Progression of regional lung strain and heterogeneity in lung injury: assessing the evolution under spontaneous breathing and mechanical ventilation

Hurtado, Daniel E.; Erranz, Benjamín; Lillo, Felipe; Sarabia‐Vallejos, Mauricio A.; Iturrieta, Pablo; Morales, Felipe; Blaha, Katherine; Medina, Tania; Rubio, Franco Díaz; Cruces, Pablo

doi:10.1186/s13613-020-00725-0

Cited by 39 publications

(36 citation statements)

References 41 publications

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“…The development of this framework to study lung deformations using DVC is extremely powerful. Although the use of such imaging techniques may not be new [ 12 , 13 , 14 , 15 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], the ability to register reliably the in situ mechanics alongside the images has streamlined its potential use in lung mechanics research. Work is continuously progressing to improve the method, to enable faster imaging to mitigate motion artefact in unfixed samples, for instance.…”

Section: Discussionmentioning

confidence: 99%

“…It is not feasible to clinically observe the mechanical cascade across length scales, and therefore, global measures are used to understand the overall function at the organ level. Macro-scale measures on clinical CT have been modelled to characterize disease progression [ 17 , 18 ], whilst other research efforts have focused on micro-computed tomography (micro-CT) [ 10 , 13 , 14 , 15 , 19 , 20 ]. Imaging in practice typically provides a snapshot view of the lung structure, though 4D methods are increasingly used.…”

Section: Introductionmentioning

confidence: 99%

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Correlating Local Volumetric Tissue Strains with Global Lung Mechanics Measurements

et al. 2021

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The mechanics of breathing is a fascinating and vital process. The lung has complexities and subtle heterogeneities in structure across length scales that influence mechanics and function. This study establishes an experimental pipeline for capturing alveolar deformations during a respiratory cycle using synchrotron radiation micro-computed tomography (SR-micro-CT). Rodent lungs were mechanically ventilated and imaged at various time points during the respiratory cycle. Pressure-Volume (P-V) characteristics were recorded to capture any changes in overall lung mechanical behaviour during the experiment. A sequence of tomograms was collected from the lungs within the intact thoracic cavity. Digital volume correlation (DVC) was used to compute the three-dimensional strain field at the alveolar level from the time sequence of reconstructed tomograms. Regional differences in ventilation were highlighted during the respiratory cycle, relating the local strains within the lung tissue to the global ventilation measurements. Strains locally reached approximately 150% compared to the averaged regional deformations of approximately 80–100%. Redistribution of air within the lungs was observed during cycling. Regions which were relatively poorly ventilated (low deformations compared to its neighbouring region) were deforming more uniformly at later stages of the experiment (consistent with its neighbouring region). Such heterogenous phenomena are common in everyday breathing. In pathological lungs, some of these non-uniformities in deformation behaviour can become exaggerated, leading to poor function or further damage. The technique presented can help characterize the multiscale biomechanical nature of a given pathology to improve patient management strategies, considering both the local and global lung mechanics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Correlating Local Volumetric Tissue Strains with Global Lung Mechanics Measurements

et al. 2021

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“…These works have been siloed from the material characterization of the airways (Eskandari et al, 2018) and parenchyma (Stamenovic and Yager, 1988;Birzle et al, 2019) at the tissue (Suki et al, 2005) or even microstructural scale (Eskandari et al, 2019). Furthermore, recent studies have recognized the important interplay between local tissue strains as it relates to mechanical overventilation in acute respiratory distress syndrome (Hurtado et al, 2020). To address these highlighted scientific gaps, we present the first, to the best of our knowledge, full-field deformation characterization of the ex vivo whole lung.…”

