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

Area of Science:

• Anesthesiology
• Cardiovascular Surgery
• Pharmacology

Background:

• Laboratory studies indicate cardioprotective effects of propofol at higher concentrations than typically used in anesthesia.
• Routine anesthesia during cardiac surgery may not achieve propofol concentrations associated with cardioprotection.
• The feasibility of achieving these experimental concentrations during cardiopulmonary bypass (CPB) via continuous infusion is not well-established.

Purpose of the Study:

• To determine if continuous propofol infusion can achieve experimental cardioprotective concentrations during cardiopulmonary bypass (CPB).
• To identify a practical propofol infusion rate for reaching target concentrations associated with cardioprotection during cardiac surgery.

Main Methods:

• A pilot study involving 24 patients undergoing aortocoronary bypass grafting with CPB.
• Patients received one of three propofol infusion rates (50, 100, or 150 microg x kg(-1) x min(-1)).
• Data were used to derive an infusion rate predicted to yield a whole blood concentration of 5 microg x mL(-1) at reperfusion, with interim analysis of 30 patients.

Main Results:

• An infusion rate-concentration curve was established (y = 0.215e^(0.0279x), r^2 = 0.781).
• A predicted infusion rate of 113 microg x kg(-1) x min(-1) was calculated to achieve 5 microg x mL(-1).
• A clinically practical rate of 120 microg x kg(-1) x min(-1) achieved a mean concentration of 5.39 (1.45) microg x mL(-1) without significant differences in cardiac index, systemic vascular resistance index, or left ventricular stroke work index between groups.

Conclusions:

• Continuous propofol infusion at 120 microg x kg(-1) x min(-1) is a clinically feasible method.
• This infusion rate effectively achieves experimental cardioprotective propofol concentrations at reperfusion during CPB.
• The findings support the potential for using propofol to enhance cardioprotection during cardiac surgery.