What is the primary cause of pneumopericardium in infants?

Mechanical ventilation is identified as the primary cause of pneumopericardium in infants because it can lead to increased pressure and air entry into the pericardial space. When infants are placed on mechanical ventilation, particularly with high airway pressures or using positive pressure ventilation, the risk of air leaks is heightened. These leaks can occur from the alveoli or the tracheobronchial tree, allowing air to escape into adjacent structures, including the pericardial space, resulting in pneumopericardium.

Other factors such as spontaneous lung collapse, congenital heart defects, and external trauma can contribute to pneumopericardium, but they are less common in comparison to the significant impact that mechanical ventilation has in clinical settings for infants.