Cardiac and circulatory effects of high-dose meptazinol in anaesthetized patients.

The haemodynamic effects of three doses of meptazinol were studied in 9 anaesthetized patients before surgery. Three patients of each group received a bolus injection of 2, 3, or 4 mg/kg. In all groups, cardiac output, mean arterial pressure, heart rate and the rate pressure product fell significantly. The systemic and pulmonary vascular resistance remained unchanged. The pulmonary capillary wedge pressure and mean pulmonary artery pressure were stable throughout the 90 minutes observation period. None of the doses of meptazinol had a deleterious effect on myocardial contractility although the observed changes were more pronounced with the 4 mg/kg dose. It is concluded that meptazinol improves the myocardial oxygen demand/supply ratio mainly through its negative chronotropic effect and a reduction of afterload.