d-dimers as an early marker for oxygenator exchange in extracorporeal membrane oxygenation

Purpose Early markers of oxygenator dysfunction during prolonged use of extracorporeal membrane oxygenation (ECMO) are important for timely exchange to avoid sudden loss of function due to clot formation within the system. The measurement of d-dimers (DDs) in plasma might be a marker for early diagnosis of thrombus formation and dysfunction of heparin-coated membrane oxygenators (MOs). Methods This is a retrospective study on prospectively collected data of 24 adult acute respiratory distress syndrome patients requiring long-term veno-venous ECMO with at least 1 MO exchange. Kinetics of coagulation, inflammation, and oxygenator function were analyzed before and after MO exchange. Results Median (interquartile range) support duration is 20 (15-29) days. Thirty-four MOs had to be replaced. Exchange occurred due to visible thrombus formation in the MO (n = 16), worsening gas exchange (n = 11), increased blood flow resistance (n = 1), and activation of coagulation with diffuse bleeding (n = 6). In 15 cases, DDs were continuously elevated and, therefore, not suitable as marker for MO exchange. In the remaining 19 cases, DDs increased significantly within 3 days before exchange from 15 (9-20) to 30 (21-35) mg/dL (P = .002) and declined significantly within 1 day thereafter to 13 (7-17) mg/dL (P = .003). Conclusions An increase in plasma DD concentration in absence of other explaining pathology can be helpful in predicting an MO exchange in miniaturized heparin-coated ECMO systems.