In contrast to recommendations provided by the author ("Anticoagulant-Induced Skin Necrosis,"Wound Wise, April), warfarin (Coumadin) is contraindi-cated in patients with acute heparin-induced thrombocytopenia (HIT) because of the initial prothrombotic effects of warfarin-induced protein C deficiency. Consequently, warfarin can increase rather than decrease the risk of thrombosis.
Direct thrombin inhibitors lepirudin (Refludan) and argatroban are currently approved for the treatment of HIT in the United States. If a patient is diagnosed with HIT, all forms of heparin (Calciparine and others) should be discontinued, and treatment with lepirudin or argatroban should be initiated immediately. Lepirudin or argatroban therapy should be continued until HIT is controlled, as evidenced by platelet recovery and absence of new thromboses. If long-term anticoagulation is required, patients may be slowly transitioned to warfarin over several days only after HIT is controlled. Lepirudin has minimal effects on warfarin monitoring. When transitioning from argatroban to warfarin, the titration algorithm described in the package insert should be used.
Early diagnosis is the key to management of HIT. Bleeding, a drop in platelet count of 30% to 50% from baseline (or to less than 150 x 109/L), and signs and symptoms of vascular occlusions must be reported promptly.
Susan D. Housholder-Hughes, MSN, RN, CCRN, APRN, BC
Ann Arbor, MI