Tension pneumothorax is a medical emergency and defined as the presence of a pneumothorax AND hemodynamic compromise.

This intubated ICU patient developed spontaneous pneumothorax and was presumed to be iatrogenic due to high-pressure ventilation.  The left central venous catheter has been in place for several days without any complications and was not likely the cause of the pneumothorax.

A rough guideline for communicating the size of the pneumothorax to the clinician is based on the maximal pleural separation from the chest wall: small (< 2 cm) vs large (>2 cm) ¹.