Haemodynamic changes following buprenorphine and morphine

Twenty-five women were investigated on the day after lower abdominal surgery in a single-blind non-cross-over trial to assess and compare the haemodynamic effects of intravenous injections of buprenorphine 0.3 mg and morphine 7.5 mg. Arterial blood pressure was measured by sphygmomanometry and cardiac output by thoracic impedance cardiography. Arterial blood pressure was significantly reduced following both drugs (p < 0.05), although the mean decrease in systolic arterial pressure was less than 8 mmHg. However, in one patient in each group the decrease was more than 20 mmHg. Cardiac output decreased but the mean reduction was less than 5%. The greatest individual decreases were 21% after buprenorphine and 30% after morphine. Myocardial contractility, assessed by systolic time indices, did not appear to change. There were no consistent differences in the haemodynamic effects of the two drugs.