Assessment of pulmonary mechanics and breathing patterns during posturally induced glossoptosis in infants.

Respiratory mechanics were studied in nine infants with glossoptosis-apnoea syndrome to determine whether glossoptosis may account for signs of both inspiratory and expiratory airway obstruction. Airflow, oesophageal pressure, inspiratory and expiratory time (Ti and Te), and inspiratory and expiratory resistance (Ri and Re) were measured before and during ventilatory phases characterised by glossoptotic pharyngeal obstruction, induced by turning the infants onto their backs. In addition, an attempt was made to correlate the abnormalities in pulmonary mechanics with the clinical features. During partial glossoptotic pharyngeal obstruction, a significant increase was observed in Te and Re and variable changes in Ti and Ri. During severe obstruction, the infants displayed obstructed inspiratory efforts often associated with stridor, as well as obstructed expiratory efforts often associated with audible grunting and retarded expiratory flow pattern. The expiratory grunt was loudest over the neck and mimicked bronchospasm over the chest. These findings indicate that glossoptotic pharyngeal obstruction induces functional airway obstruction which may affect both inspiration and expiration. Expiratory airway obstruction seems, at least in part, to be due to active braking of expiratory flow.