Document Detail


Computational fluid dynamics modeling of the upper airway of children with obstructive sleep apnea syndrome in steady flow.
MedLine Citation:
PMID:  16098533     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Computational fluid dynamic (CFD) analysis was used to model the effect of airway geometry on internal pressure in the upper airway of three children with obstructive sleep apnea syndrome (OSAS), and three controls. Model geometry was reconstructed from magnetic resonance images obtained during quiet tidal breathing, meshed with an unstructured grid, and solved at normative peak resting flow. The unsteady Reynolds-averaged Navier-Stokes equations were solved with steady flow boundary conditions in inspiration and expiration, using a two-equation low-Reynolds number turbulence model. Model results were validated using an in-vitro scale model, unsteady flow simulation, and reported nasal resistance measurements in children. Pharynx pressure drop strongly correlated to airway area restriction. Inspiratory pressure drop was primarily proportional to the square of flow, consistent with pressure losses due to convective acceleration caused by area restriction. On inspiration, in OSAS pressure drop occurred primarily between the choanae and the region where the adenoids overlap the tonsils (overlap region) due to airway narrowing, rather than in the nasal passages; in controls the majority of pressure drop was in the nasal passages. On expiration, in OSAS the majority of pressure drop occurred between the oropharynx (posterior to the tongue) and overlap region, and local minimum pressure in the overlap region was near atmospheric due to pressure recovery in the anterior nasopharynx. The results suggest that pharyngeal airway shape in children with OSAS significantly affects internal pressure distribution compared to nasal resistance. The model may also help explain regional dynamic airway narrowing during expiration.
Authors:
Chun Xu; SangHun Sin; Joseph M McDonough; Jayaram K Udupa; Allon Guez; Raanan Arens; David M Wootton
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2005-08-10
Journal Detail:
Title:  Journal of biomechanics     Volume:  39     ISSN:  0021-9290     ISO Abbreviation:  J Biomech     Publication Date:  2006  
Date Detail:
Created Date:  2006-07-19     Completed Date:  2006-12-20     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2043-54     Citation Subset:  IM    
Affiliation:
Department of Mechanical Engineering and Mechanics, Drexel University, 3141 Chestnut St., STE 2-115, and Division of Pulmonary Medicine, Chidren's Hospital of Philadelphia, PA 19104, USA.
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MeSH Terms
Descriptor/Qualifier:
Biomechanics
Child
Child, Preschool
Computer Simulation*
Female
Humans
Male
Models, Biological*
Pressure
Respiratory System / physiopathology*
Rheology
Sleep Apnea, Obstructive / physiopathology*
Grant Support
ID/Acronym/Agency:
HL-62408/HL/NHLBI NIH HHS; M01-RR00240/RR/NCRR NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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