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Macellari M, Schillaci A, Tanzini U, Trimarchi M, Quadrio M. An adjoint-based approach for the surgical correction of nasal septal deviations. Comput Biol Med 2024; 176:108566. [PMID: 38744016 DOI: 10.1016/j.compbiomed.2024.108566] [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: 12/18/2023] [Revised: 04/04/2024] [Accepted: 05/05/2024] [Indexed: 05/16/2024]
Abstract
Deviations of the septal wall are widespread anatomic anomalies of the human nose; they vary significantly in shape and location, and often cause the obstruction of the nasal airways. When severe, septal deviations need to be surgically corrected by ear-nose-throat (ENT) specialists. Septoplasty, however, has a low success rate, owing to the lack of suitable standardized clinical tools for assessing type and severity of obstructions, and for surgery planning. Moreover, the restoration of a perfectly straight septal wall is often impossible and possibly unnecessary. This paper introduces a procedure, based on advanced patient-specific Computational Fluid Dynamics (CFD) simulations, to support ENT surgeons in septoplasty planning. The method hinges upon the theory of adjoint-based optimization, and minimizes a cost function that indirectly accounts for viscous losses. A sensitivity map is computed on the mucosal wall to provide the surgeon with a simple quantification of how much tissue removal at each location would contribute to easing the obstruction. The optimization procedure is applied to three representative nasal anatomies, reconstructed from CT scans of patients affected by complex septal deviations. The computed sensitivity consistently identifies all the anomalies correctly. Virtual surgery, i.e. morphing of the anatomies according to the computed sensitivity, confirms that the characteristics of the nasal airflow improve significantly after small anatomy changes derived from adjoint-based optimization.
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Affiliation(s)
- Marcello Macellari
- Department of Aerospace Science and Technologies, Politecnico di Milano, Campus Bovisa, Milano 20156, Italy
| | - Andrea Schillaci
- Department of Aerospace Science and Technologies, Politecnico di Milano, Campus Bovisa, Milano 20156, Italy
| | - Umberto Tanzini
- Division of Head and Neck, Otorhinolaryngology unit, IRCCS San Raffaele Scientific Institute, Milano, Italy; School of Medicine, Vita-Salute San Raffaele University, Milano, Italy
| | - Matteo Trimarchi
- Department of Otolaryngology - Head and Neck Surgery, Ente Ospedaliero Cantonale, Ospedale Regionale di Lugano - Universita' della Svizzera Italiana, Lugano, Switzerland
| | - Maurizio Quadrio
- Department of Aerospace Science and Technologies, Politecnico di Milano, Campus Bovisa, Milano 20156, Italy.
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Xavier R. Overview of Nasal Airway and Nasal Breathing Evaluation. Facial Plast Surg 2024; 40:268-274. [PMID: 38331036 DOI: 10.1055/s-0044-1779043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024] Open
Abstract
Several methods are available for evaluating nasal breathing and nasal airflow, as this evaluation may be made from several different perspectives.Physiologic methods for nasal airway evaluation directly measure nasal airflow or nasal airway resistance, while anatomical methods measure nasal airway dimensions. Subjective methods evaluate nasal breathing through several validated patient-reported scales assessing nasal breathing. Computational fluid dynamics evaluates nasal airflow through the analysis of several physics' variables of the nasal airway.Being familiar to these methods is of utmost importance for the nasal surgeon to be able to understand data provided by the different methods and to be able to choose the combination of evaluation methods that will provide the information most relevant to each clinical situation.
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Wei J, He X, Yang Q, Gu Q, Zhang X, Sui X, Zhou R, Feng W. Numerical simulation of the influence of nasal cycle on nasal airflow. Sci Rep 2024; 14:12161. [PMID: 38802510 PMCID: PMC11130131 DOI: 10.1038/s41598-024-63024-9] [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: 11/02/2023] [Accepted: 05/23/2024] [Indexed: 05/29/2024] Open
Abstract
To study the characteristics of nasal airflow in the presence of nasal cycle by computational fluid dynamics. CT scan data of a healthy Chinese individual was used to construct a three-dimensional model of the nasal cavity to be used as simulation domain. A sinusoidal airflow velocity is set at the nasal cavity entrance to reproduce the breathing pattern of a healthy human. There was a significant difference in the cross-sectional area between the two sides of the nasal cavity. Particularly, the decongested side is characterized by a larger cross-section area, and consequently, by a larger volume with respect to the congested side. The airflow velocity, pressure, and nasal resistance were higher on the congested narrow side. The temperature regulation ability on the congested narrow side was stronger than that on the decongested wider side. During the nasal cycle, there are differences in the nasal cavity function between the congested and decongested sides. Therefore, when evaluating the impact of various factors on nasal cavity function, the nasal cycle should be considered.
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Affiliation(s)
- Jing Wei
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Xuan He
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Qing Yang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Qifei Gu
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Xiaodan Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Xue Sui
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Rui Zhou
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China.
| | - Wei Feng
- Department of Otolaryngology, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing, China.
