Grassino A, Goldman M D, Mead J, Sears T A
J Appl Physiol Respir Environ Exerc Physiol. 1978 Jun;44(6):829-39. doi: 10.1152/jappl.1978.44.6.829.
We related diaphragm electromyographic activity (Edi) to transdiaphragmatic pressure (Pdi) in man during graded inspiratory efforts. Estimates of rib cage and abdominal volume displacements were based on their anteroposterior (AP) diameter changes. The diaphragm was assumed to contract isometrically when subjects performed inspiratory efforts against a closed airway at specified abdominothoracic configurations, increasing Edi and Pdi while holding lung volume and rib case and abdominal AP diameters constant. The relationship between Pdi and Edi depends primarily on abdominothoracic configuration rather than lung volume. For equal increments in lung volume, the Pdi developed at constant Edi is four to eight times more sensitive to changes in abdominal than in rib cage AP diameter. We demonstrate an isofunctional state of the diaphragm at different lung volumes, when increases in lung volume and rib cage AP diameter are compensated for by slight decreases in abdominal AP diameter, resulting in a constant relationship between Edi and Pdi. We conclude that diaphragm shortening is reflected more directly in abdominal displacement than in lung volume change.
在分级吸气用力过程中，我们将人体的膈肌肌电活动（Edi）与跨膈压（Pdi）进行了关联。胸廓和腹部容积位移的估计基于其前后径（AP）的变化。当受试者在特定的胸腹构型下对着闭合气道进行吸气用力时，假定膈肌进行等长收缩，在保持肺容积、胸廓和腹部AP直径不变的情况下，Edi和Pdi增加。Pdi与Edi之间的关系主要取决于胸腹构型，而非肺容积。对于肺容积的同等增量，在Edi恒定的情况下，Pdi对腹部AP直径变化的敏感性比对胸廓AP直径变化的敏感性高4至8倍。我们证明，当肺容积增加和胸廓AP直径增加被腹部AP直径的轻微减小所补偿时，在不同肺容积下膈肌处于等功能状态，从而导致Edi和Pdi之间保持恒定关系。我们得出结论，膈肌缩短在腹部位移中比在肺容积变化中得到更直接的反映。
