| 1. |
- Mihaescu, Mihai, 1976-, et al.
(författare)
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Computational Fluid Dynamics Analysis of Upper Airway Reconstructed From Magnetic Resonance Imaging Data
- 2008
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Ingår i: Annals of Otology, Rhinology and Laryngology. - : SAGE Publications. - 0003-4894 .- 1943-572X. ; 117:4, s. 303-309
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: We performed flow computations on an accurate upper airway model in a patient with obstructive sleep apnea and computed the velocity, static pressure, and wall shear stress distribution in the model. Methods: Cartesian coordinates for airway boundaries were determined from cross-sectional magnetic resonance images, and a 3-dimensional computational model of the upper airway was constructed. Flow simulations were then performed within a FLUENT commercial software framework. Four different flow conditions were simulated during inspiration, assuming the steady-state condition. The results were analyzed from the perspectives of velocity, static pressure, and wall shear stress distribution. Results: We observed that the highest axial velocity was at the site of minimum cross-sectional area (retropalatal pharynx) resulting in the lowest level of wall static pressure. The highest wall shear stresses were at the same location. The pressure drop was significantly larger for higher flow rates than for lower flow rates. Conclusions: Our results indicate that the presence of airway narrowing, through change in the flow characteristics that result in increased flow velocity and reduced static pressure, can itself increase airway collapsibility. Additionally, the effects of wall shear stress on airway walls may be an important factor in the progression over time of the severity of obstructive sleep apnea.
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| 2. |
- Mihaescu, Mihai, 1976-, et al.
(författare)
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Computational Modeling of Upper Airway Before and After Adenotonsillectomy for Obstructive Sleep Apnea
- 2008
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Ingår i: The Laryngoscope. - 0023-852X .- 1531-4995. ; 118:2, s. 360-362
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Tidskriftsartikel (refereegranskat)abstract
- Adenotonsillectomy, the first-line surgical treatment for obstructive sleep apnea (OSA) in children, is successful in only 50% of obese children. Computational fluid dynamics tools, which have been applied to differentiate OSA patients from those without OSA based on the airway flow characteristics, can be potentially used to identify patients likely to benefit from surgical intervention. We present computational modeling of the upper airway before and after adenotonsillectomy in an obese female adolescent with OSA. The subject underwent upper airway imaging on a 1.5 Tesla magnetic resonance imaging (MRI) scanner, and three-dimensional airway models were constructed using airway boundary coordinates from cross-sectional MRI scans. Our results using computational simulations indicate that, in an obese child, the resolution of OSA after adenotonsillectomy is associated with changes in flow characteristics that result in decreased pressure differentials across the airway walls and thus lower compressive forces that predispose to airway collapse. Application of such findings to an obese child seeking surgical treatment for OSA can potentially lead to selection of the surgical procedure most likely to result in OSA resolution. Effective intervention for OSA in this high-risk group will result in reduction in morbidity and the public health concerns associated with OSA.
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| 3. |
- Sawnani, Hemant, et al.
(författare)
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Influence of Gender on Pharyngeal Airway Length in Obese Adolescents
- 2010
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Ingår i: Annals of Otology, Rhinology and Laryngology. - : SAGE Publications. - 0003-4894 .- 1943-572X. ; 119, s. 842-847
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Although pharyngeal airway length has been implicated in an increased male predisposition for obstructive sleep apnea (OSA) in adults, data in obese children and adolescents are lacking. Our objective was to determine the influence of gender on pharyngeal airway length in obese adolescents, and to apply computational simulations to better understand the effect of pharyngeal airway length on the airway's predisposition to collapse in this select group. METHODS: Obese subjects without OSA were recruited from our Sleep Center. Their pharyngeal airway length was measured on midline sagittal magnetic resonance images as the distance between the hard palate and the base of the epiglottis. Computational fluid dynamics analysis was used to study the effect of pharyngeal airway length on airflow characteristics. The gender groups were compared for anthropometric measurements and pharyngeal airway length by an unpaired Student's t-test. RESULTS: Our study group included 18 female and 16 male obese adolescents with a mean (+/-SD) age of 14.7 +/- 2.3 years and a mean body mass index of 38.9 +/- 6.9 kg/m2. The groups did not differ in age, body weight, or normalized pharyngeal airway length (0.44 +/- 0.08 mm/cm in girls versus 0.44 +/- 0.11 mm/cm in boys; p = 0.9). The computational fluid dynamics simulation indicated that the 3-dimensional flow field and airway wall pressures were not significantly affected by pharyngeal airway lengthening of up to 10 mm. CONCLUSIONS: Our results indicate that in obese adolescents, there is no influence of gender on pharyngeal airway length, and pharyngeal airway length alone does not significantly affect the airway's predisposition to collapse. These findings suggest that pharyngeal airway length may not explain the increased male gender predisposition for OSA in this select group.
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