Haemodynamic effects of a single large dose of insulin in open heart surgery

The haemodynamic effects of a single dose of 0.35, 1.5 or 7.5 IU fast acting insulin X kg bw-1 were studied in 24 patients undergoing aortocoronary bypass grafting. No inotropic drugs were used. Blood glucose was measured using a continuous blood glucose monitoring system, and was kept at the preinsulin level by administration of a 40% glucose solution. Injection of 0.35 or 1.5 IU X kg bw-1 of insulin did not have significant haemodynamic effects. Injection of 7.5 IU X kg bw-1 of insulin resulted in significant changes in cardiac index (+20.8%) and in total peripheral resistance (-13.9%) within 2 min. After 10 min a reduction of 16.8% was found in the diastolic pulmonary artery pressure. These haemodynamic effects occurred before glucose had been infused. The arterial pressure and the heart rate were unaffected. It is concluded that the injection of 7.5 IU X kg bw-1 of insulin results in an increase in cardiac index in patients who have undergone open heart surgery. The effects are not primarily related to stimulation of glycolysis.