Effect of Lactated Ringer Administration on Survival Outcomes in Critically Ill Patients With Acute Kidney Injury: A Retrospective Cohort Study

<b>Background:</b> Although lactated Ringer's (LR) solution is widely used in managing patients with acute kidney injury (AKI), its specific impact on mortality remains unclear. This retrospective cohort study aimed to evaluate the effects of LR administration on survival outcomes in severely ill patients with AKI. <b>Methods:</b> Critically ill patients with AKI were identified using data from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database. Propensity score matching (PSM) was employed to address baseline discrepancies between patients who received LR and those who did not. The association of LR administration with survival, duration of hospitalization and intensive care unit (ICU) stay, requirement for renal replacement therapy (RRT), renal function recovery, and hyperkalemia was analyzed using restricted mean survival time (RMST), logistic regression, and linear regression models. <b>Results:</b> A total of 5620 patients with AKI were included. Following PSM, LR administration was associated with prolonged survival at 28 and 90 days compared to non-LR use (28-day survival increase: 1.12 days, 95% confidence interval [CI] 0.62-1.63, <i>p</i> < 0.001; 90-day survival increase: 3.73 days, 95% CI 1.70-5.76, <i>p</i> < 0.001). The survival benefit became more pronounced, with higher LR use linked to more remarkable 90-day survival. However, LR administration did not significantly affect renal function recovery or hyperkalemia incidence. <b>Conclusion:</b> Administering LR to critically ill patients with AKI was associated with improved survival at both 28 and 90 days.