Latent Trajectories of Fluid Balance Are Associated With Outcomes in Cardiac and Aortic Surgery

Background: Fluid overload is common in critically ill patients and is associated with worse outcomes. The trends in fluid balance have not been investigated previously. This study used trajectory analysis to investigate the impact of fluid balance trends on patients who had undergone cardiac or aortic surgery. Methods: We analyzed patients who underwent cardiac or aortic surgery between August 2005 and March 2015. We excluded patients who died within the first 72 postoperative hours or received chronic dialysis before the surgery. Trajectories of urine and input-output during the first 3 postoperative days were analyzed using a latent class growth model. The primary outcomes were any stage of acute kidney injury (AKI) by Kidney Disease Improving Global Outcomes definition and de novo dialysis. Results: The in-hospital mortality was 6.6% (70 of the 1063 patients included). The fluid input-output balance trajectories had better association with the primary outcome than urine output trajectories did. The risk of AKI and de novo dialysis were highest in the group with progressively positive fluid balance adjusted by preoperative body weight (AKI: adjusted odds ratio, 7.10; 95% confidence interval, 2.02-24.93; de novo dialysis: odds ratio, 4.54; 95% confidence interval, 1.12-18.38). Conclusions: A progressively positive fluid balance is associated with AKI and de novo dialysis in patients undergoing cardiac or aortic surgery.