Evaluation of heparin anti–factor xa levels following antithrombin supplementation in pediatric patients supported with extracorporeal membrane oxygenation

OBJECTIVE Thrombotic events are potential complications in patients receiving extracorporeal membrane oxygenation (ECMO) necessitating the use of systemic anticoagulation with heparin. Heparin works by potentiating the effects of antithrombin (AT), which may be deficient in critically ill patients and can be replaced. The clinical benefits and risks of AT replacement in children on ECMO remain incompletely understood. METHODS This single-center, retrospective study reviewed 28 neonatal and pediatric patients supported on ECMO at a tertiary care hospital between April 1, 2013, and October 31, 2014, who received at least 1 dose of AT during their ECMO course. The primary outcome of the study was the change in anti–factor Xa levels after pooled human AT supplementation. Secondary outcomes included the percentage of anti–factor Xa levels within the therapeutic range surrounding AT administration; survival to decannulation; 30 days after cannulation and discharge; time to first circuit change; and incidence of bleeding and thrombotic events. RESULTS A total of 78 doses of AT were administered during the study period. The mean increase in anti–factor Xa level following AT administration in patients without a ≥10% concurrent change in heparin was 0.075 ± 0.13 international units/mL. A greater percentage of anti–factor Xa levels were therapeutic for the 48 hours following AT administration (64.2% vs 38.6%). Survival and adverse events were similar to Extracorporeal Life Support Organization averages, with the exception of a higher incidence of intracranial hemorrhage. CONCLUSIONS Patients experienced a small but significant increase in anti–factor Xa level and a greater percentage of therapeutic anti–factor Xa levels following AT supplementation.