Kikuchi Y, Stamenović D, Loring S H
Respiratory Biology Program, Harvard School of Public Health, Boston, Massachusetts 02115.
J Appl Physiol (1985). 1991 Mar;70(3):1059-67. doi: 10.1152/jappl.1991.70.3.1059.
To assess the contribution of the rib cage to chest wall elastance and hysteresis, we measured force-displacement behavior of the isolated canine rib cage during sinusoidal forcing of the sternum in the midsagittal plane at low frequencies (0.02-2.0 Hz). Elastance of the rib cage was nearly invariant with frequency of forcing from 0.02 to 1.0 Hz and decreased with increasing amplitude. Hysteresis, the width of the force-displacement loop at middisplacement (zero displacement), was nearly constant with frequency below 1.0 Hz and increased with increasing amplitude of forcing. Removal of muscle reduced elastance and hysteresis of the rib cage substantially. The data suggest that the excised dog rib cage shows dynamic behavior similar to that of the intact human rib cage and chest wall and that respiratory muscle is responsible for a major part of the behavior of the passive chest wall. We also calculated the major and minor stiffnesses in the sagittal plane, which differed by a factor of 3-11, and their directions lay close to the dorsoventral and cephalocaudal axes, respectively. Removal of muscle reduced the stiffnesses but did not change their directions. Thus, although respiratory muscles impede motion in the sagittal plane, they do not alter its pattern.
为评估胸廓对胸壁弹性和滞后作用的贡献，我们在低频（0.02 - 2.0 Hz）下，于胸骨在矢状面的正弦激励过程中，测量了离体犬胸廓的力 - 位移行为。胸廓的弹性在0.02至1.0 Hz的激励频率范围内几乎不变，并随振幅增加而降低。滞后作用，即中位位移（零位移）处力 - 位移环的宽度，在频率低于1.0 Hz时几乎恒定，并随激励振幅增加而增大。去除肌肉会显著降低胸廓的弹性和滞后作用。数据表明，切除的犬胸廓表现出与完整人体胸廓和胸壁相似的动态行为，并且呼吸肌是被动胸壁行为的主要决定因素。我们还计算了矢状面的主刚度和次刚度，它们相差3至11倍，且其方向分别靠近背腹轴和头尾轴。去除肌肉会降低刚度，但不会改变其方向。因此，尽管呼吸肌会阻碍矢状面的运动，但不会改变其运动模式。
