Postoperative acute kidney injury requiring renal replacement therapy in cardiac surgical patients: risk and protective factors

Method The study group was consisted of 1186 consecutive patients who underwent cardiac surgery from June 2012 to April 2015 in a single Cardiothoracic Surgery Department. The following 21 peri-operative variables have been investigated: Age, Gender, Euroscore II, Body Mass Index (BMI),Smoking habit, Diabetes Mellitus, Insulin use, pre-op Glomerular Filtration Rate (GFR), Peripheral Vascular Disease (PVD), Chronic obstructive pulmonary disease (COPD), chronic atrial fibrillation, REDO, Angiotensin-converting enzyme inhibitors (ACEi) use, Ejection Fraction, Pulmonary Hypertension, Urgent/emergent operations, Cardio-pulmonary bypass (CPB) time, total red blood cells (RBC) units transfused, mechanical ventilation time, Prolonged inotropic support (>24 hours), Low cardiac output syndrome (LCOS). Factors with statistical significance according to univariate analysis, underwent multivariate logistic regression analysis. Results Univariate analysis revealed the following11 factors having statistical significant relationship with postoperative AKI requiring renal replacement therapy: Euroscore II(p < 0.01), preoperative GFR (p < 0.01), COPD (p = 0,032), ACEi use (p = 0.032), pulmonary hypertension (p = 0.01), emergent/urgent status (p < 0.01), CPB time (p < 0.01), RBC units (p < 0.01), mechanical ventilation time (p < 0.01), Prolonged inotropic support (p < 0.01) and LCOS (p < 0.01). Logistic regression analysis of the above 11 factors revealed that AKI requiring renal replacement therapy is associated with prolonged inotropic support (p < 0.00), total RBC transfused units (p < 0.00), not use of ACEi (p < 0.027).