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Wen XL, Wu BZ, Li Y, Yi B, Peng X. Analysis of the aerodynamic characteristics of the upper airway in obstructive sleep apnea patients. J Dent Sci 2024; 19:329-337. [PMID: 38303889 PMCID: PMC10829548 DOI: 10.1016/j.jds.2023.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/15/2023] [Indexed: 02/03/2024] Open
Abstract
Background/purpose This study was designed to explore upper airway aerodynamic characteristics in individuals diagnosed with obstructive sleep apnea (OSA) and to evaluate correlations between these characteristics and other anatomical upper airway findings in these patients. Materials and methods This was a retrospective study of 40 OSA patients (22 male, 18 female) who were stratified into groups with mild, moderate, and severe disease based upon overnight polysomnographic (PSG) recording results. Newtom5G cone-beam CT scans (CBCT) were conducted for all patients, and the resultant images were used to reconstruct three-dimensional images of the upper airways which were used to calculate aerodynamic characteristics. Differences in these characteristics between groups were evaluated with one-way ANOVAs, while relationships between anatomical and aerodynamic characteristics were assessed through Pearson correlation analyses. Results The aerodynamic of the upper airway has typical characteristic in severe group. There was a significant negative correlation in severe group between resistance during inspiration (Rin) and volume (V) (r = -0.693, P = 0.013), minimum axial area (MMA) (r = -0.685, P = 0.014), and lateral dimension (LAT) (r = -0.724, P = 0.008), resistance during expiration (Rex) and LAT (r = -0.923, P < 0.001). Conclusion This study showed that airway resistance during inspiration and expiration are most closely associated with upper airway collapse in OSA patients, with repetitive collapse occurring during both of these breathing processes. LAT may be an important anatomical factor associated with OSA pathogenesis and treatment.
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Affiliation(s)
- Xing-Long Wen
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing, PR China
| | - Bin-Zhang Wu
- First Clinical Division, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing, PR China
| | - Yang Li
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing, PR China
| | - Biao Yi
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing, PR China
| | - Xin Peng
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing, PR China
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Ding M, Ning J, Liu X, Mi R, Cai Y. Stenotic geometry effects on airflow dynamics and respiration for central airway obstruction. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 241:107760. [PMID: 37573642 DOI: 10.1016/j.cmpb.2023.107760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/15/2023]
Abstract
BACKGROUND AND OBJECTIVE The quantitative relationship between tracheal anatomy and ventilation function can be analyzed by using engineering-derived methods, including mathematical modeling and numerical simulations. In order to provide quantitative functional evaluation for patients with tracheobronchial stenosis, we here propose an aerodynamics-based assessment method by applying computational fluid dynamics analysis on synthetic and patient-specific airway models. METHODS By using 3D reconstruction of tracheobronchial tree and computational fluid dynamics simulations, the aerodynamic environment from the stenotic central airway down to the 4th-6th bifurcation of the tracheobronchial tree is examined in both synthetic and patient-derived models. The effects of stenotic anatomy (the degree of stenosis, stenotic length and location) on the aerodynamic parameters, including pressure drop, area-average velocity, volume flow rate, wall shear stress and airflow resistance, are investigated on three-dimensional models of tracheobronchial tree. RESULTS The results from 36 synthetic models demonstrate that 70% constriction marks the onset of a precipitous decrease in airflow relative to a normal airway. The analyses of simulation results of 8 patient-specific models indicate that the Myer-Cotton stenosis grading system can be interpreted in terms of aerodynamics-derived description, such as flow resistance. The tracheal stenosis significantly influences the resistance of peripheral bronchi, especially for patients with severe stenosis. CONCLUSIONS The present study forms a systematic framework for future development of more robust, bioengineering-informed evaluation methods for quantitative assessment of respiratory function of patients with central airway obstruction.
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Affiliation(s)
- Ming Ding
- Department of Respiratory Medicine, Southeast University Zhongda Hospital, Nanjing, Jiangsu, China
| | - Jing Ning
- School of Biological Sciences and Medical Engineering, Southeast University, Nanjing, Jiangsu, China
| | - Xiuyan Liu
- Department of Respiratory Medicine, Southeast University Zhongda Hospital, Nanjing, Jiangsu, China
| | - Runze Mi
- School of Biological Sciences and Medical Engineering, Southeast University, Nanjing, Jiangsu, China
| | - Yan Cai
- School of Biological Sciences and Medical Engineering, Southeast University, Nanjing, Jiangsu, China.
