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Wang J, Zhang Y, Chen X, Tao F, Sun B, Xie J, Chen J. Targeted delivery of inhalable drug particles in the tracheobronchial tree model of a pediatric patient with bronchopneumonia: A numerical study. Respir Physiol Neurobiol 2023; 311:104024. [PMID: 36731709 DOI: 10.1016/j.resp.2023.104024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/19/2023] [Accepted: 01/28/2023] [Indexed: 02/01/2023]
Abstract
Pneumonia is a common cause of hospitalization and death in children worldwide. Inhalation therapy is one of the methods treating pneumonia However, there are limited studies that distinguish between the physiology of children and adults, especially with respect to targeted drug delivery. A tracheobronchial (TB) tree model of an 11-year-old child with bronchopneumonia is selected as a testbed for in silico trials of targeted drug delivery. The airflow and particle transport are solved by the computational fluid dynamics method at an airflow rate of 15 LPM. The results indicate that the distribution of deposited particles shows aggregation on the particle release map. Point-source aerosol release (PSAR) method can significantly reduce the deposition efficiency (DE) of particles in the TB tree model. Specifically, the PSAR method can reduce the DE of large particles (i.e., 7.5 µm and 10 µm) by 7.57% and 9.61%, respectively. This enables rapid design of patient-specific treatment for different population age groups and different airway diseases.
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Affiliation(s)
- Jianwei Wang
- School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, Jiangsu 210046, China
| | - Ya Zhang
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China
| | - Xiaole Chen
- School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, Jiangsu 210046, China.
| | - Feng Tao
- Zhongda Hospital, Southeast University, Nanjing, Jiangsu 210009, China
| | - Baobin Sun
- Zhongda Hospital, Southeast University, Nanjing, Jiangsu 210009, China
| | - Jun Xie
- School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, Jiangsu 210046, China
| | - Jingguo Chen
- Department of Otolaryngology Head and Neck Surgery, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China
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Kolewe EL, Padhye S, Woodward IR, Wee J, Rahman T, Feng Y, Briddell JW, Fromen CA. Spatial aerosol deposition correlated to anatomic feature development in 6-year-old upper airway computational models. Comput Biol Med 2022; 149:106058. [PMID: 36103743 PMCID: PMC10167792 DOI: 10.1016/j.compbiomed.2022.106058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 08/03/2022] [Accepted: 08/27/2022] [Indexed: 02/01/2023]
Abstract
The upper airways of children undergo developmental changes around age 6, yielding differences between adult and pediatric anatomies. These differences include the cricoid ring area shape, the location of narrowest constriction, and the angle of the epiglottis, all of which are expected to alter local fluid dynamic profiles and subsequent upper airway deposition and downstream aerosol delivery of inhaled therapeutics. In this work, we quantify "pediatric"-like and "adult"-like geometric and fluid dynamic features of two computed tomography (CT)-scan derived models of 6-year-old upper airways in healthy subjects and compare to an idealized model. The two CT-scan models had a mixture of "adult"- and "pediatric"-like anatomic features, with Subject B exhibiting more "pediatric"-like features than Subject A, while the idealized model exhibited entirely "adult"-like features. By computational fluid-particle dynamics, these differences in anatomical features yielded distinct local fluid profiles with altered aerosol deposition between models. Notably, the idealized model better predicted deposition characteristics of Subject A, the more "adult"-like model, including the relationship between the impaction parameter, dp2Q and the fraction of deposition across a range of flow rates and particle diameters, as well as deposition of an approximate pharmaceutical particle size distribution model. Our results with even this limited dataset suggest that there are key personalized metrics that are influenced by anatomical development, which should be considered when developing pediatric inhalable therapeutics. Quantifying anatomical development and correlating to aerosol deposition has the potential for high-throughput developmental characterization and informing desired aerosol characteristics for pediatric applications.
