SPECIAL SELECTED TOPICS- RESPIRATORY SYSTEM DISORDERS-SSTRSDO-QAA 025

1. What is the pathogenesis of pleural effusion?

Pleural effusion is the abnormal accumulation of fluid within the pleural cavity due to imbalance between pleural fluid formation and absorption. Increased hydrostatic pressure, as in congestive heart failure, produces transudative effusions.

Reduced plasma oncotic pressure due to nephrotic syndrome, liver cirrhosis, or malnutrition also causes transudates. Increased vascular permeability from infections, malignancy, pulmonary embolism, or inflammatory diseases results in exudative effusions.

Obstruction of lymphatic drainage by tumors impairs fluid removal. Hemothorax and chylothorax represent specialized forms of pleural effusion. Progressive fluid accumulation compresses the lung and causes dyspnea.

Thoracentesis and pleural fluid analysis help determine the underlying cause. Treatment is directed at correcting the primary disease.

2. Which forms of pleuritis do you know?

Pleuritis is inflammation of the pleura resulting from infections, autoimmune diseases, malignancy, or pulmonary disorders. Acute fibrinous pleuritis is characterized by deposition of fibrin on the pleural surfaces and often produces pleuritic chest pain with a pleural friction rub.

Serous pleuritis results in accumulation of clear inflammatory fluid. Suppurative pleuritis (empyema) contains purulent exudate due to bacterial infection.

Hemorrhagic pleuritis occurs in tuberculosis, malignancy, or trauma. Chronic fibrous pleuritis produces pleural thickening and adhesions. Tuberculous pleuritis is an important granulomatous form.

Chronic inflammation may lead to pleural fibrosis and restriction of lung expansion. Identification of the underlying cause guides treatment.

3. What are the main types of non-inflammatory pleural effusions?

Non-inflammatory pleural effusions are mainly transudative and result from systemic disorders rather than pleural inflammation. Hydrothorax is a transudative pleural effusion caused by congestive heart failure, nephrotic syndrome, or liver cirrhosis.

Hemothorax is the accumulation of blood in the pleural cavity following trauma, surgery, or rupture of blood vessels. Chylothorax results from leakage of lymph due to thoracic duct injury or obstruction by tumors. Urinothorax occurs rarely after urinary tract injury. These effusions usually lack significant inflammatory cells.

Large effusions compress the underlying lung and impair ventilation. Pleural fluid analysis distinguishes transudates from exudates. Management depends on treatment of the underlying condition.

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 DR.C.GANESAN M.D

PROFESSOR OF MEDICINE