Rocuronium in infants, children and adults during balanced anaesthesia

We studied 20 infants, 20 children and 20 adults during balanced anaesthesia to compare the neuromuscular blocking effects of rocuronium in these age groups. Neuromuscular function was recorded by adductor pollicis emg and a cumulative log-probit dose-response curve of rocuronium was established. Thereafter, full spontaneous recovery of the neuromuscular function was recorded. Onset time of the first dose of rocuronium was shorter in children than in infants or adults. The potency of rocuronium was greatest in infants and least in children; the ED50 doses (mean +/- SD) being 149 +/- 36 micrograms.kg-1 in infants, 205 +/- 52 micrograms.kg-1 in children and 169 +/- 47 micrograms.kg-1 in adults (P < 0.05 between infants and children) and the ED95 doses being 251 +/- 73 micrograms.kg-1, 409 +/- 71 micrograms.kg-1 and 350 +/- 77 micrograms.kg-1, respectively (P < 0.05 between all groups). The emg recovery following an average 94.5 +/- 4.8% neuromuscular blockade established by rocuronium was roughly similar in all study groups. Thus, one ED95 dose of rocuronium, unlike vecuronium, acts as an intermediate-acting agent in all age groups.