The Evaluation of Suspected Pulmonary Embolism Sir Run Run Shaw Hospital Zhouyong N Engl J Med 2003:349:1247-56

a case a 51-year-old woman pleuritic chest pain T 38.2°C pulse is 102 bpm a pleural friction rub chest radiograph is normal. She was treated with an antiinflammatory agent .Three days later, she returns, reporting dyspnea. How should she be evaluated?

Clinical problems of PE High mortality(17%~30%) High missed diagnosis High efficacy of therapy challenge: diagnosis

Pretest probability of PE* Risk factors Clinical signs and symptoms of deep venous thrombosis 3.0 PE more likely than alternatives 3.0 Heart rate >100 beats/min 1.5 Immobilization or surgery in the previous 4 wk 1.5 Previous deep venous thrombosis or pulmonary embolism 1.5 Hemoptysis 1.0 Active malignancy 1.0 Clinical probability Low <2.0 Intermediate 2.0–6.0 High >6.0 *adapted from Wells et al.

Labs & radiography D-Dimer testing Degradation product of serum fibrin Screening test due to high sensitive but nonspecific Limited to the ruling out of embolism

Ventilation-perfusion scanning(V/Q) Sensitive for emboli involving segmental or subsegmental pulmonary arteries A normal result can essentially rules out PE A scan indicating a high probability of PE is strongly associated with the presence of embolism

CT scan Better for patients with coexisting thoracic diseases Sensitive for emboli involving the main and lobar pulmonary arteries A normal result may indicate a substantially reduced likelihood of embolism but cannot rule out the possiblity of embolism

Ultrasonography of the leg veins Most source of the emboli About 50% sensitivity and cannot rule out PE May be falsely positive or may detect residual abnormality related to previous venous thrombosis Only definitely positive studies under appropriate clinical circumstances should serve as a basis for the initiation of therapy

Pulmonary angiography The gold standard for the diagnosis of PE Require more skills Invasive and more complicated such as respiratory failure,renal failure, hematoma,transfusion or even death Limited to the patients whose diagnosis cannot be established by less invasive means

Approaches to testing The choice of the initial test should based on the degree of suspicion

Special circumstances The choice of tests will vary in certain clinical circumstances As V/Q is of limited usefulness in patients with severe preexisting pulmonary parenchymal or airway disease, CT would be appropriately initial choice Angiography may be required in patients with previous embolism

Special circumstances In renal insufficient patients,the initial use of ultrasonography and V/Q,followed by selective pulmonary angiography is resonable The initial use of ultrasonography in mechanically ventilated patients and pregnant patients is suggested

Area of uncertainty The yield and cost effectiveness of different diagnosis strategies have not been directly compared in a clinical trial May echocardiography and right ventricular dysfunction biochemical markers improve the evaluation of short-term risks such as death? Should testing after completion of therapy be in the standard of care?

Guidelines Something different from other guidelines D-dimer testing is not included in the American Thoracic Society guidelines,since these guidelines were issued before D-dimer testing was in the context of clinical-probability rules. The Congress of the European Society of Cardiology recommends that D-dimer testing be followed by ultrasonography before lung-imaging studies

Back to the case The patient would have been categorized as having a low clinical probability of embolism at her initial presentation and D-dimer assay could be performed When dyspnea developed,she would have considered to have an intermediate clinical probability of embolism and could be referred directly for V/Q or CT scan.

Thank you!