FRCA Notes

Pneumothorax

The curriculum asks us to know the 'causes, symptoms and signs of a pneumothorax and explain the principles of its management'.

Resources

  • Pneumothorax describes air in the pleural space
  • Air within the pleural space can occur due to:
    • An abnormal communication between the tracheobronchial tree or alveolar space, and pleura
    • An abnormal communication between the atmosphere and pleura
    • The presence of gas-forming organisms within the pleural space
  • Hospital admission rate 14 per 100,000/yr
  • Spontaneous
    • Primary - i.e. in patients without underlying lung pathology
      • Classically occurs in young, thin and tall male patients

    • Secondary - i.e. patients have existing lung disease such as:
      • Airways disease e.g. COPD | acute severe asthma | CF
      • Infection e.g. PJP | TB
      • Connective tissue disease e.g. Marfan's syndrome | Ehlers-Danlos syndrome
      • Lung cancer
      • Patients who are >50yrs and have a smoking history without definitive diagnosis of lung disease

  • Traumatic

  • Iatrogenic
    • Subclavian or internal jugular CVC insertion
    • Brachial plexus regional anaesthesia
    • Thoracocentesis
    • Trans-bronchial or pleural biopsy
    • Trans-thoracic needle aspiration of pleural effusion
    • Use of positive pressure ventilation and barotrauma e.g. in those with ARDS

  • ± Tension

Spontaneous pneumothorax

  • Sub-pleural bullae are responsible for spontaneous pneumothoraces, found in the majority of cases during VATS for pneumothoraces including those who are non-smokers
  • The mechanism of bulla formation is unclear
    • In smokers it probably represents smoking-related, immune-mediated degradation of elastic fibres in the lung
    • The degradation causes an imbalance in the protease–antiprotease and oxidant–antioxidant systems
  • Inflammation-induced obstruction of the small airways from lung disease increases alveolar pressure, resulting in an air leak into the lung interstitium
  • There is consequent pnuemomediastinum at the hilum and, when mediastinal pressure increases enough to rupture the mediastinal pleura, pneumothorax occurs

Pneumothorax due to PPV

  • Mechanical ventilation in patients with reduced lung compliance can cause barotrauma
  • When there is a significant enough pressure gradient between the alveoli and the interstitium, alveolar rupture occurs
  • This leads to air entering the intersitium i.e. perivascular interstitial emphysema, and subsequent pneumomediastinum as above
  • This is more common in non-dependent areas of the lung

Awake patient

  • Sudden onset clinical features
  • Pleuritic chest pain
  • Dyspnoea
  • Hypoxaemia
  • Reduced chest wall movement
  • Hyper-resonant percussion and reduced air entry over the affected area
  • Tracheal deviation

Anaesthetised patient

  • Raised ventilatory pressures
  • Reduced tidal volumes being delivered
  • Reduced lung compliance

  • Hypoxia
  • Tachycardia
  • Reduced chest wall movement
  • Hyper-resonant percussion and reduced air entry over the affected area

  • Signs of tension pneumothorax:
    • Hypotension due to obstructive shock
    • Tachycardia
    • Raised CVP

  • Small, non-symptomatic, non-tension pneumothoraces may be observed if it is felt the benefit of chest drain insertion is outweighed by the risks associated with doing so

  • Otherwise:
    • Emergent needle thoracocentesis of patients with suspected/confirmed pneumothorax

    • Chest drain insertion in the 'safe triangle' (or rarely anteriorly), and attachment to a closed underwater sealing system

  • This area is probably more under the remit of Emergency Department and Respiratory colleagues, and is somewhat governed by the above-linked BTS guidelines

  • Conservatively manage if:
    • Asymptomatic
    • Minimal symptoms (no significant pain or breathlessness and no physiological compromise)
  • This includes observation and safety-netting
  • Inspiring high concentrations of oxygen may speed up the resolution of a pneumothorax by denitrogenating the pulmonary capillaries, increased the pressure gradient from the pleural space to the capillaries

  • Treat patients who need intervention with either:
    • Ambulatory management e.g. one-way valve or Heimlich valve attached to a chest drain
    • Needle aspiration or chest drain

  • Recurrence occurs in 32% of primary and 13-39% of secondary pnuemothoraces
  • Prevent recurrence with either chemical pleurodesis or thoracic surgery in patients with:
    • Recurrent secondary spontaneous pneumothorax
    • An initial presentation of tension pneumothorax, or those in high-risk occupations