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Affiliation(s)
- Emily L Kolewe
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA
| | - Saurav Padhye
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA
| | - Ian R Woodward
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA
| | - Jinyong Wee
- Department of Biomedical Research, Nemours Children's Hospital, Wilmington, DE, USA
| | - Tariq Rahman
- Department of Biomedical Research, Nemours Children's Hospital, Wilmington, DE, USA
| | - Yu Feng
- Department of Chemical Engineering, Oklahoma State University, Stillwater, OK, USA
| | - Jenna W Briddell
- Division of Otorhinolaryngology, Department of Surgery, Nemours Children's Hospital, Wilmington, DE, USA
| | - Catherine A Fromen
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA.
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Islam MS, Fang T, Oldfield C, Larpruenrudee P, Beni HM, Rahman MM, Husain S, Gu Y. Heat Wave and Bushfire Meteorology in New South Wales, Australia: Air Quality and Health Impacts. Int J Environ Res Public Health 2022; 19:10388. [PMID: 36012020 PMCID: PMC9407765 DOI: 10.3390/ijerph191610388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/09/2022] [Accepted: 08/18/2022] [Indexed: 06/15/2023]
Abstract
The depletion of air quality is a major problem that is faced around the globe. In Australia, the pollutants emitted by bushfires play an important role in making the air polluted. These pollutants in the air result in many adverse impacts on the environment. This paper analysed the air pollution from the bushfires from November 2019 to July 2020 and identified how it affects the human respiratory system. The bush fires burnt over 13 million hectares, destroying over 2400 buildings. While these immediate effects were devastating, the long-term effects were just as devastating, with air pollution causing thousands of people to be admitted to hospitals and emergency departments because of respiratory complications. The pollutant that caused most of the health effects throughout Australia was Particulate Matter (PM) PM2.5 and PM10. Data collection and analysis were covered in this paper to illustrate where and when PM2.5 and PM10, and other pollutants were at their most concerning levels. Susceptible areas were identified by analysing environmental factors such as temperature and wind speed. The study identified how these pollutants in the air vary from region to region in the same time interval. This study also focused on how these pollutant distributions vary according to the temperature, which helps to determine the relationship between the heatwave and air quality. A computational model for PM2.5 aerosol transport to the realistic airways was also developed to understand the bushfire exhaust aerosol transport and deposition in airways. This study would improve the knowledge of the heat wave and bushfire meteorology and corresponding respiratory health impacts.
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Affiliation(s)
- Mohammad S. Islam
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), 15 Broadway, Ultimo, NSW 2007, Australia
| | - Tianxin Fang
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), 15 Broadway, Ultimo, NSW 2007, Australia
| | - Callum Oldfield
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), 15 Broadway, Ultimo, NSW 2007, Australia
| | - Puchanee Larpruenrudee
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), 15 Broadway, Ultimo, NSW 2007, Australia
| | - Hamidreza Mortazavy Beni
- Department of Biomedical Engineering, Arsanjan Branch, Islamic Azad University, Arsanjan 6134937333, Iran
| | - Md. M. Rahman
- School of Computing, Engineering, and Mathematics, Western Sydney University, Penrith, NSW 2751, Australia
| | - Shahid Husain
- Department of Mechanical Engineering, Zakir Husain College of Engineering & Technology, Aligarh Muslim University, Aligarh 202001, India
| | - Yuantong Gu
- School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, QLD 4000, Australia
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Islam MS, Larpruenrudee P, Hossain SI, Rahimi-Gorji M, Gu Y, Saha SC, Paul G. Polydisperse Aerosol Transport and Deposition in Upper Airways of Age-Specific Lung. Int J Environ Res Public Health 2021; 18:6239. [PMID: 34207690 DOI: 10.3390/ijerph18126239] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/02/2021] [Accepted: 06/07/2021] [Indexed: 01/25/2023]
Abstract
A comprehensive understanding of airflow characteristics and particle transport in the human lung can be useful in modelling to inform clinical diagnosis, treatment, and management, including prescription medication and risk assessment for rehabilitation. One of the difficulties in clinical treatment of lung disorders lies in the patients’ variable physical lung characteristics caused by age, amongst other factors, such as different lung sizes. A precise understanding of the comparison between different age groups with various flow rates is missing in the literature, and this study aims to analyse the airflow and aerosol transport within the age-specific lung. ANSYS Fluent solver and the large-eddy simulation (LES) model were employed for the numerical simulation. The numerical model was validated with the available literature and the computational results showed airway size-reduction significantly affected airflow and particle transport in the upper airways. This study reports higher deposition at the mouth-throat region for larger diameter particles. The overall deposition efficiency (DE) increased with airway size reduction and flow rate. Lung aging effected the pressure distribution and a higher pressure drop was reported for the aged lung as compared to the younger lung. These findings could inform medical management through individualised simulation of drug-aerosol delivery processes for the patient-specific lung.
