Computational Fluid Dynamics Modeling of Upper Airway During Tidal Breathing Using Volume-Gated MRI in OSAS and Control Subjects

2011 ◽  
Author(s):  
Steven C. Persak ◽  
Sanghun Sin ◽  
Raanan Arens ◽  
David M. Wootton
Keyword(s):  
Fluid Dynamic ◽  
Sleep Apnea Syndrome ◽  
Three Dimensional ◽  
Upper Airway ◽  
Magnetic Resonance Images ◽  
Dynamics Modeling ◽  
Tidal Breathing ◽  
Pharyngeal Airway ◽  
Cross Section Area ◽  
Obstructive Sleep

Three-dimensional (3D) computational fluid dynamic (CFD) analysis was used to model the effect of collapsing airway geometry on internal pressure and velocity in the pharyngeal airway of sedated obese children with and without obstructive sleep apnea syndrome (OSAS). Geometry was reconstructed from volume-gated magnetic resonance images during normal tidal breathing of the respiratory cycle and solved using flow data averaged over 12 consecutive breathing cycles. In the OSAS subject, collapse initiated in the proximal nasopharynx and continued downstream into the oropharynx, while the control experienced negligible collapse. Tube laws (pressure vs. cross-section area) derived for the nasopharynx and oropharynx, indicated the oropharynx in the OSAS subject more compliant than the nasopharynx (1.028 mm2/Pa vs. 0.449 mm2/Pa) and had a lower theoretical limiting flow rate, confirming the oropharynx as the flow-limiting segment of the airway in this subject. This new method may help to differentiate anatomical and functional factors in airway collapse.

scholarly journals Noninvasive estimation of pharyngeal airway resistance and compliance in children based on volume-gated dynamic MRI and computational fluid dynamics

2011 ◽  
Vol 111 (6) ◽  
pp. 1819-1827 ◽  
Author(s):  
Steven C. Persak ◽  
Sanghun Sin ◽  
Joseph M. McDonough ◽  
Raanan Arens ◽  
David M. Wootton
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Rate ◽  
Magnetic Resonance Images ◽  
Cfd Modeling ◽  
Tidal Breathing ◽  
Upper Airways ◽  
Pharyngeal Airway ◽  
Airway Collapse ◽  
Obstructive Sleep

Computational fluid dynamics (CFD) analysis was used to model the effect of collapsing airway geometry on internal pressure and velocity in the pharyngeal airway of three sedated children with obstructive sleep apnea syndrome (OSAS) and three control subjects. Model geometry was reconstructed from volume-gated magnetic resonance images during normal tidal breathing at 10 increments of tidal volume through the respiratory cycle. Each geometry was meshed with an unstructured grid and solved using a low-Reynolds number k-ω turbulence model driven by flow data averaged over 12 consecutive breathing cycles. Combining gated imaging with CFD modeling created a dynamic three-dimensional view of airway anatomy and mechanics, including the evolution of airway collapse and flow resistance and estimates of the local effective compliance. The upper airways of subjects with OSAS were generally much more compliant during tidal breathing. Compliance curves (pressure vs. cross-section area), derived for different locations along the airway, quantified local differences along the pharynx and between OSAS subjects. In one subject, the distal oropharynx was more compliant than the nasopharynx (1.028 vs. 0.450 mm2/Pa) and had a lower theoretical limiting flow rate, confirming the distal oropharynx as the flow-limiting segment of the airway in this subject. Another subject had a more compliant nasopharynx (0.053 mm2/Pa) during inspiration and apparent stiffening of the distal oropharynx (C = 0.0058 mm2/Pa), and the theoretical limiting flow rate indicated the nasopharynx as the flow-limiting segment. This new method may help to differentiate anatomical and functional factors in airway collapse.

scholarly journals THE EFFECT OF ISOLATED SEGMENTAL CHIN OSTEOTOMY (SCO) ON THE PHARYNGEAL AIRWAY SPACE

2020 ◽  
Vol 17 (35) ◽  
pp. 495-506
Author(s):  
Larysa DAKHNO ◽  
Iryna LOGVYNENKO
Keyword(s):  
Sleep Apnea Syndrome ◽  
Upper Airway ◽  
Fold Increase ◽  
Forward Movement ◽  
Virtual Planning ◽  
Cross Sectional ◽  
Pharyngeal Airway ◽  
Facial Esthetics ◽  
Obstructive Sleep ◽  
The Face

The chin affects facial esthetics and the harmony between frontal and lateral views and is one of the most important anatomic structures of the lower third of the face. Chin osteotomy is aimed at ensuring the harmonization of the facial profile by balancing the size and form of the lower third of the face. It is assumed that the isolated genioplasty surgery will improve the pharyngeal airway space (PAS) by promoting muscle changes, specifically by pulling forward the hyoid bone and decompressing the hypopharynx region. Two patients without obstructive sleep apnea syndrome (OSAS) underwent isolated chin osteotomy for esthetic purposes. Forward movement of the chin by the Pg point was 7 mm in one case and 11 mm in another case. They were evaluated by preoperative and postoperative cone-beam computed tomography scans. The upper airway space was subdivided into retropalatal and retroglossal spaces. After this, the upper airway space was analyzed through the following criteria: 1) three-dimensional, high-altitude, cross-sectional surfaces; 2) transverse and anteroposterior diameter changes. Isolated segmental genioplasty was used after precise virtual planning and resulted in the PAS increase only in one case. There was a relevant correlation between the vertical and horizontal chin change and the hypopharynx. There was an average of a 1.6-fold increase in the total volume of the upper airway space. The retroglossal space was increased 1.5-fold. In another case, there was no relevant correlation between the vertical and horizontal chin change and the PAS. Isolated segmental chin osteotomy provides predictable esthetic results in the correction of different mandible anterior deformities and may contribute to an increased volume and a morphologic airway change. Further studies should be conducted to evaluate the effect of isolated segmental genioplasty on the pharyngeal airway space.

