RESUMEN
The onset and duration of action, and hemodynamic effects of rocuronium bromide 0.6 or 0.9 mg kg-1 were studied in 4 groups of 10 patients each during anesthesia with nitrous oxide in oxygen and fentanyl or halothane. Neuromuscular block was monitored using mechanomyography and train-of-four (TOF) stimulation. The mean time to onset of complete neuromuscular block was 55 s with the 0.6 mg kg-1 dose during both anesthetic techniques. The times to recovery of T1 (first response in the TOF stimulation) to 25 and 90% of control and to the recovery of the TOF ratio to 0.7 were 36, 45 and 54 min respectively during narcotic anesthesia, and 35, 54 and 58 min during halothane anesthesia. Complete block with the 0.9 mg kg-1 dose occurred in 50, and 52 s respectively in the fentanyl and halothane groups. The recovery of T1 to 25% occurred in 49 and 52 min, to 90% in 66 and 71 min and to TOF ratio of 0.7 in 72 and 79 min respectively during balanced and halothane anesthesia. There were no significant changes in heart rate or mean arterial pressure during the 5 min following administration of either dose of rocuronium during balanced or halothane anesthesia. A separate group of 10 patients received 0.9 mg kg-1 of rocuronium during anesthesia with nitrous oxide, oxygen and isoflurane. Complete block occurred in an average time of 45 s in these patients with 25% recovery of T1 in 53 min.(ABSTRACT TRUNCATED AT 250 WORDS)