Investigations

The diagnosis of pneumothorax is usually confirmed by imaging techniques

• chest radiology:
  • presence of a white visceral pleural line separated from the parietal pleura and chest wall by a collection of gas, resulting in a loss of lung markings in this space is a hallmark of the condition
  • standard erect PA chest x-ray
    • inspiratory films are recommended for the initial diagnosis of pneumothorax
    • expiratory films are not thought to confer additional benefit in the routine assessment of pneumothorax
  • lateral x-ray
    • may provide additional information when a suspected pneumothorax is not confirmed by a PA chest film. However, they are no longer used routinely in everyday clinical practice
  • supine and lateral decubitus x-rays
    • useful for trauma patients who cannot be safely moved, less sensitive than erect PA x-rays for the diagnosis
  • chest films may need to be repeated within a short period to assess change in the size of the pneumothorax
• ultrasound
  • specific features on ultrasound scanning are diagnostic of pneumothorax but is mainly used in the management of supine trauma patients
• CT
  • recommended for uncertain or complex cases
  • regarded as the gold standard in the detection of small pneumothoraces and in size estimation
  • useful in differentiating a pneumothorax from large bullae (1,2)

In addition to imaging, arterial blood gases will show hypoxia

• hypoxaemia is greater in cases of SSP
• not required if the oxygen saturations are adequate (>92%) on breathing (1)

Reference:

• (1) MacDuff A et al. Management of spontaneous pneumothorax: British Thoracic Society Pleural Disease Guideline 2010. Thorax. 2010;65 Suppl 2:ii18-31
• (2) Bintcliffe O, Maskell N. Spontaneous pneumothorax. BMJ. 2014;348:g2928