Thoracic Surgery for Nonneoplastic Disease

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What is a pleural effusion?

Pleural fluid is generated in normal adults at a rate of 5–10 L per 24 hours in the combined hemithoraces, but normal adults have only 20 mL of pleural fluid present at any time. Pleural effusions develop when there is either increased production or decreased resorption. Pathologic conditions leading to effusions include increased capillary permeability (inflammation, tumor), increased hydrostatic pressure (e.g., in congestive heart failure [CHF]), decreased lymphatic drainage (tumor, radiation fibrosis), decreased oncotic pressure (hypoalbuminemia), or combinations of these.

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How does one determine the cause of a pleural effusion?

History and physical examination, chest radiograph (upright and decubitus), chest computed tomography (CT) scans, and thoracentesis are used. Thoracentesis should be used to evaluate the pleural fluid. Bloody fluid is typical of trauma, pulmonary embolism, or malignancy. Milky fluid can be evidence of a chylothorax (triglyceride >110), and purulent fluid evidence of an empyema. Fluid should be checked for cell count; cytology; acid-base balance (pH); Gram stain; culture; and glucose, protein, lactate dehydrogenase (LDH), amylase, and triglyceride level. Exudates have a protein ratio >0.5 and an LDH ratio >0.6. The most common cause of transudate is CHF; the most common cause of exudate is malignancy. Glucose <60 mg/dL is seen in parapneumonic effusions, rheumatoid effusion, tuberculous pleuritis, and malignancy.

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What is the management of a pleural effusion?

Treatment for effusions differs based on the kind of effusion: transudative or exudative. Thoracentesis or a tube thoracostomy should be used to evacuate the effusion and determine the type. If the effusion is transudative, one should correct the underlying problem (e.g., CHF). If the effusion is exudative, one needs to consider operative intervention (e.g., pleurodesis or decortication). A decortication is the removal of an infective rind from the lung surface, allowing for full expansion of the lung tissue, thus filling an infected pleural space. A pleurodesis is used to treat a malignant effusion. A pleurodesis (stick the parietal and visceral pleurae together) can be performed with sclerosants (talc) or mechanical abrasion. Pleural symphysis (stuck pleura) results in decreased surface area for production, eliminates the pleural space for accumulation, and prevents lung collapse and compression. Chest tubes are generally removed when output is <150 mL per 24 hours.

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What does an air-fluid level on an initial chest radiograph indicate?

An air-fluid level before any drainage procedure may represent a bronchopleural fistula. These fistulas may resolve with chest tube drainage or require open thoracotomy for definitive repair.

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