A Mixture of Mivacurium and Rocuronium Is Comparable in Clinical Onset to Succinylcholine

Abstract

Comment: This study supports prior evidence that the addition of mivacurium to rocuronium accelerates the onset of neuromuscular block while not unduly prolonging the duration of block. The relatively fast onset of rocuronium and the relatively short duration of mivacurium make them well suited for use in combination. Although onset times equivalent to those after succinylcholine are difficult to obtain with a single nondepolarizing relaxant (unless one is willing to accept marked prolongation or side effects such as histamine release), combinations of moderate doses of drugs with different dose-related side effects may provide the clinician with a much needed alternative. The ablation of T1 twitch height occurred at 47 ± 7 sec after succinylcholine and only 51 ± 13 sec after mivacurium plus rocuronium. Similarly, good to excellent intubating conditions were obtained to approximately the same degree. However, it can be seen that the variability was greater in the combination group. Moreover, 8 of 10 patients in the succinylcholine group had excellent conditions (and possibly even a better outcome would have been obtained if >1 mg/kg had been used); only 21 of 30 patients had excellent conditions in the combination group. Although such subtle differences might not be important in most clinical settings, they could be extremely important if one really wishes to intubate as soon as possible, especially if one needs to avoid any movement or coughing.