1. The history and physical examination are critical in guiding the evaluation of pleural effusion. Chest examination of a patient with pleural effusion – dullness to percussion, decreased or absent tactile fremitus, decreased breath sounds, and decreased voice transmission, mediastinal shift to the opposite side Chest x-ray 1. Diagnostic approach to pleural effusion Diagnostic Approach to Pleural Effusion in Adults, www.aafp.org/afp/20060401/1211.html

2. The first step in the evaluation of patients with pleural effusion is to determine whether the effusion is a transudate or an exudate. Diagnostic approach to pleural effusion Harrison’s Internal Medicine 17 th edition p.1658 Transudative pleural effusionExudative pleural effusion Occurs when systemic factors that influence the formation and absorption of pleural fluid are altered Occurs when local factors that influence the formation and absorption of pleural fluid are altered The leading causes are : left ventricular failure cirrhosis The leading causes are : bacterial pneumonia malignancy viral infection pulmonary embolism

3. Transudative and exudative pleural effusions are distinguished by measuring the lactate dehydrogenase (LDH) and protein levels in the pleural fluid. Thoracentesis – invasive procedure to remove fluid or air from the pleural space for diagnostic or therapeutic purposes Harrison’s Internal Medicine 17 th edition p.1658 Diagnostic approach to pleural effusion

4. Perform diagnostic thoracentesis: – if the etiology of the effusion is unclear – if the presumed cause of the effusion does not respond to therapy as expected. Pleural effusions do not require thoracentesis: – if they are too small to safely aspirate (<1 cm thickness on a lateral decubitus film) – if their presence can be explained by underlying congestive heart failure, etc. Diagnostic approach to pleural effusion http://emedicine.medscape.com/article/299959-diagnosis

5. Light’s criteria Exudative pleural effusions meet at least one of the following criteria, whereas transudative pleural effusions meet none: 1. pleural fluid protein/serum protein >0.5 2. pleural fluid LDH/serum LDH >0.6 3. pleural fluid LDH more than two-thirds normal upper limit for serum Diagnostic approach to pleural effusion Harrison’s Internal Medicine 17 th edition p.1658

6. The criteria misidentify ~25% of transudates as exudates. If one or more of the exudative criteria are met and the patient is clinically thought to have a condition producing a transudative effusion, the difference between the protein levels in the serum and the pleural fluid should be measured. If this gradient is greater than 31 g/L (3.1 g/dL), the exudative categorization by the criteria can be ignored because almost all such patients have a transudative pleural effusion. Diagnostic approach to pleural effusion Harrison’s Internal Medicine 17 th edition p. 1658

7. The primary reason to make this differentiation is that additional diagnostic procedures are indicated with exudative effusions to define the cause of the local disease. If a patient has an exudative pleural effusion, the following tests on the pleural fluid should be obtained: description of the fluid glucose level differential cell count microbiologic studies cytology Harrison’s Internal Medicine 17 th edition p. 1658 Diagnostic approach to pleural effusion

8. Harrison’s Internal Medicine 17 th edition p. 1658