A Comparison of Computer-Controlled Versus Manual Administration of Vecuronium in Humans

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Abstract
The short elimination half-life of vecuronium suggests it may be delivered more efficiently by continuous infusion than by traditional bolus injections. The objective of this study was to compare manual administration with computer-controlled administration. Anesthesia was induced in 22 patients (American Society of Anesthesiologists [ASA] physical status I and II) with fentanyl and sodium thiopental and maintained with halothane and nitrous oxide in oxygen. Neuromuscular function was assessed at the hypothenar eminence and the adductor pollicis (train-of-four stimulation). A bolus of 0.1 mg/kg of vecuronium was given to obtain 100% twitch depression for tracheal intubation. After twitch height returned to 25% of control, relaxation was maintained by traditional bolus injections (group 1, n = 7), manually controlled continuous infusion (group 2, n = 7), or computer-controlled continuous infusion (group 3, n = 8). In all three groups the desired level of relaxation was 90% twitch depression. Variability of relaxation differed significantly among the three groups (group 1: 10.5%, group 2: 12.4%, group 3: 7.1%). Twitch height was more constant with computer control than with either bolus injections or manual infusion (P < 0.05). There was no statistically significant difference in the drug requirement (group 1: 1.60 μg/kg/min, group 2: 1.51 μg/kg/min, group 3: 1.45 μg/kg/min). Variability in the mechanomyogram (n = 12) was much higher than in the electromyogram (n = 10). Computer-controlled infusion may be a useful adjunct for the anesthesiologist who desires a stable level of patient relaxation when using short-acting, nondepolarizing relaxants.