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Johnsen SG. Computational Rhinology: Unraveling Discrepancies between In Silico and In Vivo Nasal Airflow Assessments for Enhanced Clinical Decision Support. Bioengineering (Basel) 2024; 11:239. [PMID: 38534513 DOI: 10.3390/bioengineering11030239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 02/09/2024] [Accepted: 02/17/2024] [Indexed: 03/28/2024] Open
Abstract
Computational rhinology is a specialized branch of biomechanics leveraging engineering techniques for mathematical modelling and simulation to complement the medical field of rhinology. Computational rhinology has already contributed significantly to advancing our understanding of the nasal function, including airflow patterns, mucosal cooling, particle deposition, and drug delivery, and is foreseen as a crucial element in, e.g., the development of virtual surgery as a clinical, patient-specific decision support tool. The current paper delves into the field of computational rhinology from a nasal airflow perspective, highlighting the use of computational fluid dynamics to enhance diagnostics and treatment of breathing disorders. This paper consists of three distinct parts-an introduction to and review of the field of computational rhinology, a review of the published literature on in vitro and in silico studies of nasal airflow, and the presentation and analysis of previously unpublished high-fidelity CFD simulation data of in silico rhinomanometry. While the two first parts of this paper summarize the current status and challenges in the application of computational tools in rhinology, the last part addresses the gross disagreement commonly observed when comparing in silico and in vivo rhinomanometry results. It is concluded that this discrepancy cannot readily be explained by CFD model deficiencies caused by poor choice of turbulence model, insufficient spatial or temporal resolution, or neglecting transient effects. Hence, alternative explanations such as nasal cavity compliance or drag effects due to nasal hair should be investigated.
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Segalerba E, Dini Ciacci G, Quadrio M, Pralits JO. On the comparison between pre- and post-surgery nasal anatomies via computational fluid dynamics. Biomech Model Mechanobiol 2024; 23:305-314. [PMID: 37902893 PMCID: PMC10902155 DOI: 10.1007/s10237-023-01776-5] [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: 04/12/2023] [Accepted: 09/21/2023] [Indexed: 11/01/2023]
Abstract
Nasal breathing difficulties (NBD) are widespread and difficult to diagnose; the failure rate of their surgical corrections is high. Computational fluid dynamics (CFD) enables diagnosis of NBD and surgery planning, by comparing a pre-operative (pre-op) situation with the outcome of virtual surgery (post-op). An equivalent comparison is involved when considering distinct anatomies in the search for the functionally normal nose. Currently, this comparison is carried out in more than one way, under the implicit assumption that results are unchanged, which reflects our limited understanding of the driver of the respiratory function. The study describes how to set up a meaningful comparison. A pre-op anatomy, derived via segmentation from a CT scan, is compared with a post-op anatomy obtained via virtual surgery. State-of-the-art numerical simulations for a steady inspiration carry out the comparison under three types of global constraints, derived from the field of turbulent flow control: a constant pressure drop (CPG) between external ambient and throat, a constant flow rate (CFR) through the airways and a constant power input (CPI) from the lungs can be enforced. A significant difference in the quantities of interest is observed depending on the type of comparison. Global quantities (flow rate, pressure drop and nasal resistance) as well as local ones are affected. The type of flow forcing affects the outcome of the comparison between pre-op and post-op anatomies. Among the three available options, we argue that CPG is the least adequate. Arguments favouring either CFR or CPI are presented.
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Affiliation(s)
- Eric Segalerba
- Department of Civil, Chemical and Environmental Engineering, University of Genova, Via Montallegro, 1, 16145, Genoa, Italy
| | - Gabriele Dini Ciacci
- Department of Aerospace Sciences and Technologies, Politecnico di Milano, Campus Bovisa, 20156, Milano, Italy
| | - Maurizio Quadrio
- Department of Aerospace Sciences and Technologies, Politecnico di Milano, Campus Bovisa, 20156, Milano, Italy.
| | - Jan O Pralits
- Department of Civil, Chemical and Environmental Engineering, University of Genova, Via Montallegro, 1, 16145, Genoa, Italy.
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Ormiskangas J, Valtonen O, Harju T, Rautiainen M, Kivekäs I. Computational fluid dynamics calculations in inferior turbinate surgery: a cohort study. Eur Arch Otorhinolaryngol 2023; 280:4923-4931. [PMID: 37341759 PMCID: PMC10562334 DOI: 10.1007/s00405-023-08058-x] [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: 03/29/2023] [Accepted: 06/08/2023] [Indexed: 06/22/2023]
Abstract
PURPOSE To investigate how the results of nasal computational fluid dynamics (CFD) simulations change due to inferior turbinate surgery and how the results correlate with patient specific subjective assessment and volumetric results in the nasal cavities. METHODS The steady inspiratory airflow of 25 patients was studied pre- and postoperatively with heat transfer from the mucous membrane by performing CFD calculations to patient-specific nasal cone beam computed tomography images. These results were then compared to the severity of the patients' nasal obstruction Visual Analogue Scale (VAS) and Glasgow Health Status Inventory assessments, and acoustic rhinometry measurements. RESULTS Total wall shear forces decreased statistically significantly (p < 0.01) in the operated parts of the inferior turbinates. Patients' subjective nasal obstruction VAS assessment changes between the pre- and postoperative conditions correlated statistically significantly (p = 0.04) with the wall shear force results. CONCLUSION Inferior turbinate surgery lead to decreased total wall shear force values postoperatively. Changes in subjective nasal obstruction VAS results against total wall shear force changes between the pre- and postoperative conditions were statistically significant. CFD data have a potential to be used for the evaluation of nasal airflow.
