Pleural Effusion

• A pleural effusion is a collection of fluid in the pleural space
• Types of pleural effusions


  • Exudative
  • Transudative
• Exudative effusion


  High protein content (more than 30g/L)
• Transudative effusion


  Lower protein content (less than 30g/L)
• Light’s criteria


  Used for establishing an exudative effusion using protein or lactate dehydrogenase (LDH)
• Light’s criteria


  1. Pleural fluid protein / serum protein greater than 0.5

  2. Pleural fluid LDH / serum LDH greater than 0.6

  3. Pleural fluid LDH greater than 2/3 of the normal upper limit of the serum LDH
• Causes of exudative pleural effusions

  • Cancer (e.g., lung cancer or mesothelioma)
  • Infection (e.g., pneumonia or tuberculosis)
  • Rheumatoid arthritis
• Causes of transudative pleural effusions

  • Congestive cardiac failure
  • Hypoalbuminaemia
  • Hypothyroidism
  • Meigs syndrome
• Meigs syndrome involves a triad of a benign ovarian tumour (usually a fibroma), pleural effusion and ascites. The pleural effusion and ascites resolve with the removal of the tumour
• Presentation of pleural effusion


  • The typical presenting symptom is shortness of breath
• Examination findings of pleural effusion

  • Dullness to percussion over the effusion
  • Reduced breath sounds
  • Tracheal deviation away from the effusion in very large effusions
• Investigations for pleural effusion

  Chest
• Treatment of pleural effusion

  1. Diagnosing and treating the underlying cause is the mainstay of management

  2. Conservative management may be appropriate as small effusions will resolve with treatment of the underlying cause

  3. More significant effusions often need aspiration or drainage
• Pleural aspiration


  Involves sticking a needle through the chest wall into the effusion and aspirating the fluid. Aspiration can temporarily relieve the pressure, but the effusion may recur, and further drainage may be required
• Chest drain


  Used to drain the effusion and prevent it from recurring
• Empyema refers to an infected pleural effusion
• Suspect an empyema in a patient with improving pneumonia but a new or ongoing fever
• Pleural fluid analysis


  • Requires a sample taken by aspiration or chest drain
  • Helps establish the underlying cause by measuring the protein content, LDH, cell count, pH, glucose, and microbiology testing
• Empyema is treated with a chest drain and antibiotics