Tension Pneumothorax: Introduction

The incidence of tension pneumothoraces resulting from primary and secondary spontaneous pneumothoraces is unknown, but many case reports have been published, exceeding reports of those associated with trauma. However, it is likely that the latter are significantly under-reported.

Traditional teaching has described a tension pneumothorax as an expanding pneumothorax resulting from a one-way valve effect of a pleural breach, which results in hyper-resonance on the affected side, mediastinal shift (deviated trachea) and reduced cardiac output (hypotension) secondary to kinking of the great vessels. The risk of death whilst awaiting a chest radiograph has been considered so high that decompression with a cannula (2nd intercostal space in the mid-clavicular line) has been advocated if the diagnosis is even considered and a radiograph demonstrating a tension pneumothorax is one that ‘should not have been done’.

Leigh-Smith and Harris have challenged the historically taught classical presentation and management of a tension pneumothorax [19]. Chest pain, respiratory distress, tachycardia and reduced air entry on the side of the tension pneumothorax are commonly present. Conversely, tracheal deviation, hypotension, neck vein distension and hyper-resonance are the exception rather than the rule (<25% cases) and when present represent the more extreme end of the spectrum associated with imminent arrest [20]. In spontaneous tension pneumothoraces, respiratory arrest from hypoxia usually precedes cardiac arrest [19].

Fig 1: The never event – a chest radiograph demonstrating a tension pneumothorax

Learning bite

Less than 25% of cases will have the ‘classical features’ of neck vein distension, tracheal deviation, hyper-resonance and cardiovascular instability.