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Affiliation(s)
- Jaakko Ormiskangas
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
- Faculty of Engineering and Natural Sciences, Automation Technology and Mechanical Engineering Unit, Tampere University, Tampere, Finland.
| | - Olli Valtonen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
| | - Teemu Harju
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
| | - Markus Rautiainen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
| | - Ilkka Kivekäs
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
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Jin X, Lu Y, Ren X, Guo S, Jin D, Liu B, Bai X, Liu J. Exploring the influence of nasal vestibule structure on nasal obstruction using CFD and Machine Learning method. Med Eng Phys 2023; 117:103988. [PMID: 37331745 DOI: 10.1016/j.medengphy.2023.103988] [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: 04/25/2022] [Revised: 04/12/2023] [Accepted: 05/03/2023] [Indexed: 06/20/2023]
Abstract
Motivated by clinical findings about the nasal vestibule, this study analyzes the aerodynamic characteristics of the nasal vestibule and attempt to determine anatomical features which have a large influence on airflow through a combination of Computational Fluid Dynamics (CFD) and machine learning method. Firstly, the aerodynamic characteristics of the nasal vestibule are detailedly analyzed using the CFD method. Based on CFD simulation results, we divide the nasal vestibule into two types with distinctly different airflow patterns, which is consistent with clinical findings. Secondly, we explore the relationship between anatomical features and aerodynamic characteristics by developing a novel machine learning model which could predict airflow patterns based on several anatomical features. Feature mining is performed to determine the anatomical feature which has the greatest impact on respiratory function. The method is developed and validated on 41 unilateral nasal vestibules from 26 patients with nasal obstruction. The correctness of the CFD analysis and the developed model is verified by comparing them with clinical findings.
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Affiliation(s)
- Xing Jin
- Department of Otorhinolaryngology, Head and Neck Surgery, People's Hospital, Peking University, Beijing, 100044, China
| | - Yi Lu
- Image Processing Center, Beihang University, Beijing 102206, China
| | - Xiang Ren
- School of Astronautics, Beihang University, Beijing 100191, China
| | - Sheng Guo
- Image Processing Center, Beihang University, Beijing 102206, China
| | - Darui Jin
- Image Processing Center, Beihang University, Beijing 102206, China; ShenYuan Honors College, Beihang University, Beijing 100191, China
| | - Bo Liu
- Image Processing Center, Beihang University, Beijing 102206, China.
| | - Xiangzhi Bai
- Image Processing Center, Beihang University, Beijing 102206, China; State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, Beijing 100191, China; Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100083, China.
| | - Junxiu Liu
- Jotolaryngology department, Third Hospital, Peking University, Beijing, 100191, China.
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汪 涛, 陈 东, 蔡 伟, 徐 洲, 王 钟, 王 珮, 于 洋. [Application of 3D printed nasal vestibular support in the treatment of anterior nostril stenosis]. LIN CHUANG ER BI YAN HOU TOU JING WAI KE ZA ZHI = JOURNAL OF CLINICAL OTORHINOLARYNGOLOGY, HEAD, AND NECK SURGERY 2022; 36:746-752. [PMID: 36217652 PMCID: PMC10128566 DOI: 10.13201/j.issn.2096-7993.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Indexed: 06/16/2023]
Abstract
Objective:To evaluate the efficacy of 3D printed nasal vestibular support on the recovery of nasal ventilation function and nostril shape after nostril stenosis treatment. Methods:Thirty-eight patients with unilateral traumatic nasal vestibular stenosis were selected and treated with 3D printed nasal vestibular support after operation. Subjective evaluation indicators, objective nostril local morphological and structural parameters, and nasal airflow dynamics parameters by numerical simulation were used. To evaluate the nostril morphological and nasal functional recovery after treatment. Results:The subjective nasal congestion and nostril symmetry satisfaction VAS scores of the patients after nasal vestibular support treatment were improved to varying degrees compared with those before surgery; The nostril morphological parameters showed that the Δlong-axis ratio and Δ short-axis ratio were significantly decreased after nasal vestibular support therapy (0.09±0.09 and 0.16±0.13) compared with those before surgery(0.21±0.20 and 0.28±0.21) respectively(P<0.01). And the cross-sectional area of the nasal valve on the stenotic side nasal cavity increased from(0.40±0.27) cm² before operation to (0.71±0.26) cm² after treatment(P<0.01); The nasal resistance on the stenosis side nasal cavity also decreased from (0.036±0.024) Pa·s/mL before operation to (0.022±0.008) Pa. s/mL after treatment(P<0.01), and the total nasal resistance was decreased from (0.033±0.02) Pas/mL before operation to (0.021±0.007)Pa. s/mL after treatment(P<0.01) ; It also showed that NWE(nasal warming efficiency) and NHE(nasal humidification efficiency) on the stenotic side nasal cavity were significantly decreased after nasal vestibular support therapy([95.92±2.8]% and [94.55±4.17]%) compared with those before surgery ([97.94±1.97 ]% and [96.19±2.94]%) respectively(P<0.01). Conclusion:The 3D printed nasal vestibular support for postoperative support treatment on patients with anterior nostril stenosis can reflect the advantages of personalized treatment and allow patients to obtain satisfactory results, and the use of individually designed 3D printed nasal vestibular support can make the shape of anterior nostrils and nasal cavity normal ventilation function recover well, its clinical application prospect is worth looking forward to.
