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Christou S, Chatziathanasiou T, Angeli S, Koullapis P, Stylianou F, Sznitman J, Guo HH, Kassinos SC. Anatomical variability in the upper tracheobronchial tree: sex-based differences and implications for personalized inhalation therapies. J Appl Physiol (1985) 2020; 130:678-707. [PMID: 33180641 DOI: 10.1152/japplphysiol.00144.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The morphometry of the large conducting airways is presumed to have a strong effect on the regional deposition of inhaled aerosol particles. Nevertheless, sex-based differences have not been fully quantified and are still largely ignored in designing inhalation therapies. To this end, we retrospectively analyzed high-resolution computed tomography scans for 185 individuals (90 women, 95 men) in the age range of 12-89 yr to determine airway luminal areas, airway lengths, and bifurcation angles. Only subjects free of chronic airway disease were considered. In men, luminal areas of the upper conducting airways were, on average, ∼30%-50% larger when compared with those in women, with the largest differences found in the trachea (289.72 ± 54.25 vs. 193.50 ± 42.37 mm2 for men and women, respectively). The ratio of the largest luminal area in men to the smallest luminal area in women (in any given segment) ranged between 4.5 and 8.6, the largest differences being found in the lobar bronchi. Sex-based differences were minor in the case of bifurcation angles (e.g., average main bifurcation angle: 93.04 ± 9.58° vs. 91.03 ± 9.81° for men and women, respectively), but large intersubject variability was found irrespective of sex (e.g., range of main bifurcation angle: 65.04°-122.01° vs. 69.46°-113.94° for men and women, respectively). Bronchial segments were shorter by ∼5%-20% in women relative to men, the largest differences being located in the upper lobes. False discovery rate analysis revealed statistically significant associations among morphometric measures of the right lung in women (but not in men), suggesting two phenotypes among women that we attribute to the smaller female thoracic volume.NEW & NOTEWORTHY We found significant sex-based morphometric differences in the central airways of healthy men and women that were only mildly attenuated in subsets matched for lung volume. Lumen areas were significantly larger in men (∼30%-50%). Large variability (∼75%-87%) in airway bifurcation angles (60°-122°) was found irrespective of sex. The branching pattern of the right main and right upper bronchi in women (but not in men) follows two phenotypes modulated by lung volume.
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Affiliation(s)
- Simoni Christou
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - Thanasis Chatziathanasiou
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | | | - Pantelis Koullapis
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - Fotos Stylianou
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Haiwei Henry Guo
- Department of Radiology, Stanford University School of Medicine, Stanford, California
| | - Stavros C Kassinos
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
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Olsson B, Kassinos SC. On the Validation of Generational Lung Deposition Computer Models Using Planar Scintigraphic Images: The Case of Mimetikos Preludium. J Aerosol Med Pulm Drug Deliv 2020; 34:115-123. [PMID: 32790531 DOI: 10.1089/jamp.2020.1620] [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] [Indexed: 11/13/2022] Open
Abstract
Background: Mechanistic computer models for calculation of total and regional deposition of aerosols in the lungs are important tools for predicting or understanding clinical studies and for facilitating development of pharmaceutical inhalation products. Validation of such models must be indirect since generational in vivo data are lacking. Planar scintigraphy is probably the most common method addressing regional lung deposition in humans. Scintigraphic regions of interest (ROI) contain mixtures of airway generations and can therefore not be directly compared to model results. We propose a method to translate computed deposition per generation to deposition in scintigraphic ROI to be able to compare computed results with corresponding results obtained in humans. Methods: The total and regional lung deposition computed by the one-dimensional algebraic typical-path software Mimetikos Preludium was compared for 18 study legs in 14 published deposition studies involving 9 dry powder inhaler brands to the activity in planar scintigraphic ROIs (oropharyngeal, central [C], intermediate, and peripheral [P]) using for the computed regional lung distribution a generic mapping of the contribution of each airway generation to the ROIs. Results: The computed oropharyngeal and total lung deposition correlated with high significance (p < 0.0001) to the scintigraphic results with a near one-to-one relationship. For the regional lung distribution, computed C, P, and P/C results correlated with high significance (p < 0.01) to the corresponding scintigraphic measures. The computed C (P) deposition was on average about 28% lower (8% higher) than the mean scintigraphic results. The computed P/C ratio was on average 29% higher than the mean scintigraphic ratio. Conclusions: The results indicate that both the computational deposition model and the mapping algorithm are valid. The small underprediction of the C region merits further investigations. We believe that this method may prove useful also for the validation of computational fluid particle dynamic lung deposition models.
