What are the causes of spontaneous pneumothorax?

From the Guidelines

Spontaneous pneumothorax is primarily caused by the rupture of subpleural blebs and bullae, which are found in up to 90% of cases of primary pneumothorax, with smoking being a significant risk factor. The exact aetiology of these bullous changes in otherwise healthy lungs is unclear, but smoking plays a crucial role, with a lifetime risk of developing a pneumothorax in healthy smoking men being as much as 12% compared to 0.1% in non-smoking men 1. Primary spontaneous pneumothorax typically occurs in people without underlying lung disease, whereas secondary spontaneous pneumothorax develops in patients with pre-existing lung conditions. Some key points to consider include:

• The incidence of primary pneumothorax is reported to be 18–28/100 000 per year for men and 1.2–6/100 000 per year for women 1
• Hospital admission rates for combined primary and secondary pneumothorax are reported in the UK at between 5.8/100 000 per year for women and 16.7/100 000 per year for men 1
• Mortality rates in the UK were 0.62/million per year for women and 1.26/million per year for men between 1991 and 1995 1
• Smoking cessation is essential in preventing the recurrence of pneumothorax, as emphasized by the strong relationship between smoking and the development of pneumothorax 1.

From the Research

Causes of Spontaneous Pneumothorax

The causes of spontaneous pneumothorax can be divided into two main categories: primary and secondary.

• Primary spontaneous pneumothorax (PSP) is not associated with any underlying lung disease, but is thought to be caused by diffuse and often bilateral abnormalities within the pleura, including emphysema-like changes, pleural porosity, and inflammation 2.
• Secondary spontaneous pneumothorax (SSP) is associated with underlying lung diseases, such as:
  • Cystic fibrosis 3
  • Chronic obstructive pulmonary disease (COPD) 3, 4
  • Interstitial lung disease (ILD) 3

Underlying Pathological Processes

The underlying pathological processes that contribute to spontaneous pneumothorax include:

• Rupture of subpleural blebs/bullae in the underlying lung 5
• Emphysema-like changes in the pleura 2
• Pleural porosity and inflammation 2 These processes can lead to the accumulation of air in the pleural cavity, resulting in a spontaneous pneumothorax.