Large Eddy Simulation and Reynolds-Averaged Navier–Stokes modeling of flow in a realistic pharyngeal airway model: An investigation of obstructive sleep apnea

Mihăescu, Mihai; Murugappan, Shanmugam; Kalra, Maninder; Khosla, Sid; Gutmark, Ephraim

doi:10.1016/j.jbiomech.2008.04.013

Cited by 76 publications

(59 citation statements)

References 26 publications

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“…titration of mandibular position during sleep [33,34]). Of particular interest seems to be sleep nasoendoscopy [35][36][37] and upper airway modelling in vitro [38,39], both of which could provide another aspect over conventional prediction for the success of oral appliance therapy. Our preliminary results may be helpful to nCPAP users as well as dentists and sleep physicians when discussing the use of an oral appliance as an alternative and/or temporary substitute for nCPAP.…”

Section: Discussionmentioning

confidence: 99%

Optimal positive airway pressure predicts oral appliance response to sleep apnoea

Tsuiki¹,

Kobayashi²,

Namba³

et al. 2009

Eur Respir J

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Patients with less severe obstructive sleep apnoea (OSA) are usually prescribed oral appliances and/or smaller optimal nasal continuous positive airway pressure (PnCPAP) in nCPAP therapy. We hypothesised that OSA patients with greater PnCPAP would not respond favourably to oral appliances.Oral appliances were inserted in nCPAP users after washing-out the nCPAP effect. Follow-up polysomnography was undertaken with the adjusted oral appliance in place. The predictability of PnCPAP was evaluated with receiver-operating characteristic (ROC) curves.The median baseline apnoea/hypopnoea index (AHI) was reduced with the oral appliance from 36 to 12 events?h -1 in 35 patients. When responders were defined as patients showing a follow-up AHI of ,5 events?h -1 with .50% reduction in baseline AHI, the area under the ROC curve for PnCPAP was 0.76. The best cut-off value of PnCPAP turned out to be 10.5 cmH 2 O with a high negative predictive value (0.93) and a low negative likelihood ratio (0.18). OSA patients with a PnCPAP of .10.5 cmH 2 O are unlikely to respond to oral appliance therapy. This prediction is clinically helpful to both OSA patients and medical personnel in discussing oral appliances as a temporary substitute and/or alternative for nCPAP.

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Section: Discussionmentioning

confidence: 99%

Optimal positive airway pressure predicts oral appliance response to sleep apnoea

Tsuiki¹,

Kobayashi²,

Namba³

et al. 2009

Eur Respir J

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“…The k-ω Shear-Stress Transport (SST) turbulence model was used to solve the equations with the SIMPLE algorithm. Mihaescu et al (2008) have suggested that an unsteady LES approach should be preferred to compute the flow-field within the airway in order to obtain more accurate predictions of important flow features such as flow separation. However, the k-ω SST model was chosen in this study not only because the assumption of a quasi-steady flow was made but also because this model is appropriate to flows with curvature and adverse pressure gradients (Wilcox, 1993), and has been shown to be a good predictor of experimental measurements of wall pressure in a patient airway geometry (Mylavarapu et al, 2009).…”

Section: Airflow Simulationmentioning

confidence: 99%

“…However, the use of largeeddy simulation (LES) or steady Reynolds-averaged NavierStokes (RANS) turbulence models can reduce the computational cost to simulate the flow within the airway and give accurate predictions of important flow features (Mihaescu et al, 2008;Cui and Gutheil, 2011). The validity of these models has been confirmed against in-vitro measurements in reconstructed airways (Mylavarapu et al, 2009;Kim and Chung, 2009).…”

Section: Introductionmentioning

confidence: 99%

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

Cisonni

Lucey

Walsh

et al. 2013

Journal of Biomechanics

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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 9 male subjects with OSA and 9 body-mass index (BMI)-and age-matched control male subjects without OSA. The k-ω SST 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.

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“…Meanwhile the smallest eddies are calculated by LES using a subgrid scale model. Steady RANS (with both -and -models) and unsteady LES predictions of the upper airway flow characteristics are compared by Mihaescu et al [21]. It is shown that LES is still the preferred tool to capture relevant airway-related flow features although its computational cost is expensive.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Particles Deposition in a Human Upper Airway

Liu

et al. 2014

Advances in Mechanical Engineering

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Based on the CT scanned images, a realistic geometric model from nasal cavity to upper six-generation bronchia is rebuilt. In order to effectively simulate the particle movement and deposition, LES model is used and the particles are tracked in the frame of Lagrange. Seven kinds of typical particles, including micron particles (1, 5, and 10 m) and nanoparticles (1, 5, 20, and 100 nm), and three representative respiratory intensities are adopted as computational case, respectively. Deposition efficiency ( ), deposition concentration ( ), and capture efficiency ( ) are introduced. Furthermore, the locations of particle deposition are visualized. The results indicate that the injecting particles from different nasal inlet present "transposition effect. " The values of micron particles are much higher than nanoparticles. The particle diameter plays a weaker role in nanoparticle depositions than micron particles. The highest values of and both occur in nasal cavity, while the highest up to 99.5% occurs in bronchus region.

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Large Eddy Simulation and Reynolds-Averaged Navier–Stokes modeling of flow in a realistic pharyngeal airway model: An investigation of obstructive sleep apnea

Cited by 76 publications

References 26 publications

Optimal positive airway pressure predicts oral appliance response to sleep apnoea

Optimal positive airway pressure predicts oral appliance response to sleep apnoea

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

Numerical Simulation of Particles Deposition in a Human Upper Airway

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