Laryngomalacia, tracheomalacia and vocal-cord dysfunction: Viva

Branch 1: Recognising the pattern that is not asthma

The candidate should immediately question the asthma label. A barking, seal-like cough with an expiratory wheeze that does not respond to a bronchodilator, and that may worsen after the reliever, is the classic picture of tracheomalacia rather than asthma. The history of repaired oesophageal atresia and tracheo-oesophageal fistula is the crucial clue, because these children have a structurally soft trachea from the shared foregut origin of the trachea and oesophagus. The recurrent chest infections fit a trachea that clears secretions poorly. ^[3]

The candidate should explain the localising principle: this is expiratory, intrathoracic noise, which points to the trachea, whereas asthma is small-airway disease that responds to bronchodilator. The mechanism of the salbutamol trap is that the drug relaxes airway smooth muscle and reduces the residual tone splinting the soft trachea open, so it can worsen the collapse. ^[1]