A comparison of vecuronium by continuous infusion with either isoflurane or fentanyl-nitrous oxide anesthesia

The average infusion rate and efficacy of vecuronium bromide continuous infusions for surgical relaxation in human subjects was evaluated. Nineteen adult patients requiring more than 120 min of neuromuscular blockade for surgery were randomized to receive either fentanyl-nitrous oxide (Group 1) or isoflurane-fentanyl-nitrous oxide (Group 2). Neuromuscular function was monitored using train-of-four evoked electromyography (EMG). Following an intubating dose of 0.08 mg/kg of vecuronium bromide, the first twitch was allowed to return to 10% of its control value. An infusion of vecuronium at an initial rate of 60.0 micrograms/kg/h was then started and adjusted to maintain the first twitch at 10% of control. The average infusion rate (total infusion dose divided by the duration of the infusion) was 57.2 +/- 14 micrograms/kg/h in Group 1 (n = 10) and 42.4 +/- 12 micrograms/kg/h (n = 9) in Group 2, approximately 25% less (p = 0.02). There was a significant decrease in the infusion rate with time in Group 1 (p = 0.02), but this decrease was not observed in Group 2.