Hematologic disorders in critically ill patients.
Hematologic disorders are frequently encountered in the intensive care unit. Thrombocytopenia, often defined as a platelet count below 100,000/microL, is common in critically ill patients and may be associated with adverse outcomes. A systematic evaluation of clinical and laboratory findings is necessary to ascertain the cause of the thrombocytopenia and to determine the correct therapy. Recognition of heparin-induced thrombocytopenia (HIT) is particularly important, given the risk of thrombosis associated with this condition. Prompt cessation of all heparin products is required, and anticoagulation with a direct thrombin inhibitor is recommended if HIT is strongly suspected. Coagulopathies are also common in the critically ill, and are often due to vitamin K deficiency or disseminated intravascular coagulation (DIC). A careful history and interpretation of clotting studies are useful in defining the coagulation defect. Advances in understanding the pathogenesis of DIC have generated new treatment approaches, such as the use of recombinant activated protein C. Recombinant factor VIIa (rFVIIa) is a novel drug approved for use in patients with congenital hemophilia and inhibitors. Although its use as a hemostatic agent is currently being evaluated in several off-label scenarios, including trauma, intracerebral hemorrhage, and liver disease, there are limited data to guide therapy in these conditions.