A mixture of mivacurium and rocuronium is comparable in clinical onset to succinylcholine.

STUDY OBJECTIVES: To compare the clinical onset and duration of a combination of mivacurium and rocuronium with succinylcholine, and to determine the efficacy of this mixture for rapid tracheal intubation.

DESIGN: Observer-blind prospective study.

SETTING: Teaching hospital.

PATIENTS: 70 ASA status I and II patients having general anesthesia for elective surgery.

MEASUREMENTS AND MAIN RESULTS: After induction of general anesthesia, patients randomly received succinylcholine 1.0 mg/kg, rocuronium 0.6 mg/kg, or a combination of rocuronium 0.6 mg/kg and mivacurium 0.15 mg/kg. Evoked muscular response at the adductor pollicis was measured by mechanomyography. The time from injection of muscle relaxant(s) to ablation of T1 (clinical onset) and recovery of T1 to 25% of control height (clinical duration) was recorded. Intubating conditions 45 seconds after administration of muscle relaxants were assessed. There was no significant difference in clinical onset time between succinylcholine (mean +/- SD, 47.4 +/- 6.5 seconds) and the combination of mivacurium-rocuronium (51.2 +/- 13.4 seconds). Intubating conditions with mivacurium-rocuronium were comparable to those of succinylcholine. The clinical duration of rocuronium 0.6 mg/kg (38.9 +/- 12.3 minutes) was prolonged by the addition of mivacurium (49.0 +/- 9.6 minutes).

CONCLUSIONS: This combination of mivacurium and rocuronium is comparable to succinylcholine in both clinical onset time and quality of intubating conditions. When rapid onset of dense neuromuscular blockade and intermediate clinical duration is desirable, this mixture may be an acceptable alternative to succinylcholine.