Effect of high-versus low-volume saline administration on acute kidney injury after cardiac surgery

Abstract

Background: Fluid resuscitation is critical to perioperative maintenance of adequate preload and cardiac output after cardiac surgery. Liberal use of saline, however, is reportedly associated with an increased risk of acute kidney injury (AKI) in critically ill patients. This study examined the effects of high-versus low-volume saline administration on AKI after cardiac surgery. Methods: In this retrospective study, we evaluated 1,740 consecutive patients who underwent cardiac surgery over a 2-year period. The patients were divided into high-volume saline (n=328, 18.8%) and low-volume saline (n=1,412, 81.2%) groups based on the amount of saline (>1 or ≤1 L, respectively) administered during the first 48 postoperative hours. Results: AKI, the primary outcome, was defined according to the Risk, Injury, Failure, Loss, End Stage classification. There were no significant differences in the incidence of AKI (P=0.46), new renal replacement therapy (RRT) (P=0.39), and early mortality (P=0.52) between the 2 groups. Adjustment of baseline characteristics using propensity score matching showed that high-volume of saline administration was not significantly associated with an increased risk of AKI (OR, 1.22; 95% CI, 0.77-1.93; P=0.38), new RRT (OR, 1.25; 95% CI, 0.68-2.28; P=0.45), or early mortality (HR, 0.98; 95% CI, 0.48-2.02; P=0.97). These results were validated by further adjustments for significant covariates. Conclusions: High-volume administration of saline in the period following cardiac surgery was not associated with a significant increase in the risk of AKI.