Entropy Production and the Pressure-Volume Curve of the Lung.
Entropy Production and the Pressure-Volume Curve of the Lung.
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DOI：
10.3389/fphys.2016.00073
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发表时间：
2016
影响因子：
4
通讯作者：
Suki B
中科院分区：
文献类型：
--
作者：
Oliveira CL;Araújo AD;Bates JH;Andrade JS Jr;Suki B
我们调查分析在健康和患病的肺在呼吸循环过程中的熵的产生。首先，我们通过将热力学定律应用于肺的众所周知的经肺压力-容积（P-V）曲线来计算健康肺中的熵产生，假设肺组织表现为类似于橡胶的熵弹簧。肺的体积模量B也从这些计算中导出。其次，我们将这种方法扩展到肺的弹性回缩障碍，如肺纤维化和肺气肿。这些疾病的特征是P-V关系的特殊改变。例如，在纤维化肺中，B随着疾病进展而单调增加，而在肺气肿中则相反。因此，这些疾病可以简单地通过对P-V曲线的参数进行适当的调整来模拟。利用克劳修斯的形式主义，我们表明，熵产生，ΔS，是有关的滞后面积，ΔA，封闭的P-V曲线在一个呼吸周期，即ΔS=ΔA scinT，其中T是体温。虽然ΔA高度依赖于疾病，但该公式适用于健康和患病的肺，无论疾病阶段如何。最后，我们使用一个分析预测的熵所产生的纤维化和肺气肿的肺。
We investigate analytically the production of entropy during a breathing cycle in healthy and diseased lungs. First, we calculate entropy production in healthy lungs by applying the laws of thermodynamics to the well-known transpulmonary pressure–volume (P–V) curves of the lung under the assumption that lung tissue behaves as an entropic spring similar to rubber. The bulk modulus, B, of the lung is also derived from these calculations. Second, we extend this approach to elastic recoil disorders of the lung such as occur in pulmonary fibrosis and emphysema. These diseases are characterized by particular alterations in the P–V relationship. For example, in fibrotic lungs B increases monotonically with disease progression, while in emphysema the opposite occurs. These diseases can thus be mimicked simply by making appropriate adjustments to the parameters of the P–V curve. Using Clausius's formalism, we show that entropy production, ΔS, is related to the hysteresis area, ΔA, enclosed by the P–V curve during a breathing cycle, namely, ΔS=ΔA∕T, where T is the body temperature. Although ΔA is highly dependent on the disease, such formula applies to healthy as well as diseased lungs, regardless of the disease stage. Finally, we use an ansatz to predict analytically the entropy produced by the fibrotic and emphysematous lungs.