A pneumothorax may be spontaneous, secondary to trauma or iatrogenic (including central venous catheter insertion, surgery near the pleura) or from barotrauma form prolonged IPPV). A simple pneumothorax may cause little physiological impact, but with a tension pneumothorax the increase in pressure within the haemothorax causes mediastinal shift, reduced venous return and cardiac output, with impaired ventilation to the other lung.
Diagnosis is not always straightforward, but signs include cyanosis, wheeze, ‘silent’ chest on auscultation, difficulty with ventilation, high airway pressures, change in airway pressures, with tachycardia and hypotension.
Treatment, particularly for a tension pneumothorax, is to drain release the air from the pleura. In a life-threatening situation a 14 gauge cannula can be used. If less urgent, a formal chest drain is inserted connected to an underwater drainage system.
