Pneumothorax

Definition | Classification | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Pneumothorax is the presence of air in the pleural space, causing lung collapse. It can occur spontaneously or due to trauma.

Classification

Pneumothorax is classified into:

  • Primary spontaneous pneumothorax (PSP): occurs without an underlying lung disease, typically in tall, thin young males.
  • Secondary spontaneous pneumothorax (SSP): occurs in individuals with pre-existing lung disease (e.g., COPD, cystic fibrosis, lung cancer).
  • Traumatic pneumothorax: caused by blunt or penetrating chest trauma.
  • Iatrogenic pneumothorax: due to medical procedures such as central line insertion or mechanical ventilation.
  • Tension pneumothorax: a life-threatening form where air accumulates under pressure, leading to mediastinal shift and respiratory compromise.

Aetiology

Common causes of pneumothorax include:

  • Primary: rupture of subpleural blebs (small air-filled sacs in the lungs).
  • Secondary: underlying lung diseases such as:
    • Chronic obstructive pulmonary disease (COPD).
    • Asthma.
    • Cystic fibrosis.
    • Pulmonary infections (e.g., tuberculosis, pneumonia).
  • Traumatic:
    • Blunt trauma (e.g., rib fracture puncturing the lung).
    • Penetrating trauma (e.g., stab or gunshot wound).
  • Iatrogenic:
    • Central venous catheter insertion.
    • Positive-pressure ventilation.
    • Thoracentesis or lung biopsy.

Pathophysiology

Pneumothorax occurs when air enters the pleural space, leading to:

  • Loss of negative intrapleural pressure: which causes lung collapse.
  • Decreased lung compliance: leading to reduces ventilation and oxygenation.
  • Tension pneumothorax (in severe cases): this causes mediastinal shift, compressing the heart and great vessels, leading to haemodynamic instability.

Risk factors

  • Smoking (increases risk of PSP by 20 times).
  • Tall, thin body habitus (associated with PSP).
  • Underlying lung disease (e.g., COPD, cystic fibrosis).
  • Previous pneumothorax (higher recurrence risk).
  • Chest trauma or recent thoracic procedures.
  • Mechanical ventilation (risk of barotrauma).

Signs and symptoms

  • Sudden-onset pleuritic chest pain (sharp pain worsened by breathing).
  • Dyspnoea (shortness of breath).
  • Reduced or absent breath sounds on the affected side.
  • Hyperresonance to percussion on the affected side.
  • Tracheal deviation (away from the affected side in tension pneumothorax).
  • Tachycardia and hypotension in severe cases.

Investigations

  • Chest X-ray:
    • Shows absence of lung markings and a visible pleural line.
    • Deep sulcus sign may be seen in supine patients.
    • Do not order if you are suspecting tension pneumothorax as this may delay treatment.
  • CT thorax: more sensitive for detecting small pneumothoraces or underlying lung disease.
  • Arterial blood gas (ABG): this is generally done in dyspnoeic patients and may show hypoxaemia in severe cases. Common in patients with COPD.

Management

1. Primary Spontaneous Pneumothorax:

  • If small (<2 cm) and asymptomatic → observe and repeat X-ray in 2–4 weeks.
  • If large (>2 cm) or symptomatic → needle aspiration (aspirate up to 2.5L of air).
  • If aspiration fails → Insert chest drain.

2. Secondary Spontaneous Pneumothorax:

  • If small (<1 cm) and minimal symptoms → admit for observation and oxygen therapy.
  • If >1 cm and symptomatic → insert a small-bore chest drain.
  • If persistent air leak (>48 hours) → refer for pleurodesis or surgery.

3. Traumatic Pneumothorax:

  • Always requires a chest drain.
  • Manage underlying injuries (e.g., rib fractures).

4. Tension Pneumothorax (Medical Emergency):

  • Immediate needle decompression:
    • Insert a large-bore cannula into the 2nd intercostal space, midclavicular line.
    • Follow with chest drain insertion.

5. Surgical Management (if recurrent or persistent pneumothorax):

  • Pleurodesis (chemical or surgical) to prevent recurrence.
  • Video-assisted thoracoscopic surgery (VATS) for recurrent cases.

Referral

Refer to secondary care in the following scenarios:

  • Respiratory specialist: if pneumothorax is recurrent or fails conservative management.
  • Thoracic surgery: for persistent air leaks requiring pleurodesis or surgical intervention.
  • Hospital admission:
    • Secondary pneumothorax with symptoms.
    • Tension pneumothorax (requires emergency treatment).
    • Large pneumothorax requiring drainage.
 
RespiratorymypanotesPneumothorax