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Saha SC, Huang X, Francis I, Saha G. Airway stability in sleep apnea: Assessing continuous positive airway pressure efficiency. Respir Physiol Neurobiol 2024; 325:104265. [PMID: 38653435 DOI: 10.1016/j.resp.2024.104265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/11/2024] [Accepted: 04/19/2024] [Indexed: 04/25/2024]
Abstract
Obstructive Sleep Apnea Syndrome (OSAS) disrupts millions of lives with its burden of airway obstruction during sleep. Continuous Positive Airway Pressure (CPAP) therapy has been scrutinized for its biomechanical impact on the respiratory tract. This study leverages computational fluid dynamics to investigate CPAP's effects at 9 cm H2O (882.6 Pa) on the computed-tomography-based nasal-to-14-generation full respiratory tract model compared to ambient conditions, focusing on static pressure, airflow velocity, and shear stress. Our findings reveal that CPAP significantly increases static pressure, enhancing airway patency without adverse changes in airflow velocity or harmful shear stress on lung tissue, challenging prior concerns about its safety. Notably, the larynx experiences the highest shear stress due to its narrow anatomy, yet CPAP therapy overall supports airway walls against collapse. This investigation highlights CPAP's critical role in OSAS treatment, offering reassurance about its safety and efficacy. By clarifying CPAP therapy's physiological impacts, our study contributes vital insights for optimizing OSAS management strategies, affirming CPAP's benefit in maintaining open airways with minimal tissue strain.
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Affiliation(s)
- Suvash C Saha
- School of Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW, Australia.
| | - Xinlei Huang
- School of Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW, Australia
| | - Isabella Francis
- School of Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW, Australia
| | - Goutam Saha
- School of Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW, Australia
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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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Hu Z, Dong J, Lou M, Zhang J, Ma R, Wang Y, Gong M, Wang B, Tong Z, Ren H, Zheng G, Zhang Y. Effect of different degrees of adenoid hypertrophy on pediatric upper airway aerodynamics: a computational fluid dynamics study. Biomech Model Mechanobiol 2023; 22:1163-1175. [PMID: 37256522 DOI: 10.1007/s10237-023-01707-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 02/22/2023] [Indexed: 06/01/2023]
Abstract
To improve the diagnostic accuracy of adenoid hypertrophy (AH) in children and prevent further complications in time, it is important to study and quantify the effects of different degrees of AH on pediatric upper airway (UA) aerodynamics. In this study, based on computed tomography (CT) scans of a child with AH, UA models with different degrees of obstruction (adenoidal-nasopharyngeal (AN) ratio of 0.9, 0.8, 0.7, and 0.6) and no obstruction (AN ratio of 0.5) were constructed through virtual surgery to quantitatively analyze the aerodynamic characteristics of UA with different degrees of obstruction in terms of the peak velocity, pressure drop (△P), and maximum wall shear stress (WSS). We found that two obvious whirlpools are formed in the anterior upper part of the pediatric nasal cavity and in the oropharynx, which is caused by the sudden increase in the nasal cross-section area, resulting in local flow separation and counterflow. In addition, when the AN ratio was ≥ 0.7, the airflow velocity peaked at the protruding area in the nasopharynx, with an increase 1.1-2.7 times greater than that in the nasal valve area; the △P in the nasopharynx was significantly increased, with an increase 1.1-6.8 times greater than that in the nasal cavity; and the maximum WSS of the posterior wall of the nasopharynx was 1.1-4.4 times larger than that of the nasal cavity. The results showed that the size of the adenoid plays an important role in the patency of the pediatric UA.
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Affiliation(s)
- Zhenzhen Hu
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China
| | - Jingliang Dong
- Institute for Sustainable Industries & Liveable Cities, Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia
- First Year College, Victoria University, Footscray Park Campus, Footscray, VIC, 3011, Australia
- School of Engineering, RMIT University, Bundoora, VIC, 3083, Australia
| | - Miao Lou
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China
| | - Jingbin Zhang
- Department of Imaging, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Ruiping Ma
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China
| | - Yusheng Wang
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China
| | - Minjie Gong
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China
| | - Botao Wang
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China
| | - Zhenbo Tong
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Hongxian Ren
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Guoxi Zheng
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China.
| | - Ya Zhang
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 Xiwu Road, Xi'an, 710004, Shaanxi, China.
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Tang H, Cui X, Li H, Zheng F, Chen Y, Jiang J. Effects of vertical control on anatomic and aerodynamic characteristics of the oropharyngeal airway during premolar extraction treatment of Class II hyperdivergent nonsevere crowding malocclusion. Am J Orthod Dentofacial Orthop 2023:S0889-5406(23)00256-1. [PMID: 37245126 DOI: 10.1016/j.ajodo.2023.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/01/2023] [Accepted: 05/01/2023] [Indexed: 05/29/2023]
Abstract
INTRODUCTION This study aimed to analyze the effects of premolar extraction treatment with vertical control on changes in the anatomy and aerodynamics of the oropharynx in Class II hyperdivergent malocclusion with nonsevere crowding. METHODS Thirty-nine patients with Class II hyperdivergent malocclusion were enrolled consecutively. All the participants underwent 4 premolar extractions. The high-pull J-hook and mini-implants were used to provide vertical control. Cone-beam computed tomography was performed before and after treatment. The participants were divided into a decreased lower vertical facial height group (n = 23) and an increased lower vertical facial height group (n = 16) on the basis of superimposition. The aerodynamic characteristics, including airway resistance (inspiration, Rin; expiration, Rex) and maximum velocity (inspiration, Vmaxin; expiration, Vmaxex) at inspiration and expiration, were calculated using computational fluid dynamics. Anatomic characteristics, including volume and cross-sectional area (CSAmin), were measured using the Dolphin Imaging software (Dolphin Imaging and Management Solutions, Chatsworth, Calif). RESULTS After treatment, the median volume and CSAmin increased by 2357 mm3 and 43 mm2, respectively, and median Rin and Vmaxex decreased by 0.15 Pa/L/min and 0.24 m×s-1, respectively, in decreased lower vertical facial height group. In contrast, the median CSAmin decreased by 9.5 mm2 in the increased lower vertical facial height group. All the changes were statistically significant (all P <0.05). Significant differences in volume, CSAmin, Rin, and Vmaxex were observed between the 2 groups. CONCLUSIONS Vertical control might improve the anatomic and aerodynamic characteristics of the oropharyngeal airway during premolar extraction treatment of Class II hyperdivergent malocclusion with nonsevere crowding.
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Affiliation(s)
- Hongyi Tang
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Xinyu Cui
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Huazhi Li
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Fu Zheng
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Youchao Chen
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China
| | - Jiuhui Jiang
- Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
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Hu B, Yin G, Fu S, Zhang B, Shang Y, Zhang Y, Ye J. The influence of mouth opening on pharyngeal pressure loss and its underlying mechanism: A computational fluid dynamic analysis. Front Bioeng Biotechnol 2023; 10:1081465. [PMID: 36698641 PMCID: PMC9868155 DOI: 10.3389/fbioe.2022.1081465] [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: 10/27/2022] [Accepted: 12/20/2022] [Indexed: 01/11/2023] Open
Abstract
Objective: During inspiration, mechanical energy generated from respiratory muscle produces a negative pressure gradient to fulfill enough pulmonary ventilation. The pressure loss, a surrogate for energy loss, is considered as the portion of negative pressure without converting into the kinetic energy of airflow. Mouth opening (MO) during sleep is a common symptom in patients with obstructive sleep apnoea-hypopnea syndrome (OSAHS). This study aimed to evaluate the effects of mouth opening on pharyngeal pressure loss using computational fluid dynamics (CFD) simulation. Methods: A total of four subjects who were morphologically distinct in the pharyngeal characteristics based on Friedman tongue position (FTP) grades were selected. Upper airway computed tomography (CT) scan was performed under two conditions: Mouth closing (MC) and mouth opening, in order to reconstruct the upper airway models. computational fluid dynamics was used to simulate the flow on the two different occasions: Mouth closing and mouth opening. Results: The pharyngeal jet was the typical aerodynamic feature and its formation and development were different from mouth closing to mouth opening in subjects with different Friedman tongue position grades. For FTP I with mouth closing, a pharyngeal jet gradually formed with proximity to the velopharyngeal minimum area plane (planeAmin). Downstream the planeAmin, the jet impingement on the pharyngeal wall resulted in the frictional loss associated with wall shear stress (WSS). A rapid luminal expansion led to flow separation and large recirculation region, corresponding to the interior flow loss. They all contributed to the pharyngeal total pressure loss. While for FTP I with mouth opening, the improved velopharyngeal constriction led to smoother flow and a lower total pressure loss. For FTP IV, the narrower the planeAmin after mouth opening, the stronger the jet formation and its impingement on the pharyngeal wall, predicting a higher frictional loss resulted from higher WSS. Besides, a longer length of the mouth opening-associated constant constrictive segment was another important morphological factor promoting frictional loss. Conclusion: For certain OSAHS patients with higher Friedman tongue position grade, mouth opening-related stronger jet formation, more jet breakdown and stronger jet flow separation might contribute to the increased pharyngeal pressure loss. It might require compensation from more inspiratory negative static pressure that would potentially increase the severity of OSAHS.
