Oxidative Stress after on-Pump Cardiac Surgery in Patients with Preoperative Renal Dysfunction

Background: Renal dysfunction is a global health burden with a rising prevalence and increased morbidity and mortality. Since the complex and multifactorial pathophysiology of this disease and its consequences is not entirely understood, novel mechanisms are currently under investigation, one being oxidative stress. Malondialdehyde is a product of lipid peroxidation and has been widely utilised as an indirect biomarker of oxidative stress. The aim of this study was to investigate the perioperative oxidative stress in patients with preoperative renal dysfunction undergoing on-pump cardiac surgery. Methods: In 115 patients scheduled for on-pump cardiac surgery, serum concentrations of malondialdehyde were obtained pre-, intra- and postoperatively. The patients were enrolled into two study groups regarding their preoperative renal function, and the malondialdehyde concentrations were compared between the study groups. Results: Patients with preoperative renal dysfunction were older and had a higher mean EuroSCORE II score. On postoperative days 1, 2 and 3, the serum malondialdehyde levels were significantly higher in patients with preoperative renal dysfunction compared to those with normal kidney function. Using regression analysis, preoperative renal dysfunction was shown to be an independent predictor of higher postoperative malondialdehyde levels at all tested time points. Conclusions: In a pioneering study correlating cardiopulmonary bypass and oxidative stress biomarker malondialdehyde, patients with preoperative renal dysfunction were found to exhibit more pronounced and prolonged oxidative stress resulting in protracted lipid peroxidation in the early postoperative period compared to patients with normal kidney function.