• Incidence: 15.00 cases per 100,000 person-years
  • Peak incidence: 20-30 years
  • Sex ratio: more common in males 3:1
Condition Relative
Acute exacerbation of asthma66.67
Aortic dissection0.20
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+


Risk factors
  • pre-existing lung disease: COPD, asthma, cystic fibrosis, lung cancer, Pneumocystis pneumonia
  • connective tissue disease: Marfan's syndrome, rheumatoid arthritis
  • ventilation, including non-invasive ventilation
  • catamenial pneumothorax is the cause of 3-6% of spontaneous pneumothoraces occurring in menstruating women. It is thought to be caused by endometriosis within the thorax

Clinical features

Symptoms tend to come on suddenly. Features include:


The British Thoracic Society (BTS) published updated guidelines for the management of spontaneous pneumothorax in 2010. A pneumothorax is termed primary if there is no underlying lung disease and secondary if there is.

Primary pneumothorax

Recommendations include:
  • if the rim of air is < 2cm and the patient is not short of breath then discharge should be considered
  • otherwise aspiration should be attempted
  • if this fails (defined as > 2 cm or still short of breath) then a chest drain should be inserted
  • patients should be advised to avoid smoking to reduce the risk of further episodes - the lifetime risk of developing a pneumothorax in healthy smoking men is around 10% compared with around 0.1% in non-smoking men

Secondary pneumothorax

Recommendations include:
  • if the patient is > 50 years old and the rim of air is > 2cm and/or the patient is short of breath then a chest drain should be inserted.
  • otherwise aspiration should be attempted if the rim of air is between 1-2cm. If aspiration fails (i.e. pneumothorax is still greater then 1cm) a chest drain should be inserted. All patients should be admitted for at least 24 hours
  • if the pneumothorax is less the 1cm then the BTS guidelines suggest giving oxygen and admitting for 24 hours
  • regarding scuba diving, the BTS guidelines state: 'Diving should be permanently avoided unless the patient has undergone bilateral surgical pleurectomy and has normal lung function and chest CT scan postoperatively.'

Iatrogenic pneumothorax

Recommendations include:
  • less likelihood of recurrence than spontaneous pneumothorax
  • majority will resolve with observation, if treatment is required then aspiration should be used
  • ventilated patients need chest drains, as may some patients with COPD