[Prediction of the maintenance dose of vecuronium for continuous infusion]

The purpose of this study is to examine how to predict the optimal maintenance dose of vecuronium for continuous infusion, knowing the recovery time from the block induced by the first bolus injection. All patients studied were undergoing surgical procedures and were anesthetized using thiopental, vecuronium, 50% nitrous oxide and 2% enflurane in oxygen. Mechanical twitch responses of adductor pollicis muscle caused by the stimulation of the ulnar nerve supramaximally were monitored. Vecuronium concentrations in the plasma were measured using high performance liquid chromatography. The experiments consisted of two phases. Phase 1.: To demonstrate the relationship between the recovery time (T0-T25) and the maintenance dose. Thirty patients were studied in this phase. A bolus injection was given as the first dose (1.5 mg.kg-1). During the recovery from the first block, recovery time (T1) was measured and the second dose (2 mg) was injected at the T25 (25% control twitch height). After waiting the recovery until the T25, the third dose (2 mg) was injected. The duration (T2) (min) between the second and the third injection was measured. The maintenance dose-recovery time curve was obtained. Y = 52.70.exp (-17.50 X) + 1224.53.exp (-224.27X), X = recovery time (min), Y = maintenance dose (mg.hr-1). Phase 2.: Thirty patients were studied in this phase. Patients received infusions after the bolus injection. The infusion rates were obtained from the maintenance dose-recovery time curve.(ABSTRACT TRUNCATED AT 250 WORDS)