Pneumothorax

• A pneumothorax is an abnormal collection of air in the pleural space – between the lung and the chest wall.
• A pneumothorax can be classified as primary or secondary, depending on if there is an underlying disease. It can also be classified as spontaneous or traumatic.
• The majority of cases of spontaneous pneumothorax are minor and will self resolve, but in a small number of cases, a one way valve can form, allowing more and more air into the pleural space. We call this a tension pneumothorax and it is a medical emergency.
• Primary Spontaneous Pneumothorax (PSP) risk factors:

  • Classic patient is a tall, young male
  • Smoking
  • Family history
  • Marfan Syndrome
  • Homocystinurea
  • Usually the result of a pleural 'bleb', which is a congenital defect in the tissue of the alveolar wall
• Causes of a secondary pneumothorax:

  • COPD
  • Cystic fibrosis
  • Lung cancer
  • Pneumonia
  • Tuberculosis
• Under normal circumstances, the air pressure in the pleural cavity is negative compared to the atmosphere, which allows the lungs to inflate.
• In a pneumothorax, air fills the pleural cavity, disrupting and making the air pressure more positive. This prevents the lung from fully inflating and causing it to collapse.
• In a tension pneumothorax, a one-way valve can cause air to accumulate and compress the mediastinum. This reduces venous return to the heart, which can decrease cardiac output. Accumulated air can inflame the pleural space causing pain and pleurisy.
• Pneumothorax clinical features:

  • Sudden onset shortness of breath and pleuritic chest pain
  • Diminished breath sounds
  • Hyper-resonance on percussion
  • Severe respiratory distress (tension)
  •  Tracheal deviation (tension)
  • Jugular venous distension (tension)
  • Haemodynamic instability (tension)
• Pneumothorax investigations:

  • Diagnosis is mostly clinical, however to confirm you can use a chest X-Ray or CT
• Signs of a pneumothorax on a chest X-ray:

  • Visible pleural edge, with no lung markings beyond the edge
• Pneumothorax treatment:

  • Primary: Discharge or aspirate if patient is asymptomatic and rim of air is <2cm. If >2cm, then insert chest drain.
  • Secondary: As above, but treat underlying cause
  • Tension: Decompress by inserting a large bore cannula filled with saline in the 2nd intercostal space at the mid clavicular line