Hemorrhagic complications during warfarin therapy

Overview

Hemorrhage is probably the major complication of anticoagulant treatment with vitamin K antagonists represented particularly by warfarin in our country. The main risk factors of hemorrhagic complications of “warfarinisation” are intensity and instability of the anticoagulant therapy, individual patient characteristics, drug interactions, and duration of the anticoagulant therapy. Severe hemorrhage in patients treated with warfarin is most effectively prevented by fast and complete suppression of anticoagulant effect of the drug using a prothrombin complex concentrate and slow intravenous vitamin K₁ infusion regardless of the reason for anticoagulation. This approach can minimize frequencies of hemorrhage consequences. Less severe or asymptomatic hemorrhage with an increased international normalized ratio can be effectively treated by withdrawal or reduction of warfarin dosage and/or peroral administration of vitamin K₁ (intravenous administration only in selected high-risk cases). The latter results only in a partial correction of coagulopathy, nevertheless to a such extend that is required with respect to the risk of recurrence of thrombotic event. The objective of this article is to contribute to the standardization of the treatment for patients overdosed with warfarin and/or for patients with hemorrhagic complications due to warfarin therapy. It is available at www.trombosis.cz. The guidelines include a handbook that is used for immediate, and very quick orientation in the clinical praxis.

Key words:
warfarin, hemorrhage, vitamin K, prothrombin complex concentrate, plasma, recombinant activated factor VII.