Pleural Effusion : Causes, Types, Symptoms and Treatment

Pleural effusion refers to the accumulation of excess fluid in the pleural space , potentially impairing lung expansion and gas exchange.

Anatomy Review

• Pleura : Double-layered serous membrane:
  • Visceral pleura (covers lungs)
  • Parietal pleura (lines thoracic wall)
• Pleural space : Normally contains <15 mL of lubricating fluid, maintained by hydrostatic and oncotic pressure gradients.

Classification

1. Transudative : Caused by systemic factors (e.g., imbalance in Starling forces)
2. Exudative : Caused by local inflammation or malignancy

Pathophysiology

• Transudative Effusion :
  • ↓ oncotic pressure (e.g., nephrotic syndrome, cirrhosis)
  • ↑ hydrostatic pressure (e.g., CHF)
  • Biochemistry : SG < 1.016, protein < 3 g/dL
• Exudative Effusion :
  • ↑ vascular permeability due to inflammation
  • Biochemistry : SG > 1.016, protein > 3 g/dL

Etiologies

• Transudate :
  • CHF (most common), cirrhosis, nephrotic syndrome, hypoalbuminemia, peritoneal dialysis
• Exudate :
  • TB, pneumonia (parapneumonic effusion), malignancy (lung, breast, lymphoma), pancreatitis, PE, trauma

Special Types

• Empyema : Pus in pleural space
• Chylothorax : Milky fluid due to thoracic duct injury
• Hemothorax : Gross blood in pleural space

Clinical Features

• Dyspnea
• Dry or productive cough
• Pleuritic chest pain
• Orthopnea (in large effusions)
• Hemoptysis (in malignancy)

Physical Examination

• Dullness to percussion
• ↓ breath sounds
• ↓ tactile fremitus
• Asymmetric chest expansion

Investigations

• Chest X-ray :
  • Blunting of costophrenic angles
  • Meniscus sign in upright films
• Ultrasound : Detects small effusions
• CT Chest : Identifies loculations, underlying causes
• Thoracentesis : Diagnostic and therapeutic
• Pleural fluid analysis :
  • Color, clarity, pH, protein, glucose, LDH, cell count, cytology
  • Light’s Criteria for exudate:
    • Pleural/serum protein ratio > 0.5
    • Pleural/serum LDH ratio > 0.6
    • Pleural LDH > 2/3 of upper normal serum LDH

Differential Diagnosis

• CHF
• Liver cirrhosis
• Nephrotic syndrome
• Malignancy
• TB
• Pulmonary embolism

Management

1. Treat the underlying cause :
   • CHF: Diuretics
   • Infection: Antibiotics
   • Malignancy: Chemotherapy/radiotherapy
2. Drainage :
   • Thoracentesis : First-line for symptomatic or large effusions
   • Chest tube : Empyema, chylothorax, hemothorax
3. Surgical options :
   • VATS (Video-assisted thoracoscopic surgery)
   • Pleurodesis (for recurrent malignant effusions)
4. Nutritional support :
   • No-fat diet in chylothorax

Complications

• Re-expansion pulmonary edema
• Pneumothorax
• Infection (empyema)
• Fibrosis (from unresolved empyema)

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