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Research Papers: Flows in Complex Systems

Pharyngeal Airflow Analysis in Obstructive Sleep Apnea Patients Pre- and Post-Maxillomandibular Advancement Surgery

[+] Author and Article Information
John Huynh

Graduate Orthodontic Program, Center for Advanced Dental Education, Saint Louis University, St. Louis, MO 63104jhuynh1@slu.edu

Ki Beom Kim

Graduate Orthodontic Program, Center for Advanced Dental Education, Saint Louis University, St. Louis, MO 63104kkim8@slu.edu

Mark McQuilling1

Department of Aerospace and Mechanical Engineering, and Center for Fluids at All Scales, Saint Louis University, 3450 Lindell Boulevard, St. Louis, MO 63103mmcquil2@slu.edu

1

Corresponding author.

J. Fluids Eng 131(9), 091101 (Aug 13, 2009) (10 pages) doi:10.1115/1.3192137 History: Received December 17, 2008; Revised June 27, 2009; Published August 13, 2009

The purpose of this study was to evaluate pharyngeal airflow in obstructive sleep apnea (OSA) patients following maxillomandibular advancement (MMA) surgery using computational fluid dynamics (CFD). Computerized models of four OSA patients, pre- and postsurgery, were created using cone beam computed tomography scans. CFD was used to model airflow at inspiration rates of 340 ml/s, 400 ml/s, and 460 ml/s. The relative pressure, eddy viscosity coefficient, and total area-averaged pressure drops were selected for comparison. Results show a decrease in airway resistance of over 90% for three out of four patients. In these three patients, the MMA surgery reduced the constriction along the airway, which resulted in reduced drag and therefore reduced pressure drop required to move a constant volumetric flow between pre- and postsurgery models. CFD analyses on airways of OSA patients provide data that suggest an improvement in airflow following MMA surgery with less effort required for maintaining constant flow.

Copyright © 2009 by American Society of Mechanical Engineers
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Figures

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Figure 1

3D skull depicting X, Y, and Z axes

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Figure 2

Landmarks used to determine surgical movement

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Figure 3

Typical superior and inferior borders of pharyngeal airway

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Figure 4

Outline of airway using IMAGEJ

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Figure 8

Change in hydraulic diameter along pharyngeal airway

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Figure 10

Reynolds number along pharyngeal airway of patient 2

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Figure 11

Reynolds number along pharyngeal airway of patient 3

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Figure 12

Reynolds number along pharyngeal airway of patient 4

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Figure 13

Eddy viscosity coefficient contour with streaklines

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Figure 14

Contour of eddy viscosity coefficient for patient 2 along midsagittal plane at T0. Three flow rates shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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Figure 15

Contour of eddy viscosity coefficient for patient 2 along midsagittal plane at T1. Three flow rates shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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Figure 16

Contour of eddy viscosity coefficient for patient 3 along midsagittal plane at T0. Three flow rates shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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Figure 5

PRO/ENGINEER model of the airway

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Figure 6

Typical CADTHRU models used for geometry cleanup. (a) Model after importing into CADTHRU . (b) Model with some surfaces removed in cleanup process.

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Figure 7

3D mesh model showing tetrahedral elements

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Figure 9

Reynolds number along pharyngeal airway of patient 1

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Figure 17

Contour of eddy viscosity coefficient for patient 3 along midsagittal plane at T1. Three flow rates shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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Figure 18

Contour of relative pressure (Pa) for patient 2 along midsagittal plane at T0. Three airflow speeds shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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Figure 19

Contour of relative pressure (Pa) for patient 2 along midsagittal plane at T1. Three airflow speeds shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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Figure 20

Contour of relative pressure (Pa) for patient 3 along midsagittal plane at T0. Three airflow speeds shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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Figure 21

Contour of relative pressure (Pa) for patient 3 along midsagittal plane at T1. Three airflow speeds shown: (a) 340 ml/s, (b) 400 ml/s, and (c) 460 ml/s.

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