[Clinical study of large doses of vecuronium; duration of initial and additional doses]

Neuromuscular blockade by large doses of vecuronium was investigated clinically and the duration of action of initial doses (0.2 mg.kg-1 and 0.3 mg.kg-1) and additional doses (0.01 mg.kg-1 and 0.02 mg.kg-1) were measured under enflurane-nitrous oxide anesthesia using a neuromuscular transmission monitoring system (Accelograph). In group A (initial dose = 0.2 mg.kg-1, additional dose = 0.02 mg.kg-1), the time of spontaneous recovery to 25% of control twitch height (T25) and 50% of control (T50) were 63.1 and 82.0 minutes respectively. The T50 interval of the two adjacent added doses (given at the time point of 50% recovery from the previous dose) was 31.1 minutes. Reversal time from TOF ratio = 25% to 75% after administration of edrophonium was 6.1 minutes. In group B (initial = 0.3 mg.kg-1, add. = 0.01 mg.kg-1), T25, T50, T50 interval and reversal time were 122.6, 159.4, 39.2 and 4.6 minutes respectively. In group C (initial = 0.3 mg.kg-1, add. = 0.02 mg.kg-1), above values were 119.2, 145.8, 48.4 and 6.7 minutes respectively. In this study there was no obvious side effect associated with administration of large doses of vecuronium. These methods will be very useful for long surgical procedures.