Prevention and treatment of venous thromboembolism.

All patients at moderate to high risk for the development of venous thromboembolism should receive prophylaxis. The approaches of proven value include low dose heparin, low molecular weight heparin, oral anticoagulants and intermittent pneumatic compression. The use of one of the cited heparin nomograms will ensure that all patients are rapidly brought within the therapeutic range. Because of the varying sensitivities of thromboplastins, each laboratory should establish a therapeutic range using the activated partial thromboplastin time (APTT) which will correspond to 0.2 to 0.4 U/ml of heparin. Constant vigilance and a high level of suspicion are necessary to establish the clinical diagnosis of heparin-induced thrombocytopenia, and to institute appropriate therapy. Physicians should be aware of the sensitivity of the thromboplastin being used in the performance of the International Normalised Ratio (INR). Care must be taken to ensure that patients are maintained within the target therapeutic range for INR (in most cases 2 to 3) by frequent determination of the INR and appropriate adjustments of warfarin dosage. Low molecular weight heparin is the recommended approach to the initial management of venous thromboembolism where these agents are available. Patients with an acute episode of venous thromboembolism should receive warfarin therapy for at least 3 months. At the present time it is reasonable to treat the first recurrence with oral anticoagulants for a period of 12 months and indefinitely for more than 1 recurrence. For selected patients with acute massive pulmonary embolism, thrombolytic therapy with one of the available agents is recommended. However, the role of thrombolytic therapy in patients with proximal venous thrombosis remains unclear. In selected patients with acute venous thromboembolism who have contraindications to anticoagulant therapy or who-have objectively documented recurrent disease while on adequate therapy, the insertion of an inferior vena cava filter is recommended.