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Poorbahrami K, Vignon-Clementel IE, Shadden SC, Oakes JM. A whole lung in silico model to estimate age dependent particle dosimetry. Sci Rep 2021; 11:11180. [PMID: 34045500 DOI: 10.1038/s41598-021-90509-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 05/12/2021] [Indexed: 11/08/2022] Open
Abstract
Anatomical and physiological changes alter airflow characteristics and aerosol distribution in the developing lung. Correlation between age and aerosol dosimetry is needed, specifically because youth are more susceptible to medication side effects. In this study, we estimate aerosol dosages (particle diameters of 1, 3, and 5 [Formula: see text]m) in a 3 month-old infant, a 6 year-old child, and a 36 year-old adult by performing whole lung subject-specific particle simulations throughout respiration. For 3 [Formula: see text]m diameter particles we estimate total deposition as 88, 73, and [Formula: see text] and the conducting versus respiratory deposition ratios as 4.0, 0.5, and 0.4 for the infant, child, and adult, respectively. Due to their lower tidal volumes and functional residual capacities the deposited mass is smaller while the tissue concentrations are larger in the infant and child subjects, compared to the adult. Furthermore, we find that dose cannot be predicted by simply scaling by tidal volumes. These results highlight the need for additional clinical and computational studies that investigate the efficiency of treatment, while optimizing dosage levels in order to alleviate side effects, in youth.
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Kim TH, Lee HS, Oh SJ, Hwang CW, Jung WK. Phlorotannins ameliorate extracellular matrix production in human vocal fold fibroblasts and prevent vocal fold fibrosis via aerosol inhalation in a laser-induced fibrosis model. J Tissue Eng Regen Med 2020; 14:1918-1928. [PMID: 33049121 DOI: 10.1002/term.3140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/18/2020] [Accepted: 10/06/2020] [Indexed: 12/13/2022]
Abstract
Vocal fold fibrosis is an abnormal condition characterized by unfavorable changes in the organization of the extracellular matrix in vocal fold lamina propria. To prevent and treat vocal fold fibrosis, a number of synthetic drugs, such as mitomycin C and the glucocorticoid family, are used after surgery, but these are known to have some side effects. Therefore, using both in vitro and in vivo studies, this study investigated whether phlorotannins extracted from Ecklonia cava have the potential to prevent vocal fold fibrosis with minimal side effects. The results show that phlorotannins suppressed both the expression of the fibrotic phenotypic marker and cell migration by inhibiting the activation of the mitogen-activated protein kinase (MAPK) and Smad2/3 signaling pathways in human vocal fold fibroblasts stimulated by transforming growth factor-β. Additionally, phlorotannins exhibited antifibrotic efficacy without an excessive inflammatory response in a laser-induced fibrosis rabbit model when delivered as an aerosol via inhalation. Based on these results, phlorotannins should be considered a promising candidate for use in the prevention of vocal fold fibrosis.
