When to start a renal replacement therapy in acute kidney injury (AKI) patients: many irons in the fire

In 2012, the Kidney Disease Improving Global Outcomes (KDIGO) guidelines have been released and detailed and graded recommendations concerning all the aspects of critical care nephrology (1). One of the chapters is specifically dedicated to “Dialysis Interventions for Treatment of acute kidney injury (AKI); Timing of renal replacement therapy (RRT)”. Even if the question on when to start RRT is constantly solicited by nephrologists and intensivists in case of severe AKI (2), KDIGO guidelines only provided expert opinion statements: “Initiate RRT emergently when life-threatening changes in fluid, electrolyte, and acid-base balance exist (Not Graded)” and “Consider the broader clinical context, the presence of conditions that can be modified with RRT, and trends of laboratory tests—rather than single BUN and creatinine thresholds alone—when making the decision to start RRT (Not Graded)” (1).