Pulmonary interstitial emphysema

Pulmonary interstitial emphysema (PIE) is a collection of air outside of the normal air passages in the body and instead is found inside the connective tissue of the peribronchovascular sheaths, interlobular septa, and visceral pleura. (This supportive tissue is called the pulmonary interstitium.) This collection of air, develops as a result of alveolar and terminal bronchiolar rupture. Pulmonary interstitial emphysema is more frequent in premature infants who require mechanical ventilation for severe lung disease. Infants suffering from pulmonary interstitial emphysema are typically recommended for admission to a neonatal intensive care unit.