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Affiliation(s)
- Tae-Hee Kim
- Department of Biomedical Engineering and New-Senior Healthcare Innovation Center (BK21 Plus), Pukyong National University, Busan, Republic of Korea
| | - Hyoung Shin Lee
- Department of Otolaryngology-Head and Neck Surgery, Kosin University College of Medicine, Busan, Republic of Korea
| | - Sun-Ju Oh
- Department of Pathology, Kosin University College of Medicine, Busan, Republic of Korea
| | - Chi-Woo Hwang
- Department of Otolaryngology-Head and Neck Surgery, Kosin University College of Medicine, Busan, Republic of Korea
| | - Won-Kyo Jung
- Department of Biomedical Engineering and New-Senior Healthcare Innovation Center (BK21 Plus), Pukyong National University, Busan, Republic of Korea
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Das P, Nof E, Amirav I, Kassinos SC, Sznitman J. Targeting inhaled aerosol delivery to upper airways in children: Insight from computational fluid dynamics (CFD). PLoS One 2018; 13:e0207711. [PMID: 30458054 PMCID: PMC6245749 DOI: 10.1371/journal.pone.0207711] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 11/03/2018] [Indexed: 11/28/2022] Open
Abstract
Despite the prevalence of inhalation therapy in the treatment of pediatric respiratory disorders, most prominently asthma, the fraction of inhaled drugs reaching the lungs for maximal efficacy remains adversely low. By and large drug delivery devices and their inhalation guidelines are typically derived from adult studies with child dosages adapted according to body weight. While it has long been recognized that physiological (e.g. airway sizes, breathing maneuvers) and physical transport (e.g. aerosol dynamics) characteristics are critical in governing deposition outcomes, such knowledge has yet to be extensively adapted to younger populations. Motivated by such shortcomings, the present work leverages in a first step in silico computational fluid dynamics (CFD) to explore opportunities for augmenting aerosol deposition in children based on respiratory physiological and physical transport determinants. Using an idealized, anatomically-faithful upper airway geometry, airflow and aerosol motion are simulated as a function of age, spanning a five year old to an adult. Breathing conditions mimic realistic age-specific inhalation maneuvers representative of Dry Powder Inhalers (DPI) and nebulizer inhalation. Our findings point to the existence of a single dimensionless curve governing deposition in the conductive airways via the dimensionless Stokes number (Stk). Most significantly, we uncover the existence of a distinct deposition peak irrespective of age. For the DPI simulations, this peak (∼ 80%) occurs at Stk ≈ 0.06 whereas for nebulizer simulations, the corresponding peak (∼ 45%) occurs in the range of Stk between 0.03-0.04. Such dimensionless findings hence translate to an optimal window of micron-sized aerosols that evolves with age and varies with inhalation device. The existence of such deposition optima advocates revisiting design guidelines for optimizing deposition outcomes in pediatric inhalation therapy.
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Affiliation(s)
- Prashant Das
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Eliram Nof
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Israel Amirav
- Department of Pediatrics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Stavros C. Kassinos
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Kallipoleos Avenue 75, Nicosia 1678, Cyprus
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
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Abstract
The particle dynamics in an oscillating alveolus under tidal breathing can be dramatically different from those in a static alveolus. Despite its close relevance to pulmonary drug delivery and health risk from airborne exposure, quantifications of alveolar deposition are scarce due to its inaccessibility to in vivo measurement instruments, tiny size to replicate in vitro, and dynamic wall motions to model. The objective of this study is to introduce a numerical method to quantify alveolar deposition with continuous particle release in a rhythmically oscillating alveolus by integrating the deposition curves for bolus aerosols and use this method to develop correlations applicable in assessing alveolar drug delivery efficiency or dosimetry of inhaled toxicants. An idealized blind-end terminal alveolus model was developed with rhythmically moving alveolar boundary conditions in phase with tidal breathing. The dynamic wall expansion mode and magnitude were based on experimentally measured chest wall motions and tidal volumes. A well-validated Lagrangian tracking model was used to simulate the transport and deposition of inhaled micrometer particles. Large differences were observed between dynamic and static alveoli in particle motion, deposition onset, and final alveolar deposition fraction. Alveolar deposition of bolus aerosols is highly sensitive to breath-holding duration, particle release time, and alveolar dimension. For 1 µm particles, there exists a cut-off release time (zero bolus deposition), which decreases with alveolar size (i.e., 1.0 s in a 0.2-mm-diameter alveolus and 0.56 s in a 0.8-mm-diameter alveolus). The cumulative alveolar deposition was predicted to be 39% for a 0.2-mm-diameter alveolus, 22% for a 0.4-mm-diameter alveolus, and 10% for a 0.8-mm-diameter alveolus. A cumulative alveolar deposition correlation was developed for inhalation delivery with a prescribed period of drug release and the second correlation for the time variation of alveolar deposition of ambient aerosols, both of which captured the relative dependence of the particle release time and alveolar dimension.
