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Ma H, Fujioka H, Halpern D, Bates JHT, Gaver DP. Full-lung simulations of mechanically ventilated lungs incorporating recruitment/derecruitment dynamics. FRONTIERS IN NETWORK PHYSIOLOGY 2023; 3:1257710. [PMID: 38020240 PMCID: PMC10654632 DOI: 10.3389/fnetp.2023.1257710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 10/18/2023] [Indexed: 12/01/2023]
Abstract
This study developed and investigated a comprehensive multiscale computational model of a mechanically ventilated ARDS lung to elucidate the underlying mechanisms contributing to the development or prevention of VILI. This model is built upon a healthy lung model that incorporates realistic airway and alveolar geometry, tissue distensibility, and surfactant dynamics. Key features of the ARDS model include recruitment and derecruitment (RD) dynamics, alveolar tissue viscoelasticity, and surfactant deficiency. This model successfully reproduces realistic pressure-volume (PV) behavior, dynamic surface tension, and time-dependent descriptions of RD events as a function of the ventilation scenario. Simulations of Time-Controlled Adaptive Ventilation (TCAV) modes, with short and long durations of exhalation (T Low - and T Low +, respectively), reveal a higher incidence of RD for T Low + despite reduced surface tensions due to interfacial compression. This finding aligns with experimental evidence emphasizing the critical role of timing in protective ventilation strategies. Quantitative analysis of energy dissipation indicates that while alveolar recruitment contributes only a small fraction of total energy dissipation, its spatial concentration and brief duration may significantly contribute to VILI progression due to its focal nature and higher intensity. Leveraging the computational framework, the model may be extended to facilitate the development of personalized protective ventilation strategies to enhance patient outcomes. As such, this computational modeling approach offers valuable insights into the complex dynamics of VILI that may guide the optimization of ventilation strategies in ARDS management.
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Affiliation(s)
- Haoran Ma
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, United States
| | - Hideki Fujioka
- Center for Computational Science, Tulane University, New Orleans, LA, United States
| | - David Halpern
- Department of Mathematics, University of Alabama, Tuscaloosa, AL, United States
| | - Jason H. T. Bates
- Larner College of Medicine, University of Vermont, Burlington, VT, United States
| | - Donald P. Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, United States
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Fujioka H, Romanò F, Muradoglu M, Grotberg JB. Splitting of a three-dimensional liquid plug at an airway bifurcation. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2022; 34:081907. [PMID: 36033359 PMCID: PMC9406020 DOI: 10.1063/5.0101662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/30/2022] [Indexed: 06/15/2023]
Abstract
Employing the moving particles' semi-implicit (MPS) method, this study presents a numerical framework for solving the Navier-Stokes equations for the propagation and the split of a liquid plug through a three-dimensional air-filled bifurcating tube, where the inner surface is coated by a thin fluid film, and surface tension acts on the air-liquid interface. The detailed derivation of a modified MPS method to handle the air-liquid interface of liquid plugs is presented. When the front air-liquid interface of the plug splits at the bifurcation, the interface deforms quickly and causes large wall shear stress. We observe that the presence of a transverse gravitational force causes asymmetries in plug splitting, which becomes more pronounced as the capillary number decreases or the Bond number increases. We also observe that there exists a critical capillary number below which the plug does not split into two daughter tubes but propagates into the lower daughter tube only. In order to deliver the plug into the upper daughter tube, the driving pressure to push the plug is required to overcome the hydrostatic pressure due to gravity. These tendencies agree with our previous experimental and theoretical studies.
