Prediction of infusion rates of rocuronium using the bolus test dose technique

Twenty-four patients were given a loading dose of rocuronium 1.0 mg.kg^?1 intravenously followed by boluses of 20 mg ( n  = 19) and 10 mg ( n  = 24) after return of T1 of the train-of-four to 5% of control. Neuromuscular function was assessed using a Relaxograph. The time was recorded for the return of T1 to 5% after the administration of the boluses and subsequently an infusion of rocuronium was started. The aim was to maintain T1 between 3% and 7% of control for at least 40 min without a change of infusion rate. The correlations between the duration of the test doses and the infusion rates were ?0.94 (10 mg) and ?0.86 (20 mg). The predictive accuracy of the 10 mg bolus was assessed in a further 10 patients. At the termination of the infusion three patients had a T1% that was outside the desired range of 3–7%. A 10 mg bolus that lasts 6 min indicates a need for an infusion of at least 60 mg.h^?1, 8 min (50 mg.h^?1), 10 min (40 mg.h^?1), 15 min (30 mg.h^?1), 24 min (20 mg.h^?1) and 34 min (15 mg.h^?1).