Stamenovic D, Yager D
Department of Biomedical Engineering, College of Engineering, Boston University, Massachusetts.
J Appl Physiol (1985). 1988 Dec;65(6):2565-70. doi: 10.1152/jappl.1988.65.6.2565.
Pressure-volume measurements and the punch indentation test are used to obtain the bulk modulus (kappa) and the shear modulus (mu) of lung parenchyma of air- and liquid-filled rabbit lungs. Plots of kappa and mu vs. transpulmonary pressure obtained from these measurements indicate that there is very little difference between the elastic behavior of the air- and liquid-filled lung, suggesting that the mechanism of resisting deformation in both cases is similar. On the other hand, from plots of kappa and mu vs. lung volume, it appears that the elastic moduli are higher in the air-filled lung than in the liquid-filled lung at the same volume. These differences, referred to as kappa gamma and mu gamma, as well as the difference in transpulmonary pressures (P gamma), are presumably due to the additional elastic recoil of the air-filled lung provided by alveolar surface tension (gamma). No conclusion could be reached about the shape of the kappa gamma vs. P gamma curve. However, the mu gamma vs. P gamma relationship appears to be approximately linear, with a slope of approximately 0.5. This result agrees qualitatively with the model (T. A. Wilson and H. Bachofen, J. Appl. Physiol. 52: 1064-1070, 1982) in which the part of the parenchyma that provides P gamma is pictured as mechanically analogous to an open cell liquid foam, having mu gamma = 0.4P gamma (J. Appl. Mech. Trans. ASME 51: 229-231, 1984), but it is statistically significant only at high lung volumes.
压力-容积测量和冲压压痕试验被用于获取充气和充液兔肺实质的体积弹性模量（κ）和剪切模量（μ）。从这些测量中得到的κ和μ与跨肺压的关系图表明，充气肺和充液肺的弹性行为之间差异很小，这表明在这两种情况下抵抗变形的机制是相似的。另一方面，从κ和μ与肺容积的关系图来看，在相同容积下，充气肺的弹性模量似乎高于充液肺。这些差异，称为κγ和μγ，以及跨肺压的差异（Pγ），可能是由于肺泡表面张力（γ）为充气肺提供了额外的弹性回缩。关于κγ与Pγ曲线的形状无法得出结论。然而，μγ与Pγ的关系似乎大致呈线性，斜率约为0.5。这一结果在定性上与模型（T.A.威尔逊和H.巴赫芬，《应用生理学杂志》52:1064 - 1070,1982）一致，在该模型中，提供Pγ的实质部分被描绘为在力学上类似于开孔液体泡沫，μγ = 0.4Pγ（《应用力学杂志》，《美国机械工程师学会汇刊》51:229 - 231,1984），但仅在高肺容积时具有统计学意义。