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Affiliation(s)
- Hideki Fujioka
- Center for Computational Science, Tulane University, 6823 St. Charles Avenue, New Orleans, Louisiana 70118, USA
| | - Francesco Romanò
- Univ. Lille, CNRS, ONERA, Arts et Métiers Institute of Technology, Centrale Lille, UMR 9014-LMFL-Laboratoire de Mécanique des Fluides de Lille–Kampé de Fériet, F-59000 Lille, France
| | - Metin Muradoglu
- Department of Mechanical Engineering, Koc University, Rumelifeneri Yolu Sariyer/Istanbul 34450, Turkey
| | - James B. Grotberg
- Department of Biomedical Engineering, University of Michigan, 2200 Bonisteel Blvd., Ann Arbor, Michigan 48109, USA
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Neelakantan S, Xin Y, Gaver DP, Cereda M, Rizi R, Smith BJ, Avazmohammadi R. Computational lung modelling in respiratory medicine. J R Soc Interface 2022; 19:20220062. [PMID: 35673857 PMCID: PMC9174712 DOI: 10.1098/rsif.2022.0062] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/03/2022] [Indexed: 11/12/2022] Open
Abstract
Computational modelling of the lungs is an active field of study that integrates computational advances with lung biophysics, biomechanics, physiology and medical imaging to promote individualized diagnosis, prognosis and therapy evaluation in lung diseases. The complex and hierarchical architecture of the lung offers a rich, but also challenging, research area demanding a cross-scale understanding of lung mechanics and advanced computational tools to effectively model lung biomechanics in both health and disease. Various approaches have been proposed to study different aspects of respiration, ranging from compartmental to discrete micromechanical and continuum representations of the lungs. This article reviews several developments in computational lung modelling and how they are integrated with preclinical and clinical data. We begin with a description of lung anatomy and how different tissue components across multiple length scales affect lung mechanics at the organ level. We then review common physiological and imaging data acquisition methods used to inform modelling efforts. Building on these reviews, we next present a selection of model-based paradigms that integrate data acquisitions with modelling to understand, simulate and predict lung dynamics in health and disease. Finally, we highlight possible future directions where computational modelling can improve our understanding of the structure-function relationship in the lung.
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Affiliation(s)
- Sunder Neelakantan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Yi Xin
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Donald P. Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA
| | - Maurizio Cereda
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rahim Rizi
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
- Department of Pediatric Pulmonary and Sleep Medicine, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Reza Avazmohammadi
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
- Department of Cardiovascular Sciences, Houston Methodist Academic Institute, Houston, TX, USA
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Ma H, Fujioka H, Halpern D, Gaver DP. Surfactant-Mediated Airway and Acinar Interactions in a Multi-Scale Model of a Healthy Lung. Front Physiol 2020; 11:941. [PMID: 32922307 PMCID: PMC7456900 DOI: 10.3389/fphys.2020.00941] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 07/14/2020] [Indexed: 12/03/2022] Open
Abstract
We present a computational multi-scale model of an adult human lung that combines dynamic surfactant physicochemical interactions and parenchymal tethering between ~16 generations of airways and subtended acini. This model simulates the healthy lung by modeling nonlinear stress distributions from airway/alveolar interdependency. In concert with multi-component surfactant transport processes, this serves to stabilize highly compliant interacting structures. This computational model, with ~10 k degrees of freedom, demonstrates physiological processes in the normal lung such as multi-layer surfactant transport and pressure-volume hysteresis behavior. Furthermore, this model predicts non-equilibrium stress distributions due to compliance mismatches between airway and alveolar structures. This computational model provides a baseline for the exploration of multi-scale interactions of pathological conditions that can further our understanding of disease processes and guide the development of protective ventilation strategies for the treatment of acute respiratory distress syndrome (ARDS).
