Objective: To investigate the effects of intensive insulin therapy on plasma nitric oxide (NO) and endothelin-1 (ET-1) levels in patients undergoing cardiac valve replacement under cardiopulmonary bypass (CPB).
Methods: A total of 36 patients were randomly assigned to routine therapy (RT) group and intensive insulin therapy (IT) group, with 18 patients in each group. The blood glucose levels during surgery were maintained at 3.9 to 10.0 mmol/L and those after surgery at 3.9 to 6.1 mmol/L in IT group, whereas patients in RT group didn't undergo the treatment of controlling glucose levels during operation and maintained below 13.9 mmoVL after operation. Levels of plasma NO and ET-1 in both groups were respectively measured before surgical anesthesia, at the initiation of CPB, and 0 h, 4 h, 12 h, 24 h and 48 h after the termination of CPB.
Results: In RT group, plasma NO concentration was decreased since the initiation of CPB [from (68.2 +/- 16.3) micromol/L to (67.8 +/- 8.4) micromol/L] and reached the trough at the termination of CPB [ (60.0 +/- 10.2) micromol/L, P < 0.05 compared with that before anesthesia]. Then it began to increase and neared to the preoperational level 48 h after the termination of CPB. In contrast, plasma ET-1 concentration was increased since the initiation of CPB [from (62.2 +/- 10.2) ng/L to (68.3 +/- 10.8) ng/L] and reached the peak at the termination of CPB [ (112.5 +/- 18.6) ng/L, P < 0.01 compared with that before anesthesia]. Then it began to decrease and reached the preoperational level 24 h after the termination of CPB. In IT group, however, the changes of NO and ET-1 levels at different time points during CPB and thereafter didn't reach the significance as compared with those before anesthesia.
Conclusions: Intensive insulin therapy may relieve the changes of CPB-induced NO and ET-1 levels during cardiovascular surgery, which suggests its protective effects on cardiovascular function.