Neuromuscular Effects of Vecuronium (ORG NC45) in Infants and Children during N2O, Halothane Anesthesia

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Abstract
The neuromuscular effects of vecuronium [a muscle relaxant] (ORG NC45, Norcuron) were determined during anesthesia with nitrous oxide and 0.9 MAC halothane. To determine potency, they administered vecuronium (15, 20, or 25 .mu.g/kg) to 18 infants (< 1 yr old) and 18 children (1-8 yr old). They then compared these dose-response relationships with values obtained for adults (> 18 yr old) under comparable anesthetic conditions. The ED50 (dose producing 50% depression of adductor pollicis twitch tension) of 16.5, 19.0 and 15.0 .mu.g/kg for infants, children and adults, respectively, did not differ significantly. To determine the time course of neuromuscular blockade, the vecuronium, 70 .mu.g/kg, was administered to 6 infants, 6 children and 6 adults. Onset time (time to maximal effect) was shortest for infants (1.5 .+-. 0.6 min, mean .+-. SD) compared with that for children (2.4 .+-. 1.4 min) and adults (2.9 .+-. 0.2 min). Duration (time from injection to 90% recovery) was longest for infants (73 .+-. 27 min) compared with that for children (35 .+-. 6 min) and adults (53 .+-. 21 min). Vecuronium can evidently be used in infants and children in doses similar to those recommended for adults. The time interval for supplemental doses will be longest in infants and shortest in children.