Acute pulmonary embolism

Prevention of deep venous thrombosis is fundamental in the prevention of pulmonary embolism. Deep venous thrombosis is common after all surgical procedures, but the frequency differs, as does the effectiveness of various methods of prevention. Low-dose heparin, low molecular weight heparin, graduated compression elastic stockings, intermittent pneumatic compression, and oral anticoagulants have a role in the prevention of deep venous thrombosis, depending on the risks of deep venous thrombosis and their demonstrated effectiveness (or lack of effectiveness) in the particular circumstance. The optimal method of prophylaxis is specific to the predisposing condition. Heparin continues to be a mainstay of anticoagulant therapy. Major bleeding is rare in patients treated with low doses of heparin to prevent deep venous thrombosis. With therapeutic doses, however, major bleeding occurs in about 5% of patients. The optimal dose of warfarin and the method of evaluating the anticoagulant effect of warfarin have undergone modifications in recent years. It is now recognized that the prothrombin time ratio depends on the activity of the thromboplastin used for measuring the prothrombin time. An International Normalized Ratio, which relates to a standardized thromboplastin, has been developed, thus avoiding differences of the prothrombin time ratio that occur from batch to batch of thromboplastin reagent from the same manufacturer and that occur with different thromboplastin reagents from different animal sources and different manufacturers. The bedside diagnosis of pulmonary embolism is useful in helping a physician determine the extent to which diagnostic tests should be pursued. A sound bedside impression also contributes strongly to the formulation of a noninvasive diagnosis of pulmonary embolism. The clinical manifestations of pulmonary embolism form a recognizable constellation of findings that often lead to a correct diagnosis or exclusion of pulmonary embolism. Important clues to the diagnosis of pulmonary embolism relate to the initial syndrome. The presentation of pulmonary embolism is most often in the form of the pulmonary hemorrhage-pulmonary infarction syndrome. The next most common presentation is unexplained dyspnea, unaccompanied by pulmonary hemorrhage or infarction. Least common, but most severe, is the syndrome of circulatory collapse. Immobilization, usually caused by surgery, is the most frequent predisposing factor. Most patients with clinically recognizable pulmonary embolism have dyspnea or tachypnea. Dyspnea or tachypnea or pleuritic pain occurs in nearly all patients who have clinically apparent pulmonary embolism (97%). Ordinary tests such as the electrocardiogram and chest radiograph are helpful if the physician is attentive to nonspecific abnormalities.(ABSTRACT TRUNCATED AT 400 WORDS)