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Abnormal accumulation of fluid in the pleural space
- Congestive heart failure (CHF) (40%)
- Pneumonia (25%), malignancy (15%), and pulmonary embolism (PE) (10%) account for exudative effusions.
- Malignant: Lung cancer and metastases of breast, ovary, and lymphoma
Estimated 1.3 million cases/year in the US; CHF: 500,000; pneumonia, 300,000; malignancy, 200,000; PE, 150,000; cirrhosis, 150,000; tuberculosis (TB), 2,500; pancreatitis, 20,000; collagen-vascular disease, 6,000.
- Estimated 320 cases/100,000 people in industrialized countries. In hospitalized patients with AIDS prevalence is 7–27%
- No gender predilection: ~2/3 of malignant pleural effusions occur in women.
- Occupational exposures and drugs
- PE; TB; bacterial pneumonias (40%)
- Opportunistic infections (in HIV patients when CD4 count is <150 cells/μL)
- Pleural fluid formation exceeds pleural fluid absorption.
- Transudates result from imbalances in hydrostatic and oncotic forces:
- Increase in hydrostatic and/or low oncotic pressures; increase in pleural capillary permeability; lymphatic obstruction or impaired drainage; movement of fluid from the peritoneal or retroperitoneal space
- CHF: 40% of transudative effusions; 80% bilateral. Constrictive pericarditis, atelectasis; superior vena cava syndrome
- Cirrhosis (hepatic hydrothorax): 2/3 right side; nephrotic syndrome, hypoalbuminemia; mixedema
- Urinothorax, central line misplacement; peritoneal dialysis
- Lung parenchyma infection, bacterial (parapneumonic, tuberculous pleurisy) fungal, viral, parasitic (amebiasis, Echinococcus)
- Malignancy: Lung cancer, metastases (breast, lymphoma, ovaries), mesothelioma
- Pulmonary embolism (25% of PEs are transudate)
- Collagen-vascular disease: Rheumatoid arthritis, systemic lupus erythematosus (SLE), Wegener granulomatosis, sarcoidosis
- GI: Pancreatitis, esophageal rupture, abdominal abscess, after liver transplant. Chylothorax: Thoracic duct tear, malignancy
- Hemothorax: Trauma, PE, malignancy, coagulopathy, aortic aneurysm
- Others: After coronary artery bypass graft (CABG); Dressler syndrome; uremia, asbestos exposure, radiation; drug-induced: Nitrofurantoin, bromocriptine, amiodarone, procarbazine, methysergide, hydralazine, procainamide, quinidine, methotrexate, and methysergide; Meigs syndrome; yellow-nail syndrome; ovarian stimulation syndrome; lymphangiomatosis; acute respiratory distress syndrome (ARDS)
- Chylothorax: Thoracic duct tear, malignancy
Commonly Associated Conditions
Hypoproteinemia, heart failure, cirrhosis