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.

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 Much Ado about Sleep: Current Concepts on Mechanisms and Predisposition to Pediatric Obstructive Sleep Apnea

Children ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 1032
Author(s):  
Ashley L. Saint-Fleur ◽  
Alexa Christophides ◽  
Prabhavathi Gummalla ◽  
Catherine Kier
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Biomechanical Properties ◽  
Primary Role ◽  
Airway Narrowing ◽  
Airway Collapse ◽  
Upper Airway Collapse ◽  
Obstructive Sleep ◽  
Review Current

Obstructive Sleep Apnea (OSA) is a form of sleep-disordered breathing characterized by upper airway collapse during sleep resulting in recurring arousals and desaturations. However, many aspects of this syndrome in children remain unclear. Understanding underlying pathogenic mechanisms of OSA is critical for the development of therapeutic strategies. In this article, we review current concepts surrounding the mechanism, pathogenesis, and predisposing factors of pediatric OSA. Specifically, we discuss the biomechanical properties of the upper airway that contribute to its primary role in OSA pathogenesis and examine the anatomical and neuromuscular factors that predispose to upper airway narrowing and collapsibility.

Control of segmental upper airway resistance in patients with obstructive sleep apnea

1993 ◽  
Vol 74 (6) ◽  
pp. 2694-2703 ◽  
Author(s):  
M. J. Wasicko ◽  
J. S. Erlichman ◽  
J. C. Leiter
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Normal Subjects ◽  
Emg Activity ◽  
Electromyographic Activity ◽  
Resistive Load ◽  
Airway Collapse ◽  
Upper Airway Collapse ◽  
Obstructive Sleep

We sought to determine if the upper airway response to an added inspiratory resistive load (IRL) during wakefulness could be used to predict the site of upper airway collapse in patients with obstructive sleep apnea (OSA). In 10 awake patients with OSA, we investigated the relationship between resistance in three segments of the upper airway (nasal, nasopharyngeal, and oropharyngeal) and three muscles known to influence these segments (alae nasi, tensor veli palatini, and genioglossus) while the patient breathed with or without a small IRL (2 cmH2O.l–1.s). During IRL, patients with OSA exhibited increased nasopharyngeal resistance and no significant increase in either the genioglossus or tensor veli palatini activities. Neither nasal resistance nor alae nasi EMG activity was affected by IRL. We contrasted this to the response of five normal subjects, in whom we found no change in the resistance of either segment of the airway and no change in the genioglossus EMG but a significant activation of the tensor palatini. In six patients with OSA, we used the waking data to predict the site of upper airway collapse during sleep and we had limited success. The most successful index (correct in 4 of 6 patients) incorporated the greatest relative change in segmental resistance during IRL at the lowest electromyographic activity. We conclude, in patients with OSA, IRL narrows the more collapsible segment of the upper airway, in part due to inadequate activation of upper airway muscles. However, it is difficult to predict the site of upper airway collapse based on the waking measurements where upper airway muscle activity masks the passive airway characteristics.

S300 – Comparison of Endoscopy Diagrams for Obstructive Sleep Apnea

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P175-P175
Author(s):  
Masami Nakajima ◽  
B Tucker Woodson
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Muscle Tone ◽  
False Negative ◽  
Upper Airway ◽  
Endoscopic Examination ◽  
Exact Matching ◽  
Airway Collapse ◽  
Obstructive Sleep ◽  
Muscle Groups

Objectives Most methods of waking and sedated sleep endoscopy evaluating the upper airway in obstructive sleep apnea inconsistently predict surgical results. Goals of exam have been to identify levels of obstruction or levels of tissue vibration. Examinations provide little information on airway structure. A novel method of describing airway collapse using airway structures has been developed. The objectives of this study are to compare sleep and wake examination: 1) during inspiration, and 2) expiration. Methods A retrospective review evaluated waking and sedated clinical endoscopic endoscopy. Clinical endoscopic examination was performed supine at end expiration. Sedated endoscopy used propofol anesthesia evaluated the airway during both inspiration, expiration, and with elimination of airway mechanoreceptors. Defined structural butressess included salpingo/palatopharyngeus, levator, and uvular muscle groups for the epi-pharynx and the epiglottis, lateral hypopharynx, vallecular and proximal tongue base for the hypopharynx. Structures were scored on 3 and 4 point scales with agreement indicating exact matching. Results Severity of obstruction scored higher on sedated exam than clinical exam. Structural agreement in epipharynx was 52%, 29%, and 24%, and in hypopharynx, 48%,24%, and 38%. False negative and positive assessment occurred in epipharynx (levator 30% and uvula 40%) but not in hypopharynx. Conclusions Consistent with a greater loss of muscle tone during sleep, exact agreement between wake and sleep exams was low, however, supine end expiratory exam predicted patterns of airway collapse in hypopharynx. Pattern of collapse in epipharynx is confounded by ventilation during wake.

scholarly journals Orthodontic Management of Adult Sleep Apnea: Clinical Case Reports

2021 ◽  
Author(s):  
Lahcen Ousehal ◽  
Soukaina Sahim ◽  
Hajar Bouzid ◽  
Hakima Aghoutan ◽  
Asmaa El Mabrak ◽  
...  
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Case Reports ◽  
Upper Airway ◽  
Public Health Problem ◽  
Airway Collapse ◽  
Upper Airway Collapse ◽  
Obstructive Sleep ◽  
Potential Risks ◽  
Osa Treatment

Obstructive sleep apnea (OSA) is a serious public health problem that has important impacts on the quality and life expectancy of affected individuals. It is characterized by repetitive upper airway collapse during sleep. OSA requires a multidisciplinary plan of treatment. There is increasing interest in the role of the orthodontist both in screening for adult obstructive sleep apnea and its management. Dental appliances and orthognathic surgery are two strategies that are currently used in the treatment of sleep apnea. This chapter focuses on the orthodontic management of sleep apnea in adults through three clinical cases with varying degrees of severity of sleep apnea. It provides a background on OSA treatment approaches and discusses the potential risks and benefits of each.

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