Pharyngeal Distension Associated with Upper Airway Obstruction

In children with upper airway obstruction, the pharynx becomes distended during inspiration, while the trachea below the obstruction tends to narrow. The mechanism responsible for this phenomenon was studied, utilizing anesthetized adult dogs and puppies. The pharyngeal pressure remained nearly atmospheric during inspiration above the obstruction and the pressure in the trachea below the obstruction became markedly negative. In upper airway obstruction, the pharynx was overdistended during inspiration only when the dogs were lightly anesthetized. This suggests that pharyngeal distension may represent an attempt to reduce upper airway contribution to total airway resistance.