Tracheomalacia

Tracheomalacia is excessive dynamic narrowing of the trachea because its supporting structure is too soft or its posterior membranous wall is too lax. The normal trachea contains approximately 16 to 20 incomplete, U-shaped hyaline cartilage rings that remain open posteriorly. When the cartilage loses rigidity, or the pars membranacea bows excessively into the lumen, the airway can narrow when pressure outside the trachea exceeds pressure inside it. That pressure difference is greatest during expiration, coughing, crying, straining, feeding, and exertion. The airway may look reasonably open at rest and then collapse when the child cries or tries to cough secretions upward. If the main bronchi are affected as well, the condition is called tracheobronchomalacia. In children, disease may be primary, caused by congenital immaturity or deficiency of the cartilage, or secondary to another process. Important secondary causes include prolonged intubation, tracheostomy-related injury, chronic inflammation, trauma, and external compression. An aberrant innominate artery is a common compressive cause; other possibilities include a double aortic arch, pulmonary artery sling, goitre, or mediastinal mass. Tracheomalacia is particularly associated with oesophageal atresia and tracheo-oesophageal...