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Affiliation(s)
- Haoran Ma
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, United States
| | - Hideki Fujioka
- Center for Computational Science, Tulane University, New Orleans, LA, United States
| | - David Halpern
- Department of Mathematics, University of Alabama, Tuscaloosa, AL, United States
| | - Donald P. Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, United States
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Kazemi A, Louis B, Isabey D, Nieman GF, Gatto LA, Satalin J, Baker S, Grotberg JB, Filoche M. Surfactant delivery in rat lungs: Comparing 3D geometrical simulation model with experimental instillation. PLoS Comput Biol 2019; 15:e1007408. [PMID: 31622332 PMCID: PMC6818804 DOI: 10.1371/journal.pcbi.1007408] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 10/29/2019] [Accepted: 09/18/2019] [Indexed: 11/24/2022] Open
Abstract
Surfactant Replacement Therapy (SRT), which involves instillation of a liquid-surfactant mixture directly into the lung airway tree, is a major therapeutic treatment in neonatal patients with respiratory distress syndrome (RDS). This procedure has proved to be remarkably effective in premature newborns, inducing a five-fold decrease of mortality in the past 35 years. Disappointingly, its use in adults for treating acute respiratory distress syndrome (ARDS) experienced initial success followed by failures. Our recently developed numerical model has demonstrated that transition from success to failure of SRT in adults could, in fact, have a fluid mechanical origin that is potentially reversible. Here, we present the first numerical simulations of surfactant delivery into a realistic asymmetric conducting airway tree of the rat lung and compare them with experimental results. The roles of dose volume (VD), flow rate, and multiple aliquot delivery are investigated. We find that our simulations of surfactant delivery in rat lungs are in good agreement with our experimental data. In particular, we show that the monopodial architecture of the rat airway tree plays a major role in surfactant delivery, contributing to the poor homogeneity of the end distribution of surfactant. In addition, we observe that increasing VD increases the amount of surfactant delivered to the acini after losing a portion to coating the involved airways, the coating cost volume, VCC. Finally, we quantitatively assess the improvement resulting from a multiple aliquot delivery, a method sometimes employed clinically, and find that a much larger fraction of surfactant reaches the alveolar regions in this case. This is the first direct qualitative and quantitative comparison of our numerical model with experimental studies, which enhances our previous predictions in adults and neonates while providing a tool for predicting, engineering, and optimizing patient-specific surfactant delivery in complex situations.
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Affiliation(s)
- Alireza Kazemi
- Physique de la Matière Condensée, École Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France
| | - Bruno Louis
- ERL 7000 CNRS and IMRB U955 Inserm, Université Paris Est Créteil, Créteil, France
| | - Daniel Isabey
- ERL 7000 CNRS and IMRB U955 Inserm, Université Paris Est Créteil, Créteil, France
| | - Gary F. Nieman
- Department of Surgery, Upstate Medical University, Syracuse, New York, United States of America
| | - Louis A. Gatto
- Department of Surgery, Upstate Medical University, Syracuse, New York, United States of America
| | - Joshua Satalin
- Department of Surgery, Upstate Medical University, Syracuse, New York, United States of America
| | - Sarah Baker
- Department of Surgery, Upstate Medical University, Syracuse, New York, United States of America
| | - James B. Grotberg
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Marcel Filoche
- Physique de la Matière Condensée, École Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France
- ERL 7000 CNRS and IMRB U955 Inserm, Université Paris Est Créteil, Créteil, France
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Ryans JM, Fujioka H, Gaver DP. Microscale to mesoscale analysis of parenchymal tethering: the effect of heterogeneous alveolar pressures on the pulmonary mechanics of compliant airways. J Appl Physiol (1985) 2019; 126:1204-1213. [PMID: 30676866 PMCID: PMC6589812 DOI: 10.1152/japplphysiol.00178.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 01/16/2019] [Accepted: 01/16/2019] [Indexed: 11/22/2022] Open
Abstract