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Affiliation(s)
- Bin Hu
- Department of Otolaryngology-Head Neck Surgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
| | - Guoping Yin
- Department of Otolaryngology-Head Neck Surgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China,Sleep Medicine Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
| | - Song Fu
- School of Aeronautics and Astronautics, Tsinghua University, Beijing, China
| | - Baoshou Zhang
- School of Aeronautics and Astronautics, Tsinghua University, Beijing, China
| | - Yan Shang
- School of Aeronautics and Astronautics, Tsinghua University, Beijing, China
| | - Yuhuan Zhang
- Sleep Medicine Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
| | - Jingying Ye
- Department of Otolaryngology-Head Neck Surgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China,Sleep Medicine Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China,*Correspondence: Jingying Ye,
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Oku Y, Iwasaki T, Tsujii T, Sakoda-Iwata R, Hisagai S, Ban Y, Sato H, Ishii H, Kanomi R, Yamasaki Y. Effect of palatine tonsil hypertrophy on tongue posture and maxillofacial dentition: A pharyngeal airway computational fluid dynamics study. PEDIATRIC DENTAL JOURNAL 2023. [DOI: 10.1016/j.pdj.2023.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Nomura T, Horikoshi T, Kitano Y, Yamada M, Kondo K, Kikuchi S. Postoperative functional evaluation of obstructive sleep apnea syndrome by computational fluid dynamics. Indian J Otolaryngol Head Neck Surg 2022; 74:5044-5051. [PMID: 36742941 PMCID: PMC9895218 DOI: 10.1007/s12070-021-02681-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 06/07/2021] [Indexed: 02/07/2023] Open
Abstract
The aim of this study is to evaluate the efficacy of uvulopalatopharyngoplasty and the corresponding postoperative airflow. Eleven patients diagnosed with obstructive sleep apnea syndrome who complained of snoring and apnea were enrolled in this study. Computational fluid dynamics (CFD) was implemented. CFD could be accomplished in nine cases. Airflow analysis was not possible in cases with a high respiratory event index (REI) score. Before surgery, stenosis was identified in the oropharynx and epiglottic area. And the airflow velocity and pressure were found to have significantly decreased in the oropharynx postoperatively, while in the epiglottic area, those data had increased postoperatively in some cases. The velocity and pressure of the oropharynx are related to REI score. From the CFD analysis, airflow analysis is important for evaluating the apnea state. It is suggested that the postoperative function can now be predicted preoperatively.
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Affiliation(s)
- Tsutomu Nomura
- Division of Otolaryngology, Department of Comprehensive Medical Sciences, Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, Saitama, 350–0283 Japan
| | - Tomomi Horikoshi
- Department of Otolaryngology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Yuka Kitano
- Department of Otolaryngology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Masato Yamada
- Department of Otolaryngology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
| | - Kenji Kondo
- Department of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Shigeru Kikuchi
- Department of Otolaryngology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
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Fluid dynamics of the upper airway in pediatric patients with severe laryngomalacia. Phys Eng Sci Med 2022; 45:1083-1091. [PMID: 36326986 DOI: 10.1007/s13246-022-01174-8] [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: 04/19/2022] [Accepted: 08/11/2022] [Indexed: 11/06/2022]
Abstract
Laryngomalacia is the top cause of pediatric laryngeal wheeze. We used computational fluid dynamics to study the inspiratory airflow dynamics in severe pediatric laryngomalacia. Computed tomography was performed on the upper airways of two infants, one with severe laryngomalacia and one with normal airway, and 3D models were reconstructed. ANSYS CFD-POST software was used to simulate airflow in these models to compare the volumetric flow rate, flow velocity, pressure, wall shear, and vortex. The volume flow rate in the laryngomalacia model was significantly reduced compared with the control model. Under inspiratory pressures, the peak flow velocity, pressure, and shear force in the control model appeared at the soft palate stenosis, while that in the laryngomalacia model appeared at the supraglottis stenosis. In both models, the maximum flow velocity and shear force increased with decreasing inspiratory pressure, while the minimum pressure decreased with decreasing inspiratory pressure. In the control model, the airflow vortex appeared anteriorly below the posterior section of the soft palate. In the laryngomalacia model, the vortex appeared anteriorly below the posterior section of the soft palate and anteriorly below the vocal folds. Our methodology provides a new mechanistic understanding of pediatric laryngomalacia.
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Lin S, Premaraj TS, Gamage PT, Dong P, Premaraj S, Gu L. Upper Airway Flow Dynamics in Obstructive Sleep Apnea Patients with Various Apnea-Hypopnea Index. Life (Basel) 2022; 12:1080. [PMID: 35888168 PMCID: PMC9318930 DOI: 10.3390/life12071080] [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: 05/31/2022] [Revised: 07/03/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023] Open
Abstract
BACKGROUND AND AIM This study evaluates the upper airway flow characteristics, anatomical features and analyzes their correlations with AHI in patients with varied degrees of OSA severity seeking for discernments of the underlying pathophysiological profile. MATERIALS AND METHODS Patient-specific computational fluid dynamics models were reconstructed from high-resolution cone-beam computed tomography images for 4 OSA patients classified as minimal, mild, moderate, and severe according to AHI. RESULTS The parameters, minimal cross-sectional area (MCA), and the pharyngeal airway volume did not show clear correlations with the OSA severity defined according to AHI. No correlations were found between the classically defined resistance of the airway in terms of pressure drop and AHI. The flow analysis further showed that the fluid mechanisms likely to cause airway collapse are associated with the degree of narrowing in the pharyngeal airway rather than AHI. Results also suggested that some patients classified as severe OSA according to the AHI can show less susceptibility to airway collapse than patients with relatively lower AHI values and vice versa. CONCLUSIONS The relative contribution of anatomical and non-anatomical causes to the OSA severity can significantly vary between patients. AHI alone is inadequate to be used as a marker of the pathophysiological profile of OSA. Combining airflow analysis with AHI in diagnosing OSA severity may provide additional details about the underlying pathophysiology, subsequently improving the individualized clinical outcomes.
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Affiliation(s)
- Shengmao Lin
- School of Civil Engineering and Architecture, Xiamen University of Technology, Xiamen 361024, China;
| | | | - Peshala T. Gamage
- Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA;
| | - Pengfei Dong
- Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA;
| | - Sundaralingam Premaraj
- College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, FL 33328, USA; (T.S.P.); (S.P.)
| | - Linxia Gu
- Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA;
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Cai H, Xu C, Xue H, Guo Y, Su L, Gao X. Upper airway flow characteristics of childhood obstructive sleep apnea-hypopnea syndrome. Sci Rep 2022; 12:7386. [PMID: 35513462 PMCID: PMC9072398 DOI: 10.1038/s41598-022-10367-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 04/06/2022] [Indexed: 11/17/2022] Open
Abstract
Revealing the structural morphology and inner flow field of the upper airway is important for understanding obstructive sleep apnea-hypopnea syndrome (OSAHS) incidence phenomena and pathological diagnosis in children. However, prior work on this topic has been focused on adults and the findings cannot be directly extrapolated to children because of different inducing factors. Therefore, this paper employs a simulation method to investigate upper airway flow characteristics of childhood OSAHS. It is found that the Reynold number changes highly throughout the whole upper airway, and the laminar assumption is no longer suitable for low Reynold number flow, which is much unlike classic fluid mechanics. Turbulent models of Standard k-ω and Spalart-Allmaras were developed prior to suggestion. The simulation is validated by experiments with an error of approximately 20%. Additionally, carried out in this analysis is the influence of adenoidal hypertrophy with different narrow levels. The cross-sectional area, flow velocity, pressure drop and volume rate will change greatly when the narrow level is above 64% of the upper airway, which can be a quantitative explanation for medical intervention if adenoid hypertrophy blocks 2/3 of the upper airway in the common clinical judgment of otorhinolaryngology. It is expected that this paper can be a meaningful instruction on OSAHS surgery plan making as well as recovery evaluation postoperatively.
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Affiliation(s)
- Huikun Cai
- Department of Mechanical and Electrical Engineering, Xiamen University, No. 4221-134, Xiangan South Road, Xiangan South District, Xiamen City, 361102, Fujian Province, China.
| | - Chang Xu
- Department of Mechanical and Electrical Engineering, Xiamen University, No. 4221-134, Xiangan South Road, Xiangan South District, Xiamen City, 361102, Fujian Province, China
| | - Haoyang Xue
- Department of Mechanical and Electrical Engineering, Xiamen University, No. 4221-134, Xiangan South Road, Xiangan South District, Xiamen City, 361102, Fujian Province, China
| | - Yufeng Guo
- Children's Hospital of Xiamen, Xiamen City, 361006, Fujian Province, China
| | - Lijun Su
- Department of Mechanical and Electrical Engineering, Xiamen University, No. 4221-134, Xiangan South Road, Xiangan South District, Xiamen City, 361102, Fujian Province, China
| | - Xingqiang Gao
- Children's Hospital of Xiamen, Xiamen City, 361006, Fujian Province, China
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Yamagata K, Shinozuka K, Ogisawa S, Himejima A, Azaki H, Nishikubo S, Sato T, Suzuki M, Tanuma T, Tonogi M. A preoperative predictive study of advantages of airway changes after maxillomandibular advancement surgery using computational fluid dynamics analysis. PLoS One 2021; 16:e0255973. [PMID: 34379704 PMCID: PMC8357109 DOI: 10.1371/journal.pone.0255973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 07/27/2021] [Indexed: 11/18/2022] Open
Abstract
The purpose of this study was to develop a simulation approach for predicting maxillomandibular advancement-induced airway changes using computational fluid dynamics. Eight patients with jaw deformities who underwent maxillomandibular advancement and genioglossus advancement surgery were included in this study. Computed tomography scans and rhinomanometric readings were performed both preoperatively and postoperatively. Computational fluid dynamics models were created, and airflow simulations were performed using computational fluid dynamics software; the preferable number of computational mesh points was at least 10 million cells. The results for the right and left nares, including simulation and postoperative measurements, were qualitatively consistent, and surgery reduced airflow pressure loss. Geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. Simulations were performed with either the right or left naris blocked, and the predicted values were similar to those found clinically. In addition, geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. These findings suggest that geometry prediction simulation facilitates the preoperative prediction of the postoperative structural outcome.
