Effects of age on neuromuscular blockade by vecuronium as measured by accelography under sevoflurane anesthesia

We evaluated possible differential effects of age on a single bolus intravenous injection of vecuronium using accelography under sevoflurane anesthesia. Thirty anesthetized patients were divided into three groups of 10 patients as follows: group 1=age 1-5 years; group 2=age 20-40 years, and group 3=age >70 years. Vecuronium 0.1 mg·kg(-1) was given to facilitate tracheal intubation. Onset time, i.e., the time from the start of injection of the first dose of vecuronium to development of maximal twitch depression in group 1 was significantly shorter than those in groups 2 and 3 (103.5±30.4s, 166.5±32.7s, and 202.5±56.7s; mean±SD;P<0.01). Clinical duration, i.e., the time from completion of maximal block to 25% recovery of train-of-four (TOF) ratio in group 1 was significantly shorter than that in group 3 (43.6±12.0 min and 67.3±15.6 min;P<0.01). The reversal time from 25% to 75% of the TOF ratio after the administration of neostigmine in group 1 was not significantly different from those in groups 2 and 3 (172.5±73.9s, 219.0±59.7s, and 222.0±155.7s). The authors conclude that the time to maximal twitch depression after the administration of vecuronium is significantly shorter in children than that in adults, and that the fastest recovery from vecuronium is also observed in children.