Onset and recovery of neuromuscular blockade after two doses of rocuroniumin children

Study Objective: To determine if 450 mu g/kg (1.5 times the ED95) of rocuro nium would result in a comparable onset with a shorter duration of action w hen compared with 600 mu g/kg (2 times the ED95). Design: Randomized single-blind study. Setting: Teaching hospital. Patients: 85 ASA physical status I and II children ages 2 through 12, under going elective surgery with an inhalation induction using halothane. Interventions: Group received 600 mu g/kg rocuronium, and Group 2 received 450 mu g/kg rocuronium. Measurements and Main Results: The two groups were compared using a Student 's t-test, with p < 0.05 significant. The time of onset, or time to 95% sup pression of neuromuscular twitch with standard errors, was 140 +/- 13 secon ds (range 46 to 365 sec) in Group 1 and 148 +/- 13 seconds (range 82 to 345 sec) in Group 2(NS = not significant). The times to 25% return of twitch f i om baseline (T-25) In Groups 1 and 2 were 28 +/- 1.5 minutes (range 14 to 45 min) and 25 +/- 1.6 minutes (range 10 to 55 min), respectively (NS). Th e differences between these two doses in onset of and recovery from, block were not found to be statistically significant. The results, however, exclu ded 5% of the higher dose group and 31% of the lower close group who did no t achieve 95% suppression of twitch. rime to maximal suppression of neuromu scular blockade, however, was not statistically significant for the 85 pati ents with a ti,ne of 270 +/- 28 seconds (range 91 to 605 sec) with a mean m aximal suppression of 98.7% In Group 1 and 313 +/- 25 seconds (range 91 to 899 sec) with a mean maximal suppression of 93.1% in Group 2. Conclusion: The two doses of rocuronium did not differ statistically in ons et or duration. Rocuronium at 600 mu g/kg offers more reliability than 450 mu g/kg. in achieving adequate muscle relaxation, and the lower dose may re sult in a significantly large number of patients who may have inadequate in tubating conditions. (C) 1998 by Elsevier Science Inc.