Butler J P, Lehr J L, Drazen J M
J Appl Physiol (1985). 1987 Apr;62(4):1349-55. doi: 10.1152/jappl.1987.62.4.1349.
Consideration of the lung as an elastic continuum led us to investigate the possible propagation of elastic waves. Here the relevant stiffness and density are given by the Lamé constants and density of the parenchyma. To test this hypothesis, we measured propagation velocities (c) in dog lobes by recording transit times of a velocity impulse on one side of the lobe and the subsequent arrival on the other side. We compared our measured values of c with elastic longitudinal wave velocities (c long) predicted by values of elastic moduli given by Lai-Fook et al. (J. Appl. Physiol. 40: 508-513, 1976) as a function of translobar pressure (PL) and our measured densities. Good agreement was found between c and c long. Typical values of c ranged from 250-1,500 cm/s as PL ranged from 2-20 cmH2O. No systematic difference in the c-c long relation was found between inflation and deflation, suggesting that the elastic moduli of lungs are essentially a function of pressure. No significant effect was observed by changing the physical properties of the gas within the lobe [air vs. He vs. sulfur hexafluoride (SF6)], suggesting that indeed we were observing waves associated with the coupling of parenchymal density to parenchymal stiffness.
将肺视为弹性连续介质促使我们研究弹性波的可能传播。此处，相关的刚度和密度由拉梅常数和实质组织的密度给出。为了验证这一假设，我们通过记录速度脉冲在肺叶一侧的传播时间以及随后在另一侧的到达时间，测量了犬肺叶中的传播速度（c）。我们将测得的c值与Lai-Fook等人（《应用生理学杂志》40: 508 - 513, 1976）根据弹性模量值预测的弹性纵波速度（c long）进行比较，弹性模量值是跨肺叶压力（PL）和我们测得的密度的函数。发现c与c long之间具有良好的一致性。当PL在2 - 20 cmH₂O范围内时，c的典型值范围为250 - 1500 cm/s。在充气和放气之间，未发现c - c long关系存在系统差异，这表明肺的弹性模量本质上是压力的函数。改变肺叶内气体的物理性质（空气、氦气、六氟化硫（SF₆））未观察到显著影响，这表明我们确实观察到了与实质组织密度和实质组织刚度耦合相关的波。
