Velopharyngeal mucosal surface topography in healthy subjects and subjects with obstructive sleep apnea

2017 ◽  
Vol 122 (3) ◽  
pp. 482-491 ◽  
Author(s):  
Christopher Lambeth ◽  
Jason Amatoury ◽  
Ziyu Wang ◽  
Sheryl Foster ◽  
Terence Amis ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Surface Topography ◽  
Upper Airway ◽  
Magnetic Resonance Images ◽  
Mucosal Surface ◽  
Surface Shape ◽  
Obstructive Sleep ◽  
Surface Models

Macroscopic pharyngeal anatomical abnormalities are thought to contribute to the pathogenesis of upper airway (UA) obstruction in obstructive sleep apnea (OSA). Microscopic changes in the UA mucosal lining of OSA subjects are reported; however, the impact of these changes on UA mucosal surface topography is unknown. This study aimed to 1) develop methodology to measure UA mucosal surface topography, and 2) compare findings from healthy and OSA subjects. Ten healthy and eleven OSA subjects were studied. Awake, gated (end expiration), head and neck position controlled magnetic resonance images (MRIs) of the velopharynx (VP) were obtained. VP mucosal surfaces were segmented from axial images, and three-dimensional VP mucosal surface models were constructed. Curvature analysis of the models was used to study the VP mucosal surface topography. Principal, mean, and Gaussian curvatures were used to define surface shape composition and surface roughness of the VP mucosal surface models. Significant differences were found in the surface shape composition, with more saddle/spherical and less flat/cylindrical shapes in OSA than healthy VP mucosal surface models ( P < 0.01). OSA VP mucosal surface models were also found to have more mucosal surface roughness ( P < 0.0001) than healthy VP mucosal surface models. Our novel methodology was utilized to model the VP mucosal surface of OSA and healthy subjects. OSA subjects were found to have different VP mucosal surface topography, composed of increased irregular shapes and increased roughness. We speculate increased irregularity in VP mucosal surface may increase pharyngeal collapsibility as a consequence of friction-related pressure loss. NEW & NOTEWORTHY A new methodology was used to model the upper airway mucosal surface topography from magnetic resonance images of patients with obstructive sleep apnea and healthy adults. Curvature analysis was used to analyze the topography of the models, and a new metric was derived to describe the mucosal surface roughness. Increased roughness was found in the obstructive sleep apnea vs. healthy group, but further research is required to determine the functional effects of the measured difference on upper airway airflow mechanics.

scholarly journals Modelling mucosal surface roughness in the human velopharynx: a computational fluid dynamics study of healthy and obstructive sleep apnea airways

2018 ◽  
Vol 125 (6) ◽  
pp. 1821-1831
Author(s):  
Christopher Lambeth ◽  
Ziyu Wang ◽  
Kristina Kairaitis ◽  
Abouzar Moshfegh ◽  
Ahmad Jabbarzadeh ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Obstructive Sleep Apnea ◽  
Shear Stress ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Fold Increase ◽  
Mucosal Surface ◽  
Airway Collapse ◽  
Obstructive Sleep ◽  
And Control

We previously published a unique methodology for quantifying human velopharyngeal mucosal surface topography and found increased mucosal surface roughness in patients with obstructive sleep apnea (OSA). In fluid mechanics, surface roughness is associated with increased frictional pressure losses and resistance. This study used computational fluid dynamics (CFD) to analyze the mechanistic effect of different levels of mucosal surface roughness on velopharyngeal airflow. Reconstructed velopharyngeal models from OSA and control subjects were modified, giving each model three levels of roughness, quantified by the curvature-based surface roughness index (CBSRI0.6) (range 24.8–68.6 mm−1). CFD using the k-ω shear stress transport turbulence model was performed (unidirectional, inspiratory, steady-state, 15l/min volumetric flow rate), and the effects of roughness on flow velocity, intraluminal pressure, wall shear stress, and velopharyngeal resistance ( Rv) were examined. Across all models, increasing roughness increased maximum flow velocity, wall shear stress, and flow disruption while decreasing intraluminal pressures. Linear mixed effects modeling demonstrated a log-linear relationship between CBSRI0.6 and Rv, with a common slope (log( Rv)/CBSRI0.6) of 0.0079 [95% confidence interval (CI) 0.0015–0.0143; P = 0.019] for all subjects, equating to a 1.9-fold increase in Rv when roughness increased from control to OSA levels. At any fixed CBSRI0.6, the estimated difference in log( Rv) between OSA and control models was 0.9382 (95% CI 0.0032–1.8732; P = 0.049), equating to an 8.7-fold increase in Rv. This study supports the hypothesis that increasing mucosal surface roughness increases velopharyngeal airway resistance, particularly for anatomically narrower OSA airways, and may thus contribute to increased vulnerability to upper airway collapse in patients with OSA. NEW & NOTEWORTHY Increased mucosal surface roughness in the velopharynx of patients with obstructive sleep apnea (OSA) has recently been identified, but its role in OSA pathogenesis is unknown. This is the first study to model the impact of increased roughness on airflow mechanics in the velopharynx. We report that increasing roughness significantly affects airflow, increasing velopharyngeal resistance and potentially increasing the vulnerability to upper airway collapse, particularly in those patients with an already compromised anatomy.

