The determinants of propofol induction of anesthesia dose

Recently it was reported that the pharmacokinetics of propofol are modified by changes in cardiac output. The objective of this study was to evaluate the effects of cardiac output and other factors on the hypnotic dose of propofol. One-hundred surgical patients were administered indocyanine green immediately before the induction of anesthesia to measure their cardiac outputs and blood volumes. Propofol (250 mug . kg(-1) . min(-1)) was infused IV for 8 min, and the hypnotic dose of propofol and the time to hypnosis were recorded. The plasma concentration of propofol immediately after 2 mg/kg infusion was measured. Multiple regression analysis show ed that, in addition to age and weight, cardiac output was a small but significant factor for predicting the hypnotic dose of propofol (R-2 = 0.468, P < 0.001), the time to hypnosis (R-2 = 0.454, P < 0.001), and the plasma concentration of propofol (R-2 = 0.248, P < 0.01). Cardiac output, age, and weight showed similar partial coefficients for the hypnotic dose (0.128, 0.137, and 0.140, respectively).