The influence of extracorporeal circulation on oxidant and antioxidant systems

Cardiopulmonary bypass (CPB) is a compulsory method presently used for treatment of many cardiovasculer diseases which need surgery.Oxidant stress formed during and after operations are one of the main determinants of morbidity and mortality after cardiac surgery and CBP. Mechanisms that occur during these processes are still not clear.This study was performed on the 22 patients ( ages: between 42 and 70) who were admitted for coronary bypass grafting operation to the Department of Cardiovascular Surgery at Gazi University Medical Faculty Hospital.Blood samples were taken from patients at seven different stages of operation. These stages were, in turn, pre-operative intensive care stage (A), during anesthesia (B), after pump-in phase (C), after aortic cross- clamping stage (D), after release of the aortic cross-clamping (aortic declamping) stage (E), after pump-out phase (F) and post-operative intensive care stage (G).Malondialdehyde (MDA) and NOx (Nitrite + Nitrate) levels were measured as an indicator of oxidant stres and Total sulfhydryl group (RSH) leves as antioxidant.While MDA and NOx levels were low at the A and B stage, they started to rise with the C stage and reached their peak levels at the F stage. Later, their levels showed decrease at the G stage. There was a decrease at the RSH levels and a negative corelation between RSH levels and the MDA levels at all stage. The lowest level of RSH was observed at the F stage and started to rise at G stage.The data obtained from the MDA and RSH levels were concordant with the oxidant stress and decreasing antioxidant capacity resulted from the surgical trauma and the artificial surface of extracorporeal circulation (EC).İncreasing NOx levels may result from the mechanical irritation of endothelium because of the surgical operations and from the expression of eNOS by red blood cells exposed to mechanical stress because of circulation in the artifical surfaces of EC.The investigation of NOS, S-nitrosohemoglobin or nitrosilhemoglobin may be useful for further studies.