Effect of the velopharynx on intraluminal pressures in reconstructed pharynges derived from individuals with and without sleep apnea.

The most collapsible part of the upper airway in the majority of individuals is the velopharynx which is the segment positioned behind the soft palate. As such it is an important morphological region for consideration in elucidating the pathogenesis of obstructive sleep apnea (OSA). This study compared steady flow properties during inspiration in the pharynges of nine male subjects with OSA and nine body-mass index (BMI)- and age-matched control male subjects without OSA. The k-ωSST turbulence model was used to simulate the flow field in subject-specific pharyngeal geometric models reconstructed from anatomical optical coherence tomography (aOCT) data. While analysis of the geometry of reconstructed pharynges revealed narrowing at velopharyngeal level in subjects with OSA, it was not possible to clearly distinguish them from subjects without OSA on the basis of pharyngeal size and shape alone. By contrast, flow simulations demonstrated that pressure fields within the narrowed airway segments were sensitive to small differences in geometry and could lead to significantly different intraluminal pressure characteristics between subjects. The ratio between velopharyngeal and total pharyngeal pressure drops emerged as a relevant flow-based criterion by which subjects with OSA could be differentiated from those without.

[1]  Tracie Barber,et al.  Computational fluid dynamics for the assessment of upper airway response to oral appliance treatment in obstructive sleep apnea. , 2013, Journal of biomechanics.

[2]  Yingxi Liu,et al.  Fluid–structure interaction modeling of upper airways before and after nasal surgery for obstructive sleep apnea , 2012, International journal for numerical methods in biomedical engineering.

[3]  A. Malhotra,et al.  Upper airway length may be associated with the severity of obstructive sleep apnea syndrome , 2008, Sleep and Breathing.

[4]  S. Isono,et al.  Obesity and obstructive sleep apnoea: Mechanisms for increased collapsibility of the passive pharyngeal airway , 2012, Respirology.

[5]  David C. Wilcox,et al.  Comparison of two-equation turbulence models for boundary layers with pressure gradient , 1993 .

[6]  Mihai Mihaescu,et al.  Large eddy simulation of the pharyngeal airflow associated with obstructive sleep apnea syndrome at pre and post-surgical treatment. , 2011, Journal of biomechanics.

[7]  Heow Pueh Lee,et al.  Passive movement of human soft palate during respiration: A simulation of 3D fluid/structure interaction. , 2012, Journal of biomechanics.

[8]  A I Pack,et al.  Upper airway and soft tissue anatomy in normal subjects and patients with sleep-disordered breathing. Significance of the lateral pharyngeal walls. , 1995, American journal of respiratory and critical care medicine.

[9]  Seung-Kyu Chung,et al.  The correlation between pharyngeal narrowing and the severity of sleep-disordered breathing , 2008, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[10]  Raanan Arens,et al.  Identification of upper airway anatomic risk factors for obstructive sleep apnea with volumetric magnetic resonance imaging. , 2003, American journal of respiratory and critical care medicine.

[11]  H. Driver,et al.  Effect of nasal or oral breathing route on upper airway resistance during sleep , 2003, European Respiratory Journal.

[12]  Zhongping Chen,et al.  High-speed upper-airway imaging using full-range optical coherence tomography , 2012, Journal of biomedical optics.

[13]  Shanmugam Murugappan,et al.  Large Eddy Simulation and Reynolds-Averaged Navier-Stokes modeling of flow in a realistic pharyngeal airway model: an investigation of obstructive sleep apnea. , 2008, Journal of biomechanics.

[14]  K. Narkiewicz,et al.  Obesity and Obstructive Sleep Apnoea , 2008, Manual of Hypertension of the European Society of Hypertension.

[15]  Anthony D. Lucey,et al.  Large-Amplitude Oscillations of a Finite-Thickness Cantilevered Flexible Plate in Viscous Channel Flow , 2010 .

[16]  Tamer A. Zaki,et al.  Direct numerical simulations of flow in realistic mouth-throat geometries , 2013 .

[17]  W. De Backer,et al.  Correlation between the severity of sleep apnea and upper airway morphology in pediatric and adult patients , 2010, Current opinion in allergy and clinical immunology.

[18]  David D Sampson,et al.  Quantitative upper airway imaging with anatomic optical coherence tomography. , 2006, American journal of respiratory and critical care medicine.

[19]  Yohan Payan,et al.  Simulation of the Retroglossal Fluid-Structure Interaction During Obstructive Sleep Apnea , 2006, ISBMS.

[20]  Shanmugam Murugappan,et al.  Validation of computational fluid dynamics methodology used for human upper airway flow simulations. , 2009, Journal of biomechanics.

[21]  Mark McQuilling,et al.  Pharyngeal Airflow Analysis in Obstructive Sleep Apnea Patients Pre- and Post-Maxillomandibular Advancement Surgery , 2009 .

[22]  B. Wuyam,et al.  Characterization of pharyngeal resistance during sleep in a spectrum of sleep-disordered breathing. , 2000, Journal of applied physiology.

[23]  Raanan Arens,et al.  Changes in upper airway size during tidal breathing in children with obstructive sleep apnea syndrome. , 2005, American journal of respiratory and critical care medicine.

[24]  D. White,et al.  Pharyngeal resistance in normal humans: influence of gender, age, and obesity. , 1985, Journal of applied physiology.

[25]  Irving P. Herman,et al.  Physics of the Human Body , 2008 .

[26]  E. Gutheil,et al.  Large eddy simulation of the unsteady flow-field in an idealized human mouth-throat configuration. , 2011, Journal of biomechanics.

[27]  Wilfried De Backer,et al.  Novel imaging techniques using computer methods for the evaluation of the upper airway in patients with sleep-disordered breathing: a comprehensive review. , 2008, Sleep medicine reviews.

[28]  David D. Sampson,et al.  Measurement, Reconstruction, and Flow-Field Computation of the Human Pharynx With Application to Sleep Apnea , 2010, IEEE Transactions on Biomedical Engineering.

[29]  David Sampson,et al.  In vivo size and shape measurement of the human upper airway using endoscopic longrange optical coherence tomography. , 2003, Optics express.

[30]  G. Liistro,et al.  Pharyngeal shape and dimensions in healthy subjects, snorers, and patients with obstructive sleep apnoea. , 1990, Thorax.

[31]  Tibor S. Balint,et al.  Instability of a cantilevered flexible plate in viscous channel flow , 2005 .

[32]  D. Sampson,et al.  Evaluation of pharyngeal shape and size using anatomical optical coherence tomography in individuals with and without obstructive sleep apnoea , 2008, Journal of sleep research.

[33]  P. Parizel,et al.  Correlation between severity of sleep apnea and upper airway morphology based on advanced anatomical and functional imaging. , 2007, Journal of biomechanics.

[34]  David D. Sampson,et al.  Anatomical Optical Coherence Tomography for Long-Term, Portable, Quantitative Endoscopy , 2008, IEEE Transactions on Biomedical Engineering.

[35]  Seung-Kyu Chung,et al.  Investigation on the respiratory airflow in human airway by PIV , 2009, J. Vis..

[36]  Anthony D. Lucey,et al.  Interaction between a cantilevered-free flexible plate and ideal flow , 2009 .

[37]  A. V. Hirtum,et al.  Numerical and experimental study of expiratory flow in the case of major upper airway obstructions with fluid–structure interaction , 2008 .

[38]  Yohan Payan,et al.  When a fluid-structure interaction keeps you awake : a physical approach to Obstructive Sleep Apnea. , 2007 .