Hemodynamics of Massive PE
Prevention of PE
Know the risk factors for pulmonary embolism.
Understand the importance of pretest probability for the diagnostic approach to pulmonary embolism.
Be able to contrast sensitivity versus specificity of CT angiogram and leg ultrasound in the diagnostic approach to pulmonary embolism.
Know the indications and contraindications for thrombotic therapy of pulmonary embolism.
Venous thromboembolic disease is a pathologic formation of a thrombus within the venous system of the lower extremities or the pulmonary arteries. Pulmonary embolism (thromboembolism) is responsible for 200,000 to 300,000 hospital admissions per year. Risk factors include those that are inherited or acquired and affect Virchow's triad: vascular endothelial injury, hypercoagulable state, and venous stasis. Clinical findings are nonspecific and include signs and symptoms suggestive of either deep vein thrombosis or pulmonary embolism. A chest radiograph may be normal in up to 25% of patients. Arterial blood gasses may also be normal. A nonelevated D-dimer is a useful test to make pulmonary embolism unlikely. B-type natriuretic peptide and troponin may be elevated. CT pulmonary angiography is the best diagnostic test as to sensitivity and specificity other than digital subtraction dye angiogram that, although remaining the gold standard, is much more invasive and less often used. Ventilation perfusion lung scan, venous compression ultrasonography, and echocardiography may also be very useful adjuncts for diagnosis or exclusion of pulmonary embolism. Anticoagulation is initially with unfractionated or low-molecular-weight heparin. Thrombolytic therapy, if not contraindicated, is used in patients with pulmonary embolism–induced hemodynamic instability. Inferior vena cava filters are used in patients with contraindication to anticoagulation or with hemodynamic instability and contraindication to thrombolytic therapy. Surgical thrombectomy may be considered in situations of severe hemodynamic instability with contraindication to thrombolytic therapy and close proximity to the operating room and cardiopulmonary bypass.