The pharyngeal effect of partial nasal obstruction.

The case histroy and cinematoradiographic findings of a baby with partial nasal obstruction are presented. This infant's restriction to air entry at the nose led to severe airway obstruction during inspiration by a forward movement of the posterior pharyngeal wall and backward movement of the tongue and lower jaw. At the height of inspiration, there was total airway occlusion in the pharynx. These events can be explained by the pressure drop that takes place behind a restriction if air is sucked through it forcibly from an area of atmospheric pressure. Studies of postpalatal pressures in adults and infants demonstrate such a drop in pressure during nasal breathing if the nose is partly obstructed. If the adult or infant is able to respond to the diminished nasal airway by mouth breathing, there is no postpalatal pressure drop. It is suggested that partial nasal obstruction in a sleeping obligatory nasal-breathing infant could result in a sucking back of the tongue over the larynx in this "cafe coronary" type of situation. This could be the mechanism of the obstructive type of apnea recorded by Steinschneider, and of the asphyxial type of death that is suggested by autopsies on some "cot death" victims. This hypothesis is consistent with the frequency of infection of rhinitis and pharyngitis in victims of sudden infant death syndrome and with the seasonal incidence. Prevention of this obstructive type of apnea would depend on the recognition of infants showing inspiratory and expiratory changes in pharyngeal airway size as can be seen externally by the movements in the carotid triangle of the neck and confirmed by roentgenography or cinematoradiography.