Empyema

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Patient Advice

Definition

Empyema refers to the accumulation of pus within the pleural space, typically resulting from infection such as bacterial pneumonia or thoracic surgery. It is a serious condition requiring prompt medical attention.

Aetiology

The primary causes of empyema include:

• Bacterial Pneumonia: The most common cause, often due to Streptococcus pneumoniae or Staphylococcus aureus.
• Complications of Thoracic Surgery or Trauma: Direct introduction of infection.
• Spread of Infection: From adjacent structures or bloodstream (haematogenous spread).
• Oesophageal Rupture: Rarely, leading to secondary infection of the pleural space.

Pathophysiology

Empyema develops in three stages:

• Exudative Stage: Inflammation leads to pleural fluid accumulation.
• Fibrinopurulent Stage: Bacterial invasion causes pus formation and fibrin deposition, leading to loculated fluid.
• Organising Stage: Chronic inflammation causes fibrosis and pleural thickening, restricting lung expansion.

Risk Factors

Factors increasing the risk of empyema include:

• Untreated or poorly managed bacterial pneumonia.
• Immunosuppression (e.g., HIV, chemotherapy).
• Underlying lung diseases such as COPD or bronchiectasis.
• Recent thoracic surgery or trauma.
• Alcohol misuse or malnutrition.

Signs and Symptoms

Typical clinical features of empyema include:

• Persistent Fever: Despite antibiotic therapy for pneumonia.
• Pleuritic Chest Pain: Sharp pain worsened by deep breathing or coughing.
• Productive Cough: Often with purulent sputum.
• Dyspnoea: Progressive shortness of breath.
• Reduced Breath Sounds: On the affected side during auscultation.

Investigations

Diagnostic tests and expected findings include:

• Chest X-ray: Shows pleural effusion or loculated fluid, with possible mediastinal shift.
• Ultrasound of the Thorax: Identifies fluid collections and guides aspiration.
• CT Thorax: Provides detailed imaging of loculated effusions and pleural thickening.
• Thoracentesis (Pleural Fluid Aspiration): Diagnostic test of choice:
  • Appearance: Turbid or purulent fluid.
  • pH: <7.2 suggests empyema.
  • Glucose: Low (<3.3 mmol/L).
  • Protein: High levels suggest exudate.
  • Gram Stain and Culture: Identifies causative organisms.
• Blood Tests: Raised white cell count and C-reactive protein (CRP).

Management

1. Medical Management

• Antibiotics: Broad-spectrum antibiotics, such as co-amoxiclav, initially IV, then oral for 2–4 weeks based on culture results.
• Analgesia: Paracetamol or ibuprofen for pain relief.
• Supportive Care: Oxygen therapy if hypoxic and adequate hydration.

2. Drainage of Pleural Fluid

• Needle Aspiration: For diagnostic purposes or small effusions.
• Intercostal Chest Drain (Tube Thoracostomy): Standard treatment for moderate to large empyema.
• Intrapleural Fibrinolytic Therapy: considered in selected cases

3. Surgical Management

• Video-Assisted Thoracoscopic Surgery (VATS): For removing infected material and adhesions in complex or resistant cases.
• Thoracotomy: Rarely required, for severe or chronic empyema.

Patient Advice

Key advice includes:

• Complete the full course of antibiotics as prescribed.
• Attend follow-up appointments to monitor resolution of the infection.
• Report symptoms such as persistent fever, chest pain, or breathlessness promptly.
• Maintain a healthy diet and avoid smoking to aid lung recovery.