THE CARDIOVASCULAR CHANGES ASSOCIATED WITH EQUIPOTENT ANESTHESIA WITHEITHER PROPOFOL OR ISOFLURANE - PARTICULAR EMPHASIS ON RIGHT-VENTRICULAR FUNCTION

The differences in effects of anaesthetic agents on right ventricular function have not been studied. We have developed a cross-over study d esign to compare the effects of propofol and isoflurane on cardiac and specifically right ventricular function. Ten patients were anaestheti sed with equivalent MAC of isoflurane to MIR of propofol. After measur ements had been taken on the randomly assigned first agent the patient s were crossed over to the other agent and measurements,were repeated. Cardiac function was assessed using a pulmonary artery catheter with a fast response thermistor. There were no differences in heart rate or blood pressure between the two agents suggesting that equivalent anae sthetic doses had been given. There were significantly (P < 0.05) high er cardiac output (4.0 to 4.5 l.min(-1)), right ventricular ejection f raction (35.1 to 39.4%), stroke volume (35.4 to 39.6 ml) and right ven tricular end-diastolic volume index (102 to 110 ml.m(2-1)) with propof or compared to isoflurane. We conclude that propofol results in improv ed right ventricular performance compared to isoflurane. We have also shown that anaesthetic agents can be compared using a cross-over study design, and have demonstrated that MAC of isoflurane and MIR of propo fol can be directly compared. We suggest that propofol may be a more s uitable agent than isoflurane for anaesthesia in patients who may alre ady have impaired right ventricular function and in whom maintaining h igh cardiac output may be beneficial.