Tracheobronchomegaly
Exposure to positive pressure ventilation results in deformation of the trachea related to airway barotrauma.(40) Although the precise mechanism is unknown, airway barotrauma may result in disruption of the muscle-cartilage junction, alterations in the arrangement in the fibers of the airway cartilage and smooth muscle, or thinning of the airway cartilage.(41) The deformation of the airway predisposes pre-mature animals to developing tracheomegaly.(42) Similarly, exposure to invasive positive pressure ventilation in extremely pre-term infant results in increased tracheal diameter and volume. Though the degree of tracheomegaly is typically fairly mild, cases may be extreme (Fig. 2A-C). Further, the tracheal enlargement appears correlated with the duration of exposure to positive pressure and persists even after extubation. (43) Currently, the impact of tracheomegaly on outcomes in BPD is entirely unknown; however, a greater tracheal volume increases anatomic dead space and could impair gas exchange. Similarly, there are no current treatment options targeted at treatment of tracheomegaly.