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Affiliation(s)
- Kanako Yamagata
- Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan.,Laboratory of Fluid-Structural Simulation and Design, Strategic Innovation and Research Center, Teikyo University, Tokyo, Japan
| | - Keiji Shinozuka
- Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan
| | - Shouhei Ogisawa
- Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan
| | - Akio Himejima
- First Department of Oral and Maxillofacial Surgery, Osaka Dental University, Osaka, Japan
| | - Hiroaki Azaki
- Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan
| | - Shuichi Nishikubo
- Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan
| | - Takako Sato
- Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan
| | - Masaaki Suzuki
- Department of Otolaryngology, Teikyo University Chiba Medical Center, Chiba, Japan
| | - Tadashi Tanuma
- Laboratory of Fluid-Structural Simulation and Design, Strategic Innovation and Research Center, Teikyo University, Tokyo, Japan
| | - Morio Tonogi
- Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan
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A New Method for Anterior Boundary Demarcation of the Nasopharynx in Three-Dimensional Analysis. J Craniofac Surg 2021; 33:400-403. [PMID: 34320585 DOI: 10.1097/scs.0000000000008033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
ABSTRACT Three-dimensional (3D) measurements of the upper airway have been extensively applied and researched, but the division of the airway is carried out in various ways, especially when demarcating the anterior boundary of the nasopharynx. The present study was to propose a new method based on the anatomical definition for the anterior boundary demarcation of the nasopharynx used in three-dimensional analysis. Twenty computed tomography scans (age 9.5 ± 2.5 years, 11 males, and 9 females) of head and neck were randomly selected and transferred to Materialism's interactive medical image control system 19.0 for segmentation of the nasopharynx. Precise localization of the reference points that determining the nasopharyngeal anterior and inferior boundaries was managed by recording their coordinates in the interface of the software. The area of the anterior and the inferior boundaries, and the volume of the nasopharynx were measured and repeated with a 2-week interval for the consistency test. Both the interobserver reliability as well as the intra-observer reliability were very high (intraclass correlation coefficients, 0.985-0.997). Paired t test showed no significant difference between the first and the second examinations. This new simple method proposed for demarcation of the nasopharyngeal anterior boundary was based on the innate anatomical boundary, which was statistically reliable, technically convenient, and clinically reasonable.
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Bitners AC, Sin S, Agrawal S, Lee S, Udupa JK, Tong Y, Wootton DM, Choy KR, Wagshul ME, Arens R. Effect of sleep on upper airway dynamics in obese adolescents with obstructive sleep apnea syndrome. Sleep 2021; 43:5819384. [PMID: 32280981 DOI: 10.1093/sleep/zsaa071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Indexed: 02/06/2023] Open
Abstract
STUDY OBJECTIVES The biomechanical basis of obstructive sleep apnea syndrome (OSAS) may influence upper airway dynamics. In this study, we investigate dynamic changes during respiration in wakefulness and sleep in obese adolescents with and without OSAS. METHODS Respiratory-gated dynamic magnetic resonance imaging (MRI) at the retropalatal and retroglossal regions was performed with simultaneous measurement of SpO2 and nasal-oral mask airflow and pressure. Airway cross-sectional area (CSA) was determined using AMIRA. Percent change in CSA was calculated from five continuous tidal breaths in states of wakefulness and sleep. Mixed effects models were used to evaluate interactions between group (OSAS/control), site (retropalatal/retroglossal), and stage (wake/sleep). RESULTS We studied 24 children with OSAS (mean age 15.49 ± 2.00 years, mean apnea-hypopnea index [AHI] 16.53 ± 8.72 events/h) and 19 controls (mean age 14.86 ± 1.75 years, mean AHI 2.12 ± 1.69 events/h). Groups were similar in age, sex, height, weight, and BMI Z-score. Participants with OSAS had a 48.17% greater increase in percent change of airway CSA during sleep than controls (p < 0.0001), while there was no difference between groups during wakefulness (p = 0.6589). Additionally, participants with OSAS had a 48.80% increase in percent change of airway CSA during sleep as compared with wakefulness (p < 0.0001), whereas no such relationship was observed in controls (p = 0.5513). CONCLUSIONS This study demonstrates significant effects of sleep on upper airway dynamics in obese children with OSAS. Dynamic MRI with physiological data can potentially provide further insight into the biomechanical basis of OSAS and assist in more effective management.
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Affiliation(s)
| | - Sanghun Sin
- Department of Pediatrics, Division of Respiratory and Sleep Medicine, Children's Hospital at Montefiore, Bronx, NY
| | - Sabhyata Agrawal
- Department of Pediatrics, Division of Respiratory and Sleep Medicine, Children's Hospital at Montefiore, Bronx, NY
| | - Seonjoo Lee
- Department of Biostatistics and Psychiatry, Columbia University and New York State Psychiatric Institute, New York, NY
| | - Jayaram K Udupa
- Department of Radiology, University of Pennsylvania, Philadelphia, PA
| | - Yubing Tong
- Department of Radiology, University of Pennsylvania, Philadelphia, PA
| | - David M Wootton
- Department of Mechanical Engineering, Cooper Union, New York, NY
| | - Kok Ren Choy
- Department of Mechanical Engineering, Cooper Union, New York, NY
| | - Mark E Wagshul
- Albert Einstein College of Medicine, Bronx, NY.,Department of Radiology, Montefiore Medical Center, Bronx, NY
| | - Raanan Arens
- Albert Einstein College of Medicine, Bronx, NY.,Department of Pediatrics, Division of Respiratory and Sleep Medicine, Children's Hospital at Montefiore, Bronx, NY
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Chen S, Wang J, Liu D, Lei L, Wu W, Liu Z, Lee C. Open oral cavity has little effects on upper airway aerodynamics in children with obstructive sleep apnea syndrome: A computational fluid dynamics study based on patient-specific models. J Biomech 2021; 121:110383. [PMID: 33848827 DOI: 10.1016/j.jbiomech.2021.110383] [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: 06/17/2020] [Revised: 02/10/2021] [Accepted: 03/10/2021] [Indexed: 11/15/2022]
Abstract
Obstructive sleep apnea syndrome (OSAS) is a common disorder with recurrent pharyngeal airway collapse and sleep disruption. Recently, great progress has been made in investigating the physical mechanism of OSAS development and treatment using computational fluid dynamics (CFD). However, previous studies always neglected the oral cavity artificially in the patient's upper airway CFD model, but did not give any specific explanation. The oral cavity effect on the OSAS upper airway flow is still a matter of unclear. This paper reconstructed the patient-specific upper airway models based on the cone beam computed tomography images of ten children subjects (seven boys and three girls) and used CFD to simulate both the steady and unsteady expiration and inspiration states in the upper airway model with or without the oral cavity. A series of pressure measurement experiments based on the in vitro 1:1 scaled airway model were performed to validate the reliability of the present CFD methods. Finally, the CFD results indicate that the open oral cavity is almost a region of flow stasis with constant pressure, and both the upper airway aerodynamics with and without the oral cavity have the similar trends, with the maximum average relative difference less than 6%. The present study shows that the open oral cavity causes very little impacts on the upper airway flow of the children patients with OSAS using the nasal respiration only, and confirms the reasonability of ignoring the oral cavity for CFD simulation.
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Affiliation(s)
- Shuai Chen
- Department of Orthodontics, School and Hospital of Stomatology, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration & Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan 250012, China
| | - Jingying Wang
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China.
| | - Dongxu Liu
- Department of Orthodontics, School and Hospital of Stomatology, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration & Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan 250012, China.
| | - Li Lei
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China
| | - Wei Wu
- Department of Stomatology, The Affiliated Hospital of Qingdao University, Qingdao 266000, China; Department of Stomatology, Weifang People's Hospital, Weifang 261041, China
| | - Zhenggang Liu
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China
| | - Chunhian Lee
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China
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Tang H, Liu P, Xu Q, Hou Y, Guo J. A comparative analysis of aerodynamic and anatomic characteristics of upper airway before and after mini-implant-assisted rapid maxillary expansion. Am J Orthod Dentofacial Orthop 2021; 159:e301-e310. [PMID: 33541787 DOI: 10.1016/j.ajodo.2020.12.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/01/2020] [Accepted: 12/01/2020] [Indexed: 10/22/2022]
Abstract
INTRODUCTION The objective of this research was to observe changes in aerodynamics and anatomic characteristics of the upper airway after mini-implants assisted rapid maxillary expansion and to evaluate the correlation between the 2 changes of the upper airway in young adults. METHODS Thirty consecutive patients (mean age, 23.82 ± 3.90 years; median, 24.5 years; 9 males, 21 females) were involved. Cone-beam computed tomography was taken before activation and over 3 months. Three-dimensional models of the upper airway were reconstructed on the basis of cone-beam computed tomography. The anatomic characteristics of the upper airway, including volume, area, transverse, and sagittal diameter, were measured. The aerodynamic characteristics of the upper airway were calculated on the basis of 3-dimensional models using computational fluid dynamics. The correlation between the changes in aerodynamics and anatomic characteristics of the upper airway was explored. RESULTS The enlargements of the volume of the total pharynx, nasopharynx, and oropharynx were found (9.99%, 20.7%, and 8.84%, respectively). The minimum cross-sectional area increased significantly (13.6%). The airway resistance (R) and maximum velocity (Vmax) decreased significantly in both the inspiration and expiration phase (inspiration: R, -26.8%, Vmax, -15.7%; expiration: R, -24.7%, Vmax, -16.5%). The minimum wall shear stress reduced significantly only in the inspiration phase (-26.3%). The correlations between decreased R and increased volume and minimum cross-sectional area were observed. CONCLUSIONS Mini-implants assisted rapid maxillary expansion is an effective device for improving anatomic characteristics represented by the total volume of the upper airway and minimum cross-sectional area, which contributed to the respiratory function depending on the favorable changes of aerodynamic characteristics including resistance, velocity, and minimum wall shear stress.
