Classification and diagnosis of pneumothorax

Pneumothorax is the presence of air between the parietal and visceral pleura, and is classified as:

• spontaneous pneumothorax, which occurs without a precipitating external event and can be subdivided into
  • primary—no evidence of underlying lung disease
  • secondary—lung disease is present (most commonly chronic obstructive pulmonary disease [COPD], but also asthma, interstitial lung disease or cystic fibrosis)
• traumatic pneumothorax, which is caused by blunt or penetrating thoracic trauma. Iatrogenic pneumothorax is a traumatic pneumothorax induced by a medical procedure.

Spontaneous pneumothorax usually presents with sudden onset of pleuritic chest pain and breathlessness, and is diagnosed primarily on history and inspiratory chest X-ray. Expiratory chest X-ray is not recommended because it may exaggerate the size of pneumothorax. Computed tomography (CT) scan may be required for patients unable to sit upright because pneumothorax may be difficult to see on chest X-ray taken in the supine position. CT scan may also be required for patients with coexisting lung disease.

Specific chest signs depend on the size of the pneumothorax and may be difficult to detect. In a large pneumothorax, physical signs include absent breath sounds, tachypnoea, decreased chest wall movement, hyperresonance to percussion, decreased vocal resonance and tracheal deviation to the opposite side.