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Extracorporeal membrane oxygenation (ECMO) circuit causes activation of multiple systems, including thrombin generation, inflammation, platelet activation and endothelial dysfunction. Prolonged hemostatic activation can lead to consumption of coagulation factors and reduced platelet aggregation. Commonly used medications may also inhibit platelets.
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A delicate balance between the use of antihemostatic agents to reduce thrombotic events in the circuit and patient and the preservation of hemostatic
Management of Anticoagulation and Hemostasis for Pediatric Extracorporeal Membrane Oxygenation
Section snippets
Key points
The ECMO Circuit
A typical ECMO circuit consists of cannulas, polyvinyl tubing with or without heparin coating, a roller or centrifugal pump, and a silicone membrane oxygenator. These components of the ECMO circuit are artificial and lead to activation of multiple hemostatic systems, including platelets, factor XII and kallikrein-kinin system, tissue factor and von Willebrand factor, fibrinolysis, and inflammation.5, 6, 7, 8, 9 The initial contact of blood on the circuit leads to the cleavage of XII to XIIa and
Anticoagulation monitoring
A recent survey conducted between November 2010 and May 2011 indicated substantial variability in anticoagulation management policies and blood product administration in ECMO centers throughout the world.25 This survey also highlighted that activated clotting time (ACT) remains the preferred anticoagulation monitoring tool (97% of respondents), although many centers have been incorporating a variety of additional anticoagulation monitoring tools, including antithrombin III activity (ATIII)
Anticoagulation agents
Most anticoagulants have not been well studied in children on ECMO except UFH. UFH with varying dosages remains the most common anticoagulation agent used for ECMO.25 UFH binds to ATIII to form a UFH-ATIII complex that results in conformational change in ATIII and increases its activity by 2000-fold to 3000-fold.46, 47 These UFH and ATIII complexes inactivate thrombin and prevent further thrombin generation. UFH exerts direct, but weak inhibition of factor Xa. Its biological activity depends on
Antiplatelet agents
Activation of platelets on the ECMO circuit has been described. However, the use of antiplatelet agents (aspirin, dipyridamole, clopidogrel, pentoxifylline, and abciximab) is extremely rare on ECMO as compared with pediatric VAD patients.38 A recent survey reported an increase from 21.4% in 2000 to 2002 to 67.2% of patients receiving an antiplatelet agent in pediatric VAD patients.56 Although experience from pediatric VAD patients may suggest utility of antiplatelet agents in ECMO (despite very
Hemostatic adjuncts
Hemostatic adjuncts in bleeding patients, such as antifibrinolytic agents ε-aminocaproic acid and tranexamic acid, recombinant factor VIIa (FVIIa), and prothrombin complex concentrates, are sparingly used during ECMO because of the concern for severe thrombotic events (Table 3).67, 68, 69, 70, 71, 72, 73, 74, 75
Blood products transfusion
Blood products are frequently administered on neonatal and pediatric ECMO to maintain normal hemostasis.76, 77, 78 Stiller and colleagues77 reported that pediatric ECMO patients on an average received 25 mL of platelet concentrate (PC), 60 mL of packed red blood cells (pRBCs), and 50 mL of fresh frozen plasma (FFP) transfusions for each kilogram body weight every day on ECMO. PC, cryoprecipitate, and FFP transfusion threshold are based on patient age, coagulation deficiencies, ongoing bleeding,
Summary
Anticoagulation and hemostatic management of pediatric ECMO patients have many unique challenges. To overcome these challenges and improve outcomes on ECMO, several measures are required. First, a multidisciplinary team, including surgeons, intensivists, hematologists, anesthesiologists, perfusionists, respiratory therapists, pharmacists, and specialized ECMO nurses, is needed to provide optimal care and cohesive implementation of antihemostatic guidelines. The second measure a comprehensive
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Cited by (0)
Disclosures: Partially supported by National Institutes of Health (U54 HL112303).