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Bocanegra Evans H, Segnini JM, Doosttalab A, Cordero J, Castillo L. Effect of cartilaginous rings in tracheal flow with stenosis. BMC Biomed Eng 2023; 5:5. [PMID: 37259126 PMCID: PMC10234078 DOI: 10.1186/s42490-023-00068-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 02/24/2023] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND In respiratory fluid dynamics research, it is typically assumed that the wall of the trachea is smooth. However, the trachea is structurally supported by a series of cartilaginous rings that create undulations on the wall surface, which introduce perturbations into the flow. Even though many studies use realistic Computer Tomography (CT) scan data to capture the complex geometry of the respiratory system, its limited spatial resolution does not resolve small features, including those introduced by the cartilaginous rings. RESULTS Here we present an experimental comparison of two simplified trachea models with Grade II stenosis (70% blockage), one with smooth walls and second with cartilaginous rings. The use a unique refractive index-matching method provides unprecedented optical access and allowed us to perform non-intrusive velocity field measurements close to the wall (e.g., Particle Image Velocimetry (PIV)). Measurements were performed in a flow regime comparable to a resting breathing state (Reynolds number ReD = 3350). The cartilaginous rings induce velocity fluctuations in the downstream flow, enhancing the near-wall transport of momentum flux and thus reducing flow separation in the downstream flow. The maximum upstream velocity in the recirculation region is reduced by 38%, resulting in a much weaker recirculation zone- a direct consequence of the cartilaginous rings. CONCLUSIONS These results highlight the importance of the cartilaginous rings in respiratory flow studies and the mechanism to reduce flow separation in trachea stenosis.
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Affiliation(s)
- Humberto Bocanegra Evans
- School of Mechanical Engineering, Purdue University, 1500 Kepner Dr Room 104, West Lafayette, IN, 47905, USA
| | - Jose Montoya Segnini
- School of Mechanical Engineering, Purdue University, 1500 Kepner Dr Room 104, West Lafayette, IN, 47905, USA
| | - Ali Doosttalab
- School of Mechanical Engineering, Purdue University, 1500 Kepner Dr Room 104, West Lafayette, IN, 47905, USA.
| | - Joehassin Cordero
- Department of Otolaryngology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Luciano Castillo
- School of Mechanical Engineering, Purdue University, 1500 Kepner Dr Room 104, West Lafayette, IN, 47905, USA
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Tucker ML, Wilson DG, Bergstrom DJ, Carmalt JL. Computational fluid dynamic analysis of upper airway procedures in equine larynges. Front Vet Sci 2023; 10:1139398. [PMID: 37138910 PMCID: PMC10149674 DOI: 10.3389/fvets.2023.1139398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/24/2023] [Indexed: 05/05/2023] Open
Abstract
Introduction Computational fluid dynamics (CFD) has proven useful in the planning of upper airway surgery in humans, where it is used to anticipate the influence of the surgical procedures on post-operative airflow. This technology has only been reported twice in an equine model, with a limited scope of airflow mechanics situations examined. The reported study sought to widen this application to the variety of procedures used to treat equine recurrent laryngeal neuropathy (RLN). The first objective of this study was to generate a CFD model of an ex-vivo box model of ten different equine larynges replicating RLN and four therapeutic surgeries to compare the calculated impedance between these procedures for each larynx. The second objective was to determine the accuracy between a CFD model and measured airflow characteristics in equine larynges. The last objective was to explore the anatomic distribution of changes in pressure, velocity, and turbulent kinetic energy associated with the disease (RLN) and each surgical procedure performed. Methods Ten equine cadaveric larynges underwent inhalation airflow testing in an instrumented box while undergoing a concurrent computed tomographic (CT) exam. The pressure upstream and downstream (outlet) were measured simultaneously. CT image segmentation was performed to generate stereolithography files, which underwent CFD analysis using the experimentally measured outlet pressure. The ranked procedural order and calculated laryngeal impedance were compared to the experimentally obtained values. Results and discussion The CFD model agreed with the measured results in predicting the procedure resulting in the lowest post-operative impedance in 9/10 larynges. Numerically, the CFD calculated laryngeal impedance was approximately 0.7 times that of the measured calculation. Low pressure and high velocity were observed around regions of tissue protrusion within the lumen of the larynx. RLN, the corniculectomy and partial arytenoidectomy surgical procedures exhibited low pressure troughs and high velocity peaks compared to the laryngoplasty and combined laryngoplasty/corniculectomy procedures. CFD modeling of the equine larynx reliably calculated the lowest impedance of the different surgical procedures. Future development of the CFD technique to this application may improve numerical accuracy and is recommended prior to consideration for use in patients.