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Affiliation(s)
- 涛 汪
- 上海交通大学医学院附属第九人民医院耳鼻咽喉头颈外科(上海,200011)Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200011, China
| | - 东 陈
- 上海交通大学医学院附属第九人民医院耳鼻咽喉头颈外科(上海,200011)Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200011, China
| | - 伟宇 蔡
- 上海交通大学医学院附属第九人民医院口腔修复科Department of Prosthodontics, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University
| | - 洲 徐
- 上海交通大学医学院附属第九人民医院耳鼻咽喉头颈外科(上海,200011)Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200011, China
| | - 钟颖 王
- 上海交通大学医学院附属第九人民医院耳鼻咽喉头颈外科(上海,200011)Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200011, China
| | - 珮华 王
- 上海交通大学医学院附属第九人民医院耳鼻咽喉头颈外科(上海,200011)Department of Otolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200011, China
| | - 洋 于
- 上海交通大学医学院附属第九人民医院3D打印中心Department of 3D Printing Center, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University
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Tjahjono R, Salati H, Inthavong K, Singh N. Correlation of Nasal Mucosal Temperature and Nasal Patency—A Computational Fluid Dynamics Study. Laryngoscope 2022; 133:1328-1335. [PMID: 37158263 DOI: 10.1002/lary.30327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/06/2022] [Accepted: 07/19/2022] [Indexed: 11/07/2022]
Abstract
OBJECTIVES Recent evidence suggests that detection of nasal mucosal temperature, rather than direct airflow detection, is the primary determinant of subjective nasal patency. This study examines the role of nasal mucosal temperature in the perception of nasal patency using in vivo and computational fluid dynamics (CFD) measurements. METHODS Healthy adult participants completed Nasal Obstruction Symptom Evaluation (NOSE) and Visual Analogue Scale (VAS) questionnaires. A temperature probe measured nasal mucosal temperature at the vestibule, inferior turbinate, middle turbinate, and nasopharynx bilaterally. Participants underwent a CT scan, used to create a 3D nasal anatomy model to perform CFD analysis of nasal mucosal and inspired air temperature and heat flux along with mucosal surface area where heat flux >50 W/m2 (SAHF50). RESULTS Eleven participants with a median age of 27 (IQR 24; 48) were recruited. Probe-measured temperature values correlated strongly with CFD-derived values (r = 0.87, p < 0.05). Correlations were seen anteriorly in the vestibule and inferior turbinate regions between nasal mucosal temperature and unilateral VAS (r = 0.42-0.46; p < 0.05), between SAHF50 and unilateral VAS (r = -0.31 to -0.36; p < 0.05) and between nasal mucosal temperature and SAHF50 (r = -0.37 to -0.41; p < 0.05). Subjects with high patency (VAS ≤10) had increased heat flux anteriorly compared with lower patency subjects (VAS >10; p < 0.05). CONCLUSION Lower nasal mucosal temperature and higher heat flux within the anterior nasal cavity correlates with a perception of improved unilateral nasal patency in healthy individuals. LEVEL OF EVIDENCE 4 Laryngoscope, 133:1328-1335, 2023.
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Affiliation(s)
- Richard Tjahjono
- Department of Otolaryngology Head and Neck Surgery Westmead Hospital Sydney New South Wales Australia
- Sydney Medical School, University of Sydney Sydney New South Wales Australia
| | - Hana Salati
- Faculty of Engineering RMIT University Melbourne Victoria Australia
| | - Kiao Inthavong
- Faculty of Engineering RMIT University Melbourne Victoria Australia
| | - Narinder Singh
- Department of Otolaryngology Head and Neck Surgery Westmead Hospital Sydney New South Wales Australia
- Sydney Medical School, University of Sydney Sydney New South Wales Australia
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Ormiskangas J, Valtonen O, Harju T, Rautiainen M, Kivekäs I. Computational fluid dynamics assessed changes of nasal airflow after inferior turbinate surgery. Respir Physiol Neurobiol 2022; 302:103917. [PMID: 35500884 DOI: 10.1016/j.resp.2022.103917] [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: 09/01/2021] [Revised: 04/01/2022] [Accepted: 04/26/2022] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To demonstrate how Computational Fluid Dynamics (CFD) simulations can reveal important airflow changes in the nasal cavities due to surgical interventions. MATERIAL AND METHODS The steady inspiratory airflow of eight patients was studied pre- and postoperatively with heat transfer from the mucous membrane by performing CFD calculations to patient specific cone beam computed tomography (CBCT) images. Eight patients with the largest distance from pre- and postoperative mean changes in inferior turbinate volumetry and Visual Analogue Scale (VAS) results were selected. RESULTS Calculated CFD heat transfer results from the anterior parts of the inferior turbinates, where surgical interventions were performed, decreased significantly. The heat transfer results were in line with VAS changes. CONCLUSION Surgical interventions reduced heat transfer in the operated parts of the inferior turbinates and were in line with VAS changes. CFD is an option in assessing patient well-being as a function of airflow parameters from mucous membrane with larger data sets. The limitations of the study were the small sample size and the preliminary nature of the study.