Aerodynamics Analysis of the Impact of Nasal Surgery on Patients with Obstructive Sleep Apnea and Nasal Obstruction

ORL ◽  
2021 ◽  
pp. 1-8
Author(s):  
Lifeng Li ◽  
Demin Han ◽  
Hongrui Zang ◽  
Nyall R. London
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Nasal Obstruction ◽  
Upper Airway ◽  
Apnea Hypopnea Index ◽  
Nasal Surgery ◽  
Subjective Sleep Quality ◽  
Obstructive Sleep ◽  
Significant Difference ◽  
The Impact

<b><i>Objective:</i></b> The purpose of this study was to evaluate the effects of nasal surgery on airflow characteristics in patients with obstructive sleep apnea (OSA) by comparing the alterations of airflow characteristics within the nasal and palatopharyngeal cavities. <b><i>Methods:</i></b> Thirty patients with OSA and nasal obstruction who underwent nasal surgery were enrolled. A pre- and postoperative 3-dimensional model was constructed, and alterations of airflow characteristics were assessed using the method of computational fluid dynamics. The other subjective and objective clinical indices were also assessed. <b><i>Results:</i></b> By comparison with the preoperative value, all postoperative subjective symptoms statistically improved (<i>p</i> &#x3c; 0.05), while the Apnea-Hypopnea Index (AHI) changed little (<i>p</i> = 0.492); the postoperative airflow velocity and pressure in both nasal and palatopharyngeal cavities, nasal and palatopharyngeal pressure differences, and total upper airway resistance statistically decreased (all <i>p</i> &#x3c; 0.01). A significant difference was derived for correlation between the alteration of simulation metrics with subjective improvements (<i>p</i> &#x3c; 0.05), except with the AHI (<i>p</i> &#x3e; 0.05). <b><i>Conclusion:</i></b> Nasal surgery can decrease the total resistance of the upper airway and increase the nasal airflow volume and subjective sleep quality in patients with OSA and nasal obstruction. The altered airflow characteristics might contribute to the postoperative reduction of pharyngeal collapse in a subset of OSA patients.

Upper Airway Sensation in Snoring and Obstructive Sleep Apnea

2001 ◽  
Vol 164 (2) ◽  
pp. 250-255 ◽  
Author(s):  
R. JOHN KIMOFF ◽  
EMILIA SFORZA ◽  
VICTORIA CHAMPAGNE ◽  
LINDA OFIARA ◽  
DANIEL GENDRON
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Obstructive Sleep

scholarly journals Computed tomographic evaluation of the role of craniofacial and upper airway morphology in obstructive sleep apnea in Chinese

2004 ◽  
Vol 98 (4) ◽  
pp. 301-307 ◽  
Author(s):  
Bing Lam ◽  
Clara G.C Ooi ◽  
Wilfred C.G Peh ◽  
I Lauder ◽  
Kenneth W.T Tsang ◽  
...  
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Computed Tomographic ◽  
Obstructive Sleep ◽  
Airway Morphology

Computational Modeling of Upper Airway Before and After Adenotonsillectomy for Obstructive Sleep Apnea

2008 ◽  
Vol 118 (2) ◽  
pp. 360-362 ◽  
Author(s):  
Mihai Mihaescu ◽  
Shanmugam Murugappan ◽  
Ephraim Gutmark ◽  
Lane F. Donnelly ◽  
Maninder Kalra
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Computational Modeling ◽  
Upper Airway ◽  
Obstructive Sleep ◽  
Before And After
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