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Affiliation(s)
- Jinxiang Xi
- Department of Mechanical and Biomedical Engineering, California Baptist University, Riverside, CA, USA
| | - Khaled Talaat
- Department of Nuclear Engineering, The University of New Mexico, Albuquerque, NM, USA
| | - Xiuhua April Si
- Department of Mechanical and Biomedical Engineering, California Baptist University, Riverside, CA, USA
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Tenenbaum-Katan J, Artzy-Schnirman A, Fishler R, Korin N, Sznitman J. Biomimetics of the pulmonary environment in vitro: A microfluidics perspective. Biomicrofluidics 2018; 12:042209. [PMID: 29887933 PMCID: PMC5973897 DOI: 10.1063/1.5023034] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 03/20/2018] [Indexed: 05/08/2023]
Abstract
The entire luminal surface of the lungs is populated with a complex yet confluent, uninterrupted airway epithelium in conjunction with an extracellular liquid lining layer that creates the air-liquid interface (ALI), a critical feature of healthy lungs. Motivated by lung disease modelling, cytotoxicity studies, and drug delivery assessments amongst other, in vitro setups have been traditionally conducted using macroscopic cultures of isolated airway cells under submerged conditions or instead using transwell inserts with permeable membranes to model the ALI architecture. Yet, such strategies continue to fall short of delivering a sufficiently realistic physiological in vitro airway environment that cohesively integrates at true-scale three essential pillars: morphological constraints (i.e., airway anatomy), physiological conditions (e.g., respiratory airflows), and biological functionality (e.g., cellular makeup). With the advent of microfluidic lung-on-chips, there have been tremendous efforts towards designing biomimetic airway models of the epithelial barrier, including the ALI, and leveraging such in vitro scaffolds as a gateway for pulmonary disease modelling and drug screening assays. Here, we review in vitro platforms mimicking the pulmonary environment and identify ongoing challenges in reconstituting accurate biological airway barriers that still widely prevent microfluidic systems from delivering mainstream assays for the end-user, as compared to macroscale in vitro cell cultures. We further discuss existing hurdles in scaling up current lung-on-chip designs, from single airway models to more physiologically realistic airway environments that are anticipated to deliver increasingly meaningful whole-organ functions, with an outlook on translational and precision medicine.
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Affiliation(s)
- Janna Tenenbaum-Katan
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Arbel Artzy-Schnirman
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Rami Fishler
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Netanel Korin
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
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Deng Q, Ou C, Chen J, Xiang Y. Particle deposition in tracheobronchial airways of an infant, child and adult. Sci Total Environ 2018; 612:339-346. [PMID: 28854390 DOI: 10.1016/j.scitotenv.2017.08.240] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/22/2017] [Accepted: 08/22/2017] [Indexed: 05/04/2023]
Abstract
BACKGROUND Particle deposition in human airways is important for assessing both health effects of inhaled particles and therapeutic efficacy of inhaled drug aerosols, but is not well understood for infants and children. OBJECTIVE We investigate particle deposition in infants and children by using computational fluid dynamics (CFD), and compare this with particle deposition in adults. METHODS We chose three population age groups: 7-month infant, 4-year old child, and 20-year old adult. Both airway structures and breathing conditions are considered to vary as a human grows from infancy to adulthood. We investigated deposition of micron-size particles (1-10μm) in both the upper (G3-G6) and lower (G9-G12) tracheobronchial (TB) airways under sedentary conditions. RESULTS We found that particle deposition in both upper and lower airways is the highest in an infant, next in a child, and lowest in an adult. As age increases, particle deposition decreases in the upper airways but increases in the lower. For infants, inertial impaction is the dominant deposition mechanism, thus particles are deposited more in the upper airways than in the lower. However, particles are deposited more in the lower airways than in the upper in adults, as gravitational sedimentation is the dominant deposition mechanism. CONCLUSION Given the differences in the airway structure and particle deposition mechanisms, particle deposition in infants and children differs from that in adults, not only in the efficiency of deposition but also in the site. Our findings provide evidence that "children are not small adults".
