Tracheomalacia

Excerpt

The term tracheomalacia indicates a condition characterized by a structural abnormality of the tracheal cartilage inducing excessive collapsibility of the trachea. It constitutes about half of the congenital pathologies of the trachea and is distinguished in diffuse and localized varieties depending on the extent of the disease. The distinction also concerns the primary forms due to an alteration of the development of the trachea and the secondary conditions produced by causes that act after the normal development of the organ. The primary forms can be diffuse or localized; the secondary ones are generally localized.

Primary diffuse tracheomalacia is a rare congenital defect characterized by the immaturity of the cartilaginous rings (usually involving the distal third of the trachea), which leads to a weakness of the entire tracheal structure. It is more frequent in premature babies and can be associated with laryngomalacia or affect the trachea and other respiratory tracts. When the main bronchi are also affected, this condition is termed tracheobronchomalacia. Congenital tracheomalacia can combine with other congenital defects (e.g., cardiac defects), tracheoesophageal fistula, developmental delay, and gastroesophageal reflux (GER). Some conditions, such as vascular rings, can produce a localized primary defect in the development of the trachea.

The secondary forms are acquired conditions that induce a weakening of the tracheal wall. These conditions can be ascribable to inflammatory processes that produce diffuse tracheomalacia, although these secondary forms are also the result of external compressions due to cardiovascular structures or other masses which produce localized areas of weakness of the tracheal wall.

In pathophysiological terms, the structural alterations of the trachea alter its mechanics. As by Poiseuille Law, even a small amount of narrowing in the lumen of the trachea can cause a significant decrease in airflow. Depending on the causative pathology (primary or secondary tracheomalacia and underlying diseases), patients’ symptoms may spontaneously resolve over the natural history of the disease or can cause persistent respiratory distress.