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Affiliation(s)
- Hongyi Tang
- Department of Orthodontics, School and Hospital of Stomatology, Shandong University, Shandong Key Laboratory of Oral Tissue Regeneration, and Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan, Shandong, China
| | - Panpan Liu
- Department of Orthodontics, School and Hospital of Stomatology, Shandong University, Shandong Key Laboratory of Oral Tissue Regeneration, and Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan, Shandong, China
| | - Qiuping Xu
- Department of Orthodontics, School and Hospital of Stomatology, Shandong University, Shandong Key Laboratory of Oral Tissue Regeneration, and Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan, Shandong, China
| | - Yingyue Hou
- Department of Orthodontics, School and Hospital of Stomatology, Shandong University, Shandong Key Laboratory of Oral Tissue Regeneration, and Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan, Shandong, China
| | - Jing Guo
- Department of Orthodontics, School and Hospital of Stomatology, Shandong University, Shandong Key Laboratory of Oral Tissue Regeneration, and Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan, Shandong, China.
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Morphologic and Aerodynamic Changes of Upper Airway in Pediatric Hemifacial Microsomia Patients Undergoing Distraction Osteogenesis. J Craniofac Surg 2020; 31:2132-2135. [PMID: 33136841 DOI: 10.1097/scs.0000000000006899] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Current studies on hemifacial microsomia (HFM) patients undergoing unilateral distraction osteogenesis (DO) mainly confined to description of facial morphology. This study was to investigate the effect of unilateral DO on upper airway in pediatric HFM patients using computational fluid dynamics. The investigators implemented the present retrospective study composed of 20 patients (age 9.5 ± 2.5 years, 11 males, 9 females) with moderate HFM performed unilateral DO on the ramus of mandible. Computational fluid dynamics models of the upper airway were obtained based on the computed tomography data sets which were taken before and 6 months after distraction. Morphologic and aerodynamic parameters were respectively computed and compared at peak inspiration. Paired t-tests were used to compare the differences between the before and after parameters with the significance set at P < 0.05. The authors observed that after DO, oropharynx and nasopharynx were the major expanded regions, average pressure increased in all cross-sections, average velocity decreased significantly except in the superior border of the epiglottis plane, and the airflow resistance significantly reduced in the whole upper airway (P < 0.05). The results indicate that unilateral DO may expand the constricted oropharynx and nasopharynx, obtain a relatively symmetrical airway shape and decrease the airflow resistance which consequently reduce the workload necessary for breathing and facilitate inspiration.
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Faizal WM, Ghazali NNN, Khor CY, Badruddin IA, Zainon MZ, Yazid AA, Ibrahim NB, Razi RM. Computational fluid dynamics modelling of human upper airway: A review. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 196:105627. [PMID: 32629222 PMCID: PMC7318976 DOI: 10.1016/j.cmpb.2020.105627] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/21/2020] [Indexed: 05/12/2023]
Abstract
BACKGROUND AND OBJECTIVE Human upper airway (HUA) has been widely investigated by many researchers covering various aspects, such as the effects of geometrical parameters on the pressure, velocity and airflow characteristics. Clinically significant obstruction can develop anywhere throughout the upper airway, leading to asphyxia and death; this is where recognition and treatment are essential and lifesaving. The availability of advanced computer, either hardware or software, and rapid development in numerical method have encouraged researchers to simulate the airflow characteristics and properties of HUA by using various patient conditions at different ranges of geometry and operating conditions. Computational fluid dynamics (CFD) has emerged as an efficient alternative tool to understand the airflow of HUA and in preparing patients to undergo surgery. The main objective of this article is to review the literature that deals with the CFD approach and modeling in analyzing HUA. METHODS This review article discusses the experimental and computational methods in the study of HUA. The discussion includes computational fluid dynamics approach and steps involved in the modeling used to investigate the flow characteristics of HUA. From inception to May 2020, databases of PubMed, Embase, Scopus, the Cochrane Library, BioMed Central, and Web of Science have been utilized to conduct a thorough investigation of the literature. There had been no language restrictions in publication and study design of the database searches. A total of 117 articles relevant to the topic under investigation were thoroughly and critically reviewed to give a clear information about the subject. The article summarizes the review in the form of method of studying the HUA, CFD approach in HUA, and the application of CFD for predicting HUA obstacle, including the type of CFD commercial software are used in this research area. RESULTS This review found that the human upper airway was well studied through the application of computational fluid dynamics, which had considerably enhanced the understanding of flow in HUA. In addition, it assisted in making strategic and reasonable decision regarding the adoption of treatment methods in clinical settings. The literature suggests that most studies were related to HUA simulation that considerably focused on the aspects of fluid dynamics. However, there is a literature gap in obtaining information on the effects of fluid-structure interaction (FSI). The application of FSI in HUA is still limited in the literature; as such, this could be a potential area for future researchers. Furthermore, majority of researchers present the findings of their work through the mechanism of airflow, such as that of velocity, pressure, and shear stress. This includes the use of Navier-Stokes equation via CFD to help visualize the actual mechanism of the airflow. The above-mentioned technique expresses the turbulent kinetic energy (TKE) in its result to demonstrate the real mechanism of the airflow. Apart from that, key result such as wall shear stress (WSS) can be revealed via turbulent kinetic energy (TKE) and turbulent energy dissipation (TED), where it can be suggestive of wall injury and collapsibility tissue to the HUA.
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Affiliation(s)
- W M Faizal
- Department of Mechanical Engineering Technology, Faculty of Engineering Technology, University Malaysia Perlis, 02100 Padang Besar, Perlis, Malaysia; Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - N N N Ghazali
- Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - C Y Khor
- Department of Mechanical Engineering Technology, Faculty of Engineering Technology, University Malaysia Perlis, 02100 Padang Besar, Perlis, Malaysia
| | - Irfan Anjum Badruddin
- Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. Box 9004, Abha, 61413, Asir, Kingdom Saudi Arabia; Mechanical Engineering Department, College of Engineering, King Khalid University, PO Box 394, Abha, 61421, Kingdom of Saudi Arabia.
| | - M Z Zainon
- Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Aznijar Ahmad Yazid
- Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Norliza Binti Ibrahim
- Department of Oral and Maxillofacial Clinical Science, Faculty of Dentistry, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Roziana Mohd Razi
- Department of Paediatric Dentistry and Orthodontics, Faculty of Dentistry, University of Malaya, 50603, Kuala Lumpur, Malaysia
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Yanagisawa-Minami A, Sugiyama T, Iwasaki T, Yamasaki Y. Primary site identification in children with obstructive sleep apnea by computational fluid dynamics analysis of the upper airway. J Clin Sleep Med 2020; 16:431-439. [PMID: 31992411 DOI: 10.5664/jcsm.8224] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
STUDY OBJECTIVES Obstructive sleep apnea (OSA) is a respiratory disorder caused by the obstruction of the upper airway during sleep. The identification of the primary site of OSA is essential to determine treatment strategy. This study aimed to establish computational fluid dynamics (CFD) analysis for determining the clinical severity of OSA and the primary site of OSA. METHODS Twenty children (mean age, 6 years) were divided into OSA and control groups according to their apnea-hypopnea index. Three-dimensional airways were constructed from computed tomography data. The pharyngeal airway morphology and the pressure and velocity of the upper airway were evaluated using CFD analysis. RESULTS The maximum velocity and negative pressure of the upper airway in the OSA group were significantly correlated with the severity of OSA (rs = .741, P < .001; rs = -.653, P = .002). A velocity higher than 12 m/s indicated the primary site of OSA. In addition, we found that the primary site of OSA is not necessarily the same as the collapsible conduit site. CONCLUSIONS CFD analysis allows both the evaluation of the disease severity of OSA and the identification of the primary site of OSA in children. The primary site of OSA is not necessarily the same as the collapsible conduit site; therefore, CFD analysis can be used to identify the appropriate intervention for treating OSA.
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Affiliation(s)
- Ayaka Yanagisawa-Minami
- Department of Pediatric Dentistry, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima, Kagoshima, Japan
| | - Takeshi Sugiyama
- Department of Pediatrics, Yamanashi University Graduate School of Medicine, Yamanashi, Japan.,Pediatrics, Ichinomiya-Nishi Hospital, Aichi, Japan
| | - Tomonori Iwasaki
- Department of Pediatric Dentistry, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima, Kagoshima, Japan
| | - Youichi Yamasaki
- Department of Pediatric Dentistry, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima, Kagoshima, Japan
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Numerical simulation of nasal airflows and thermal air modification in newborns. Med Biol Eng Comput 2019; 58:307-317. [PMID: 31848979 DOI: 10.1007/s11517-019-02092-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 11/27/2019] [Indexed: 12/23/2022]
Abstract
Warming, filtering, and humidification of inspired air are major functions of the upper airway, which can be negatively altered by local disorders or surgical interventions. These functions have not been described in neonates because of ethical and technical problems difficult to solve. Numerical simulations can get around these limitations. The objective of this study was to analyze physiological nasal airflow and thermal distribution using computational fluid dynamics (CFD) techniques in neonates. CT imaging of neonates was collected from the Pediatric Radiology Department of our center. CFD has been used to simulate nasal airflow numerically, with ambient air set at 19 °C, following the recommendations for a neonate's bedroom. Thermal distribution within the nasal cavity was analyzed and coupled with airflow patterns over complete respiratory cycles. Sixteen patients have been included in the study. During inspiration, important air warming is noticed in the first centimeter of the nasal cavity (+ 8 °C at the anterior end of the inferior turbinate). During the expiration phase, the temperature decreases slightly (- 3 °C) between the pharynx and the nostrils. A model with asymmetric nasal fossae showed that nasal obstruction leads to decreased airflow and abnormally high temperatures in the obstructed side (+ 2 °C at the nasal valve, + 4 °C at the choana). According to our results, the nasal valve area is of crucial importance in air warming in neonates, when ambient air is 19 °C, since about 70% of air warming is performed in this area. When needed, surgical interventions should respect the anatomy of this zone and restore normal airflows and warming. Graphical abstract .
