Management of Pleural Effusions

Diagnostic Criteria

The European Respiratory Society suggests that Light's criteria remain the gold standard for differentiating exudates from transudates with a sensitivity of 98% and specificity of 72% 1, 2
An effusion is classified as exudative if it meets any one of the following criteria: pleural fluid/serum protein ratio >0.5, pleural fluid/serum LDH ratio >0.6, or pleural fluid LDH >67% of the upper limit of normal for serum LDH 3, 1
Alternative criteria when serum samples are unavailable include pleural fluid LDH >67% of the upper limit of normal or pleural fluid cholesterol >55 mg/dL 1

The primary management of heart failure, which accounts for 80% of transudates, involves optimizing cardiac function and reducing fluid overload 2
Interventions for heart failure include diuretic therapy, fluid restriction, cardiac resynchronization therapy, or valvular surgery when indicated 4
For refractory cases of heart failure, options include ultrasound-guided thoracentesis for symptomatic relief or indwelling pleural catheters for recurrent effusions 4, 5

Diagnostic thoracentesis with cytology is diagnostic in 60% of cases of malignant effusions, which account for 26% of exudates 3
Management options for malignant effusions include therapeutic thoracentesis for symptomatic relief, indwelling pleural catheter for recurrent effusions, or chemical pleurodesis 4
The European Respiratory Society recommends anti-tuberculosis therapy for tuberculous effusions, with consideration of therapeutic thoracentesis for large, symptomatic effusions 2

Radiological findings alone cannot replace biochemical analysis for transudate-exudate differentiation, according to the European Respiratory Journal 6
Ultrasound characteristics, such as anechoic appearance or presence of septations, can aid in differentiating transudates from exudates but should be used in conjunction with biochemical analysis 4

The British Thoracic Society recommends performing diagnostic thoracentesis using a fine bore (21G) needle with a 50 ml syringe, and sending pleural fluid for protein and LDH (with simultaneous serum samples) for Light's criteria, cytology, pH, Gram stain, culture in both sterile vials and blood culture bottles, and AAFB stain and TB culture 7
The European Respiratory Society suggests that cytology is diagnostic in 60% of malignant effusions, and if cytology is negative but malignancy suspected, proceed to ultrasound/CT-guided pleural biopsy or thoracoscopy 7

The American Thoracic Society recommends assessing appearance and odor of the pleural fluid, and measuring hematocrit if the effusion is bloody; if pleural fluid hematocrit >50% of peripheral blood hematocrit, diagnose hemothorax (usually malignancy, pulmonary embolus, trauma, or asbestos-related) 7
The British Thoracic Society suggests that turbid/milky fluid should be centrifuged; if supernatant clears, suspect empyema; if remains turbid, suspect chylothorax or pseudochylothorax 7

The American College of Chest Physicians recommends treating the underlying cause rather than the effusion itself, and for heart failure management, optimize cardiac function with diuretic therapy, fluid restriction, cardiac resynchronization therapy, or valvular surgery when indicated 7
The European Respiratory Society suggests that for suspected malignancy, obtain contrast-enhanced CT thorax with fluid present to visualize pleural nodularity and identify biopsy sites, and perform thoracic ultrasound looking for diaphragmatic or pleural thickening and nodularity (highly suggestive of malignancy) 7