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Affiliation(s)
| | - Stavros C Kassinos
- Computational Science Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
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Shachar-Berman L, Ostrovski Y, Koshiyama K, Wada S, Kassinos SC, Sznitman J. Targeting inhaled fibers to the pulmonary acinus: Opportunities for augmented delivery from in silico simulations. Eur J Pharm Sci 2019; 137:105003. [DOI: 10.1016/j.ejps.2019.105003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/03/2019] [Accepted: 07/10/2019] [Indexed: 02/02/2023]
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Janke T, Koullapis P, Kassinos SC, Bauer K. PIV measurements of the SimInhale benchmark case. Eur J Pharm Sci 2019; 133:183-189. [PMID: 30940542 DOI: 10.1016/j.ejps.2019.03.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 11/08/2018] [Revised: 02/26/2019] [Accepted: 03/27/2019] [Indexed: 11/15/2022]
Abstract
Particle Image Velocimetry (PIV) measurements with the aim of providing experimental data for the SimInhale benchmark case are presented within this work. We, therefore, present a refractive index matched, transparent model of the benchmark geometry, in which the velocity and turbulent kinetic energy fields are examined at flow rates comparable to 15, 30 and 60 L/min (Re ≈ 1000-4500) in air. Furthermore, these results are compared with Large Eddy Simulations (LES). The results reveal a Reynolds number independence of the qualitative velocity field in the range covered within this work. Good agreement is found between the PIV and LES data, with a slight over-prediction of turbulent kinetic energies by the simulations. The obtained experimental data will be part of a common, publicly accessible ERCOFTAC database along with additional results published recently.
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Affiliation(s)
- T Janke
- Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg, Germany.
| | - P Koullapis
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - S C Kassinos
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - K Bauer
- Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Freiberg, Germany
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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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Affiliation(s)
- Elias Fattal
- UMR CNRS 8612, Institut Galien Paris-Sud, University of Paris-Sud, School of Pharmacy, 5 Rue Jean Baptiste Clément, 92290 Châtenay-Malabry, France.
| | - Stavros C Kassinos
- Computational Sciences Laboratory, Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1 University Avenue, 2109 Nicosia, Cyprus.
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Koullapis P, Kassinos SC, Muela J, Perez-Segarra C, Rigola J, Lehmkuhl O, Cui Y, Sommerfeld M, Elcner J, Jicha M, Saveljic I, Filipovic N, Lizal F, Nicolaou L. Regional aerosol deposition in the human airways: The SimInhale benchmark case and a critical assessment of in silico methods. Eur J Pharm Sci 2017; 113:77-94. [PMID: 28890203 DOI: 10.1016/j.ejps.2017.09.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [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: 06/15/2017] [Revised: 09/01/2017] [Accepted: 09/04/2017] [Indexed: 10/18/2022]
Abstract
Regional deposition effects are important in the pulmonary delivery of drugs intended for the topical treatment of respiratory ailments. They also play a critical role in the systemic delivery of drugs with limited lung bioavailability. In recent years, significant improvements in the quality of pulmonary imaging have taken place, however the resolution of current imaging modalities remains inadequate for quantifying regional deposition. Computational Fluid-Particle Dynamics (CFPD) can fill this gap by providing detailed information about regional deposition in the extrathoracic and conducting airways. It is therefore not surprising that the last 15years have seen an exponential growth in the application of CFPD methods in this area. Survey of the recent literature however, reveals a wide variability in the range of modelling approaches used and in the assumptions made about important physical processes taking place during aerosol inhalation. The purpose of this work is to provide a concise critical review of the computational approaches used to date, and to present a benchmark case for validation of future studies in the upper airways. In the spirit of providing the wider community with a reference for quality assurance of CFPD studies, in vitro deposition measurements have been conducted in a human-based model of the upper airways, and several groups within MP1404 SimInhale have computed the same case using a variety of simulation and discretization approaches. Here, we report the results of this collaborative effort and provide a critical discussion of the performance of the various simulation methods. The benchmark case, in vitro deposition data and in silico results will be published online and made available to the wider community. Particle image velocimetry measurements of the flow, as well as additional numerical results from the community, will be appended to the online database as they become available in the future.
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Affiliation(s)
- P Koullapis
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - S C Kassinos
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - J Muela
- Heat and Mass Transfer Technological Centre, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - C Perez-Segarra
- Heat and Mass Transfer Technological Centre, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - J Rigola
- Heat and Mass Transfer Technological Centre, Universitat Politècnica de Catalunya, Terrassa, Spain
| | - O Lehmkuhl
- Barcelona Supercomputing Center, Barcelona, Spain
| | - Y Cui
- Chair of Applied Mechanics, Friedrich-Alexander University Erlangen-Nuremberg, Germany
| | - M Sommerfeld
- Institute of Process Engineering, Otto von Guericke-University Magdeburg, Halle, Germany
| | - J Elcner
- Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic
| | - M Jicha
- Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic
| | - I Saveljic
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - N Filipovic
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - F Lizal
- Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic
| | - L Nicolaou
- Department of Mechanical Engineering, Imperial College London, London, UK.
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Ma S, Kassinos SC, Kassinos DF. Assessing the Impact of Concentration-Dependent Fluid Properties on Concentration Polarization in Crossflow Membrane Systems. Ind Eng Chem Res 2008. [DOI: 10.1021/ie0713893] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shengwei Ma
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos St., P.O. Box 20537, Nicosia 1678, Cyprus, and Department of Civil and Environmental Engineering, University of Cyprus
| | - Stavros C. Kassinos
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos St., P.O. Box 20537, Nicosia 1678, Cyprus, and Department of Civil and Environmental Engineering, University of Cyprus
| | - Despo Fatta Kassinos
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos St., P.O. Box 20537, Nicosia 1678, Cyprus, and Department of Civil and Environmental Engineering, University of Cyprus
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Ma S, Kassinos SC, Fatta Kassinos D, Akylas E. Effects of selective water withdrawal schemes on thermal stratification in Kouris Dam in Cyprus. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1440-1770.2007.00353.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Shengwei Ma
- Department of Mechanical and Manufacturing Engineering,
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