Anticoagulation options for patients with heparin-induced thrombocytopenia requiring renal support in the intensive care unit.

World wide, heparins are the most commonly used anticoagulants for renal replacement therapy (RRT). In the intensive care unit (ICU) keeping the RRT circuit patent is more difficult than during routine outpatient hemodialysis, as ICU patients typically have sepsis and/or inflammation resulting in activation of the procoagulant pathways, with reduced antithrombin. One important cause of repeated RRT circuit clotting is heparin-induced thrombocytopenia (HIT), which should not be overlooked in patients with a reduced platelet count. If HIT is clinically suspected then all heparins should be withdrawn, and the patient systemically anticoagulated with either a direct thrombin inhibitor, such as argatroban and/or hirudin, or the heparinoid danaparoid. The availability and licensing of these alternative anticoagulants varies from country to country. Argatroban has to be continuously infused, which is an advantage for continuous RRT, but not for intermittent RRT, and can be monitored by activated partial thromboplastin time. Hirudin has a prolonged half life, which is extended by hirudin antibodies, and requires specialist monitoring to prevent over anticoagulation. Although the half life of danaparoid is increased in renal failure, it can be given as boluses for intermittent and continuous RRT, or by continuous infusion during continuous RRT, but requires factor Xa monitoring.