Insulin as a vasodilating agent in the first hour after cardiopulmonary bypass

To study the vasodilating effect of insulin after termination of ECC in aortocoronary bypass surgery, 21 patients were randomized to treatment with 7.5 U of fast-acting insulin/kg b.w. as a bolus injection followed by continuous infusion of 15 U/kg b.w. for 1 hour, or to serve as controls. Insulin administration was begun when the last proximal anastomosis had been completed. Cardiac output and central pressures were monitored for 1 hour after termination of ECC. Systemic vascular resistance in both groups was lower at the end of ECC than before surgery (reduction 39% in the controls, 51% in the insulin-treated group). During the following hour the peripheral resistance increased significantly in the controls (from 20 +/- 2 to 29 +/- 2 mmHg X min X m2/l), but no change was found in the insulin group. It is concluded that insulin can maintain a low vascular resistance after aortocoronary bypass surgery.