Computational Fluid Dynamics and Dynamic 3D Morphological Study of Upper Airway in Obstructive Sleep Apnea

Background and Purpose Obstructive sleep apnea (OSA) is a common sleep disorder of adults and children, which is characterized by repetitive transient reversible upper airway obstructions during sleep. This sleep disorder would result in excessive daytime sleepiness, fatigue and increase the possibility of cardiovascular disorders. OSA was mainly diagnosed by polysomnography (PSG), ENT inspections and lateral cephalometry X-ray film. But these examinations cannot describe 3D morphological change of the whole upper airway. 3D CT imaging technique rather provides the possibility to demonstrate the whole information the upper airway. According to the published literatures and our previous investigation (NMRP160281), the static 3D image of upper airway by CT scan and the functional study provided by computing fluid dynamics (CFD) simulation showed the relationship between clinical severity and characteristics of upper airway geometry. To improve the simulation of CFD for better physiological similarity, more parameters are required, i.e. compliance of conduit wall (upper airway) and individualized flow change during tidal volume. The purpose of this study is to reconstruct serial upper airway surface meshes by dynamic CT scanning of upper airway synchronized with monitored respiratory tidal volume during scanning. This series of upper airway meshes can demonstrate the change of upper airway wall during respiration and utilized to study the compliance of upper airway and the relationship with tidal volume. The reality of CFD simulation can be consequently improved and the clinical application can be promoted. Material and Methods This study will collect both normal participants (excluding respiratory disorders, craniofacial deformities and no episodes of sleep breathing disorder diagnosed with PSG) and OSA as control and study groups. Participants would have dynamic CT scanning of head and neck region to obtain the required serial upper respiratory images. During scanning, physiological data of tidal volumes would be recorded by respiratory monitor with respiratory mask. These CT images would be synchronized with the phases of tidal volumes to calculate the compliance and change of upper airway during respiration. Serial 3D surface mesh of corresponding CT images would be reconstructed by 3D visualization software. These surface meshes could be transformed to be proper mesh for CFD simulation. Anticipated Accomplishment and Results 1. Thirty OSA patients and ten normal participants are planned to be collected in this study. 2. We hope to build a CFD mesh model of upper airway capable to be applied on both clinical and basic research. 3. Characteristic of upper airway between normal control and study groups can be compared for understanding of the pathophysiology of OSAs. 4. We hope to establish a medical image tool for both diagnosis and treatment purposes.

Project ID:PC9902-1670
External Project ID:NSC98-2314-B182-016-MY2