Comparative effects of desflurane and isoflurane on vecuronium-induced neuromuscular blockade

Study Objective: To evaluate the neuromuscular effects o f a nondepolarizing muscle relaxant (vecuronium) during anesthesia with equipotent concentrations of either desflurane or isof lurane. Design: Randomized open study comparing effects of desflurane and isoflurane on vecuronium-induced neuromuscular blockade. Setting: University-affiliated medical center. Patients: Forty-five healthy adults undergoing elective surgical procedures randomly assigned to receive either desflurane, nitrous oxide (N 2O), and vecuroniuma or isoflurane, N 2O, and vecuronium for maintenance of general anesthesia. Interventions: Following a standardized induction sequence, patients receiving either desflurane and N 2O or iso flurane and N 2O were administered bolus doses of vecuronium equal to 0.01, 0.02, or 0.03 mg/kg intravenously (IV) during the maintenance period. Neuromuscular transmission was measured using a Relaxograph monitor. Measurements and Main Results: Vecuronium produced similar depression of neuromuscular function at equipotent (50% of the minimum alveolar concentration) end-tidal concentrations of isoflurane 0.6% and desflurane 3.0%. Following administration of vecuronium 0.01 to 0.03 mg/kg IV, onset times (3.4 ± 0.4 minutes to 3.2 ± 0.4 minutes and 3.2 ± 0.5 minutes to 3.0 ± 0.6 minutes), maximum T 1 twitch depression (80% ± 10% to 95% ± 9%, and 81% ± 9% to 97% ± 10%), clinical duration of blockade (12 ± 5 minutes to 20 ± 8 minutes and 10 ± 5 minutes to 19 ± 17 minutes), and T 1 recovery times (10 ± 3 minutes to 12 ± 6 minutes and 10 ± 3 minutes to 12 ± 4 minutes) were similar in the isoflurane and desflurane treatment groups, respectively (means ± SD). Conclusion: Vecuronium has similar neuromuscular effects when administered in the presence of desflurane 3% and isofurane 0.6%.