of the phrenic and ulnar nerves, respectively, were studied during thiopental, fentanyl, and nitrous oxide-oxygen anesthesia. In 6 patients, cumulative doses of 0.15, 0.25, 0.35, 0.45, and 0.60 mg.kg-1 rocuronium were given over a 9-min period. The doses for 50% (ED50) and 95% (ED95) depression of twitch height were calculated. In another 12 patients, the times for maximal effect and 10%, 25%, 50%, 75%, and 90% recovery of the twitch height were calculated after a bolus dose of 0.60 mg.kg-1 rocuronium.


RESULTS
ED50 and ED95 were higher for the diaphragm (0.26 +/- 0.07 and 0.50 +/- 0.20 mg.kg-1, respectively) than for the adductor pollicis (0.14 +/- 0.05 and 0.24 +/- 0.04 mg.kg-1). Rocuronium 0.60 mg.kg-1 produced 100% paralysis of the adductor pollicis in all patients and of the diaphragm in 9 of 12 patients. The onset time for muscle relaxation after 0.6 mg.kg-1 rocuronium was shorter for the adductor pollicis than for the diaphragm (80 +/- 20 vs. 120 +/- 62 s). Times for 10%, 25%, 75%, and 90% recovery of twitch height were 34 +/- 10, 40 +/- 13, 56 +/- 20, and 64 +/- 21 min, respectively, for the adductor pollicis, and significantly shorter for the diaphragm: 17 +/- 10, 23 +/- 9, 33 +/- 13, and 35 +/- 10 min, respectively.


CONCLUSIONS
The diaphragm is more resistant than the adductor pollicis to rocuronium, as shown by greater ED50 and ED95 and faster recovery of the twitch height. The intubating dose of 0.60 mg.kg-1 is close to the ED95 of 0.50 mg.kg-1 for the diaphragm.
Cantineau
J P
JP
Department of Anesthesia, University of Paris, Henri Mondor Hospital, Creteil, France.
Porte
F
F
d'Honneur
G
G
Duvaldestin
P
P
D000328:Adult; D000732:Androstanols / Q000494:pharmacology*; D000758:Anesthesia / Q000379:methods*; D003964:Diaphragm / Q000187:drug effects* / Q000294:innervation; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000187:drug effects* / Q000294:innervation; D009469:Neuromuscular Junction / Q000187:drug effects*; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D010791:Phrenic Nerve / Q000502:physiology; D000077123:Rocuronium; D013933:Thumb; D014459:Ulnar Nerve / Q000502:physiology
D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D000077123:Rocuronium