Pediatric extracorporeal membrane oxygenation (ECMO) provides lifesaving cardiopulmonary support for patients with a multitude of clinical diagnoses, resulting from cardiac and/or respiratory failure refractory to conventional supports (¹). The utilization of pediatric ECMO has doubled over the last decade (¹) with survival outcomes ranging from 58% to 87% across all indications for ECMO in pediatric and neonatal populations (²). With the increased utilization of pediatric ECMO, practitioners must be familiar with the risks associated with ECMO use, particularly the risks of bleeding and thrombosis (³). Thrombosis in a component of the ECMO circuit is a common complication; the highest in the neonatal population, occurring in 0.98 to 1.24 per 1000 ECMO hours and then decreasing in the pediatric population, with the lowest rate in the adult population (¹). Circuit thrombosis in ECMO occurs following blood exposure to the biomaterial of the ECMO circuit resulting in activation of platelets along with the coagulation, inflammation, and compliment cascades (³). Sites of thrombosis are generally located at tubing/connector junctions, where the shear rate of blood is lowest (⁴). Neonatal and pediatric circuits are particularly prone to thrombosis secondary to lower flows that predispose to hemostasis, smaller cannula sizes and circuits, less predictive response to heparin, and less available antithrombin compared with adults (^3,5). Clot formation on the arterial side, post-oxygenator is most worrisome, as they can lead to arterial strokes and organ ischemia (⁶).

The Extracorporeal Life Support Organization registry collects outcome data on clot formation but relies upon visual identification by the ECMO provider, which can lead to potential underreporting of these complications. Noninvasive real-time ultrasonic sensors are a newer means of thrombus detection; however, presently are not widely used (⁷). The Pediatric ECMO Anticoagulation Collaborative Consensus Conference was recently published and provides recommendations on patient and circuit thrombosis management; however, the recommendations are based on expert opinion alone (⁸) and highlight the need for more research in this area.