Comparing Dialysis Modalities for Critically Ill Patients

During the past two decades, continuous renal replacement techniques (CRRT) have altered the landscape of dialysis options for critically ill patients. Adoption of these techniques has been fairly rapid in developed countries with advanced intensive care unit support systems and is gradually expanding to the developing world (1). However, not everyone has been enamored with the advancements; the main reason cited is a lack of evidence for a benefit in mortality (2). Consequently, nephrologists and critical care physicians are periodically subjected to debates among prominent experts on the superiority—or lack thereof—of these techniques. In this issue, Ronco et al. (3) make a case for the superiority of CRRT, whereas Himmelfarb (2) provided a contrary viewpoint. Although the debate is informative, it is not focusing on the major issues about which we should be concerned.During the past four decades, the mortality that is associated with acute kidney injury (AKI) in critically ill patients has not substantially changed (4). Dialysis imparts an additional risk to that imposed by uncomplicated AKI regardless of the modality used (5,6). It is unclear how AKI confers an increased risk for adverse outcomes and why dialysis adds to that risk. Answers to the former are emerging from recent studies that demonstrated the profound downstream effects of even minor alterations in renal function and the recognition of “organ cross-talk” (7,8); however, no studies have evaluated the latter. Despite advancements that have occurred …