Anticoagulation

The contact between patient blood and the ECMO foreign surface is associated with activation of coagulation factors and complement factors, platelets and fibrinogen consumption [21-24], which may lead to bleeding [25] and thromboembolic [26] complications. For these reasons, continuous anticoagulation is necessary throughout the ECMO treatment. Anticoagulation during VV-ECMO is commonly achieved by continuous intravenous heparin infusion, targeted to a partial thromboplastin time (aPTT) of 45-60 s and/or to an activated clotting time (ACT) of 1.5-2 times normal. Transfusion policy regarding platelet count varies among centres. Transfusion thresholds between 50,000 and 100,000/qL have been reported. Activation of the coagulation cascade and clot formation in the circuit are accompanied by a progressive decrease in platelet count and fibrinogen level and consumption of coagulation factors that may lead to a syndrome similar to disseminated intravascular coagulation. For this reason, activation of the coagulation and circuit thrombosis, along with oxygenator performance and/or increase of transmembrane pressure, must be monitored to understand the need for a prompt replacement of ECMO circuit. D-dimer levels have been shown to be a reliable variable to detect circuit thrombosis.