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Affiliation(s)
- Jaakko Ormiskangas
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland; Faculty of Engineering and Natural Sciences, Automation Technology and Mechanical Engineering Unit, Tampere University, Tampere, Finland.
| | - Olli Valtonen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland; Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
| | - Teemu Harju
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland; Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
| | - Markus Rautiainen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland; Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
| | - Ilkka Kivekäs
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland; Department of Otorhinolaryngology - Head and Neck Surgery, Tampere University Hospital, Tampere, Finland
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Schmidt N, Behrbohm H, Goubergrits L, Hildebrandt T, Brüning J. Comparison of rhinomanometric and computational fluid dynamic assessment of nasal resistance with respect to measurement accuracy. Int J Comput Assist Radiol Surg 2022; 17:1519-1529. [PMID: 35821562 DOI: 10.1007/s11548-022-02699-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 06/05/2022] [Indexed: 11/29/2022]
Abstract
PURPOSE Computational fluid dynamics (CFD)-based calculation of intranasal airflow became an important method in rhinologic research. Current evidence shows weak to moderate correlation as well as a systematic underprediction of nasal resistance by numerical simulations. In this study, we investigate whether these differences can be explained by measurement uncertainties caused by rhinomanometric devices and procedures. Furthermore, preliminary findings regarding the impact of tissue movements are reported. METHODS A retrospective sample of 17 patients, who reported impaired nasal breathing and for which rhinomanometric (RMM) measurements using two different devices as well as computed tomography scans were available, was investigated in this study. Three patients also exhibited a marked collapse of the nasal valve. Agreement between both rhinomanometric measurements as well as between rhinomanometry and CFD-based calculations was assessed using linear correlation and Bland-Altman analyses. These analyses were performed for the volume flow rates measured at trans-nasal pressure differences of 75 and 150 Pa during inspiration and expiration. RESULTS The correlation between volume flow rates measured using both RMM devices was good (R2 > 0.72 for all breathing states), and no relevant differences in measured flow rates was observed (21.6 ml/s and 14.8 ml/s for 75 and 150 Pa, respectively). In contrast, correlation between RMM and CFD was poor (R2 < 0.5) and CFD systematically overpredicted RMM-based flow rate measurements (231.8 ml/s and 328.3 ml/s). No differences between patients with and without nasal valve collapse nor between inspiration and expiration were observed. CONCLUSION Biases introduced during RMM measurements, by either the chosen device, the operator or other aspects as for example the nasal cycle, are not strong enough to explain the gross differences commonly reported between RMM- and CFD-based measurement of nasal resistance. Additionally, tissue movement during breathing is most likely also no sufficient explanation for these differences.
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Affiliation(s)
- Nora Schmidt
- Department of Otorhinolaryngology and Facial Plastic Surgery, Park-Klinik Weissensee, Schönstraße 80, 13086, Berlin, Germany.
| | - Hans Behrbohm
- Department of Otorhinolaryngology and Facial Plastic Surgery, Park-Klinik Weissensee, Schönstraße 80, 13086, Berlin, Germany
| | - Leonid Goubergrits
- Institute of Computer-Assisted Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas Hildebrandt
- Institute of Computer-Assisted Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jan Brüning
- Institute of Computer-Assisted Cardiovascular Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
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高 翔, 武 骏, 魏 洪, 徐 文, 韩 德. [Correlation between nasal mucosal temperature change and nasal airflow perception]. LIN CHUANG ER BI YAN HOU TOU JING WAI KE ZA ZHI = JOURNAL OF CLINICAL OTORHINOLARYNGOLOGY, HEAD, AND NECK SURGERY 2022; 36:401-406. [PMID: 35483696 PMCID: PMC10128267 DOI: 10.13201/j.issn.2096-7993.2022.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Indexed: 06/14/2023]
Abstract
The mechanism of nasal airflow perception remains little known. It is currently believed that the main mechanism for perceiving nasal patency is to activate transient receptor potential melastatin subtype 8. Computer fluent dynamics show that increased airflow and heat flux are associated with higher subjective scores. Similarly, physical measurements of the nasal cavity using a temperature probe show a correlation between the lower nasal mucosa temperature and better results. Trigeminal function detection also indirectly confirms this. This literature review aimed to explore the role of nasal mucosal temperature change in the subjective perception of nasal patency and the secondary aim was to appraise the relevant evidence about the mechanism.
