ABSTRACT
Pulmonary air leaks include urgent life-threatening neonatal emergencies like pulmonary interstitial emphysema, pneumomediastinum, pneumothorax or pneumopericardium.1 The incidence of pulmonary air leaks in the neonates has increased in recent years, possibly because an increasing number of sick infants with respiratory distress on assisted ventilation are now surviving to develop this complication.2 The sequence of events in the occurrence of pulmonary air leaks is similar regardless of whether it is caused by uneven alveolar ventilation, air trapping and high transpulmonary pressure swings. The rupture of terminal air sacs causes air to escape into the pulmonary interstitium, resulting in pulmonary interstitial emphysema. The air tracks along the sheaths of pulmonary blood vessels to the lung hilum and air may then rupture into mediastinum, pleura or pericardium.3 It has also been suggested that air directly enters the pleural cavity following a rupture of a subpleural bleb.4 Rarely systemic air embolism may be a terminal event of pulmonary air leaks.5,6
Pulmonary interstitial emphysema (PIE) is predominantly seen in preterm infants with respiratory distress syndrome (RDS) who are on assisted ventilation.1
Occasionally it follows vigorous resuscitative efforts. The lesion represents air that has dissected along perivascular sheath within pulmonary interstitium. The compression caused by interstitial ‘airconduits’ interferes with ventilation and reduces pulmonary perfusion leading to CO2 retention and hypoxemia.
