The neonatologist must maintain a balance between the ventilatory needs of the infant and the complications that can result from positive pressure ventilation. The lung volumes on the daily neonatal CXR are used as a guide to determine the ventilator settings. If the compliance of the lungs is too low, or the mean airway pressure is too high, barotrauma will result. The signs of barotrauma should be identified on the neonatal CXR. Pneumothorax has already been discussed.

Pulmonary interstitial emphysema (PIE) results from rupture of the alveoli with air accumulating in the peribronchial and perivascular spaces. PIE is recognized by linear lucencies radiating from the hilum. However, PIE can also be cystic in appearance, which can be difficult to distinguish from chronic lung disease. Correlation with the clinical course is helpful as PIE occurs early and is associated with high ventilatory settings, and chronic lung disease occurs later in the hospital course with lower ventilatory settings. PIE is an ominous sign because it indicates the poor compliance of the lungs and is frequently followed by a pneumothorax. In addition to adjusting the ventilatory settings as much as tolerated, it is helpful to put the most affected side down.