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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: 11] [Impact Index Per Article: 2.2] [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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Sutherland K, Kairaitis K, Yee BJ, Cistulli PA. From CPAP to tailored therapy for obstructive sleep Apnoea. Multidiscip Respir Med 2018; 13:44. [PMID: 30524729 PMCID: PMC6276208 DOI: 10.1186/s40248-018-0157-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 10/30/2018] [Indexed: 12/20/2022] Open
Abstract
Obstructive Sleep Apnoea (OSA) is a common sleep disorder that is associated with daytime symptoms and a range of comorbidity and mortality. Continuous Positive Airway Pressure (CPAP) therapy is highly efficacious at preventing OSA when in use and has long been the standard treatment for newly diagnosed patients. However, CPAP therapy has well recognised limitations in real world effectiveness due to issues with patient acceptance and suboptimal usage. There is a clear need to enhance OSA treatment strategies and options. Although there are a range of alternative treatments (e.g. weight loss, oral appliances, positional devices, surgery, and emerging therapies such as sedatives and oxygen), generally there are individual differences in efficacy and often OSA will not be completely eliminated. There is increasing recognition that OSA is a heterogeneous disorder in terms of risk factors, clinical presentation, pathophysiology and comorbidity. Better characterisation of OSA heterogeneity will enable tailored approaches to therapy to ensure treatment effectiveness. Tools to elucidate individual anatomical and pathophysiological phenotypes in clinical practice are receiving attention. Additionally, recognising patient preferences, treatment enhancement strategies and broader assessment of treatment effectiveness are part of tailoring therapy at the individual level. This review provides a narrative of current treatment approaches and limitations and the future potential for individual tailoring to enhance treatment effectiveness.
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Affiliation(s)
- Kate Sutherland
- 1Charles Perkins Centre, The University of Sydney, Sydney, Australia.,2Faculty of Medicine & Health, The University of Sydney School of Medicine, Sydney, Australia.,3Centre for Sleep Health & Research, Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, Sydney, Australia
| | - Kristina Kairaitis
- 1Charles Perkins Centre, The University of Sydney, Sydney, Australia.,2Faculty of Medicine & Health, The University of Sydney School of Medicine, Sydney, Australia.,4Ludwig Engel Centre for Respiratory Research, Westmead Institute for Medical Research, University of Sydney, Sydney, Australia.,5Department of Respiratory and Sleep Medicine, Westmead Hospital, Sydney, Australia
| | - Brendon J Yee
- 2Faculty of Medicine & Health, The University of Sydney School of Medicine, Sydney, Australia.,6NHMRC Centre for Integrated Research and Understanding of Sleep (CIRUS) and NHMRC NeuroSleep Centre Woolcock Institute of Medical Research, Sydney, Australia.,7Department of Respiratory and Sleep Medicine, Royal Prince Alfred Hospital, Sydney, Australia
| | - Peter A Cistulli
- 1Charles Perkins Centre, The University of Sydney, Sydney, Australia.,2Faculty of Medicine & Health, The University of Sydney School of Medicine, Sydney, Australia.,3Centre for Sleep Health & Research, Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, Sydney, Australia
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22
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Bates AJ, Schuh A, McConnell K, Williams BM, Lanier JM, Willmering MM, Woods JC, Fleck RJ, Dumoulin CL, Amin RS. A novel method to generate dynamic boundary conditions for airway CFD by mapping upper airway movement with non-rigid registration of dynamic and static MRI. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3144. [PMID: 30133165 DOI: 10.1002/cnm.3144] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/21/2018] [Accepted: 08/12/2018] [Indexed: 06/08/2023]
Abstract
Computational fluid dynamics (CFD) simulations of airflow in the human airways have the potential to provide a great deal of information that can aid clinicians in case management and surgical decision making, such as airway resistance, energy expenditure, airflow distribution, heat and moisture transfer, and particle deposition, as well as the change in each of these due to surgical interventions. However, the clinical relevance of CFD simulations has been limited to date, as previous models either did not incorporate neuromuscular motion or any motion at all. Many common airway pathologies, such as obstructive sleep apnea (OSA) and tracheomalacia, involve large movements of the structures surrounding the airway, such as the tongue and soft palate. Airway wall motion may be due to many factors including neuromuscular motion, internal aerodynamic forces, and external forces such as gravity. Therefore, to realistically model these airway diseases, a method is required to derive the airway wall motion, whatever the cause, and apply it as a boundary condition to CFD simulations. This paper presents and validates a novel method of capturing in vivo motion of airway walls from magnetic resonance images with high spatiotemporal resolution, through a novel combination of non-rigid image, surface, and surface-normal-vector registration. Coupled with image-synchronous pneumotachography, this technique provides the necessary boundary conditions for dynamic CFD simulations of breathing, allowing the effect of the airway's complex motion to be calculated for the first time, in both normal subjects and those with conditions such as OSA.
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Affiliation(s)
- Alister J Bates
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Bioengineering, Imperial College London, UK
| | - Andreas Schuh
- Department of Computing, Imperial College London, UK
| | - Keith McConnell
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Brynne M Williams
- Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - J Matthew Lanier
- Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Matthew M Willmering
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Jason C Woods
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, USA
- Departments of Radiology and Physics, University of Cincinnati, Cincinnati, OH, USA
| | - Robert J Fleck
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Radiology, University of Cincinnati, Cincinnati, OH, USA
| | - Charles L Dumoulin
- Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, USA
| | - Raouf S Amin
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, USA
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Naughton JP, Lee AY, Ramos E, Wootton D, Stupak HD. Effect of Nasal Valve Shape on Downstream Volume, Airflow, and Pressure Drop: Importance of the Nasal Valve Revisited. Ann Otol Rhinol Laryngol 2018; 127:745-753. [PMID: 30191730 DOI: 10.1177/0003489418791597] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The relative importance of the nasal valve relative to the remainder of the nasal airway remains unknown. The goal of this article was to objectively measure the shape of the nasal inlet and its effect on downstream airflow and nasal cavity volume using a physical model and a physiologic flow model. METHODS A patient who had isolated nasal valve surgery and had pre- and postoperative computed tomography scans available for analysis was studied. Nasal inlet shape measurements, computational fluid dynamics, and nasal volume analysis were performed using the computed tomography data. In addition, a physical model was used to determine the effect of nasal obstruction on downstream soft tissue. RESULTS The postoperative shape of the nasal inlet was improved in terms of length and degree of tortuosity. Whereas the operated-on region at the nasal inlet showed an only 25% increase in cross-sectional area postoperatively, downstream nonoperated sites in the nasal cavity revealed increases in area ranging from 33% to 51%. Computational fluid dynamics analysis showed that airway resistance decreased by 42%, and pressure drop was reduced by 43%. Intraluminal mucosal expansion was found with nasal obstruction in the physical model. CONCLUSION By decreasing the degree of bending and length at the nasal valve, inspiratory downstream nonoperated sites of the nasal cavity showed improvement in volume and airflow, suggesting that the nasal valve could play an oversized role in modulating the aerodynamics of the airway. This was confirmed with the physical model of nasal obstruction on downstream mucosa.
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Affiliation(s)
- John P Naughton
- 1 Department of Otorhinolaryngology-Head & Neck Surgery, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Andrew Y Lee
- 1 Department of Otorhinolaryngology-Head & Neck Surgery, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Eric Ramos
- 2 Department of Mechanical Engineering, The Cooper Union, New York, New York, USA
| | - David Wootton
- 2 Department of Mechanical Engineering, The Cooper Union, New York, New York, USA
| | - Howard D Stupak
- 1 Department of Otorhinolaryngology-Head & Neck Surgery, Albert Einstein College of Medicine, Bronx, New York, USA
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Kimbell JS, Basu S, Garcia GJM, Frank-Ito DO, Lazarow F, Su E, Protsenko D, Chen Z, Rhee JS, Wong BJ. Upper airway reconstruction using long-range optical coherence tomography: Effects of airway curvature on airflow resistance. Lasers Surg Med 2018; 51:150-160. [PMID: 30051633 DOI: 10.1002/lsm.23005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/04/2018] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Adenotonsillectomy (AT) is commonly used to treat upper airway obstruction in children, but selection of patients who will benefit most from AT is challenging. The need for diagnostic evaluation tools without sedation, radiation, or high costs has motivated the development of long-range optical coherence tomography (LR-OCT), providing real-time cross-sectional airway imaging during endoscopy. Since the endoscope channel location is not tracked in conventional LR-OCT, airway curvature must be estimated and may affect predicted airway resistance. The study objective was to assess effects of three realistic airway curvatures on predicted airway resistance using computational fluid dynamics (CFD) in LR-OCT reconstructions of the upper airways of pediatric patients, before and after AT. METHODS Eight subjects (five males, three females, aged 4-9 years) were imaged using LR-OCT before and after AT during sedated endoscopy. Three-dimensional (3D) airway reconstructions included three airway curvatures. Steady-state, inspiratory airflow simulations were conducted under laminar conditions, along with turbulent simulations for one subject using the k-ω turbulence model. Airway resistance (pressure drop/flow) was compared using two-tailed Wilcoxon signed rank tests. RESULTS Regardless of the airway curvatures, CFD findings corroborate a surgical end-goal with computed post-operative airway resistance significantly less than pre-operative (P < 0.01). The individual resistances did not vary significantly for different airway curvatures (P > 0.25). Resistances computed using turbulent simulations differed from laminar results by less than ∼5%. CONCLUSIONS The results suggest that reconstruction of the upper airways from LR-OCT imaging data may not need to account for airway curvature to be predictive of surgical effects on airway resistance. Lasers Surg. Med. 51:150-160, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Julia S Kimbell
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Saikat Basu
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Guilherme J M Garcia
- Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin.,Medical College of Wisconsin, Biotechnology and Bioengineering Center, Milwaukee, Wisconsin
| | - Dennis O Frank-Ito
- Otolaryngology-Head and Neck Surgery, Duke University Medical Center, Durham, North Carolina
| | - Frances Lazarow
- Beckman Laser Institute, University of California, Irvine, California
| | - Erica Su
- Beckman Laser Institute, University of California, Irvine, California
| | - Dimitry Protsenko
- Beckman Laser Institute, University of California, Irvine, California
| | - Zhongping Chen
- Beckman Laser Institute, University of California, Irvine, California
| | - John S Rhee
- Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Brian J Wong
- Beckman Laser Institute, University of California, Irvine, California.,Otolaryngology-Head and Neck Surgery, University of California, Irvine, California
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Patel TR, Li C, Krebs J, Zhao K, Malhotra P. Modeling congenital nasal pyriform aperture stenosis using computational fluid dynamics. Int J Pediatr Otorhinolaryngol 2018; 109:180-184. [PMID: 29728177 PMCID: PMC5942217 DOI: 10.1016/j.ijporl.2018.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 02/15/2018] [Accepted: 04/02/2018] [Indexed: 10/17/2022]
Abstract
OBJECTIVES Congenital nasal pyriform aperture stenosis (CNPAS) is a rare cause of airway obstruction in the neonate. Computational airway modeling has not been done in neonates and young infants to understand the impact of stenosis on functional nasal airflow. In this study, we 1) applied computational fluid dynamics (CFD) model to the airway of a neonate with CNPAS and 2) compare airflow dynamics of a normal and CNPAS airway. METHODS Three-dimensional models of the nasal airway of a normal neonate and a neonate with CNPAS were created using computed tomography scans of the facial bones. Measured anatomic parameters included volume, surface area, and cross-sectional area. CFD simulation was then performed. Simulated flow parameters included pressure, average velocity, and resistance. RESULTS The neonate with CNPAS had a lesser volume (2.74 cm3 vs. 4.50 cm3) and surface area (18.8 cm2 vs. 45.5 cm2) than the normal airway. The CNPAS airway had a lesser bilateral cross-sectional area and average cross-sectional velocity throughout the length of the model. While there is a large pressure drop in the normal airway immediately after the entry point, the pressure drop in the CNPAS airway occurs more posteriorly. The total nasal resistance was approximately eight-fold greater in the CNPAS airway than the normal. CONCLUSIONS CFD analysis can be performed on airways of neonates with nasal obstruction, such as in CNPAS. A CFD model may help characterize severity of airway obstruction as it can predict the three-dimensional pattern of airflow. Determining the role of CFD in clinical management of CNPAS requires further investigation.
