Effect of low-dose propofol infusion on total-body oxygen consumption after coronary artery surgery

To investigate the effect of low-dose propofol infusion on total-body oxygen consumption (VO2) after coronary artery bypass grafting (CABG) surgery.

A prospective, randomized, placebo-controlled, double-blind study.

Cardiovascular intensive care unit in a university hospital.

Thirty patients after elective, uncomplicated CABG surgery.

Patients were administered a continuous infusion of propofol with a fixed rate of 1 mg/kg/h (n = 15) or placebo (n = 15) during the spontaneous rewarming period of approximately 5 hours after surgery. A light level of sedation (Ramsay sedation score > or =2) was maintained by administering small doses of diazepam, 0.1 mg/kg, as required. Morphine, 0.05 mg/kg, was administered for analgesia as required.

Total-body VO2 was measured by indirect calorimetry. In addition, shivering (on a five-grade scale), hemodynamics, and plasma catecholamine and serum cortisol concentrations were measured. Diazepam, 5.6+/-7.4 mg (mean +/- standard deviation), was administered to the patients receiving propofol, and 16.1+/-12.2 mg was administered to the patients receiving placebo (p < 0.05). There was no difference in the dose of morphine between the groups (3.2+/-3.9 v 4.2+/-5.5 mg in the propofol and placebo groups, respectively). At any time during the study, VO2 was not different between the groups. VO2 increased from 130+/-29 to 172+/-29 mL/min/m2 in the propofol group and from 118+/-24 to 167+/-27 mL/min/m2 in the placebo group. Mean arterial pressure and heart rate were lower in the propofol group (p < 0.05). Stress hormone levels did not differ between the groups.

Low-dose propofol infusion and additional diazepam as required does not decrease total-body VO2 compared with a pure diazepam bolus-dose technique when administered for light sedation during the immediate recovery period after CABG surgery.