Pipecuronium-induced neuromuscular blockade during nitrous oxide-fentanyl, isoflurane, and halothane anesthesia in adults and children.

To determine in adults and children the dose-response relationship and the duration of action of pipecuronium bromide during fentanyl-nitrous oxide (N2O), isoflurane, and halothane anesthesia, the authors studied 30 ASA Physical Status 1-2 adults (age: 16-55 yr) and 30 ASA Physical Status 1-2 children (age: 1.7-11.5 yr) during minor elective surgery. Patients were anesthetized with N2O/O2 (60:40) supplemented with either fentanyl (4 micrograms/kg), or isoflurane (adults, 0.9%; children, 1.2%), or halothane (adults, 0.6%; children, 0.7%). Neuromuscular (NM) blockade was measured by electromyography. Incremental iv doses of pipecuronium were administered to determine the cumulative dose-response relationship of pipecuronium until a 95% twitch depression (ED95) had been obtained. In adults, ED50 was 31.7 +/- 2.9 micrograms/kg (mean +/- SE) during fentanyl-N2O/O2, reduced by isoflurane (18.0 +/- 4.8 micrograms/kg, P less than 0.05) but not by halothane (25.0 +/- 2.6 micrograms/kg, NS). ED95 was 59.4 +/- 5.4 micrograms/kg during fentanyl-N2O/O2, reduced by isoflurane (42.3 +/- 2.5 micrograms/kg, P less than 0.05), but not by halothane (49.7 +/- 3.1 micrograms/kg, NS). In children, ED50 was 43.9 +/- 4.7 micrograms/kg during fentanyl-N2O/O2, reduced by isoflurane (23.1 +/- 1.6 micrograms/kg, P less than 0.05), and halothane (33.2 +/- 3.2 micrograms/kg, P less than 0.05). ED95 was 79.3 +/- 9.8 micrograms/kg during fentanyl-N2O/O2, and reduced by isoflurane (49.1 +/- 3.1 micrograms/kg, P less than 0.05), but not by halothane (62.5 +/- 7.3 micrograms/kg, NS). Comparison between adults and children reveals no statistically significant differences, except for ED50 during fentanyl-N2O/O2 anesthesia which was increased in children.(ABSTRACT TRUNCATED AT 250 WORDS)