Normal tracheal cartilages are round, and because of this shape, they can withstand positive pressure forces without collapsing. In tracheomalacia, the tracheal rings are not shaped properly, and are usually flattened, making them very collapsible from positive pressure forces, like coughing or sneezing. Severe tracheomalacia in infancy can require a tracheostomy tube to keep the airway open, but this is rare. Symptoms from tracheomalacia generally improve as the child gets older, and even when it does require tracheostomy, this can usually be removed when the child is older.
There are surgeries that can be performed to improve this in very specific cases. Tracheomalacia is commonly found with other conditions, like tracheo-esophageal fistula or vascular compression of the trachea. Symptoms include barky cough, chronic cough, prolonged URI symptoms after a cold, and sometimes noisy breathing.