1. The Evaluation of Suspected Pulmonary Embolism
Sir Run Run Shaw Hospital
Zhouyong
N Engl J Med 2003:349:

2. 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?

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

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

5. 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

6. 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

7. 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

8. 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

9. 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

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

14. 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

15. 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

16. 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?

17. 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

18. 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.

19. Thank you!