Empyema

Purulent fluid collection in the pleural space, most commonly caused by pneumonia

Aetiology

  • Majority of cases are as a complication of pneumonia
  • Remainder are primary empyema (iatrogenic or idiopathic)

Risk factors

  • Immunodeficiency
  • Immunosuppression
  • Abnormal innate immunological defense
  • Repeated insult e.g. aspiration

Pathophysiology

  • Simple pleural effusion (pH >7.2, high glucose, negative gram stain) → complicated pleural effusion → pH <7.2, low glucose, positive gram stain) → empyema (mostly aerobic organisms, sometimes anaerobes e.g. from severe pneumonia)

Clinical presentation

  • Slow to resolve pneumonia - typically patient will partially recover, then will develop a spike in temperature
  • May be signs of pleural effusion on examination

Investigations

  • CXR - fluid level
  • USS - to confirm a collection of pleural fluid, may be used for thoracentesis (will be pus)
  • CT - not routinely used, can differentiate between an empyema and an abscess

Management

  • Broad spectrum IV antibiotics initially (amoxicillin and metronidazole)
  • Oral antibiotics once cultures come back directed towards cultured bacteria, usually 5 weeks of co-amoxiclav
  • Chest tube drainage - 5th intercostal space, midaxillary line in the safe triangle (anterior border of latissimus dorsi, posterior border of pectoralis major, axial line superior to nipple)