Extracorporeal membrane oxygenation (ECMO) is a supportive therapy, which provides cardiopulmonary and end-organ support in critically ill patients when other measures fail. These patients receive large amounts of fluid for volume resuscitation, blood products and caloric intake, which results in fluid overload and which in turn is associated with impairment of oxygen transport and increased incidence of multiple organ failure especially heart, lungs and brain. It is common to see a decrease in urine output during ECMO that may be associated with acute renal failure. The acute renal failure is a manifestation of multiple organ system failure due to acute decompensated heart failure, sepsis, hemolysis, use of vasopressors/inotropes, nephrotoxic medications, and activation of complement system during ECMO support. It is associated with poor prognosis and higher mortality in ECMO patients. Continuous renal replacement therapy (CRRT) in patients on ECMO provides an efficient and potentially beneficial method of fluid overload and acute kidney injury management. In addition, recent data suggest that the use of CRRT may remove inflammatory cytokine released as a result of circulation of blood across synthetic surfaces during ECMO. The two most common methods to provide CRRT are through the use of an inline hemofilter or through a traditional CRRT device connected to the extracorporeal circuit. The primary objective of this chapter is to discuss current state and role of renal replacement therapy in patients on ECMO and address the controversies and challenges about its application
