Fluid balance and acute kidney injury: the missing link for predicting adverse outcomes?

This Practice Point commentary discusses the findings from the secondary analysis of a large systematic cohort study of critically ill patients that evaluated the influence of fluid overload on outcomes from acute kidney injury (AKI). Payen et al. reported a 36% incidence of AKI among the 3,147 patients enrolled in the Sepsis Occurrence in Acutely Ill Patients (SOAP) study. Mortality rate at 60 days was more than twofold higher among patients who had AKI than among those without AKI. Among patients with AKI, mortality rates were increased in patients with oliguria and in those treated with renal replacement therapy. A positive fluid balance was an independent risk factor for 60-day mortality. The interpretation and implications of these findings for clinical practice are highlighted in this commentary. Fluid balance is probably an important factor that determines outcomes in patients with AKI who are in an intensive care unit, but additional studies are required to confirm these findings.