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Affiliation(s)
- Qihong Deng
- School of Energy Science and Engineering, Central South University, Changsha, China; XiangYa School of Public Health, Central South University, Changsha, China.
| | - Cuiyun Ou
- School of Energy Science and Engineering, Central South University, Changsha, China
| | - Jiao Chen
- School of Energy Science and Engineering, Central South University, Changsha, China
| | - Yuguang Xiang
- School of Energy Science and Engineering, Central South University, Changsha, China
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Oakes JM, Roth SC, Shadden SC. Airflow Simulations in Infant, Child, and Adult Pulmonary Conducting Airways. Ann Biomed Eng 2017; 46:498-512. [PMID: 29264667 DOI: 10.1007/s10439-017-1971-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 12/13/2017] [Indexed: 10/18/2022]
Abstract
The airway structure continuously evolves from birth to adulthood, influencing airflow dynamics and respiratory mechanics. We currently know very little about how airflow patterns change throughout early life and its impact on airway resistance, namely because of experimental limitations. To uncover differences in respiratory dynamics between age groups, we performed subject-specific airflow simulations in an infant, child, and adult conducting airways. Airflow throughout the respiration cycle was calculated by coupling image-based models of the conducting airways to the global respiratory mechanics, where flow was driven by a pressure differential. Trachea diameter was 19, 9, and 4.5 mm for the adult (36 years, female), child (6 years, male), and infant (0.25 years, female), respectively. Mean Reynolds number within the trachea was nearly the same for each subject (1100) and Womersley number was above unity for all three subjects and largest for the adult, highlighting the significance of transient effects. In general, air speeds and airway resistances within the conducting airways were inversely correlated with age; the 3D pressure drop was highest in the infant model. These simulations provide new insight into age-dependent flow dynamics throughout the respiration cycle within subject-specific airways.
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Affiliation(s)
- Jessica M Oakes
- Department of Bioengineering, Northeastern University, Boston, MA, USA.
| | - Steven C Roth
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Shawn C Shadden
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
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Surate Solaligue DE, Rodríguez-Castillo JA, Ahlbrecht K, Morty RE. Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia. Am J Physiol Lung Cell Mol Physiol 2017; 313:L1101-L1153. [PMID: 28971976 DOI: 10.1152/ajplung.00343.2017] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/21/2017] [Accepted: 09/23/2017] [Indexed: 02/08/2023] Open
Abstract
The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.
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Affiliation(s)
- David E Surate Solaligue
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, German Center for Lung Research, Giessen, Germany
| | - José Alberto Rodríguez-Castillo
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, German Center for Lung Research, Giessen, Germany
| | - Katrin Ahlbrecht
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, German Center for Lung Research, Giessen, Germany
| | - Rory E Morty
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany; and .,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center, German Center for Lung Research, Giessen, Germany
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Hofemeier P, Koshiyama K, Wada S, Sznitman J. One (sub-)acinus for all: Fate of inhaled aerosols in heterogeneous pulmonary acinar structures. Eur J Pharm Sci 2017; 113:53-63. [PMID: 28954217 DOI: 10.1016/j.ejps.2017.09.033] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 02/07/2023]
Abstract
Computational Fluid Dynamics (CFD) have offered an attractive gateway to investigate in silico respiratory flows and aerosol transport in the depths of the lungs. Yet, not only do existing models lack sufficient anatomical realism in capturing the heterogeneity and morphometry of the acinar environment, numerical simulations have been widely restricted to domains capturing a mere few percent of a single acinus. Here, we present to the best of our knowledge the most detailed and comprehensive in silico simulations to date on the fate of aerosols in the acinar depths. Our heterogeneous acinar domains represent complete sub-acinar models (i.e. 1/8th of a full acinus) based on the recent algorithm of Koshiyama & Wada (2015), capturing statistics of human acinar morphometry (Ochs et al. 2004). Our simulations deliver high-resolution, 3D spatial-temporal data on aerosol transport and deposition, emphasizing how variances in acinar heterogeneity only play a minor role in determining general deposition outcomes. With such tools at hand, we revisit whole-lung deposition predictions (i.e. ICRP) based on past 1D lung models. While our findings under quiet breathing substantiate general deposition trends obtained with past predictions in the alveolar regions, we underscore how deposition fractions are anticipated to increase, in particular during deep inhalation. For such inhalation maneuver, our simulations support the notion of significantly augmented deposition for all aerosol sizes (0.005-5.0μm). Overall, our efforts not only help consolidate our mechanistic understanding of inhaled aerosol transport in the acinar depths but also continue to bridge the gap between "bottom-up" in silico models and regional deposition predictions from whole-lung models. Such quantifications provide what is deemed more accurate deposition predictions in morphometrically-faithful models and are particularly useful in assessing inhalation strategies for deep airway deposition (e.g. systemic delivery).
