Pneumothorax

• Spontaneous pneumothorax occurs without any apparent cause, often in young, tall, thin individuals.
• Primary pneumothorax = in a patient without known respiratory disease

  Secondary pneumothorax = in a patient with pre existing respiratory disease

  Tension pneumothorax = severe pneumothorax with displacement of trachea / mediastinum and haemodynamic instability
• Causes of secondary pneumothorax include:

  • Chronic obstructive pulmonary disease - most common cause, rupture of air bulla
  • Asthma
  • Cystic fibrosis - endobronchial obstruction causing increased pressure in the alveoli, leading to alveolar rupture
  • Marfan syndrome
• Causes of tension pneumothorax include:

  • Penetrating/blunt trauma
  • Mechanical ventilation or non-invasive ventilation
  • Conversion of simple pneumothorax to tension pneumothorax
• Risk factors for pneumothorax include:

  • Smoking
  • Tall and thin build
  • Male sex
  • Young age (in primary pneumothorax)
• A small pneumothorax may be asymptomatic.

  Typical symptoms of pneumothorax include:

  • Ipsilateral pleuritic chest pain
  • Dyspnoea
  • Cough
• Other important areas to cover in the history include:

  • Recent trauma to the chest wall
  • Smoking history: quantify in pack-years (1 pack-year equates to smoking 20 cigarettes a day for a whole year)
  • Family history of pneumothorax
• Typical clinical findings in pneumothorax include (on the same side as the pneumothorax):

  • Hyper-resonant lung percussion
  • Reduced breath sounds
  • Reduced lung expansion
• In addition, typical clinical findings in tension pneumothorax include:

  • Tracheal deviation away from the pneumothorax
  • Severe tachycardia
  • Hypotension
• Investigations for pneumothorax:

  • FBC in trauma patients
  • ABG
  • Pulse oximetry
  • Lung ultrasound in trauma patients - absence of lung sliding sound
  • CXR - rim between lung margin and chest wall
  • Margin >2cm is a large pneumothorax
  • CT chest - may be used to identify small pneumothoraces missed by chest X-ray, can also help identify the cause of the pneumothorax
• Management of a tension pneumothorax is emergency decompression with a large bore cannula and then chest drain insertion
• Management of primary pneumothorax:

  • > 2 cm or SOB - aspirate
  • Can be discharged if successful and repeat CXR in 2-4 weeks
  • Chest drain if unsuccessful
• Management of secondary pneumothorax:

  • 1-2 cm margin - aspirate
  • > 2 cm or SOB - chest drain
  • Admit and observe
  • High flow oxygen (caution in COPD)
• patients should not fly until full resolution of pneumothorax
• A pneumothorax is a collection of air inside the pleural space, which is the space between the lungs and chest wall 
• Types:

  • Primary = no known respiratory disease
  • Secondary = pre-existing respiratory disease
  • Patients >50 years old and those with a significant smoking history are more likely to develop a secondary pneumothorax
  • Tension = severe pneumothorax involving the displacement of mediastinal structures and haemodynamic compromise
• Causes of primary pneumothorax:

  • Often unknown
  • May be due to rupture of a subpleural air bled (found in the pleural space) - the bleb itself is caused by alveolar rupture, which lets air travel through the interlobular septum into the subpleural space
• Pathophysiology:

  • The alveolar and atmospheric pressures are greater than the intrapleural pressure
  • Connections between the alveoli and pleural space, or surrounding atmosphere and pleural space, will lead to air moving down a pressure gradient into the pleural space
  • This increases the intrapleural pressure, potentially compressing the lungs
• Tension pneumothorax pathophysiology:

  • Air enters the pleural space through a one-way valve and is therefore unable to leave the pleural space
  • The intrapleural pressure exceeds the atmospheric pressure, leading the collapse of the ipsilateral lung and a shift of the mediastinum away from the pneumothorax
  • In severe cases, the increased intrapleural pressure can compress the heart and surrounding vasculature, reducing cardiac output and venous return
  • If left untreated can lead to cardiac arrest
• Disease related complications:

  • Respiratory failure
  • Cardiac arrest (tension)
  • Pneumopericardium (air in the pericardial space)
• Treatment related complications:

  • Pain
  • Re-expansion pulmonary oedema - typically occurs after drainage of large pneumothorax. Rapid re-expansion of a previously collapsed lung can lead to increased permeability of pulmonary vessels. Leads to fluid moving into the lung parenchyma.
  • Subcutaneous emphysema - when chest drain is inserted into the subcutaneous tissue, rather than the pleural space