Target-achieved propofol concentration during on-pump cardiac surgery: a pilot dose-finding study

Propofol concentrations that produce laboratory-based cardioprotective effects are generally greater than those produced under routine anesthesia during cardiac surgery. It is unknown whether experimental cardioprotective propofol concentrations can routinely be achieved during cardiopulmonary bypass (CPB) using continuous infusion. Twenty-four patients scheduled for primary aortocoronary bypass grafting with CPB were allocated to receive one of three propofol infusion rates; 50, 100, or 150 mu g center dot A kg(-1) center dot A min(-1) in an open-label pilot study. Data were described using a line of best fit to derive an experimental clinical maneuver predicted to produce a whole blood concentration of 5 mu g center dot A mL(-1) at reperfusion. A predetermined interim analysis of 30 patients who were receiving the derived maneuver in an ongoing study was used to evaluate the maneuver. Cardiac index (CI), systemic vascular resistance index (SVRI), and left ventricular stroke work index (LVSWI) were recorded. The infusion rate-concentration curve had an equation of y = 0.215e (0.0279x) , where y represents the whole blood concentration and x represents the infusion rate (r (2) = 0.781). The predicted infusion rate to achieve a mean concentration of 5 mu g center dot A mL(-1) was 113 mu g center dot A kg(-1) center dot A min(-1). The nearest practical rate is 120 mu g center dot A kg(-1) center dot A min(-1), producing a concentration of 5.39 (1.45) mu g center dot A mL(-1). The values for CI, SVRI, and LVSWI were similar between groups at corresponding time periods. An infusion rate of 120 mu g center dot A kg(-1) center dot A min(-1) is clinically practical and capable of achieving experimental cardioprotective propofol concentrations at reperfusion.