Neuromuscular effect of pipecuronium bromide in infants and children during nitrous oxide-alfentanil anesthesia

To determine in infants and children the neuromuscular effect of pipecuronium during alfentanil-N2O/O2 anesthesia, the authors studied 32 ASA Physical Status 1 and 2 pediatric patients undergoing minor elective surgery, divided into three groups according to their age: group 1 included 12 infants, 1.9 +/- 0.2 months old (mean +/- SE; range, 20 days to 3 months), weighing 5.2 +/- 0.3 kg; group 2, 10 infants, 6.1 +/- 0.9 months old (range, 3-11 months), 6.9 +/- 0.4 kg; and group 3, 10 children 5.6 +/- 0.9 yr old (range, 2-9 yr), 19.6 +/- 2.2 kg. Neuromuscular blockade at the ulnar nerve-adductor pollicis muscle was measured by electromyography. Incremental iv doses of pipecuronium were given (one 20 micrograms/kg first dose, followed by 10 micrograms/kg increments) to reach a 95 +/- 2% twitch depression (ED95). In children ED50 and ED95 of pipecuronium were 45.0 +/- 5.8 micrograms/kg (mean +/- SE) and 70.5 +/- 9.3 micrograms/kg, respectively. In 3- to 12-month-old infants ED50 and ED95 were 25.8 +/- 1.5 micrograms/kg and 48.7 +/- 3.5 micrograms/kg, respectively, and both significantly (P less than 0.05) less than those in children. In 0- to 3-month-old infants ED50 and ED95 were 23.7 +/- 1.7 micrograms/kg and 46.5 +/- 2.9 micrograms/kg, respectively, and also significantly (P less than 0.05) less than those measured in children. Time from maximal initial neuromuscular blockade to 75% recovery was 64.5 +/- 8.8 min in children and significantly shorter (P less than 0.05) in the two infant groups (0- to 3-month-old: 38.7 +/- 5.7 min, 3- to 12-month-old: 43.8 +/- 5.3 min, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)