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Affiliation(s)
- 翔 高
- 首都医科大学附属北京同仁医院耳鼻咽喉头颈外科 耳鼻咽喉头颈科学教育部重点实验室(首都医科大学)(北京,100730)Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital and Key Laboratory of Otolaryngology Head and Neck Surgery, Ministry of Education, Capital Medical University, Beijing, 100730, China
| | - 骏 武
- 首都医科大学附属北京同仁医院耳鼻咽喉头颈外科 耳鼻咽喉头颈科学教育部重点实验室(首都医科大学)(北京,100730)Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital and Key Laboratory of Otolaryngology Head and Neck Surgery, Ministry of Education, Capital Medical University, Beijing, 100730, China
| | - 洪政 魏
- 首都医科大学附属北京同仁医院耳鼻咽喉头颈外科 耳鼻咽喉头颈科学教育部重点实验室(首都医科大学)(北京,100730)Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital and Key Laboratory of Otolaryngology Head and Neck Surgery, Ministry of Education, Capital Medical University, Beijing, 100730, China
| | - 文 徐
- 首都医科大学附属北京同仁医院耳鼻咽喉头颈外科 耳鼻咽喉头颈科学教育部重点实验室(首都医科大学)(北京,100730)Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital and Key Laboratory of Otolaryngology Head and Neck Surgery, Ministry of Education, Capital Medical University, Beijing, 100730, China
| | - 德民 韩
- 首都医科大学附属北京同仁医院耳鼻咽喉头颈外科 耳鼻咽喉头颈科学教育部重点实验室(首都医科大学)(北京,100730)Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital and Key Laboratory of Otolaryngology Head and Neck Surgery, Ministry of Education, Capital Medical University, Beijing, 100730, China
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Rohde R, Friedland DR. Clinical perspectives on nasopharyngeal morphology in humans. Anat Rec (Hoboken) 2022; 305:2065-2074. [PMID: 35388627 DOI: 10.1002/ar.24926] [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: 01/31/2022] [Accepted: 03/12/2022] [Indexed: 12/11/2022]
Abstract
The nasopharynx is an integral component of the upper aerodigestive tract, whose morphologic features share an intimate relationship with a vast array of clinical, functional, and quality of life conditions related to contemporary humans. Its composite architecture and central location amidst the nasal cavity, pharyngotympanic tube, palate, and skull base bears implications for basic physiologic functions including breathing, vocalization, and alimentation. Over the course of evolution, morphological modifications of nasopharyngeal anatomy have occurred in genus Homo which serve to distinguish the human upper aerodigestive tract from that of other mammals. Understanding of these adaptive changes from both a comparative anatomy and clinical perspective offers insight into the unique blueprint which underpins many clinical pathologies currently encountered by anthropologists, scientists, and otorhinolaryngologists alike. This discussion intends to familiarize readers with the fundamental role that nasopharyngeal morphology plays in upper aerodigestive tract conditions, with consideration of its newfound clinical relevance in the era of the COVID-19 pandemic.
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Affiliation(s)
- Rebecca Rohde
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - David R Friedland
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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MATARACI FURKAN, KARIMOV ULVI, OZDEMIR IBEDII, YILDIRIM DUZGUN, ALTINDAG AYTUG. CFD SIMULATIONS AND ANALYSES OF ASYMPTOMATIC AND SYMPTOMATIC NASAL AIRWAY OBSTRUCTIONS. J MECH MED BIOL 2022. [DOI: 10.1142/s0219519422500051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The numerical simulations of the flow in nasal airways were performed for two different clinical cases. The results comprised the distributions of scalars at five different sections and included contours of pressure, velocity magnitude, turbulent kinetic energy and vorticity magnitude. Simulations showed the air branching occurring at the inferior meatus is unaffected by the variations in the volumetric flow rate or the changes in the flow regime through the olfactory cleft. However, the contractions and the following rapid change in the cross-section of the nasopharynx preclude the upward penetration of the vacuum field set by the lungs during the inhalation process. As a result, considerably low velocities and significant cross-sectional nonuniformities are observed, which lead to the appearances of the secondary flow structures and strong unsteadiness. Increased interactions between the airflow and the walls of the nasal cavity resulted in an increase in the vorticity on the right middle meatus and upper inferior meatus. The vorticity was also very high in the nostrils, where the flow was not fully developed.
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Affiliation(s)
- FURKAN MATARACI
- Fluids Group, Faculty of Mechanical Engineering, Istanbul Technical University, Gumussuyu 34437, Istanbul, Turkey
| | - ULVI KARIMOV
- Fluids Group, Faculty of Mechanical Engineering, Istanbul Technical University, Gumussuyu 34437, Istanbul, Turkey
| | - I. BEDII OZDEMIR
- Fluids Group, Faculty of Mechanical Engineering, Istanbul Technical University, Gumussuyu 34437, Istanbul, Turkey
| | - DUZGUN YILDIRIM
- Department of Medical Imaging, Vocational School of Health Sciences, Acibadem University, Istanbul, Turkey
| | - AYTUG ALTINDAG
- Otorhinolaryngology Department, Medical Faculty, Biruni University, Istanbul, Turkey
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Reid AWN, Chen X, Wen H, Li H, Wang Z, Hu Y, Zhang F, Bele E, Tan PJ, East C. The Virtual Nose: Assessment of Static Nasal Airway Obstruction Using Computational Simulations and 3D-Printed Models. Facial Plast Surg Aesthet Med 2021; 24:20-26. [PMID: 33902335 DOI: 10.1089/fpsam.2020.0576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: The use of virtual noses to predict the outcome of surgery is of increasing interests, particularly, as detailed and objective pre- and postoperative assessments of nasal airway obstruction (NAO) are difficult to perform. The objective of this article is to validate predictions using virtual noses against their experimentally measured counterpart in rigid 3D-printed models. Methods: Virtual nose models, with and without NAO, were reconstructed from patients' cone beam computed tomography scans, and used to evaluate airflow characteristics through computational fluid dynamics simulations. Prototypes of the reconstructed models were 3D printed and instrumented experimentally for pressure measurements. Results: Correlation between the numerical predictions and experimental measurements was shown. Analysis of the flow field indicated that the NAO in the nasal valve increases significantly the wall pressure, shear stress, and incremental nasal resistance behind the obstruction. Conclusions: Airflow predictions in static virtual noses correlate well with detailed experimental measurements on 3D-printed replicas of patient airways.
