Optimal Dose of Combination of Rocuronium and Cisatracurium

BACKGROUND: The combinations of rocuronium and cisatracurium have a synergic effect. The investigators studied whether the prediction is possible to have a sufficient effect of reducing the dose when combining the two neuromuscular blocking agents through monitoring neuromuscular relaxation during surgery. METHODS: Each group were intubating dose group (Group I, n=27) combined Effective Dose (ED)95 rocuronium and ED95 cisatracurium, small amount reducing group (Group S, n=27) reduced 10% of each ED95 and large amount reducing group (Group L, n=27) reduced 20% of each ED95. Before patients arrived in the operating room, rocuronium and cisatracurium were prepared by a nurse who was not involved in this study. Each study drug was administrated to the patient and timer was started with TOF-Watch® monitoring. Train-of-four (TOF) of the ulnar nerve was used as setting of 2 Hz per 12 sec. The investigators checked time to TOF ratio=0 (Onset), time to 1st TOF ratio\>25% (Duration 25%) and TOF 25-75% (recovery index) under total i.v. anesthesia (TIVA). One way ANOVA was used for statistical analysis (α=0.05, β=0.2).