Pulmonary Interstitial Emphysema (PIE)

Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed

Etiology/Pathophysiology:
Complication of mechanical ventilation in neonates with respiratory distress. The interstitial air collects as a multitude of small distinct bubbles of extra-alveolar air causing increased lung volume and acting as a pulmonary splint to stiffen the lung leading to compromise of pulmonary ventilation and vascular perfusion (air block). If high pressure ventilation continues, the bubbles of interstitial air coalesce, further worsening the air block. PIE is almost always a precursor to progressive air leak and tension pneumothorax.

Pathology:
Air in the pulmonary interstitium.

Imaging Findings:
Usually unilateral hyperinflation, that causes mediastinal shift. Small distinct cyst like lucencies that may be round, linear or oval are distributed uniformly in the affected area of lung and persist throughout the respiratory cycle. The increased lung volume is evidenced by flattening of the diaphragm and increased transverse and AP chest diameters. Pneumomediastinum and pneumothorax are frequently seen complications.

DDX:

• Air in distended small airways and alveoli - branching pattern of air that disappears during expiration.
• Bronchopulmonary dysplasis - this is usually seen in patients who are greater than 3 weeks old, whereas PIE is usually seen within the first 2 weeks of life.

References:
See References Chapter.

Section Top | Title Page

URL: http://www.virtualpediatrichospital.org/