Early predictors of acute kidney injury after Cardiac Surgery

Background: Acute kidney injury (AKI) represents a significant postoperative complication affecting approximately 50% of cardiac surgery patients, with early detection and intervention being crucial for improved outcomes. Methods: We evaluated early biomarkers of cardiac surgery-associated AKI (CSA-AKI) in 60 patients undergoing elective cardiac procedures requiring extracorporeal circulation, including coronary artery bypass grafting and/or valve replacement surgery. Exclusion criteria encompassed preoperative sepsis, existing renal replacement therapy, advanced age (>80 years), emergency surgical intervention, established chronic renal or hepatic dysfunction, and malignancy. The investigation protocol included sequential measurement of serum neutrophil gelatinase-associated lipocalin (NGAL), neutrophil-lymphocyte ratio (NLR), blood urea nitrogen (BUN), and creatinine at preoperative baseline and at 6th and 24th hours postoperatively. Serum creatinine and BUN were reassessed at 48 hours after surgery. All serum specimens were preserved at −20 ◦C pending laboratory analysis of NGAL and standard hematological parameters. Results: Upon application of Kidney Disease: Improving Global Outcomes (KDIGO) criteria, twenty participants (33.3%) developed CSA-AKI. Comparative analysis revealed significant elevations in both NLR and NGAL at 6th and 24th hours postoperatively relative to preoperative baseline values (p < 0.05) in both AKI and non-AKI cohorts. However, the temporal progression pattern of these biomarkers demonstrated parallel trajectories across both groups (p > 0.05). Conclusions: Our findings suggest that systematic evaluation of serum NGAL and NLR concentrations at preoperative baseline and at 6 and 24 hours following cardiac surgery may facilitate expeditious identification of patients developing AKI, potentially enabling earlier therapeutic intervention.