The effect of ephedrine on the onset time of rocuronium

The time from loss of consciousness to tracheal intubation is a period during which the patient is at risk of hypoxia and pulmonary aspiration. The length of this period is usually determined by the establishment of neuromuscular blockade, so it is usually desirable to use a muscle relaxant with a short onset time. The onset time is partly determined by the speed with which these drugs reach the neuromuscular junction, a factor that appears to be proportional to cardiac output and muscle blood flow (1). Since ephedrine can increase these variables (2,3), our hypothesis was that it could reduce the onset time of muscle relaxants. The aim of this study was to evaluate the effects of a single dose of ephedrine, given at the moment of induction, on the onset time of rocuronium and on blood pressure and heart rate evolution during the induction sequence.