Pleural Effusion

Accumulation of fluid within the pleural space

Aetiology

Transudative

  • Caused by disturbances in oncotic pressure, commonly cardiac failure and liver cirrhosis
  • Low protein content (< 30g/L)

Exudative

  • Fluids that have left the circulatory system and have gone into lesions or areas of inflammation, commonly due to malignancy or infection
  • High protein content (> 30g/L)

Clinical presentation

Symptoms

  • Chest pain
  • Dry cough
  • Dyspnoea
  • Difficulty taking deep breaths

Signs

  • Reduced chest expansion on affected side
  • Stony dull percussion

Investigations

CXR

  • >500ml will cause a clear fluid level

Aspiration (thoracentesis)

Colour
  • Straw coloured - cardiac failure, hypoalbuminaemia
  • Bloody - trauma, malignancy, infection, infarction
  • Turbid/milky - empyema, chylothorax
  • Foul smelling - anaerobic empyema
  • Food particles - oesophageal rupture
Cytology
  • Lymphocytes indicate malignancy or TB
  • Neutrophils indicate an acute process
Microbiology
  • Gram stain
  • Microscopy
  • Culture
  • PCR
  • AFB stain
pH
  • >7.2 = simple effusion
  • <7.2 = complicated effusion
Glucose
  • Low in infection, TB, malignancy

Pleural biopsy

  • If diagnosis not possible from fluid sampling

Management

  • Treat underlying disorder
  • Infection - simple effusion (pH >7.2) can be treated with antibiotics only, complicated effusion (pH <7.2) requires a chest drain and antibiotics