Effects of oral cavity appliance on pharyngeal cavity airflow dynamics and deformations of upper airway wall in patients with OSAHS

ZHANG Yu; LI Yongming; AN Zhibin

doi:10.3969/j.issn.1002-7386.2017.19.008

Abstract：Objective To establish pharyngeal cavity fluid-structure interaction finite element models with or without oral appliance (OA) by means of three-dimensional reconstruction software to analyze the changes of pharyngeal cavity airflow dynamics and upper airway wall by using fluid structure interaction method in patients with obstructive sleep apnea hypopnea syndrome (OSAHS),and to explore the action mechanism of OA in treatment of OSAHS.Methods The changes of upper airway and surrounding tissues in an adult patient with moderate OSAHS before wearing OA and on 3 months after wearing OA were examined by MRI.The DICOM format images were imported into 3D reconstruction software-Mimics 15.0,NX 8.5,Geomagic Studio 10.0.Mimics 15.0 software to reconstruct the model of upper airway and soft palate,then to establish the pharyngeal cavity and upper airway wall fluid-structure interaction (FSI) finite element models by using ANSYS Workbench 13.0 software,finally the FSI finite element model was imported into the software ANSYS-CFD to carry out FSI numerical calculation.Results After wearing OA,FSI numerical calculation results showed that at the peak of inspiration, the maximum airflow velocity in the area of palate and pharynx was decreased from 9.677m/s to 7.020m/s,and the maximum negative pressure was reduced from-64.18Pa to-37.88Pa,moreover, the maximum deformation degree in upper airway wall was decreased from 0.629mm to 0.244mm.At the peak of expiration,the maximum airflow velocity in the area of palate and pharynx was decreased from 10.44m/s to 7.441m/s,the maximum negative pressure was reduced from-36.25Pa to-23.79Pa,and the maximum deformation degree in upper airway wall was decreased from 0.648mm to 0.310mm.Conclusion After wearing OA in patients with OSAHS,at the peak of inspiration and expiration,the negative pressure and deformation degree in upper airway are decreased, so that the pharyngeal cavity is less prone to collapse,thereby,which can relieve the symptoms of snoring and apnea of patients.