Microscale to mesoscale analysis of parenchymal tethering: the effect of heterogeneous alveolar pressures on the pulmonary mechanics of compliant airways
Microscale to mesoscale analysis of parenchymal tethering: the effect of heterogeneous alveolar pressures on the pulmonary mechanics of compliant airways
复制标题
实质束缚的微观到中尺度分析：异质肺泡压力对顺应性气道肺力学的影响
DOI：
10.1152/japplphysiol.00178.2018
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发表时间：
2019
影响因子：
3.3
通讯作者：
Gaver, Donald P.
中科院分区：
文献类型：
--
作者：
Ryans, Jason M.;Fujioka, Hideki;Gaver, Donald P.
在健康的肺中，支气管被周围的肺实质栓开;对于这些支气管周围结构的均匀分布，解决方案是众所周知的。一个悬而未决的问题仍然是关于一组分布的肺泡塌陷的影响，因为可以发生在疾病。在这里，我们解决这个问题，通过开发和分析微尺度有限元模型的系统不均匀充气肺泡，以确定范围和程度的实质拴系效应对邻近的可塌陷气道。该分析表明，微机械应力延伸到气道半径的1.5倍范围内，并且该行为主要由该区域中塌陷肺泡的分数而不是分布决定。微尺度数据的中尺度分析确定了有效剪切模量Geff，其准确地表征了作为周围肺泡的平均经肺压力的函数的实质支持。我们通过分析一个简单的模型，一个单一的可折叠的气道周围的不均匀膨胀的肺泡（一个“猪在毯子”模型），这定量地证明了增加的实质顺应性和减少的气道口径，发生与减少实质支持hypoinflated阻塞的肺泡。这项研究提供了一个构建模块，从该模块可以以计算上可行的方式开发整个肺的模型，该方式将模拟异质性肺机械相互依赖性。这种多尺度模型可以为保护性通气策略的发展提供基本的见解，以减少呼吸机引起的肺损伤的发生率或严重程度。新&值得注意的是，肺不稳定导致气道和肺泡塌陷，可导致灾难性的肺功能衰竭。本研究阐明肺泡萎陷的微观力学效应，并确定其对邻近萎陷气道的影响范围。中尺度分析揭示了一个主关系，可以使用一个计算效率高的方式来定量模拟肺泡机械异质性，存在于急性呼吸窘迫综合征（ARDS），易患肺体积创伤和/或肺不张。这种分析可能导致计算上可行的模拟异质器官水平的机械相互作用，可以照亮新的保护性通气策略，以减少呼吸机引起的肺损伤。
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 & NOTEWORTHYA 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.