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Pleural Effusions

  • Pleural effusions – accumulation of serous fluid within the pleural cavity
    • Detected on X-ray when >300ml
    • Detected clinically when >500ml

Pathophysiology

Transudate

  • ↑capillary hydrostatic pressure
  • ↓capillary oncotic pressure

Exudates

  • ↑capillary permeability – e.g. due to inflammation

Transudates

  • Can be bilateral – often larger on the right side
  • Protein content <30g/L
  • LDH <200IU/L
  • Causes
    • Heart failure
    • Hypoproteinaemia (e.g. nephrotic syndrome)
    • Constrictive pericarditis
    • Hypothyroidism
    • Ovarian tumours producing right-sided pleural effusion – Meigs syndrome

Exudates

  • Protein >30g/L
  • LDH >200IU/L
  • Light’s criteria for diagnosis of an exudative effusion – see box
  • Causes
    • Bacterial pneumonia
    • Bronchial carcinoma
    • Tuberculosis
    • Acute pancreatitis

Clinical features (if effusion is >500ml)

  • Pain on inspiration
  • Coughing
  • Pleural rub
  • Reduced chest wall expansion
  • Reduced/absent breath sounds

Diagnosis

  • CXR – curved shadow at lung base; blunting of costophrenic angle
  • USS – more accurate than CXR
    • Transudate – clear hypoechoic space
    • Exudates – presence of moving floating densities
  • Pleura aspiration – information on colour and texture of fluid
  • Biopsy – pathological and microbiological analysis

Treatment

  • Aspiration to relieve dyspnoea – fluid should be removed slowly as fast removal can cause pulmonary oedema
  • Treat underlying cause

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