Treatment of heparin-induced thrombocytopenia during extracorporeal membrane oxygenation

Bleeding and thromboembolic events are among the most frequent complications of treatment with extracorporeal membrane oxygenation (ECMO). Causative is mainly a multifactorial unspecific activation of the coagulation system, which leads to increased consumption and to functional disorders of platelets. Additionally, anticoagulation with unfractionated heparin can trigger an immunologically mediated heparin-induced thrombocytopenia (HIT). Approximately 3.7% of patients treated by ECMO are affected by this potentially life-threatening side effect of HIT. Although HIT is primarily characterized by a sudden and significant drop in the number of platelets, patients have a high risk for thromboembolic complications (50-75%). Therefore, an immediate discontinuation of heparin administration and effective alternative anticoagulation is necessary in cases of clinically suspected HIT. A confirmation of the HIT diagnosis using specific laboratory tests should not be waited for. Although the data situation is based on experience with a very limited number of patients, there is nevertheless consensus that direct thrombin inhibitors (DTI) are safe and effective alternatives to heparin for anticoagulation during ECMO treatment. With bivalirudin and argatroban two suitable drugs with different pharmacological profiles are currently available. It is important to keep in mind that no specific antidote exists and a meticulous and sometimes substantial adaptation of the dosage in cases of impairment of renal or liver function is essential to avoid bleeding complications. The anticoagulation level can be monitored by a close control of coagulation. The administration of factor Xa inhibitors as alternative anticoagulants in ECMO treatment cannot currently be recommended.