The effect of propofol on systemic vascular resistance during cardiopulmonary bypass: a comparative study with...

30 patients undergoing elective coronary artery bypass grafting surgery were allocated randomly to receive either propofol--2.5mg/kg--(N = 10, Group I) or thiopentone--4mg/kg--(N = 10, Group II) during cardiopulmonary bypass with constant pump flow and temperature. Two groups and another control group-receiving no medication-(N = 10, Group III) were compared with respect to the changes in hemodynamic parameters, especially systemic vascular resistance (SVR). After propofol, SVR decreased from 2489 +/- 302 to 1594 +/- 286 dyn sec cm-5 and remained significantly less than the control values until 16.6 +/- 4 min. after the administration of propofol. Following thiopentone administration, SVR decreased from 2653 +/- 298 to 2162 +/- 279 dyn sec cm-5 and remained so for the following 9.4 +/- 3 min. There were more significant decreases in especially cardiac index, perfusion pressure and SVR in the propofol group compared with thiopentone or control groups. Cardiopulmonary bypass has been shown to be a useful model for studying the isolated effects of anesthetic drugs on hemodynamic parameters. In our study, we tried to discuss the mechanism of the hypotensive effects of anesthetic agents, especially propofol and give an idea about the possible precautions that should be taken.