A 55-year-old man presents with pleuritic chest pain, breathlessness, and fever. CXR shows a left-sided pleural effusion. Diagnostic thoracentesis: pH 7.12, glucose 32 mg/dL, LDH 1800 U/L, protein 5.4 g/dL, WBC 28,000 cells/µL (predominantly neutrophils). No organisms on Gram stain. This is a:

• A Complicated parapneumonic effusion requiring chest tube drainage ✓
• B Simple parapneumonic effusion managed with antibiotics alone
• C Malignant effusion requiring pleurodesis
• D Transudative effusion from heart failure

Explanation

BTS guidelines classify a parapneumonic effusion as complicated (requiring drainage) when any of the following are present: pleural fluid pH <7.2, glucose <3.4 mmol/L (<60 mg/dL), LDH >1000 U/L, or positive culture/Gram stain, or frank pus (empyema). This patient fulfils all criteria: pH 7.12, glucose 32 mg/dL, and LDH 1800 U/L. Chest tube drainage plus antibiotics is mandatory; MIST1/MIST2 trials also support intrapleural fibrinolytic therapy (tPA + DNase) if drainage is inadequate. Simple parapneumonic effusions (pH >7.3, glucose >60, no organisms) respond to antibiotics alone. Malignant effusions have different characteristics. This is clearly an exudate.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.