Ward M E, Ward J W, Macklem P T
Meakins-Christie Laboratories, McGill University Clinic, Royal Victoria Hospital, Montreal, Quebec, Canada.
J Appl Physiol (1985). 1992 Apr;72(4):1338-47. doi: 10.1152/jappl.1992.72.4.1338.
We present a model of chest wall mechanics that extends the model described previously by Macklem et al. (J. Appl. Physiol. 55: 547-557, 1983) and incorporates a two-compartment rib cage. We divide the rib cage into that apposed to the lung (RCpul) and that apposed to the diaphragm (RCab). We apply this model to determine rib cage distortability, the mechanical coupling between RCpul and RCab, the contribution of the rib cage muscles to the pressure change during spontaneous inspiration (Prcm), and the insertional component of transdiaphragmatic pressure in humans. We define distortability as the relationship between distortion and transdiaphragmatic pressure (Pdi) and mechanical coupling as the relationship between rib cage distortion and the pressure acting to restore the rib cage to its relaxed configuration (Plink), as assessed during bilateral transcutaneous phrenic nerve stimulation. Prcm was calculated at end inspiration as the component of the pressure displacing RCpul not accounted for by Plink or pleural pressure. Prcm and Plink were approximately equal during quiet breathing, contributing 3.7 and 3.3 cmH2O on average during breaths associated with a change in Pdi of 3.9 cmH2O. The insertional component of Pdi was measured as the pressure acting on RCab not accounted for by the change in abdominal pressure during an inspiration without rib cage distortion and was 40 +/- 12% (SD) of total Pdi. We conclude that there is substantial resistance of the human rib cage to distortion, that, along with rib cage muscles, contributes importantly to the fall in pleural pressure over the costal surface of the lung.
我们提出了一种胸壁力学模型，该模型扩展了Macklem等人（《应用生理学杂志》55: 547 - 557, 1983）之前描述的模型，并纳入了一个双腔胸廓。我们将胸廓分为与肺相邻的部分（RCpul）和与膈肌相邻的部分（RCab）。我们应用这个模型来确定胸廓的可变形性、RCpul和RCab之间的机械耦合、胸廓肌肉在自主吸气过程中对压力变化的贡献（Prcm）以及人体经膈压的插入分量。我们将可变形性定义为变形与经膈压（Pdi）之间的关系，将机械耦合定义为胸廓变形与作用于使胸廓恢复到松弛状态的压力（Plink）之间的关系，这是在双侧经皮膈神经刺激期间评估的。Prcm在吸气末计算为使RCpul移位的压力中未被Plink或胸膜压力所解释的部分。在安静呼吸期间，Prcm和Plink大致相等，在与Pdi变化3.9 cmH2O相关的呼吸过程中，平均分别贡献3.7和3.3 cmH2O。Pdi的插入分量测量为在无胸廓变形的吸气过程中作用于RCab且未被腹压变化所解释的压力，占总Pdi的40±12%（标准差）。我们得出结论，人类胸廓对变形有很大的阻力，这与胸廓肌肉一起，对肺肋表面胸膜压力的下降有重要贡献。
