Pressure-driven micro-poro-mechanics: A variational framework for modeling the response of porous materials

Álvarez-Barrientos, Felipe; Hurtado, Daniel E.; Genet, Martin

doi:10.1016/j.ijengsci.2021.103586

Cited by 13 publications

(4 citation statements)

References 52 publications

(65 reference statements)

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“…To study the evolution of stress fields in our lung simulations, we considered the effective hydrostatic and von Mises stress tensor invariants (Sarabia-Vallejos et al, 2019;Álvarez-Barrientos et al, 2021)…”

Section: Resultsmentioning

confidence: 99%

“…To study the evolution of stress fields in our lung simulations, we considered the effective hydrostatic and von Mises stress tensor invariants ( Sarabia-Vallejos et al, 2019 ; Álvarez-Barrientos et al, 2021 )

and

with

Figure 6A reports the temporal evolution of the (effective) hydrostatic stress fields. Interestingly, at the time of peak volume ( t 1 ) we observe a significant variability in the levels of hydrostatic stress in the simulations considering different constitutive models, with CM5 resulting in the highest values.…”

Section: Resultsmentioning

confidence: 99%

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Whole-lung finite-element models for mechanical ventilation and respiratory research applications

Avilés-Rojas

Hurtado

2022

Front. Physiol.

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Mechanical ventilation has been a vital treatment for Covid-19 patients with respiratory failure. Lungs assisted with mechanical ventilators present a wide variability in their response that strongly depends on air-tissue interactions, which motivates the creation of simulation tools to enhance the design of ventilatory protocols. In this work, we aim to create anatomical computational models of the lungs that predict clinically-relevant respiratory variables. To this end, we formulate a continuum poromechanical framework that seamlessly accounts for the air-tissue interaction in the lung parenchyma. Based on this formulation, we construct anatomical finite-element models of the human lungs from computed-tomography images. We simulate the 3D response of lungs connected to mechanical ventilation, from which we recover physiological parameters of high clinical relevance. In particular, we provide a framework to estimate respiratory-system compliance and resistance from continuum lung dynamic simulations. We further study our computational framework in the simulation of the supersyringe method to construct pressure-volume curves. In addition, we run these simulations using several state-of-the-art lung tissue models to understand how the choice of constitutive models impacts the whole-organ mechanical response. We show that the proposed lung model predicts physiological variables, such as airway pressure, flow and volume, that capture many distinctive features observed in mechanical ventilation and the supersyringe method. We further conclude that some constitutive lung tissue models may not adequately capture the physiological behavior of lungs, as measured in terms of lung respiratory-system compliance. Our findings constitute a proof of concept that finite-element poromechanical models of the lungs can be predictive of clinically-relevant variables in respiratory medicine.

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Section: Resultsmentioning

confidence: 99%

“…To study the evolution of stress fields in our lung simulations, we considered the effective hydrostatic and von Mises stress tensor invariants ( Sarabia-Vallejos et al, 2019 ; Álvarez-Barrientos et al, 2021 )

and

with

Section: Resultsmentioning

confidence: 99%

Whole-lung finite-element models for mechanical ventilation and respiratory research applications

Avilés-Rojas

Hurtado

2022

Front. Physiol.

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“…Further, the study shows that an increase in porosity, which can be directly associated with alveolar airspace enlargement, may signify a loss of parenchymal elastance, a mechanical relationship that has long been observed in lungs with pulmonary emphysema ( Nagai et al, 1991 ). Therefore, a deep understanding of the porosity distribution in the whole lung plays a vital role in the creation of microstructurally-informed constitutive models ( Eskandari et al, 2019 ; Álvarez-Barrientos et al, 2021 ) that can predict the overall properties of the lung, as well as in informing organ-level computational models of the respiratory system ( Eskandari et al, 2015 ).…”

Section: Discussionmentioning

confidence: 99%

Three-Dimensional Whole-Organ Characterization of the Regional Alveolar Morphology in Normal Murine Lungs

2021

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Alveolar architecture plays a fundamental role in the processes of ventilation and perfusion in the lung. Alterations in the alveolar surface area and alveolar cavity volume constitute the pathophysiological basis of chronic respiratory diseases such as pulmonary emphysema. Previous studies based on micro-computed tomography (micro-CT) of lung samples have allowed the geometrical study of acinar units. However, our current knowledge is based on the study of a few tissue samples in random locations of the lung that do not give an account of the spatial distributions of the alveolar architecture in the whole lung. In this work, we combine micro-CT imaging and computational geometry algorithms to study the regional distribution of key morphological parameters throughout the whole lung. To this end, 3D whole-lung images of Sprague–Dawley rats are acquired using high-resolution micro-CT imaging and analyzed to estimate porosity, alveolar surface density, and surface-to-volume ratio. We assess the effect of current gold-standard dehydration methods in the preparation of lung samples and propose a fixation protocol that includes the application of a methanol-PBS solution before dehydration. Our results show that regional porosity, alveolar surface density, and surface-to-volume ratio have a uniform distribution in normal lungs, which do not seem to be affected by gravitational effects. We further show that sample fixation based on ethanol baths for dehydration introduces shrinking and affects the acinar architecture in the subpleural regions. In contrast, preparations based on the proposed dehydration protocol effectively preserve the alveolar morphology.

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“…Specifically for the lungs, several models and estimation procedures have been proposed in the literature. Various constitutive laws have been considered for the parenchyma, either based on micromechanics [Concha et al, 2018;Álvarez-Barrientos et al, 2021] or directly at the tissue scale . Some such laws have been used within full organ scale models, mostly focusing on air flows and gas exchanges [Yin et al, 2010;Roth et al, 2017], although some models were used for detailed solid mechanics analysis [Tawhai et al, 2009;Berger et al, 2016].…”

Section: Introductionmentioning

confidence: 99%

Estimation of Regional Pulmonary Compliance in Idiopathic Pulmonary Fibrosis Based on Personalized Lung Poromechanical Modeling

Patte

Brillet

Fétita

et al. 2022

Journal of Biomechanical Engineering

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Pulmonary function is tightly linked to the lung mechanical behavior, especially large deformation during breathing. Interstitial lung diseases, such as Idiopathic Pulmonary Fibrosis (IPF), have an impact on the pulmonary mechanics and consequently alter lung function. However, IPF remains poorly understood, poorly diagnosed and poorly treated. Currently, the mechanical impact of such diseases is assessed by pressure-volume curves, giving only global information. We developed a poromechanical model of the lung that can be personalized to a patient based on routine clinical data. The personalization pipeline uses clinical data, mainly CT-images at two time steps and involves the formulation of an inverse problem to estimate regional compliances. The estimation problem can be formulated both in terms of “effective”, i.e., without considering the mixture porosity, or “rescaled”, i.e., where the first-order effect of the porosity has been taken into account, compliances. Regional compliances are estimated for one control subject and three IPF patients, allowing to quantify the IPF-induced tissue stiffening. This personalized model could be used in the clinic as an objective and quantitative tool for IPF diagnosis.

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Pressure-driven micro-poro-mechanics: A variational framework for modeling the response of porous materials

Cited by 13 publications

References 52 publications

Whole-lung finite-element models for mechanical ventilation and respiratory research applications

Whole-lung finite-element models for mechanical ventilation and respiratory research applications

Three-Dimensional Whole-Organ Characterization of the Regional Alveolar Morphology in Normal Murine Lungs

Estimation of Regional Pulmonary Compliance in Idiopathic Pulmonary Fibrosis Based on Personalized Lung Poromechanical Modeling

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