[Prevention of pulmonary embolism]

Pulmonary embolism (PE) is one of the most common causes of death in hospitalized patients. Several groups of patients at high risk of developing venous thromboembolic complications have been identified. The effect of primary prophylaxis on the incidence of fatal PE has been demonstrated only in a few studies, while evidence for a benefit of pharmacologic and physical modalities of prophylaxis in preventing venous thrombosis has been documented in many prospective randomized clinical trials. The preventive measures differ according to the type of patient at risk, and in some groups of patients at risk several prophylactic regimen can be used. Application of low-dose heparin is the best documented prophylactic modality. General primary prophylaxis in 100 patients at risk could save one life. However, low-dose heparin is of limited efficacy in patients at high risk for thromboembolism. The following anithrombotic regimens are recommended in these patients: adjusted - dose heparin; oral anticoagulants with low intensity of anticoagulation; dextran; heparin in combination with dihydroergotamine; low-molecular-weight heparin fractions (LMWH). It is likely that prevention with LMWH will become the most important prophylactic modality in the near future. Mechanical methods of prophylaxis should be used primarily in combination with pharmacologic prevention. In low-risk patients mechanical methods alone offer sufficient prophylaxis. Low-dose heparin which is effective for primary prevention is not effective in secondary prophylaxis to prevent extension or embolization of established thrombosis. Inadequate anticoagulant therapy results in increased risk of recurrent thromboembolism. The general application of primary prophylaxis in patients at risk is superior to secondary prophylaxis with treatment of established thromboembolism.