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Affiliation(s)
- Tirth R. Patel
- College of Medicine, The Ohio State University; 370 West
9th Avenue, Columbus, Ohio, USA 43210
| | - Chengyu Li
- Department of Otolaryngology-Head and Neck Surgery, The Ohio State University Wexner Medical Center, 915 Olentangy River Road Suite 4000, Columbus, OH 43212, USA.
| | - Jillian Krebs
- Department of Otolaryngology—Head and Neck Surgery, The Ohio
State University Wexner Medical Center; 915 Olentangy River Road Suite 4000,
Columbus, Ohio, USA 43212
| | - Kai Zhao
- Department of Otolaryngology-Head and Neck Surgery, The Ohio State University Wexner Medical Center, 915 Olentangy River Road Suite 4000, Columbus, OH 43212, USA.
| | - Prashant Malhotra
- Department of Otolaryngology-Head and Neck Surgery, The Ohio State University Wexner Medical Center, 915 Olentangy River Road Suite 4000, Columbus, OH 43212, USA; Department of Otolaryngology, Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA.
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Subramaniam DR, Arens R, Wagshul ME, Sin S, Wootton DM, Gutmark EJ. Biomechanics of the soft-palate in sleep apnea patients with polycystic ovarian syndrome. J Biomech 2018; 76:8-15. [PMID: 29793766 DOI: 10.1016/j.jbiomech.2018.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 05/01/2018] [Accepted: 05/07/2018] [Indexed: 11/28/2022]
Abstract
Highly compliant tissue supporting the pharynx and low muscle tone enhance the possibility of upper airway occlusion in children with obstructive sleep apnea (OSA). The present study describes subject-specific computational modeling of flow-induced velopharyngeal narrowing in a female child with polycystic ovarian syndrome (PCOS) with OSA and a non-OSA control. Anatomically accurate three-dimensional geometries of the upper airway and soft-palate were reconstructed for both subjects using magnetic resonance (MR) images. A fluid-structure interaction (FSI) shape registration analysis was performed using subject-specific values of flow rate to iteratively compute the biomechanical properties of the soft-palate. The optimized shear modulus for the control was 38 percent higher than the corresponding value for the OSA patient. The proposed computational FSI model was then employed for planning surgical treatment for the apneic subject. A virtual surgery comprising of a combined adenoidectomy, palatoplasty and genioglossus advancement was performed to estimate the resulting post-operative patterns of airflow and tissue displacement. Maximum flow velocity and velopharyngeal resistance decreased by 80 percent and 66 percent respectively following surgery. Post-operative flow-induced forces on the anterior and posterior faces of the soft-palate were equilibrated and the resulting magnitude of tissue displacement was 63 percent lower compared to the pre-operative case. Results from this pilot study indicate that FSI computational modeling can be employed to characterize the mechanical properties of pharyngeal tissue and evaluate the effectiveness of various upper airway surgeries prior to their application.
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Affiliation(s)
| | - Raanan Arens
- Division of Respiratory and Sleep Medicine, The Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Mark E Wagshul
- Gruss Magnetic Resonance Research Center, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Sanghun Sin
- Division of Respiratory and Sleep Medicine, The Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY, USA
| | - David M Wootton
- Department of Mechanical Engineering, The Cooper Union for the Advancement of Science and Art, New York, NY, USA
| | - Ephraim J Gutmark
- Department of Aerospace Engineering and Engineering Mechanics, CEAS, University of Cincinnati, Cincinnati, OH, USA; UC Department of Otolaryngology - Head and Neck Surgery, Cincinnati, OH, USA.
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Slaats MALJ, Loterman D, van Holsbeke C, Vos W, Van Hoorenbeeck K, de Backer J, de Backer W, Wojciechowski M, Boudewyns A, Verhulst S. The Role of Functional Respiratory Imaging in Treatment Selection of Children With Obstructive Sleep Apnea and Down Syndrome. J Clin Sleep Med 2018; 14:651-659. [PMID: 29609707 DOI: 10.5664/jcsm.7064] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 01/17/2018] [Indexed: 12/14/2022]
Abstract
STUDY OBJECTIVES The complexity of the pathogenesis of obstructive sleep apnea (OSA) in children with Down syndrome (DS) is illustrated by a prevalence of residual OSA after adenotonsillectomy. The aim of this study was to investigate whether upper airway imaging combined with computation fluid dynamics could characterize treatment outcome after adenotonsillectomy in these children. METHODS Children with DS and OSA were prospectively included. All children underwent an evaluation of the upper airway and an ultra-low dose computed tomography scan of the upper airway before adenotonsillectomy. The upper airway tract was extracted from the scan and combined with computational fluid dynamics. Results were evaluated using control polysomnography after adenotonsillectomy. RESULTS Thirty-three children were included: 18 boys, age 4.3 ± 2.3 years, median body mass index z-score 0.6 (-2.9 to 3.0), and median obstructive apnea-hypopnea index was 15.7 (3-70) events/h. The minimal upper airway cross-sectional area was significantly smaller in children with more severe OSA (P = .03). Nineteen children underwent a second polysomnography after adenotonsillectomy. Seventy-nine percent had persistent OSA (obstructive apneahypopnea index > 2 events/h). A greater than 50% decrease in obstructive apnea-hypopnea index was observed in 79% and these children had a significantly higher volume of the regions below the tonsils. CONCLUSIONS This is the first study to characterize treatment outcome in children with DS and OSA using computed tomography upper airway imaging. At baseline, children with more severe OSA had a smaller upper airway. Children with a less favorable response to adenotonsillectomy had a smaller volume of regions below the tonsils, which could be due to enlargement of the lingual tonsils, glossoptosis, or macroglossia. COMMENTARY A commentary on this article appears in this issue on page 501.
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Affiliation(s)
| | | | | | - Wim Vos
- Technology, Biomedical Physics, FluidDA, Kontich, Belgium
| | | | - Jan de Backer
- Technology, Biomedical Physics, FluidDA, Kontich, Belgium
| | - Wilfried de Backer
- Department of Pulmonology, University Hospital Antwerp, Antwerp, Belgium
| | | | - An Boudewyns
- Department of Pediatrics, University Hospital Antwerp, Antwerp, Belgium
| | - Stijn Verhulst
- Department of Pediatrics, Pediatric Sleep Lab at Antwerp University Hospital, Antwerp, Belgium
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Liu Y, Mitchell J, Chen Y, Yim W, Chu W, Wang RC. Study of the upper airway of obstructive sleep apnea patient using fluid structure interaction. Respir Physiol Neurobiol 2018; 249:54-61. [DOI: 10.1016/j.resp.2018.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/30/2017] [Accepted: 01/04/2018] [Indexed: 11/17/2022]
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Chen H, Li Y, Reiber JH, de Lange J, Tu S, van der Stelt P, Lobbezoo F, Aarab G. Analyses of aerodynamic characteristics of the oropharynx applying CBCT: obstructive sleep apnea patients versus control subjects. Dentomaxillofac Radiol 2018; 47:20170238. [PMID: 29076751 DOI: 10.1259/dmfr.20170238] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVES To determine the most relevant aerodynamic characteristic of the oropharynx related to the collapse of the upper airway in obstructive sleep apnea (OSA) patients; and to determine the correlation between the most relevant aerodynamic characteristic(s) of the oropharynx and anatomical characteristics of the oropharynx in OSA patients. METHODS 31 mild to moderate OSA patients (mean ± SD age = 43.5 ± 9.7 years) and 13 control subjects (mean ± SD age = 48.5 ± 16.2 years) were included in this prospective study. The diagnosis of OSA patients was based on an overnight polysomnographic recording. To exclude the presence of OSA in the control subjects, they were asked to fill out a validated questionnaire to determine the risk of OSA. NewTom5G cone beam CT (CBCT) scans were obtained from both OSA patients and control subjects. Computational models of the oropharynx were reconstructed based on CBCT images. The aerodynamic characteristics of the oropharynx were calculated based on these computational models. Pearson correlation analysis was used to analyse the correlation between the most relevant aerodynamic characteristic(s) and anatomical characteristics of the oropharynx in OSA patients. RESULTS Compared with controls, the airway resistance during expiration (Rex) of the OSA patients was significantly higher (p = 0.04). There was a significant negative correlation between Rex and the minimum cross-sectional area (CSAmin) of the oropharynx (r = -0.41, p = 0.02), and between Rex and the volume of the oropharynx (r = -0.48, p = 0.01) in OSA patients. After excluding an outlier, there is only significant correlation between Rex and the CSAmin of the oropharynx (r = -0.45, p = 0.01). CONCLUSIONS Within the limitations of this study, we concluded that the most relevant aerodynamic characteristic of the oropharynx in the collapse of the upper airway in OSA patients is Rex. Therefore, the repetitive collapse of the upper airway in OSA patients may be explained by a high Rex, which is related to the CSAmin of the oropharynx.
