A pneumothorax is defined as the abnormal collection of air between the visceral and parietal space of the lung i.e. the pleural space. It typically presents with acute shortness of breath, pleuritic chest pain and is more common in those with damaged or stretched lungs. Despite clear cut guidelines from BTS, real-life management varies considerably with a general trend to reduce the use of aspiration (except if under tension) with conservative outpatient monitoring rather than chest drains (see Yoon et al). This depends on the different aetiologies & degree of hypoxia/haemodynamic instability.

Common aetiologies

  1. Spontaneous:
    • Commonly occurs in tall and thin males smokers with previously normal lungs.
    • Most likely caused by rupture of subpleural bleb or bulla
  2. Secondary:
    • Occurs in people with pre-existing lung conditions, usually COPD, asthma or cystic fibrosis
  3. Traumatic:
    • Penetrating injury to the chest, oesophageal rupture, iatrogenic causes e.g. during subclavian or jugular venous cannulation, thoracocentesis, pleural or lung biopsy, or positive pressure-assisted ventilation

Risk factors

  • Collagen disorders e.g. Marfan’s syndrome, Ehlers-Danlos syndrome
  • Smoking
  • Tall & thin males


  • Tension pneumothorax is a life-threatening condition caused by the progressive accumulation of air in the pleural space.
  • It is normally presented with severe respiratory distress, tachycardia, hypotension, cyanosis, distended neck veins and tracheal deviation away from the side of pneumothorax.
  • In more severe cases, it can result in cardiac arrest and death if life-saving treatment is not given urgently
  • Do bear in mind that in early cases or young patients, they may compensate very well and so the lack of a significantly unwell patient shouldn’t deter you from considering this diagnosis


Chest X-ray is the main investigation to diagnose a pneumothorax.

Whilst the above pneumothoraces are incredibly obvious, they can be very subtle. One trick is to increase the contrast and trace the edge of the lung looking for any subtle areas of absent lung markings. In particular, diseased lungs might collapse atypically e.g. from the back. You might see an almost fully expanded lung in 2D but in 3D it might be significantly collapsed. If unsure, discuss with seniors and the radiology team to consider a CT chest.


  1. Spontaneous pneumothorax:
    • Can be divided into primary or secondary spontaneous pneumothorax based on:
      • Age (<50 or >50)
      • Pre-existing lung diseases, (ask history long standing of SOB/cough)
    • The size of pneumothorax & patient’s condition will then determine the treatment. British Thoracic Society (BTS) guidelines (2010): size of pneumothorax is measured from chest wall to lung edge at the level of the hilum (see image below)
      • <2 cm: small – conservative management including observation, oxygen, analgesia with follow up at 2-4 weeks
      • ≥2 cm: large – needle decompression and/or chest drain
    • Note: that patients should be advised to avoid air travel until follow-up CXR confirms full resolution of pneumothorax.
    • Diving should also be permanently avoided unless the patient has undergone bilateral surgical pleurectomy and has normal lung function and chest CT scan post-operatively.
    • Smoking cessation reduces recurrence risk dramatically

  1. Tension pneumothorax:
    • A-E assessment in any emergency situations
    • Give 15L oxygen via a non-rebreather mask
    • Do an emergency needle decompression using a large bore cannula inserted in the second intercostal space, mid-clavicular line
    • A chest drain needs to be inserted into the fourth and sixth intercostal space in mid-axillary line (see image below) after the needle decompression
    • Should the patient be haemodynamically unstable, treatment should NOT be delayed for a CXR to confirm diagnosis

Pneum 5
The safe triangle for chest drain insertion


  1. Radiopedia – Pneumothorax
  2. Radiopedia – Tension pneumothorax
  3. British Thoracic Society Guidelines
  4. British Lung Foundation
  5. Patient – Pneumothorax

Written by Dr Marjorie Teo (FY1)
Reviewed & edited by Dr George Hulston (Respiratory Registrar) & Dr Akash Doshi (Endocrinology ST4)
Edited by Mudassar Khan (Y4 Medical Student)

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