In the healthy lung, bronchi are tethered open by the surrounding parenchyma; for a uniform distribution of these peribronchial structures, the solution is well known. An open question remains regarding the effect of a distributed set of collapsed alveoli, as can occur in disease. Here, we address this question by developing and analyzing microscale finite-element models of systems of heterogeneously inflated alveoli to determine the range and extent of parenchymal tethering effects on a neighboring collapsible airway. This analysis demonstrates that micromechanical stresses extend over a range of ∼5 airway radii, and this behavior is dictated primarily by the fraction, not distribution, of collapsed alveoli in that region. A mesoscale analysis of the microscale data identifies an effective shear modulus, Geff, that accurately characterizes the parenchymal support as a function of the average transpulmonary pressure of the surrounding alveoli. We demonstrate the use of this formulation by analyzing a simple model of a single collapsible airway surrounded by heterogeneously inflated alveoli (a "pig-in-a-blanket" model), which quantitatively demonstrates the increased parenchymal compliance and reduction in airway caliber that occurs with decreased parenchymal support from hypoinflated obstructed alveoli. This study provides a building block from which models of an entire lung can be developed in a computationally tenable manner that would simulate heterogeneous pulmonary mechanical interdependence. Such multiscale models could provide fundamental insight toward the development of protective ventilation strategies to reduce the incidence or severity of ventilator-induced lung injury. NEW & NOTEWORTHY A destabilized lung leads to airway and alveolar collapse that can result in catastrophic pulmonary failure. This study elucidates the micromechanical effects of alveolar collapse and determines its range of influence on neighboring collapsible airways. A mesoscale analysis reveals a master relationship that can that can be used in a computationally efficient manner to quantitatively model alveolar mechanical heterogeneity that exists in acute respiratory distress syndrome (ARDS), which predisposes the lung to volutrauma and/or atelectrauma. This analysis may lead to computationally tenable simulations of heterogeneous organ-level mechanical interactions that can illuminate novel protective ventilation strategies to reduce ventilator-induced lung injury.
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Affiliation(s)
- Jason M Ryans
- Department of Biomedical Engineering, Tulane University , New Orleans, Louisiana
| | - Hideki Fujioka
- Information Technology and Center for Computational Science, Tulane University, New Orleans, Louisiana
| | - Donald P Gaver
- Department of Biomedical Engineering, Tulane University , New Orleans, Louisiana
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Yamaguchi E, Nolan LP, Gaver DP. Microscale distribution and dynamic surface tension of pulmonary surfactant normalize the recruitment of asymmetric bifurcating airways. J Appl Physiol (1985) 2017; 122:1167-1178. [DOI: 10.1152/japplphysiol.00543.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 12/16/2016] [Accepted: 01/04/2017] [Indexed: 01/03/2023] Open
Abstract
We investigate the influence of bifurcation geometry, asymmetry of daughter airways, surfactant distribution, and physicochemical properties on the uniformity of airway recruitment of asymmetric bifurcating airways. To do so, we developed microfluidic idealized in vitro models of bifurcating airways, through which we can independently evaluate the impact of carina location and daughter airway width and length. We explore the uniformity of recruitment and its relationship to the dynamic surface tension of the lining fluid and relate this behavior to the hydraulic (PHyd) and capillary (PCap) pressure drops. These studies demonstrate the extraordinary importance of PCap in stabilizing reopening, even in highly asymmetric systems. The dynamic surface tension of pulmonary surfactant is integral to this stability because it modulates PCap in a velocity-dependent manner. Furthermore, the surfactant distribution at the propagating interface can have a very large influence on recruitment stability by focusing surfactant preferentially to specific daughter airways. This implies that modification of the surfactant distribution through novel modes of ventilation could be useful in inducing uniformly recruited lungs, aiding in gas exchange, and reducing ventilator-induced lung injury. NEW & NOTEWORTHY The dynamic surface tension of pulmonary surfactant is integral to the uniformity of asymmetric bifurcation airway recruitments because it modulates capillary pressure drop in a velocity-dependent manner. Also, the surfactant distribution at the propagating interface can have a very large influence on recruitment stability by focusing surfactant preferentially to specific daughter airways. This implies that modification of the surfactant distribution through novel modes of ventilation could be useful in inducing uniformly recruited lungs, reducing ventilator-induced lung injury.
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Affiliation(s)
- Eiichiro Yamaguchi
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana
| | - Liam P. Nolan
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana
| | - Donald P. Gaver
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana
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