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Affiliation(s)
- Hui Chen
- 1 Department of Oral Radiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Amsterdam , The Netherlands.,2 Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Amsterdam , The Netherlands
| | - Yingguang Li
- 3 Division of Image Processing, Department of Radiology, Leiden University Medical Centre , Leiden University Medical Centre , Leiden , The Netherlands
| | - Johan Hc Reiber
- 3 Division of Image Processing, Department of Radiology, Leiden University Medical Centre , Leiden University Medical Centre , Leiden , The Netherlands
| | - Jan de Lange
- 4 Department of Oral and Maxillofacial Surgery, Academic Centre for Dentistry Amsterdam (ACTA) and Academic Medical Centre (AMC), University of Amsterdam and Vrije Universiteit Amsterdam , Academic Centre for Dentistry Amsterdam (ACTA) and Academic Medical Centre (AMC), University of Amsterdam and Vrije Universiteit Amsterdam , Amsterdam , The Netherlands
| | - Shengxian Tu
- 5 Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University , Shanghai , China
| | - Paul van der Stelt
- 1 Department of Oral Radiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Amsterdam , The Netherlands
| | - Frank Lobbezoo
- 2 Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Amsterdam , The Netherlands
| | - Ghizlane Aarab
- 2 Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam , Amsterdam , The Netherlands
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Subramaniam DR, Mylavarapu G, Fleck RJ, Amin RS, Shott SR, Gutmark EJ. Effect of airflow and material models on tissue displacement for surgical planning of pharyngeal airways in pediatric down syndrome patients. J Mech Behav Biomed Mater 2017; 71:122-135. [DOI: 10.1016/j.jmbbm.2017.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 03/04/2017] [Accepted: 03/06/2017] [Indexed: 12/01/2022]
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Slaats M, Vos W, Van Holsbeke C, De Backer J, Loterman D, De Backer W, Boudewyns A, Verhulst S. Predicting the effect of treatment in paediatric OSA by clinical examination and functional respiratory imaging. Pediatr Pulmonol 2017; 52:799-805. [PMID: 28267299 DOI: 10.1002/ppul.23684] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 12/15/2016] [Accepted: 02/09/2017] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The aim of this study was to investigate whether functional respiratory imaging (FRI) or clinical examination could predict treatment outcome for obstructive sleep apnea (OSA) in normal-weight, non-syndromic children. METHODS Normal weight children diagnosed with OSA by polysomnography were prospectively included. All children got a thorough evaluation and an ultra-low dose computed tomography scan of the upper airway (UA). A 3-D reconstruction was built combined with computational fluid dynamics for FRI. Decisions on the need and type of surgery were based upon findings during drug-induced sleep endoscopy. A second polysomnography was performed 3-12 months after surgery. RESULTS Ninety-one children were included: 62 boys, 5.0 ± 2.7 years, and BMI z-score of -0.1 ± 1.2. Children with more severe OSA had a smaller volume of the overlap region between the adenoids and tonsils. Nineteen out of 60 patients had persistent OSA (oAHI >2/h). A lower conductance in the UA and a higher tonsil score predicted successful treatment. CONCLUSIONS A less constricted airway, as characterized by both FRI and a lower tonsil score, was associated with a less favorable response to (adeno) tonsillectomy. Further studies after treatment using FRI and DISE are warranted to further characterize the UA of these subjects.
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Affiliation(s)
- Monique Slaats
- Department of Paediatrics, Antwerp University Hospital, Edegem, Belgium.,Laboratory of Experimental Medicine and Paediatrics (LEMP), University of Antwerp, Universiteitsplein 1, Antwerp, Belgium
| | | | | | | | | | - Wilfried De Backer
- Laboratory of Experimental Medicine and Paediatrics (LEMP), University of Antwerp, Universiteitsplein 1, Antwerp, Belgium.,Department of Respiratory Medicine, Antwerp University Hospital, Edegem, Belgium
| | - An Boudewyns
- Department of Otorhinolaryngology, Antwerp University Hospital, Edegem, Belgium
| | - Stijn Verhulst
- Department of Paediatrics, Antwerp University Hospital, Edegem, Belgium.,Laboratory of Experimental Medicine and Paediatrics (LEMP), University of Antwerp, Universiteitsplein 1, Antwerp, Belgium
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Zhang XQ, Wang H, Zhou J, Zeng P, Zhao Y, Zhang Y, Liu C, Jiang LQ, Lan YJ. Efficacy of minimally invasive tonsil surgery for treatment of obstructive sleep apnea-hypopnea syndrome in children. Braz J Med Biol Res 2017; 50:e5846. [PMID: 28443988 PMCID: PMC5441284 DOI: 10.1590/1414-431x20175846] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 02/20/2017] [Indexed: 11/22/2022] Open
Abstract
This study aimed to investigate the efficacy of minimally invasive tonsil surgery for the treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS) in children. Tonsil ablation or turbinate reduction was performed on 49 pediatric patients with OSAHS by minimally invasive tonsil surgery. In order to evaluate the efficacy of surgery, a comparison was conducted between pre-operation and post-operation data in terms of the symptoms, signs and polysomnography test. Total effectiveness rate of the surgery was 83.7%. Subgroup analysis was also performed based on the severity of their conditions: mild, moderate, and severe groups had an effectiveness rate of 90.0, 88.9, and 66.7%, respectively (Hc=6.665, P<0.05). Postoperatively, the apnea-hypopnea index, the minimum oxygen saturation (SaO2), and corresponding symptoms improved compared to pre-operation conditions (P<0.05). Minimally invasive tonsil surgery was a safe and effective method for treating OSAHS in children.
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Affiliation(s)
- X.-Q. Zhang
- Sleep Medicine Center, West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Occupational Health, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - H. Wang
- Sleep Medicine Center, West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Occupational Health, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - J. Zhou
- Sleep Medicine Center, West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - P. Zeng
- Sleep Medicine Center, West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Y. Zhao
- Sleep Medicine Center, West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Y. Zhang
- Department of Occupational Health, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - C. Liu
- Sleep Medicine Center, West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Occupational Health, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - L.-Q. Jiang
- Sleep Medicine Center, West China Fourth Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Y.-J. Lan
- Department of Occupational Health, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
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Yajima Y, Oshima M, Iwai T, Kitajima H, Omura S, Tohnai I. Computational fluid dynamics study of the pharyngeal airway space before and after mandibular setback surgery in patients with mandibular prognathism. Int J Oral Maxillofac Surg 2017; 46:839-844. [PMID: 28412180 DOI: 10.1016/j.ijom.2017.03.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 01/21/2017] [Accepted: 03/21/2017] [Indexed: 10/19/2022]
Abstract
The purpose of this study was to investigate the relationship between the pressure drop in the pharyngeal airway space (ΔPPAS) and the minimum cross-sectional area (minCSA) of the pharyngeal airway before and after mandibular setback surgery using computational fluid dynamics, in order to prevent iatrogenic obstructive sleep apnoea. Eleven patients with mandibular prognathism underwent bilateral sagittal split osteotomy for mandibular setback. Three-dimensional models of the upper airway were reconstructed from preoperative and postoperative computed tomography images, and simulations were performed using computational fluid dynamics. ΔPPAS and the minCSA of the pharyngeal airway were calculated, and the relationship between them was evaluated by non-linear regression analysis. In all cases, the minCSA was found at the level of the velopharynx. After surgery, ΔPPAS increased significantly and the minCSA decreased significantly. The non-linear regression equation expressing the relationship between these variables was ΔPPAS=3.73×minCSA-2.06. When the minCSA was <1cm2, ΔPPAS increased greatly. The results of this study suggest that surgeons should consider bimaxillary orthognathic surgery rather than mandibular setback surgery to prevent the development of iatrogenic obstructive sleep apnoea when correcting a skeletal class III malocclusion.
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Affiliation(s)
- Y Yajima
- Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan
| | - M Oshima
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - T Iwai
- Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan.
| | - H Kitajima
- Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan
| | - S Omura
- Department of Oral and Maxillofacial Surgery/Orthodontics, Yokohama City University Medical Center, Yokohama, Kanagawa, Japan
| | - I Tohnai
- Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan
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Alsufyani NA, Noga ML, Witmans M, Major PW. Upper airway imaging in sleep-disordered breathing: role of cone-beam computed tomography. Oral Radiol 2017. [DOI: 10.1007/s11282-017-0280-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor. Sci Rep 2016; 6:39443. [PMID: 27991580 PMCID: PMC5171831 DOI: 10.1038/srep39443] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 11/22/2016] [Indexed: 01/28/2023] Open
Abstract
The upper airway is a complex tissue structure that is prone to collapse. Current methods for studying airway obstruction are inadequate in safety, cost, or availability, such as CT or MRI, or only provide localized qualitative information such as flexible endoscopy. Long range optical coherence tomography (OCT) has been used to visualize the human airway in vivo, however the limited imaging range has prevented full delineation of the various shapes and sizes of the lumen. We present a new long range OCT system that integrates high speed imaging with a real-time position tracker to allow for the acquisition of an accurate 3D anatomical structure in vivo. The new system can achieve an imaging range of 30 mm at a frame rate of 200 Hz. The system is capable of generating a rapid and complete visualization and quantification of the airway, which can then be used in computational simulations to determine obstruction sites.
