Retropalatal and retroglossal airway compliance in patients with obstructive sleep apnea.

Highlights • Retropalatal luminal area is smaller than retroglossal area at end-expiration. • Retropalatal airway is more dynamically-compliant than retroglossal airway. • Negative effort dependence is associated with inspiratory retropalatal narrowing. Abstract Objectives We hypothesized that preferential retropalatal as compared to retroglossal collapse in patients with obstructive sleep apnea was due to a narrower retropalatal area and a higher retropalatal compliance. Patients with a greater retropalatal compliance would exhibit a recognizable increase in negative effort dependence (NED). Methods Fourteen patients underwent upper airway endoscopy with simultaneous recordings of airflow and pharyngeal pressure during natural sleep. Airway areas were obtained by manually outlining the lumen. Compliance was calculated by the change of airway area from end-expiration to a pressure swing of −5 cm H 2 O. NED was quantified for each breath as [peak inspiratory flow minus flow at −5 cm H 2 O]/[peak flow] × 100. Results Compared to the retroglossal airway, the retropalatal airway was smaller at end-expiration (p < 0.001), and had greater absolute and relative compliances (p < 0.001). NED was positively associated with retropalatal relative area change (r = 0.47; p < 0.001). Conclusions Retropalatal airway is narrower and more collapsible than retroglossal airway. Retropalatal compliance is reflected in the clinically-available NED value. [ABSTRACT FROM AUTHOR]