Pleural Effusion

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

Definition

Pleural Effusion refers to the abnormal accumulation of fluid within the pleural space. It can be classified as transudative or exudative based on the underlying cause and fluid composition.

Aetiology

Common causes of pleural effusion include:

1. Transudative Effusion:

• Heart Failure: Increased hydrostatic pressure leads to fluid accumulation.
• Liver Cirrhosis: Hypoalbuminaemia reduces oncotic pressure.
• Nephrotic Syndrome: Severe protein loss reduces oncotic pressure.

2. Exudative Effusion:

• Pneumonia: Inflammatory response causes pleural fluid exudation.
• Malignancy: Tumour infiltration increases vascular permeability.
• Tuberculosis: Granulomatous inflammation in the pleura.
• Pancreatitis: Associated with retroperitoneal inflammation.

Pathophysiology

The development of pleural effusion involves:

• Increased Hydrostatic Pressure: Seen in heart failure.
• Reduced Oncotic Pressure: Due to hypoalbuminaemia.
• Increased Capillary Permeability: Inflammatory conditions like pneumonia or malignancy.
• Reduced Lymphatic Drainage: Secondary to malignancy or infection.

Risk Factors

Common risk factors include:

• Underlying chronic conditions such as heart failure, liver disease, or kidney disease.
• Infections like pneumonia or tuberculosis.
• Exposure to asbestos (increasing risk of mesothelioma).
• Malignancies, especially lung and breast cancer.

Signs and Symptoms

Clinical features of pleural effusion include:

• Dyspnoea: Gradual onset shortness of breath.
• Pleuritic Chest Pain: Sharp pain worsened by deep breathing.
• Cough: Usually dry or non-productive.
• Reduced Breath Sounds: Over the affected area on auscultation.
• Dullness to Percussion: Indicative of fluid in the pleural space.

Investigations

Key investigations and expected findings include:

• Chest X-ray:
  • Blunting of the costophrenic angles.
  • Meniscus sign indicating fluid level.
• Thoracic Ultrasound: Confirms presence of fluid and guides aspiration.
• Diagnostic Thoracentesis: Aspiration of pleural fluid to analyse:
  • Appearance: Clear (transudate) or cloudy/purulent (exudate).
  • pH: <7.2 suggests infection or empyema.
  • Protein and Lactate Dehydrogenase (LDH): Used to classify as transudate or exudate (Light’s criteria).
  • Microbiology: Gram stain and culture for infection.
  • Cytology: To detect malignant cells.
• CT Thorax: Detailed imaging to assess underlying cause, such as malignancy or empyema.

Management

1. Treat Underlying Cause

• Heart Failure: Optimise diuretic therapy (e.g., furosemide).
• Infection: Empirical antibiotics based on likely organisms (e.g., co-amoxiclav for pneumonia).
• Malignancy: Oncological referral for chemotherapy or radiotherapy.

2. Drainage of Pleural Fluid

• Diagnostic Thoracentesis: For symptomatic relief and diagnostic purposes.
• Intercostal Chest Drain: For large or loculated effusions.
• Pleurodesis: To prevent recurrent effusions in malignancy.

3. Surgical Management

• Video-Assisted Thoracoscopic Surgery (VATS): For draining empyema or pleural biopsy in complex cases.

Patient Advice

Key advice includes:

• Adhere to prescribed treatment for the underlying cause.
• Attend follow-up appointments to monitor effusion resolution.
• Seek medical attention if symptoms worsen, such as increased breathlessness or chest pain.
• Maintain a healthy lifestyle to manage underlying conditions.