Evaluation of the pharyngeal airway using computational fluid dynamics in patients with acromegaly

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.

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Computational fluid dynamics for the assessment of upper airway changes in skeletal Class III patients treated with mandibular setback surgery

The Angle Orthodontist ◽

10.2319/122715-892.1 ◽

2016 ◽

Vol 86 (6) ◽

pp. 976-982 ◽

Cited By ~ 11

Author(s):

Darshit H. Shah ◽

Ki Beom Kim ◽

Mark W. McQuilling ◽

Reza Movahed ◽

Ankit H. Shah ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Pressure Drop ◽

Negative Correlation ◽

Significant Negative Correlation ◽

Class Iii ◽

Time Points ◽

Pharyngeal Airway ◽

Mandibular Setback ◽

Mandibular Setback Surgery

ABSTRACT Objective: To analyze and compare pharyngeal airflow characteristics pre- and post–mandibular setback surgery in patients with Class III skeletal dysplasia using cone beam computed tomography (CBCT) and computational fluid dynamics (CFD). Materials and Methods: Records of 29 patients who had received orthodontic treatment along with mandibular setback surgery were obtained. CBCT scans were obtained at three time points: T1 (before surgery), T2 (average of 6 months after surgery), and T3 (average of 1 year after surgery). Digitized pharyngeal airway models were generated from these scans. CFD was used to simulate and characterize pharyngeal airflow. Results: Mean airway volume was significantly reduced from 35,490.324 mm3 at T1 to 24,387.369 mm3 at T2 and 25,069.459 mm3 at T3. Significant increase in mean negative pressure was noted from 3.110 Pa at T1 to 6.116 Pa at T2 and 6.295 Pa at T3. There was a statistically significant negative correlation between the change in airway volume and the change in pressure drop at both the T2 and T3 time points. There was a statistically significant negative correlation between the amount of mandibular setback and change in pressure drop at the T2 time point. Conclusions: Following mandibular setback surgery, pharyngeal airway volume was decreased and relative mean negative pressure was increased, implying an increased effort required from a patient for maintaining constant pharyngeal airflow. Thus, high-risk patients undergoing a large amount of mandibular setback surgery should be evaluated for obstructive sleep apnea and the proposed treatment plan be revised based on the risk for potential airway compromise.

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Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study

Orthodontics and Craniofacial Research ◽

10.1111/ocr.12371 ◽

2020 ◽

Vol 23 (3) ◽

pp. 313-322 ◽

Cited By ~ 2

Author(s):

Yoshito Shirazawa ◽

Tomonori Iwasaki ◽

Kazuhiro Ooi ◽

Yutaka Kobayashi ◽

Ayaka Yanagisawa‐Minami ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Pharyngeal Airway ◽

Mandibular Setback ◽

Ventilation Condition ◽

Mandibular Setback Surgery

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Herbst appliance effects on pharyngeal airway ventilation evaluated using computational fluid dynamics

The Angle Orthodontist ◽

10.2319/080616-603.1 ◽

2017 ◽

Vol 87 (3) ◽

pp. 397-403 ◽

Cited By ~ 10

Author(s):

Tomonori Iwasaki ◽

Hideo Sato ◽

Hokuto Suga ◽

Ayaka Minami ◽

Yuushi Yamamoto ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Three Dimensional ◽

Control Group ◽

Herbst Appliance ◽

Oropharyngeal Airway ◽

Pharyngeal Airway ◽

Obstructive Sleep ◽

Before And After ◽

Computational Fluid Dynamics Cfd

ABSTRACT Objective: To evaluate the effect of a Herbst appliance on ventilation of the pharyngeal airway (PA) using computational fluid dynamics (CFD). Materials and Methods: Twenty-one Class II patients (10 boys; mean age, 11.7 years) who required Herbst therapy with edgewise treatment underwent cone-beam computed tomography (CBCT) before and after treatment. Nineteen Class I control patients (8 boys; mean age, 11.9 years) received edgewise treatment alone. The pressure and velocity of the PA were compared between the groups using CFD based on three-dimensional CBCT images of the PA. Results: The change in oropharyngeal airway velocity in the Herbst group (1.95 m/s) was significantly larger than that in the control group (0.67 m/s). Similarly, the decrease in laryngopharyngeal airway velocity in the Herbst group (1.37 m/s) was significantly larger than that in the control group (0.57 m/s). Conclusion: The Herbst appliance improves ventilation of the oropharyngeal and laryngopharyngeal airways. These results may provide a useful assessment of obstructive sleep apnea treatment during growth.

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Computational Fluid Dynamic Analysis of the Pharyngeal Airway after Bimaxillary Orthognathic Surgery in Patients with Mandibular Prognathism

Processes ◽

10.3390/pr9010152 ◽

2021 ◽

Vol 9 (1) ◽

pp. 152

Author(s):

Puneet Wadhwa ◽

Hyon-Seok Jang ◽

Se-Hyun Park ◽

Hyoung-Ho Kim ◽

Eui-Seok Lee

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Pressure Drop ◽

Orthognathic Surgery ◽

Treatment Plan ◽

Pressure Coefficient ◽

Patient Specific ◽

Mandibular Prognathism ◽

Pharyngeal Airway ◽

Bimaxillary Orthognathic Surgery

This study aimed to analyze pharyngeal airflow characteristics and their relationship with the skeletal movement of the maxilla and mandible after bimaxillary orthognathic surgery in patients with skeletal class III (mandibular prognathism) malocclusion. Cone-beam computed tomography (CBCT) was conducted before surgery (T0), immediately after surgery (T1), and at least six months after surgery (T2). Digital imaging and communications in medicine files were transferred to InVivo (Anatomage) software to measure the skeletal changes after surgery. The changes in the maxillary and mandibular position, tongue position, and hyoid bone position were analyzed. Patient-specific models were reconstructed using 3D-Doctor software. The models after converting to the stereolithography (STL) file for Ansys integrated computer engineering and manufacturing code for computational fluid dynamics (ICEM CFD), commercial software were used for calculating the geometry, pressure drop and adjusted pressure coefficient value. The total volume of the upper airway including nasal cavity was reduced by 23% immediately after surgery and recovered to 92.2% of the initial volume six months after surgery. The airflow computation analysis showed a decrease in the pressure drop values immediately after surgery and six months after surgery. The adjusted pressure coefficients were slightly different but the change was statistically insignificant. The airflow characteristics computed using the computational fluid dynamics were correlated to the surgical changes. The surgical changes can affect the aerodynamics of the pharyngeal airway. In clinical practice, this knowledge is useful for developing a suitable orthognathic surgery treatment plan.

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