Anthropometric Variables as Predictors for Duration of Action of Vecuronium-Induced Neuromuscular Block

Abstract

Comment: Clinicians generally are aware of the pitfall of administering nondepolarizing muscle relaxants to morbidly obese patients on the basis of weight alone. This study shows that best dosing and redosing of vecuronium is achieved with anthropometric data that are cumbersome to use in clinical practice, an index that uses either ideal body weight or thickness of skin folds and surface area. In the study, initial doses of vecuronium were used in combination with induction agents presumably to facilitate endotracheal intubation. Current practice would suggest that this is not appropriate for patients at the far end of the study's spectrum, 126 kg. Most practitioners would agree that there must be concern for at least two major anesthetic problems in patients who are obese, risk of aspiration after gastric reflux and potential for loss of the airway with difficult intubation. A rapid sequence induction and intubation would seem to be in order. The major value of this study is that it provides a foundation for vecuronium dosing in clinical studies. However, in regression analysis the best anthropometric variable showed a correlation coefficient of only 0.389 for the induction dose of vecuronium. To date most studies have used a “per kg” basis, which had a correlation coefficient of 0.312.