American family physician
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Pleural effusion affects 1.5 million patients in the United States each year. New effusions require expedited investigation because treatments range from common medical therapies to invasive surgical procedures. The leading causes of pleural effusion in adults are heart failure, infection, malignancy, and pulmonary embolism. ⋯ Parapneumonic effusions are the most common cause of exudates. A pH level less than 7.2 is indicative of complicated parapneumonic effusion and warrants prompt consultation for catheter or chest tube drainage, possible tissue plasminogen activator/deoxyribonuclease therapy, or thoracoscopy. Malignant effusions are another common cause of exudative effusions, with recurrent effusions having a poor prognosis.