What is the differential diagnosis of the patient suspected of having pulmonary emboli?

Other diagnoses that should be entertained in patients suspected of pulmonary embolism include infectious pneumonitis, viral pleuritis, atelectasis, cardiovascular collapse secondary to sepsis or hemorrhage, pulmonary edema, bronchial asthma, and hyperventilation syndrome.

How is the diagnosis of pulmonary embolism confirmed?

The diagnosis of pulmonary embolism requires laboratory confirmation, because clinical diagnosis is quite unreliable. Helpful diagnostic tests include tests for lower-extremity deep vein thrombosis (see question 5), ventilation/perfusion lung scans, and pulmonary angiography. Pulmonary angiography remains the gold standard. Although angiography is safe when performed by experienced angiographers, morbidity and mortality are increased in patients with pulmonary hypertension, cor pulmonale, or acute right ventricular strain. Ventilation/perfusion lung scanning is safer and less invasive than angiography but also less specific. Specificity is improved when only segmental or larger perfusion defects are considered significant. When ventilation/perfusion lung scans are nondiagnostic, some authorities advocate evaluation for evidence of lower-extremity deep vein thromboses before proceeding to angiography. Although definitive proof of deep vein thromboses does not prove pulmonary embolism, it renders the issue inconsequential, because anticoagulation is generally indicated for both conditions.

What is the treatment of pulmonary embolism?

Treatment of pulmonary embolism includes cardiopulmonary supportive measures (fluids and vasopressors for hemodynamic support, oxygen) and specific measures for thromboembolism, such as anticoagulation, placement of an intracaval filter, or thrombolytic therapy. Anticoagulation remains the treatment of choice for most patients. The primary debate regards length of therapy. The goal of therapy is to prevent new clot formation and/or thrombus growth while existing clots become organized or resolve. Because organization and resolution require 7-10 days, all patients must be anticoagulated during this period. Controversy surrounds the need for more chronic anticoagulation. Although most authorities recommend anticoagulation for 3 months for deep vein thromboses and 6 months for proved pulmonary embolism, some advocate anticoagulation beyond 7-10 days only in patients at high risk for recurrence {continued thromboembolic risk factors [see questions 1 and 2] and/or persistent venous obstruction, as assessed by impedance plethysmography). Either oral warfarin or subcutaneous heparin is effective if chronic anticoagulation is indicated.

What are the indications for intracaval filters?

Absolute indications for interruption of the inferior vena cava through insertion of a filter include failure of anticoagulation and/or a contraindication to anticoagulation. In addition, some experts advocate placement of an intracaval filter for massive pulmonary embolism, because failure of anticoagulation in this setting frequently has a fatal outcome.

When is thrombolytic therapy indicated for pulmonary embolism?

Although thrombolytic therapy for pulmonary embolism in general is associated with more rapid clot dissolution than anticoagulation (heparin) alone, no well-controlled studies have demonstrated a difference in morbidity or mortality between the two therapeutic modalities. Thrombolytic therapy is therefore indicated only for massive pulmonary embolism characterized by refractory hypotension and/or refractory hypoxemia.


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