Topics in Lung Disease: Noninfectious Pleural Effusions

Noninfectious pleural effusions arise from an imbalance between fluid entering and leaving the pleural space. Effusions are classified as transudative or exudative, based on protein and lactate dehydrogenase levels. Common symptoms are dyspnea, cough, and chest pain. Physical examination findings may include dullness to percussion and decreased breath sounds. Transudates are associated with conditions such as congestive heart failure and cirrhosis, whereas exudates are linked to pneumonia, malignancy, pulmonary embolism, and gastrointestinal disorders. Diagnosis relies on chest imaging and image-guided thoracentesis for pleural fluid analysis. The differentiation between transudative and exudative effusions is primarily based on Light criteria, which include ratios of effusion to serum concentrations of protein and lactate dehydrogenase. Additional testing (eg, cytology, glucose level, microbiological studies) may be necessary for indeterminate cases. Management focuses on treating the underlying condition. Interventions such as therapeutic thoracentesis, pleurodesis, or surgical procedures may be needed, depending on the etiology of the effusion. Accurate classification and targeted treatment are key for optimizing patient outcomes.