Age-dependence of the dose-response curve of vecuronium in pediatric patients during balanced anesthesia.

The effect of age on the log-based cumulative dose-response curve of vecuronium was determined in ten age groups of 80 pediatric patients ranging from neonates to adolescents during thiopental-fentanyl-N2O/O2 anesthesia. Neuromuscular block was recorded as the evoked thenar electromyographic response to train-of-four stimulation of the ulnar nerve (2 Hz at 20-second intervals). The dose-response curves were parallel to each other in all ten age groups studied. In neonates and infants, the ED95 of vecuronium was 47 +/- 11 (SD) micrograms/kg. This was significantly lower than the ED95 of 81 +/- 12 micrograms/kg in children between 3 and 10 years of age (P less than 0.01). In patients aged 13 years or older, the ED95 was 55 +/- 12 micrograms/kg, which did not differ from the neonatal and infant values but was significantly lower than the ED95 of children between 3 and 10 years of age. The results indicate that the dose of vecuronium necessary for tracheal intubation is age-dependent. The individual ED95 values varied between 22 and 103 micrograms/kg. This suggests that an individually optimal dose of vecuronium can be administered to pediatric patients only if neuromuscular block is adequately monitored.