Duration of vecuronium-induced neuromuscular blockade predicted by dose and onset time

We investigated the adequacy of using dose and onset time as variables to predict the duration of action of vecuronium in patients. The onset time until 95% twitch depression and the duration until 25% twitch recovery were measured for doses ranging from 0.1 to 0.3 mg kg^-1. Statistical analyses were performed by simple and multiple regressions. The duration of action was better predicted by dose (r² = 0.61) than by onset time (r² = 0.51). However, the predictability was significantly improved by a multiple regression model of the variables, and the explanatory power was largest when using the square root of duration as the dependent variable (r² = 0.69). We conclude that the duration of neuromuscular blockade after vecuronium can be predicted more accurately by the combined use of dose and onset time than by dose alone.