Postoperative Fluid Therapy in Adult Cardiac Surgical Patients and Acute Kidney Injury: A Prospective Observational Study

Background Normal saline (0.9% NS) is a common intravenous fluid used worldwide. Recent studies have shown that NS use is associated with increased incidence of acute kidney injury (AKI) and a need for renal replacement therapy (RRT). The practice is changing toward using balanced solutions to prevent AKI. Postcardiac surgery patients are more prone to develop AKI after cardiopulmonary bypass (CPB). We aim to study the type of fluid administrated, incidence of AKI, need for RRT, and overall outcome of these patients. Methods This prospective observational study was conducted in the cardiothoracic intensive care unit (cardiothoracic and vascular surgery intensive care unit) in a cohort of 197 adult patients who underwent on pump cardiac surgery in our hospital from July 2021 to October 2021 as a pilot study. Data was analyzed using SPSS 20.0 (IBM, Chicago, Illinois, United States). A p-value < 0.05 was considered significant. Results In our study, 58 (29.34%) patients developed AKI in the first three postoperative days and 16 (8.12%) patients required RRT. Incidence of AKI was found to be higher in patients who received NS only, as fluid of choice was 34.48% compared with other intravenous fluids. Patients with AKI had higher positive fluid balance (p < 0.001), longer CPB (p < 0.001), and aortic cross clamp (p = 0.006) times. Intensive care unit and hospital stay and mortality rates were higher in AKI patients than those without AKI (p < 0.001). Conclusion Our study demonstrated that NS was the commonly used crystalloid in our patients and was associated with increased incidence of AKI and RRT when compared with other balanced salts solutions.