scholarly journals Volumes of Velopharyngeal and Glossopharyngeal Airway Were Not Changed after Uvulopalatopharyngoplasty: Report of Three Cases

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Yoichi Nishimura ◽  
Naoko Fujii ◽  
Takahisa Yamamoto ◽  
Mahmood A. Hamed ◽  
Misato Nishimura ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Obstructive Sleep Apnea Syndrome ◽  
Sleep Apnea Syndrome ◽  
Three Dimensional ◽  
Pharyngeal Airway ◽  
Obstructive Sleep ◽  
Computed Tomography Scanning ◽  
Apnea Syndrome

Objective. The aim of this study was to investigate the changes in velopharyngeal and glossopharyngeal airway morphology and volume after uvulopalatopharyngoplasty in three adult obstructive sleep apnea syndrome patients who had bilateral large tonsils using three-dimensional computed tomography.Case Report. All three patients (one male and two females) who presented with a history of heavy snoring and excessive daytime sleepiness were examined with overnight nocturnal polysomnography, which indicated moderate-to-severe obstructive sleep apnea syndrome. Because all patients had large tonsils, uvulopalatopharyngoplasty was expected to enlarge the pharyngeal airway. Polysomnography and three-dimensional computed tomography scanning were performed and compared, both before and 3 months after uvulopalatopharyngoplasty.Results. Unexpectedly, although the morphology of the glossopharyngeal airway clearly changed after UPPP, the volume changes in the velopharyngeal and glossopharyngeal airways were negligible.

scholarly journals Three-dimensional analyses of palatal morphology and its relation to upper airway area in obstructive sleep apnea

2016 ◽  
Vol 87 (2) ◽  
pp. 300-306 ◽  
Author(s):  
Defne Kecik
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Three Dimensional ◽  
Upper Airway ◽  
Control Group ◽  
Pharyngeal Airway ◽  
Obstructive Sleep ◽  
Lateral Cephalograms ◽  
Airway Morphology ◽  
Pharyngeal Area

ABSTRACT Objective: To evaluate the relationship between palatal morphology and pharyngeal airway morphology in patients who have obstructive sleep apnea (OSA) and compare with a nonsnoring and nonapneic control group. Materials and Methods: Three-dimensional maxillary dental cast measurements from 25 OSA patients (6 women, 19 men) with a mean age of 41.5 (4.8) years, and 25 control group participants (14 women, 11 men) without any symptom of OSA with a mean age of 38.3 (3.7) were correlated with an analysis of pharyngeal area evaluated with lateral cephalograms. Intermolar and intercanine widths and palatal volumes were calculated on the dental casts, and the upper airway area measurements were performed on lateral cephalograms. Results: OSA patients had smaller oropharyngeal volume and upper airway when compared with controls (P < .001). Palatal area measurements were significantly smaller in OSA (P < .001). OSA patients had significantly narrower maxilla with smaller intermolar and intercanine widths (P < .001). A positive correlation was found between the palatal morphology and pharyngeal dimensions. Conclusions: A significant correlation exists between palatal morphology and pharyngeal airway.

MRI study of regional variations of pharyngeal wall compliance in cats

1998 ◽  
Vol 85 (5) ◽  
pp. 1884-1897 ◽  
Author(s):  
Michael J. Brennick ◽  
Malcolm D. Ogilvie ◽  
Susan S. Margulies ◽  
Luke Hiller ◽  
Warren B. Gefter ◽  
...  
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Three Dimensional ◽  
Upper Airway ◽  
Cross Sectional ◽  
Pharyngeal Wall ◽  
Regional Variations ◽  
Pharyngeal Airway ◽  
Obstructive Sleep ◽  
Mri Study

Upper airway compliance indicates the potential of the airway to collapse and is relevant to the pathogenesis of obstructive sleep apnea. We hypothesized that compliance would vary over the rostral-to-caudal extent of the pharyngeal airway. In a paralyzed isolated upper airway preparation in cats, we controlled static upper airway pressure during magnetic resonance imaging (MRI, 0.391-mm resolution). We measured cross-sectional area and anteroposterior and lateral dimensions from three-dimensional reconstructed MRIs in axial slices orthogonal to the airway centerline. High-retropalatal (HRP), midretropalatal (MRP), and hypopharyngeal (HYP) regions were defined. Regional compliance was significantly increased from rostral to caudal regions as follows: HRP < MRP < HYP ( P < 0.0001), and compliance differences among regions were directly related to collapsibility. Thus our findings in the isolated upper airway of the cat support the hypothesis that regional differences in pharyngeal compliance exist and suggest that baseline regional variations in compliance and collapsibility may be an important factor in the pathogenesis and treatment of obstructive sleep apnea.

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