Jahed M, Lai-Fook S J, Bhagat P K
Biomedical Engineering Center, University of Kentucky, Lexington 40506.
J Appl Physiol (1985). 1990 May;68(5):2171-6. doi: 10.1152/jappl.1990.68.5.2171.
The velocities of longitudinal and transverse stress waves transmitted through inflated lung parenchyma depend on the lung stiffness, as defined by the bulk and shear moduli, and the lung density. We examined the relationship between stress wave velocities and lung density. A saline-filled reservoir was connected to the vessels of caudal dog lobes held inflated at 5 cmH2O transpulmonary pressure, and vascular volume and extravascular lung water were increased in steps by increasing vascular pressure. At each step, we measured the transmitted signals at locations 2 and 7 cm from an impulse surface distortion by means of microphones embedded in the lung surface. Longitudinal and transverse wave velocities were computed by using cross-correlation analysis of microphone signal pairs. Both wave velocities decreased as lung density increased: as a first approximation, wave velocities were inversely proportional to the square root of lung density. This behavior is consistent with the propagation of small-amplitude stress waves through an elastic continuum. Estimated bulk and shear moduli were 26 and 3.5 cmH2O, respectively, and were consistent with results from quasi-static deformation tests.
通过充气肺实质传播的纵向和横向应力波的速度取决于肺硬度（由体积模量和剪切模量定义）以及肺密度。我们研究了应力波速度与肺密度之间的关系。将一个充满盐水的储液器连接到在5 cmH₂O跨肺压下保持充气的犬尾叶血管上，并通过增加血管压力逐步增加血管容积和血管外肺水。在每一步中，我们通过嵌入肺表面的麦克风测量距脉冲表面畸变2 cm和7 cm处的传输信号。纵向和横向波速度通过使用麦克风信号对的互相关分析来计算。随着肺密度增加，两种波速度均降低：初步近似，波速度与肺密度的平方根成反比。这种行为与小振幅应力波通过弹性连续介质的传播一致。估计的体积模量和剪切模量分别为26和3.5 cmH₂O，与准静态变形试验的结果一致。