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Affiliation(s)
- Philipp Hofemeier
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Kenishiro Koshiyama
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Shigeo Wada
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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Hofemeier P, Sznitman J. The role of anisotropic expansion for pulmonary acinar aerosol deposition. J Biomech 2016; 49:3543-3548. [PMID: 27614613 PMCID: PMC5075582 DOI: 10.1016/j.jbiomech.2016.08.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/13/2016] [Accepted: 08/16/2016] [Indexed: 02/02/2023]
Abstract
Lung deformations at the local pulmonary acinar scale are intrinsically anisotropic. Despite progress in imaging modalities, the true heterogeneous nature of acinar expansion during breathing remains controversial, where our understanding of inhaled aerosol deposition still widely emanates from studies under self-similar, isotropic wall motions. Building on recent 3D models of multi-generation acinar networks, we explore in numerical simulations how different hypothesized scenarios of anisotropic expansion influence deposition outcomes of inhaled aerosols in the acinar depths. While the broader range of particles acknowledged to reach the acinar region (dp=0.005-5.0μm) are largely unaffected by the details of anisotropic expansion under tidal breathing, our results suggest nevertheless that anisotropy modulates the deposition sites and fractions for a narrow band of sub-micron particles (dp~0.5-0.75μm), where the fate of aerosols is greatly intertwined with local convective flows. Our findings underscore how intrinsic aerosol motion (i.e. diffusion, sedimentation) undermines the role of anisotropic wall expansion that is often attributed in determining aerosol mixing and acinar deposition.
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Affiliation(s)
- Philipp Hofemeier
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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Abstract
Background It has been hypothesized that by coupling magnetic particles to inhaled therapeutics, the ability to target specific lung regions (eg, only acinar deposition), or even more so specific points in the lung (eg, tumor targeting), can be substantially improved. Although this method has been proven feasible in seminal in vivo studies, there is still a wide gap in our basic understanding of the transport phenomena of magnetic particles in the pulmonary acinar regions of the lungs, including particle dynamics and deposition characteristics. Methods Here, we present computational fluid dynamics-discrete element method simulations of magnetically loaded microdroplet carriers in an anatomically inspired, space-filling, multi-generation acinar airway tree. Breathing motion is modeled by kinematic sinusoidal displacements of the acinar walls, during which droplets are inhaled and exhaled. Particle dynamics are governed by viscous drag, gravity, and Brownian motion as well as the external magnetic force. In particular, we examined the roles of droplet diameter and volume fraction of magnetic material within the droplets under two different breathing maneuvers. Results and discussion Our results indicate that by using magnetic-loaded droplets, 100% of the particles that enter are deposited in the acinar region. This is consistent across all particle sizes investigated (ie, 0.5–3.0 µm). This is best achieved through a deep inhalation maneuver combined with a breath-hold. Particles are found to penetrate deep into the acinus and disperse well, while the required amount of magnetic material is maintained low (<2.5%). Although particles in the size range of ~90–500 nm typically show the lowest deposition fractions, our results suggest that this feature could be leveraged to augment targeted delivery.
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Affiliation(s)
- Yan Ostrovski
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Philipp Hofemeier
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, Israel
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