pediatrics
Pulmonary Air Leak Syndromes
Pulmonary Interstitial Emphysema (PIE)
Pulmonary interstitial emphysema is leakage of air from alveoli into the pulmonary interstitium, lymphatics, or subpleural space. It usually occurs in infants with poor lung compliance, such as those with Respiratory Distress Syndrome in Neonates who are being treated with mechanical ventilation, but it may occur spontaneously. One or both lungs may be involved, and pathology may be focal or generalized within each lung. If dissection of air is widespread, respiratory status may acutely worsen because lung compliance suddenly is reduced. Chest x-ray shows a variable number of cystic or linear lucencies in the lung fields. Some lucencies are elongated; others appear as enlarged subpleural cysts ranging from a few millimeters to several centimeters in diameter. This air-leak syndrome may resolve dramatically over 1 or 2 days or persist on x-ray for weeks. Some infants with severe respiratory disease and pulmonary interstitial emphysema develop Bronchopulmonary Dysplasia (BPD) (BPD), and the cystic changes of long-standing pulmonary interstitial emphysema then merge into the x-ray picture of BPD. Treatment of pulmonary interstitial emphysema is mainly supportive. For Mechanical Ventilation , lowering tidal volume and airway pressure by switching to a high-frequency oscillatory ventilator or high-frequency jet ventilator may help. If one lung is significantly more involved than the other, the infant may be laid down on the side of the lung with the more severe pulmonary interstitial emphysema; this will help to compress the lung with pulmonary interstitial emphysema, thereby decreasing air leakage and perhaps improving ventilation of the normal (elevated) lung. If one lung is very severely affected and the other is mildly affected or uninvolved, differential bronchial intubation and ventilation of the less-involved lung also may be attempted. However, it can be technically challenging to selectively intubate the left main bronchus; total atelectasis of the nonintubated lung soon results. Because only one lung is now being ventilated, ventilator settings and fraction of inspired oxygen (FIO2) may need to be altered. After 24 to 48 hours, the endotracheal tube is pulled back into the trachea, at which time the air leak may have stopped. 