Inflation instability in the lung: an analytical model of a thick-walled alveolus with wavy fibres under large deformations
Inflation instability in the lung: an analytical model of a thick-walled alveolus with wavy fibres under large deformations
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DOI：
10.1098/rsif.2021.0594
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发表时间：
2021-10-13
影响因子：
3.9
通讯作者：
Suki, Bela
中科院分区：
文献类型：
--
作者：
Jawde, Samer Bou;Karrobi, Kavon;Suki, Bela
中空弹性结构的膨胀可能变得不稳定，如果其壁中的张力没有随着体积的增加而足够迅速地上升，则会表现出失控现象。生物系统避免这种通货膨胀不稳定的原因仍然知之甚少。这最好地由肺来例证，肺在其功能容积范围内膨胀而没有不稳定。本研究的目的是确定肺实质的成分如何决定组织应力，以保护肺泡在充气过程中免受不稳定相关的过度膨胀。本文提出了一个由波状弹性纤维组成的厚壁肺泡的分析模型，并研究了其在大变形下的压力-体积特性。使用二次谐波产生成像，我们发现，胶原波度遵循β分布。使用此分布来拟合人体压力-容积曲线，我们估计胶原蛋白和弹性蛋白的有效刚度分别为1247 kPa和18.3 kPa。此外，我们证明，线性弹性，但波浪形胶原纤维是足以实现膨胀的稳定性，在生理压力范围内，如果肺泡厚度与半径比大于0.05。因此，我们的模型确定的肺泡几何形状和胶原蛋白波纹膨胀稳定性所需的约束，并提供了一个多尺度的肺泡压力和纤维在健康和患病的肺的压力之间的联系。
Inflation of hollow elastic structures can become unstable and exhibit a runaway phenomenon if the tension in their walls does not rise rapidly enough with increasing volume. Biological systems avoid such inflation instability for reasons that remain poorly understood. This is best exemplified by the lung, which inflates over its functional volume range without instability. The goal of this study was to determine how the constituents of lung parenchyma determine tissue stresses that protect alveoli from instability-related overdistension during inflation. We present an analytical model of a thick-walled alveolus composed of wavy elastic fibres, and investigate its pressure-volume behaviour under large deformations. Using second-harmonic generation imaging, we found that collagen waviness follows a beta distribution. Using this distribution to fit human pressure-volume curves, we estimated collagen and elastin effective stiffnesses to be 1247 kPa and 18.3 kPa, respectively. Furthermore, we demonstrate that linearly elastic but wavy collagen fibres are sufficient to achieve inflation stability within the physiological pressure range if the alveolar thickness-to-radius ratio is greater than 0.05. Our model thus identifies the constraints on alveolar geometry and collagen waviness required for inflation stability and provides a multiscale link between alveolar pressure and stresses on fibres in healthy and diseased lungs.