(1319) The Overall Morphological Change of Pharyngeal Lumen Might Predict the Outcomes of Oral Appliance

Introduction: This study aims to analyze the power losses change of pharyngeal airflow after using oral appliance (OA) in OSAHS patients with different overall pharyngeal morphological characteristic by computational fluid dynamic (CFD) analysis. The power losses of pharyngeal airflow can be mainly attributed to the effect of frictions at the pharyngeal wall, the internal fluctuations of the pharyngeal airflow and the dissipation of turbulence.

Methods: 18 OSAHS patients are enrolled. Computed tomography (CT) scans under two conditions (with and without OA) are acquired. Upper airway surface models are constructed and are rendered for CFD simulation.

Results: There are four overall pharyngeal morphological characteristics: hourglass, overall constriction, long constrict neck and funnel type. For patients with an overall hourglass-shaped pharyngeal lumen(n=7), the power losses of pharyngeal airflow after using OA decreased significantly (p < 0.05). The improved minimum cross-sectional area (Amin) pharyngeal lumen led to the slower flow rate and lower frictional losses. For patients with overall constriction, long constrict neck and funnel type pharyngeal lumen(n=11), the power losses of pharyngeal airflow after using OA increased significantly (p < 0.05). For these patients, tongue retrodisplacement and unchanged Amin both contributed to the higher flow turbulence and frictional losses.

Conclusions: CFD analyses indicated the overall pharyngeal morphological features was important factors for predicting the outcomes of OA.