Hemodynamic Effects of Morphine and Pentazocine Differ in Cardiac Patients

Abstract

The hemodynamic effects of 8 mg of morphine given intravenously to eight patients were compared in a randomized, double-blind protocol with the effects of 48 mg of intravenous pentazocine given to nine patients. All 17 patients had arteriographically proved coronary-artery disease. Administration of morphine significantly decreased oxygen consumption (-11.6 per cent), cardiac index (-8.6 per cent) and left ventricular end-diastolic pressure (-20.5 per cent). In contrast, pentazocine significantly elevated mean aortic pressure (+12.5 per cent), left ventricular end-diastolic pressure (+20.2 per cent) and mean pulmonary-artery pressure (+36.3 per cent). Because of the different effects of morphine and pentazocine on cardiac output and arterial pressure, cardiac work was decreased 8.2 per cent by morphine and increased 22.1 per cent by pentazocine. The differing hemodynamic effects of morphine and pentazocine suggest that consideration should be given to each patient's cardiovascular status before administration of these analgesic drugs and to the hemodynamic effects of the agent selected.