Neuromuscular efficacy and histamine-release hemodynamic changes produced by rocuronium versus atracurium: a comparative study.

BACKGROUND Rocuronium and atracurium are muscle relaxants used for short-and intermediate-duration surgical procedures. This study compares rocuronium and atracurium with regard to neuromuscular efficacy, hemodynamic changes, and their effects on plasma histamine concentration. MATERIALS AND METHODS Sixty adult patients scheduled for general surgical operations lasting less than 120 minutes were clinically randomized to receive either 0.6mg/kg rocuronium (group-1, n=30) or 0.5mg/kg atracurium (group-2, n=30). Twitch response to a course of four electrical stimulations, baseline heart rate, and mean blood pressure were monitored, as well as histamine levels through venous blood samples. RESULTS The onset time of neuromuscular block was 54+/-22 seconds in the rocuronium group, vs. 94+/-26 seconds in atracurium group (p=0.001). The clinical duration of the intubating dose was 34+/-6.9 minutes in the rocuronium group, vs. 45+/-7.1 minutes in atracurium group (p<0.001). Tracheas were intubated in less than 90 seconds from the time of the injection of the muscle relaxant in only 20 of the 30 patients in the atracurium group, but in all 30 patients in the rocuronium group (p=0.005). Atracurium, but not rocuronium, produced significant reduction of mean arterial blood pressure and increased heart rate at all times. Atracurium resulted in a significant increase in plasma histamine concentrations at one and three minutes of 232% and 149% (as percentage changes from control values, p<0.01). This corresponded significantly with the decrease in mean arterial blood pressure and the increase in heart rate (p<0.01). Rocuronium did not result in significant changes in plasma histamine concentrations. Further, 62+/-10% of the patients in the atracurium group, and none of rocuronium group, had clinical signs of histamine release. CONCLUSION Rocuronium provides more suitable conditions for rapid tracheal intubation than atracurium, is associated with a shorter clinical duration, has less effect on mean arterial blood pressure and heart rate, and has less histamine releasing potency when compared to atracurium.