Pleural effusions can occur as the consequence of a localized disease (exudative), or they can be a manifestation of systemic disease (transudative). They are fairly common, and chest physicians are often asked to diagnose and manage them. This chapter reviews the criteria for exudative and transudative pleural effusions, as well as the diagnostic techniques and medical management of several types of nonmalignant pleural effusions, including parapneumonic, connective tissue disease–related effusions, hepatic hydrothorax, and chylothorax. Therapeutic methods, including ultrasound-guided thoracentesis and the indications for chest tube drainage and pleuroscopy, are discussed as well as the use of thrombolytic therapy.
Four types of fluid can occupy the pleural space: serous fluid (hydrothorax), blood (hemothorax), lipid (chylothorax), and pus (empyema). Once the presence of a pleural effusion is established, it is important to determine whether it is a transudate or an exudate. A transudative pleural effusion indicates the presence of a systemic process, implicating organ systems other than the lung. This transudative pleural effusion is caused by medical conditions that lead to volume overload, such as renal failure, heart failure, and hypoalbuminemia (Table 129-1). In contrast, exudative pleural effusions indicate a local pleural process and necessitate a different treatment approach (Table 129-2). In 1972, Light defined the classic criteria for distinguishing between exudative and transudative pleural effusions.1 To qualify as an exudate, the pleural effusion must meet at least one of the following criteria: pleural fluid lactate dehydrogenase (LDH) >200 IU/L, ratio of pleural fluid LDH to serum LDH >0.6, or a ratio of pleural fluid protein to serum protein >0.5 (Table 129-3). These criteria have a high sensitivity and low specificity. The sensitivity and specificity increase with the number of criteria met.
Table 129-1TRANSUDATIVE PLEURAL EFFUSIONS |Favorite Table|Download (.pdf) Table 129-1TRANSUDATIVE PLEURAL EFFUSIONS
|Congestive heart failure |
Superior vena cava obstruction
Table 129-2EXUDATIVE PLEURAL EFFUSIONS |Favorite Table|Download (.pdf) Table 129-2EXUDATIVE PLEURAL EFFUSIONS
|INFECTIOUS ||INFLAMMATORY ||LYMPHATIC ABNORMALITIES |
|Pneumonia (bacterial and mycobacterial) ||Pancreatitis ||Yellow nail syndrome |
|Subphrenic abscesses ||Radiation |
Acute respiratory distress syndrome
|Malignancy (primary lung or metastatic) ||Immunologic disorders |
|Increased negative intrapleural pressure |
Table 129-3LIGHT CRITERIA FOR EXUDATIVE PLEURAL EFFUSIONS |Favorite Table|Download (.pdf) Table 129-3LIGHT CRITERIA FOR EXUDATIVE PLEURAL EFFUSIONS
|Fluid/serum protein >0.5 |
Fluid/serum LDH >0.6
Fluid LDH >two-thirds upper limit of normal
DIAGNOSTIC APPROACHES TO PLEURAL EFFUSIONS
The chest radiograph is usually the first diagnostic tool to assess a pleural effusion. An effusion that causes blunting of the ...