Identification of modifiable risk factors for acute kidney injury after cardiac surgery

Objectives: Acute kidney injury (AKI) is a common problem after cardiac surgery and is associated with an increase in morbidity, mortality and duration of hospital stay. With this study we aimed to identify potential risk factors for cardiac surgery associated AKI (CS-AKI) in a single-centre population with a special focus on modifiable risk factors. Methods: Retrospective single-centre cohort study of 565 consecutive patients who underwent isolated coronary artery bypass grafting (CABG) with the use of cardiopulmonary bypass. AKI was defined by the AKIN classification. Known risk scores were applied when possible. Results: Of the population, 14.7% were diagnosed with AKI. When considering baseline characteristics we found a significant difference in age, preoperative estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD) stage and urgency of surgery between the CS-AKI group and the control population. Regarding the intraoperative characteristics, patients with CS-AKI had a significantly lower haematocrit and were more likely to receive a transfusion of packed cells. Postoperative administration of furosemide and packed cell transfusions were also associated with AKI. We found no differences in other characteristics (history of diabetes mellitus, history of congestive heart failure, sex, body mass index (BMI), history of cardiac surgery, low cardiac output and need for intra-aortic balloon pump (IABP), duration of cardiopulmonary bypass (CPB) and cross clamping). Conclusion: In our series we could identify intraoperative administration of packed cells and postoperative administration of furosemide or packed cells as potentially modifiable risk factors in the development of AKI.