Tracheomalacia
Tracheomalacia represents a spectrum of disorders of the main trachea that lead to floppiness or collapse of the airway. When this occurs in the smaller airways it is called bronchomalacia. This defect can occur congenitally (from birth) or can be acquired by compression from structures outside of the airway such as an enlarged heart. Typically the cartilage support structure is weak and collapses during expiration or coughing. Often the non-rigid muscle in the posterior trachea can be weak and can also lead to airway floppiness.
Symptoms
The trachea is the main airway that connects nose and mouth to lungs. The orange arrow represents a camera looking down into the airways and can reveal the images below. Cartoon drawn by Breathing NYC team.
Symptoms can be very mild to severe. Symptoms can include noisy breathing, chronic or persistent coughing, high pitched breathing sounds, a rattling or wheezy noise with breathing or children can be completely asymptomatic. Symptoms typically worsen with respiratory infections and can often lead to a persistent cough after all other viral symptoms have resolved. In its most severe forms, secretions below the site of collapse can be retained and lead to respiratory infections including pneumonias.
Diagnosis
Diagnosis may include a chest radiograph or CT scan of the chest, but the gold standard for diagnosis is a flexible bronchoscopy where a camera is placed into the airway while your child is asleep. This is similar to a colonoscopy except with a different (much smaller) camera of course!
Cartoon view from a bronchoscope. Normal trachea (left) with widely patent airway supported by cartilage rings. The carina, where the right and left mainstem bronchi branch from the trachea is quite visible. Tracheomalacia (right) with floppy trachealis muscle and abnormal appearing cartilage support structures.
Normal trachea (left). Severe tracheomalacia (right) with near complete occlusion of the airway.
Why this occurs:
As we breathe in (blue arrows) our diaphragm (large muscle that separates the lungs from the abdominal contents) contracts and our chest inflates. This opens up the lungs as well as the airways. When we exhale, the diaphragm relaxes and the caliber of the airway subtly decreases in healthy children (A) but can significantly decrease with tracheomalacia due to a floppy posterior trachealis muscle (B) or a combination of a floppy posterior trachealis muscle and compression of the anterior trachea from a large vessel or other structure (C). One can appreciate how narrow the airway can get, particularly when we exhale forcefully as is the case when we cough.
Treatment
There are no great treatments for tracheomalacia. Often, the treatment is supportive, meaning we treat acute illnesses as they arise, however in the rare severe case, children may require non-invasive respiratory support (CPAP) or surgical interventions. An expert in the treatment of airway disorders should be consulted for the evaluation and treatment of tracheomalacia.