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Affiliation(s)
- Alex W N Reid
- Department of Plastic and Reconstructive Surgery, Cambridge University Hospitals, NHS Foundation Trust, Cambridge, United Kingdom
| | - Xinye Chen
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Haoxiang Wen
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Haoyuan Li
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Zhixing Wang
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Yanchang Hu
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Feng'Ao Zhang
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Eral Bele
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - P J Tan
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Charles East
- Department of ENT/Facial Plastic Surgery, University College Hospitals London NHS Trust, London, United Kingdom
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Computational Fluid Dynamics Analysis of Nasal Airway Changes after Treatment with C-Expander. Appl Bionics Biomech 2021; 2021:8874833. [PMID: 33868456 PMCID: PMC8032540 DOI: 10.1155/2021/8874833] [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: 06/07/2020] [Revised: 03/10/2021] [Accepted: 03/23/2021] [Indexed: 11/17/2022] Open
Abstract
The use of the C-expander is an effective treatment modality for maxillary skeletal deficiencies which can cause ailments and significantly reduce life expectancy in late adolescents and young adults. However, the morphological and dynamic effects on the nasal airway have not been reported. The main goal of this study was to evaluate the nasal airway changes after the implementation of a C-expander. A sample of nine patients (8 females, 1 male, age range from 15 to 29 years) was included. The morphology parameters and nasal airway ventilation parameters of pretreatment and posttreatment were measured. All study data were normally distributed. A paired t-test was used to evaluate the changes before and after treatment. After expansion, the mean and standard deviation values of intercanine maxillary width (CMW) and intermolar maxillary width (MMW) increased from 35.75 ± 2.48 mm and 54.20 ± 3.17 mm to 37.87 ± 2.26 mm (P < 0.05) and 56.65 ± 3.10 mm (P < 0.05), respectively. The nasal cavity volume increased from 20320.00 ± 3468.25 mm3 to 23134.70 ± 3918.84 mm3 (P < 0.05). The nasal pressure drop decreased from 36.34 ± 3.99 Pa to 30.70 ± 3.17 Pa (P < 0.05), while the value of the maximum velocity decreased from 6.50 ± 0.31 m/s to 5.85 ± 0.37 m/s (P < 0.05). Nasal resistance dropped remarkably from 0.16 ± 0.14 Pa/ml/s to 0.08 ± 0.06 Pa/ml/s (P < 0.05). The use of C-expander can effectively broaden the area and volume of the nasal airway, having a positive effect in the reduction of nasal resistance and improvement of nasal airway ventilation. For patients suffering from maxillary width deficiency and respiratory disorders, a C-expander may be an alternative method to treat the disease.
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Berger M, Giotakis AI, Pillei M, Mehrle A, Kraxner M, Kral F, Recheis W, Riechelmann H, Freysinger W. Agreement between rhinomanometry and computed tomography-based computational fluid dynamics. Int J Comput Assist Radiol Surg 2021; 16:629-638. [PMID: 33677758 PMCID: PMC8052237 DOI: 10.1007/s11548-021-02332-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 02/23/2021] [Indexed: 11/21/2022]
Abstract
Purpose Active anterior rhinomanometry (AAR) and computed tomography (CT) are standardized methods for the evaluation of nasal obstruction. Recent attempts to correlate AAR with CT-based computational fluid dynamics (CFD) have been controversial. We aimed to investigate this correlation and agreement based on an in-house developed procedure. Methods In a pilot study, we retrospectively examined five subjects scheduled for septoplasty, along with preoperative digital volume tomography and AAR. The simulation was performed with Sailfish CFD, a lattice Boltzmann code. We examined the correlation and agreement of pressure derived from AAR (RhinoPress) and simulation (SimPress) and these of resistance during inspiration by 150 Pa pressure drop derived from AAR (RhinoRes150) and simulation (SimRes150). For investigation of correlation between pressures and between resistances, a univariate analysis of variance and a Pearson’s correlation were performed, respectively. For investigation of agreement, the Bland–Altman method was used. Results The correlation coefficient between RhinoPress and SimPress was r = 0.93 (p < 0.001). RhinoPress was similar to SimPress in the less obstructed nasal side and two times greater than SimPress in the more obstructed nasal side. A moderate correlation was found between RhinoRes150 and SimRes150 (r = 0.65; p = 0.041). Conclusion The simulation of rhinomanometry pressure by CT-based CFD seems more feasible with the lattice Boltzmann code in the less obstructed nasal side. In the more obstructed nasal side, error rates of up to 100% were encountered. Our results imply that the pressure and resistance derived from CT-based CFD and AAR were similar, yet not same. Supplementary Information The online version contains supplementary material available at 10.1007/s11548-021-02332-1.
