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.