10th January 2024

Presentation

The classical presentation of a spontaneous pneumothorax is sudden-onset ipsilateral pleuritic chest pain, associated shortness of breath and hypoxia. However, these symptoms in PSP can be relatively minor, so patients may not present at the exact time of onset. Patients who have underlying lung disease are typically more symptomatic, with dyspnoea the most commonly reported symptom due to the already damaged underlying lung parenchyma. This can result in patients with SSP reporting symptoms out of proportion to the size of pneumothorax identified on diagnostic imaging (see diagnosis).

An important clinical distinction to make is between the ‘simple’ spontaneous pneumothorax and the tension pneumothorax. Tension pneumothoraces are medical emergencies that are more commonly seen among the most unwell patients: in major trauma, in the critical care environment, but they can also be seen in the medical on-call take environment. The typical symptoms of simple pneumothorax are present (dyspnoea, chest pain), but these are more frequently accompanied by respiratory distress, with or without cardiovascular collapse. Tension pneumothorax is also an important reversible cause of respiratory and cardiac arrest with prompt treatment (see management).

Signs

Simple spontaneous pneumothorax (primary or secondary) 

In the very small pneumothorax, there may be little to no clinical findings to appreciate on examination. When a larger pneumothorax has developed, clinical findings that can be elicited include:

• Asymmetrical chest expansion. Due to air building up within the pleural space, the lung itself becomes gradually more compressed. This results in reduced lung expansion on inspiration on the affected side.
• Hyper-resonant percussion.
• Diminished breath sounds.
• Central trachea. 
• Evidence of respiratory distress. This includes high respiratory rate, use of accessory muscles of respiration and hypoxia. Patients who have secondary spontaneous pneumothoraces are more likely to present in this way.

Tension pneumothorax 

A tension pneumothorax is an uncommon clinical condition but should ideally undergo diagnosis based on clinical history and examination. Prompt recognition and treatment of the below features can result in rapid resolution of respiratory distress and dramatic clinical improvement for patients.

• Asymmetrical chest expansion. 
• Hyper-resonant percussion.
• Diminished breath sounds.
• Tracheal deviation away from the side of the above clinical findings. 
• Hypotension and tachycardia – suggestive of impending cardiovascular collapse.
• Respiratory distress.