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Affiliation(s)
- Manuel Berger
- Department of Environmental, Process and Energy Engineering, MCI, The Entrepreneurial School, Innsbruck, Austria
- Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Aris I Giotakis
- Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria.
| | - Martin Pillei
- Department of Environmental, Process and Energy Engineering, MCI, The Entrepreneurial School, Innsbruck, Austria
- Department of Fluid Mechanics, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Andreas Mehrle
- Department of Mechatronics, MCI, The Entrepreneurial School, Innsbruck, Austria
| | - Michael Kraxner
- Department of Environmental, Process and Energy Engineering, MCI, The Entrepreneurial School, Innsbruck, Austria
| | - Florian Kral
- Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Wolfgang Recheis
- University Hospital of Radiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Herbert Riechelmann
- Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Wolfgang Freysinger
- Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
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Xavier R, Menger DJ, de Carvalho HC, Spratley J. An Overview of Computational Fluid Dynamics Preoperative Analysis of the Nasal Airway. Facial Plast Surg 2021; 37:306-316. [PMID: 33556971 DOI: 10.1055/s-0041-1722956] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Evaluation of the nasal airway is crucial for every patient with symptoms of nasal obstruction as well as for every patient with other nasal symptoms. This assessment of the nasal airway comprises clinical examination together with imaging studies, with the correlation between findings of this evaluation and symptoms reported by the patient being based on the experience of the surgeon. Measuring nasal airway resistance or nasal airflow can provide additional data regarding the nasal airway, but the benefit of these objective measurements is limited due to their lack of correlation with patient-reported evaluation of nasal breathing. Computational fluid dynamics (CFD) has emerged as a valuable tool to assess the nasal airway, as it provides objective measurements that correlate with patient-reported evaluation of nasal breathing. CFD is able to evaluate nasal airflow and measure variables such as heat transfer or nasal wall shear stress, which seem to reflect the activity of the nasal trigeminal sensitive endings that provide sensation of nasal breathing. Furthermore, CFD has the unique capacity of making airway analysis of virtual surgery, predicting airflow changes after trial virtual modifications of the nasal airway. Thereby, CFD can assist the surgeon in deciding surgery and selecting the surgical techniques that better address the features of each specific nose. CFD has thus become a trend in nasal airflow assessment, providing reliable results that have been validated for analyzing airflow in the human nasal cavity. All these features make CFD analysis a mainstay in the armamentarium of the nasal surgeon. CFD analysis may become the gold standard for preoperative assessment of the nasal airway.
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Affiliation(s)
- Rui Xavier
- Department of Otorhinolaryngology, Hospital Luz Arrabida, Porto, Portugal
| | - Dirk-Jan Menger
- Department of Otorhinolaringology, University Medical Center, Utrecht, The Netherlands
| | - Henrique Cyrne de Carvalho
- Department of Medicine, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Jorge Spratley
- Department of Otorhinolaringology, Faculdade de Medicina da Universidade do Porto, Centro Hospitalar e Universitário S. João and Centro de Investigação em Tecnologias e Serviços de Saúde (CINTESIS), Porto, Portugal
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Can computational fluid dynamic models help us in the treatment of chronic rhinosinusitis. Curr Opin Otolaryngol Head Neck Surg 2020; 29:21-26. [PMID: 33315616 DOI: 10.1097/moo.0000000000000682] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The aim of this study was to review the recent literature (January 2017-July 2020) on computational fluid dynamics (CFD) studies relating to chronic rhinosinusitis (CRS), including airflow within the pre and postoperative sinonasal cavity, virtual surgery, topical drug and saline delivery (sprays, nebulizers and rinses) and olfaction. RECENT FINDINGS Novel CFD-specific parameters (heat flux and wall shear stress) are highly correlated with patient perception of nasal patency. Increased ostial size markedly improves sinus ventilation and drug delivery. New virtual surgery tools allow surgeons to optimize interventions. Sinus deposition of nasal sprays is more effective with smaller, low-inertia particles, outside of the range produced by many commercially available products. Saline irrigation effectiveness is improved using greater volume, with liquid entering sinuses via 'flooding' of ostia rather than direct jet entry. SUMMARY CFD has provided new insights into sinonasal airflow, air-conditioning function, the nasal cycle, novel measures of nasal patency and the impact of polyps and sinus surgery on olfaction. The deposition efficiency of topical medications on sinus mucosa can be markedly improved through parametric CFD experiments by optimising nasal spray particle size and velocity, nozzle angle and insertion location, while saline irrigation effectiveness can be optimized by modelling squeeze bottle volume and head position. More sophisticated CFD models (inhalation and exhalation, spray particle and saline irrigation) will increasingly provide translational benefits in the clinical management of CRS.
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