Tracheal intubation condition--a comparison between one minute after rocuronium alone, one minute after rocuronium combined with atracurium and one minute after atracurium with rocuronium at one minute priming interval.

Abstract

Rocuronium, a monoquaternary steroid analogue of vecuronium, is designed to provide a rapid onset of action. Experimentally, it has been shown that two non-depolarizing neuromuscular relaxants administered together can produce either a neuromuscular block of a size expected to be the sum of the individual doses (additive effect) or a larger neuromuscular block (synergistic effect). Experimental observations have suggested that during onset rocuronium acts synergistically with other nondepolarizing agents, but that at a steady state the combined action is additive. To investigate whether rocuronium can speed up the onset of atracurium for intubation, 120 patients who consented to receive elective surgery requiring tracheal intubation were randomly assigned to 3 equally divided groups to receive one of the following three different combinations of muscle relaxants: twice ED95 of rocuronium (0.6 mg/kg group 1), an equipotent mixture of ED95 of rocuronium and atracurium (0.3 mg/kg and 0.25 mg/kg respectively, group 2), and rocuronium 0.1 mg/kg to prime atracurium 0.42 mg/kg at 1 min interval. Intubation conditions were assessed 1 minute after intravenous muscle relaxant injection, and scored as good, acceptable and poor based on four clinical evaluators: the ease of laryngoscopy (score of 1-3), the relaxation of vocal cord (1-3), the degree of coughing (1-3), and movement of extremity (1-3). Adding up together, intubation condition that scored 4-5 was considered to be good, 6-7 acceptable, and 8-12 poor. The conditions produced in the rocuronium and the mixture groups were similar and both were moderately better than those of the priming group. Good intubation conditions were achieved in 58% patients of the rocuronium group, 63% of the mixture group and 43% of the priming group. By Pearson Chi-square test, the comparisons did not show statistical significance between groups. Statistically, rocuronium alone, mixture of equipotent atracurium and rocuronium, and using rocuronium to prime atracurium all provided similar onset for satisfactory intubation.