Section: Introductionmentioning

confidence: 99%

Novel Mechanical Strain Characterization of Ventilated ex vivo Porcine and Murine Lung using Digital Image Correlation

et al. 2020

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Respiratory illnesses, such as bronchitis, emphysema, asthma, and COVID-19, substantially remodel lung tissue, deteriorate function, and culminate in a compromised breathing ability. Yet, the structural mechanics of the lung is significantly understudied. Classical pressure-volume air or saline inflation studies of the lung have attempted to characterize the organ’s elasticity and compliance, measuring deviatory responses in diseased states; however, these investigations are exclusively limited to the bulk composite or global response of the entire lung and disregard local expansion and stretch phenomena within the lung lobes, overlooking potentially valuable physiological insights, as particularly related to mechanical ventilation. Here, we present a method to collect the first non-contact, full-field deformation measures of ex vivo porcine and murine lungs and interface with a pressure-volume ventilation system to investigate lung behavior in real time. We share preliminary observations of heterogeneous and anisotropic strain distributions of the parenchymal surface, associative pressure-volume-strain loading dependencies during continuous loading, and consider the influence of inflation rate and maximum volume. This study serves as a crucial basis for future works to comprehensively characterize the regional response of the lung across various species, link local strains to global lung mechanics, examine the effect of breathing frequencies and volumes, investigate deformation gradients and evolutionary behaviors during breathing, and contrast healthy and pathological states. Measurements collected in this framework ultimately aim to inform predictive computational models and enable the effective development of ventilators and early diagnostic strategies.

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“…ARDS is a non-cardiogenic form of pulmonary edema that results in bilateral parenchymal infiltrates. The disease is now recognized to have biologic and mechanical heterogeneity with significant differences in compliance, opening pressure, and time-constant between different lung segments 5 , 6 , 7 , 8 , 9 . Such differences make the selection of parameters for mechanical ventilation very challenging, and finding one parameter to fit all the different lung segments may not be possible.…”

Section: Introductionmentioning

confidence: 99%

Selective Lobe Ventilation and a Novel Platform for Pulmonary Drug Delivery

Maracaja

Khanna

Royster

et al. 2021

Journal of Cardiothoracic and Vascular Anesthesia

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The current methods of mechanical ventilation and pulmonary drug delivery do not account for the heterogeneity of acute respiratory distress syndrome (ARDS), or its dependence on gravity. The severe lung disease caused by SARS-CoV-2-2019 is one of the many causes of ARDS. SARS-CoV-2 has caused more than 2.7 million deaths world-wide and has challenged all therapeutic options for mechanical ventilation. Thus, new therapies are necessary to prevent deaths and long-term complications of severe lung diseases and prolonged mechanical ventilation. We have developed a novel device that allows selective lobe ventilation, selective lobe recruitment and provides a new platform for pulmonary drug delivery. A major advantage of separating lobes that are mechanically heterogeneous is to allow customization of ventilator parameters to match the needs of segments with similar compliance, for better overall ventilation perfusion relationship (V/Q) and prevention of ventilator induced lung injury (VILI) of more compliant lobes. This device accounts for lung heterogeneity and is a potential new therapy for acute lung injury by allowing selective lobe mechanical ventilation using two novel modes of mechanical ventilation (differential positive end-expiratory pressure and asynchronous ventilation) and two new modalities of alveolar recruitment (selective lobe recruitment and continuous positive airway pressure of lower lobes with continuous ventilation of upper lobes). We report initial experience with this novel device which includes a brief overview of device development, the initial in vitro, ex-vivo and in-vivo testing, layout future research, potential benefits, new therapies, and expected challenges prior to uniform implementation in clinical practice.

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Progression of regional lung strain and heterogeneity in lung injury: assessing the evolution under spontaneous breathing and mechanical ventilation

Cited by 39 publications

References 41 publications

Correlating Local Volumetric Tissue Strains with Global Lung Mechanics Measurements

Correlating Local Volumetric Tissue Strains with Global Lung Mechanics Measurements

Novel Mechanical Strain Characterization of Ventilated ex vivo Porcine and Murine Lung using Digital Image Correlation

Selective Lobe Ventilation and a Novel Platform for Pulmonary Drug Delivery

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