Tension Pneumothorax: Management
In view of the fact that clinical signs may differ little from a pneumothorax that is not under tension, it is recommended that stable patients in the ED should have urgent chest radiographs performed in the resuscitation room rather than undergoing ‘blind emergency needle decompression’, which is not without complication.
Mediastinal shift may be seen in severe cases, but the most common radiological feature found with tension pneumothoraces is widened rib spaces and a flattened hemi-diaphragm on the affected side. Leigh-Smith and Harris have proposed the following criteria for when decompression of a suspected pneumothorax should be performed before an urgent radiograph [19].
- SpO2< 92% on O2
- Systolic BP< 90 mmHg
- Respiratory rate <10
- Decreased level of consciousness on O2
- Cardiac arrest
Finally, the potentially catastrophic belief that the ‘absence of a hiss’ on needle decompression rules out a tension pneumothorax has been categorically shown to be false. Although presence of a hiss and clinical improvement almost certainly confirms the diagnosis, the absence of a hiss may be due to the cannula being too short, kinked or blocked. Studies on trauma patients (though not directly comparable) have found that a 14g cannula placed in the second intercostal space would be too short to penetrate the parietal pleura in up to one-third of patients. This method can be quick and effective but failure of decompression in a peri-arrest patient should be followed by creating an open thoracostomy in the 5th intercostal space.
Learning bite
‘Absence of a hiss’ does not exclude a tension pneumothorax. The cannula may be too short, kinked or blocked.