In this case these appearances are typical of barotrauma. Barotrauma occurs between 4 and 15% of all patients undergoing mechanical ventilation.

Pulmonary barotrauma is the alveolar rupture due to the use of positive pressure. Clinical manifestations of barotrauma are multiple interstitial emphysema, pneumothorax, pneumomediastinum, subcutaneous emphysema, pneumoperitoneum, tension lung cysts and subpleural air cysts. As noted, all these forms of barotrauma are developed by a ruptured alveolus, overdistended with penetration of air into the perivascular interstitium  or interstitial emphysema.