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Alzahrany M, Banerjee A. Effect of inhaled gas density on the pendelluft-induced lung injury. J Biomech 2016; 49:4039-4047. [PMID: 27839697 DOI: 10.1016/j.jbiomech.2016.10.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 10/14/2016] [Accepted: 10/25/2016] [Indexed: 10/20/2022]
Abstract
Helium, sulfur hexafluoride-oxygen, and air were modeled to examine the role of the gas density on the pendelluft-induced lung injury (PILI) under high frequency oscillatory ventilation (HFOV). Large eddy simulation coupled with physiological resistance-compliance boundary conditions was applied to capture pendelluft-induced gas entrapment and mechanical stresses in an image-based human lung model. The flow characteristics were strongly dependent on the inspired gas density. The flow partitioning, globally between the left and right lung and locally between adjacent units branches, was significantly affected by the density of inhaled gas and was more balanced when inspiring lighter gas. The incomplete loops of flow-volume and volume-pressure curves were significantly influenced by the variations of the flow redistribution, resistance, and turbulence associated with the pendelluft mechanism. Inhaling light gas reduced the entrapped gas volume and mechanical stress surrounding carina ridges signifying the important role of inhaled gas properties on PILI. In general, lung ventilation by HFOV with a gas mixture of large amounts of Helium is thought to mitigate ventilator complications.
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Affiliation(s)
- Mohammed Alzahrany
- Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, PA 18015, USA
| | - Arindam Banerjee
- Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, PA 18015, USA.
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Wootton DM, Sin S, Luo H, Yazdani A, McDonough JM, Wagshul ME, Isasi CR, Arens R. Computational fluid dynamics upper airway effective compliance, critical closing pressure, and obstructive sleep apnea severity in obese adolescent girls. J Appl Physiol (1985) 2016; 121:925-931. [PMID: 27445297 DOI: 10.1152/japplphysiol.00190.2016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/18/2016] [Indexed: 11/22/2022] Open
Abstract
Obstructive sleep apnea syndrome (OSAS) is associated with anatomical abnormalities restricting upper airway size and functional factors decreasing pharyngeal dilator activity in sleep. In this study we hypothesized that OSAS is also associated with altered pharyngeal mechanical compliance during wakefulness. Five OSAS and six control obese girls between 14 and 18 years of age were studied. All underwent polysomnography, critical closing pressure (Pcrit) studies, and dynamic MRI of the upper airway during awake tidal breathing. Effective airway compliance was defined as the slope of cross-sectional area vs. average pressure between maximum inspiration and maximum expiration along the pharyngeal airway. Pharyngeal pressure fields were calculated by using image-based computational fluid dynamics and nasal resistance. Spearman correlations were calculated to test associations between apnea-hypopnea index (AHI), Pcrit, and airway compliance. Effective compliances in the nasopharynx (CNP) and velopharynx (CVP) were lower and negative in OSAS compared with controls: -4.4 vs. 1.9 (mm2/cmH2O, P = 0.012) and -2.1 vs. 3.9 (mm2/cmH2O, P = 0.021), respectively, suggesting a strong phasic pharyngeal dilator activity during inspiration in OSAS compared with controls. For all subjects, CNP and AHI correlated negatively (rS = -0.69, P = 0.02), and passive Pcrit correlated with CNP (rS = -0.76, P = 0.006) and with AHI (rS = 0.86, P = 0.0006). Pharyngeal mechanics obtained during wakefulness could be used to characterize subjects with OSAS. Moreover, negative effective compliance during wakefulness and its correlation to AHI and Pcrit suggest that phasic dilator activity of the upper pharynx compensates for negative pressure loads in these subjects.
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Affiliation(s)
- David M Wootton
- Department of Mechanical Engineering, The Cooper Union for the Advancement of Science and Art, New York, New York;
| | - Sanghun Sin
- Children's Hospital at Montefiore, New York, New York
| | - Haiyan Luo
- Department of Mechanical Engineering, The Cooper Union for the Advancement of Science and Art, New York, New York
| | - Alireza Yazdani
- Department of Mechanical Engineering, The Cooper Union for the Advancement of Science and Art, New York, New York
| | | | | | | | - Raanan Arens
- Children's Hospital at Montefiore, New York, New York; Albert Einstein College of Medicine, New York, New York
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Di Francesco RC, Kreibich MS. Is the difference in the volume of the pharyngeal space, as measured by acoustic pharyngometry, before and after tonsillectomy proportional to the volume of the excised tonsils? Clinics (Sao Paulo) 2016; 71:285-90. [PMID: 27276399 PMCID: PMC4874264 DOI: 10.6061/clinics/2016(05)08] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Accepted: 03/04/2016] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE Adenotonsillectomy is recognized as an effective therapy for snoring and sleep disorders in children. It is important to understand whether adenotonsillectomy significantly increases the volume of the pharyngeal space. The goal of this study was to evaluate the change in oropharyngeal volume after adenotonsillectomy and the correlation of this change with the objective volume of the tonsils and body mass index. METHODS We included 27 subjects (14 males) with snoring caused by tonsil and adenoid hypertrophy. The mean age of the subjects was 7.92 (±2.52) years. Children with craniofacial malformations or neuromuscular diseases or syndromes were excluded. The parents/caregivers answered an adapted questionnaire regarding sleep-disordered breathing. All patients were subjected to weight and height measurements and body mass index was calculated. The subjects underwent pharyngometry before and after adenotonsillectomy and the volume of both excised tonsils together was measured in cm3 in the operating room. RESULTS Pharyngometric analysis showed that the mean pharyngeal volume was 28.63 (±5.57) cm3 before surgery and 31.23 (±6.76) cm3 after surgery; the volume of the oropharynx was significantly increased post-surgery (p=0.015, Wilcoxon test). No correlation was found between the objective tonsil volume and the post-surgical volume increase (p=0.6885). There was a fair correlation between the oropharyngeal volume and body mass index (p=0.0224). CONCLUSION Adenotonsillectomy increases the volume of the pharyngeal space, but this increase does not correlate with the objective tonsil size. Furthermore, greater BMI was associated with a smaller increase in the pharyngeal volume. Oropharyngeal structures and craniofacial morphology may also play a role in the increase in oropharyngeal volume.
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Bone Age and Serum Osteocalcin Levels in Children With Obstructive Sleep Apnea Hypopnea Syndrome Before and After Adenotonsillectomy. Am J Ther 2016; 24:e189-e195. [PMID: 26938749 DOI: 10.1097/mjt.0000000000000303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Our aim was to study the changes in bone age and serum osteocalcin levels before and after adenotonsillectomy (AT) in children with obstructive sleep apnea hypopnea syndrome (OSAHS). A total of 58 OSAHS children (37 males and 21 females) with the mean age of 6.68 ± 1.11 years were enrolled and assessed by x-ray-based bone age estimation and enzyme-linked immunosorbent assay-based measurement of serum osteocalcin levels, before surgery and 6 months after AT. SPSS 19.0 software was used for statistical analysis. Our results revealed that bone age and serum osteocalcin levels in OSAHS patients were significantly lower than normal controls before AT (P < 0.05). Within 6 months after surgery, the bone age and the serum osteocalcin levels were significantly elevated in OSAHS patients (P < 0.05), compared with those before surgery. Serum osteocalcin levels and bone age are negatively correlated with apnea-hypopnea index, oxygen desaturation index, the percentage of the total recorded time spent below 90% oxygen saturation, and Epworth sleepiness scale scores (all P < 0.05). Our findings suggested that bone age and serum osteocalcin levels may be correlated with the development of OSAHS in children. AT may improve bone age and serum osteocalcin levels in OSAHS children.
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Alzahrany M, Banerjee A. A biomechanical model of pendelluft induced lung injury. J Biomech 2015; 48:1804-10. [PMID: 25997727 DOI: 10.1016/j.jbiomech.2015.04.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 04/27/2015] [Accepted: 04/30/2015] [Indexed: 11/30/2022]
Abstract
Lung ventilation using high frequency oscillatory techniques have been documented to attain adequate gas exchange through various gas transport mechanisms. Among them, the pendelluft flow is considered one of the most crucial mechanisms. In this work, we computationally investigate the induction of abnormal mechanical stresses and a regionally trapped volume of gas due to pendelluft flow. Large eddy simulation was used to model the turbulence in an upper tracheobronchial lung geometry that was derived from CT scans. The pendelluft flow was captured by modeling physiological boundary conditions at the truncated level of the lung model that is sensitive to the coupled resistance and compliance of individual patients. The flow-volume and volume-pressure loops are characterized by irregular shapes and suggest abnormal regional lung ventilation. Incomplete loops were observed indicating gas trapping in these regions signifying a potential for local injury due to incomplete ventilation from a residual volume build-up at the end of the expiration phase. In addition, the gas exchange between units was observed to create a velocity gradient causing a region of high wall shear stress surrounding the carina ridges. The recurrence of the pendelluft flow could cause a rupture to the lung epithelium layer. The trapped gas and wall shear stress were observed to amplify with increasing compliance asymmetry and ventilator operating frequency. In general, despite the significant contribution of the pendelluft flow to the gas exchange augmentation there exists significant risks of localized lung injury, phenomena we describe as pendelluft induced lung injury or PILI.
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Affiliation(s)
- Mohammed Alzahrany
- Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, 18015 PA, USA
| | - Arindam Banerjee
- Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, 18015 PA, USA.
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