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Affiliation(s)
- Michelle L. Tucker
- Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
- *Correspondence: Michelle L. Tucker
| | - David G. Wilson
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Donald J. Bergstrom
- Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK, Canada
| | - James L. Carmalt
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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Computational Fluid Dynamic Analysis of the Pharyngeal Airway after Bimaxillary Orthognathic Surgery in Patients with Mandibular Prognathism. Processes (Basel) 2021. [DOI: 10.3390/pr9010152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
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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Poynot WJ, Gonthier KA, Dunham ME, Crosby TW. Classification of tracheal stenosis in children based on computational aerodynamics. J Biomech 2020; 104:109752. [PMID: 32224051 DOI: 10.1016/j.jbiomech.2020.109752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 02/12/2020] [Accepted: 03/13/2020] [Indexed: 10/24/2022]
Abstract
Tracheal stenosis is a health condition in which local narrowing of the upper trachea can cause breathing difficulties and increased incidence of infection, among other symptoms. Occurring most commonly due to intubation of infants, tracheal stenosis often requires corrective surgery. It is challenging to determine the most effective surgical strategy for a given patient as current clinical methods used to assess tracheal stenosis are simplistic and subjective, and are not rigorously based on aerodynamic considerations. This paper summarizes a non-invasive approach based on computational fluid dynamics (CFD) and medical imaging to establish relationships between trachea anatomy and inspiration performance. Though patient-specific CFD analysis has gained recent popularity, an objective of this study is to computationally formulate dimensionless analytical correlations between anatomy and performance that are applicable to any member of a class of patients and that can be interpreted within the context of the Myer-Cotton stenotic airway classification system. These correlations can provide aerodynamics-based insight for the development of more robust stenosis evaluation methods and may allow for time-efficient assessment of corrective surgical strategies.
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Affiliation(s)
- William J Poynot
- Department of Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Keith A Gonthier
- Department of Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Michael E Dunham
- Department of Otolaryngology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Tyler W Crosby
- Department of Otolaryngology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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Taherian S, Rahai H, Lopez S, Shin J, Jafari B. Evaluation of human obstructive sleep apnea using computational fluid dynamics. Commun Biol 2019; 2:423. [PMID: 31799426 PMCID: PMC6872714 DOI: 10.1038/s42003-019-0668-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 10/28/2019] [Indexed: 11/21/2022] Open
Abstract
Obstructive sleep apnea (OSA) severity might be correlated to the flow characteristics of the upper airways. We aimed to investigate the severity of OSA based on 3D models constructed from CT scans coupled with computational fluid dynamics (CFD) simulations. The CT scans of seven adult patients diagnosed with OSA were used to reconstruct the 3D models of the upper airways and CFD modeling and analyses were performed. Results from the fluid simulations were compared with the apnea-hypopnea index. Here we show a correlation between a CFD-based parameter, the adjusted pressure coefficient (Cp*), and the respective apnea-hypopnea index (Pearson's r = 0.91, p = 0.004), which suggests that the anatomical-based model coupled with CFD could provide functional and localized information for different regions of the upper airways.
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Affiliation(s)
- Shahab Taherian
- Center for Energy and Environmental Research and Services, California State University Long Beach, Long Beach, CA USA
- Department of Internal Medicine, University of California Irvine School of Medicine, Irvine, CA USA
| | - Hamid Rahai
- Center for Energy and Environmental Research and Services, California State University Long Beach, Long Beach, CA USA
| | - Samuel Lopez
- Center for Energy and Environmental Research and Services, California State University Long Beach, Long Beach, CA USA
| | - Jamie Shin
- Center for Energy and Environmental Research and Services, California State University Long Beach, Long Beach, CA USA
| | - Behrouz Jafari
- Department of Internal Medicine, University of California Irvine School of Medicine, Irvine, CA USA
- Section of Pulmonary, Critical Care, and Sleep Medicine, Veterans Affairs Long Beach Healthcare System, Long Beach, CA USA
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