Ford G T, Gillett D, Anthonisen N R
J Appl Physiol Respir Environ Exerc Physiol. 1979 Dec;47(6):1143-7. doi: 10.1152/jappl.1979.47.6.1143.
When an isolated lung lobe is partially submerged, volume moves from the submerged part to the unsubmerged part. We partially submerged isolated dog lobes of known weight and volume, and measured airway pressure and, by water displacement, the volume of the submerged part. The lobe was then air-dried and sectioned at the waterline and each part weighed. Multiplying lobar volume by the fractional weight of the submerged part yielded the volume of the submerged part before immersion, and therefore the volume shift to the unsubmerged part due to immersion. Dividing this volume shift by the immersion-induced change in airway pressure gave the compliance (Cr') of the unsubmerged part. Cr' was compared to Cr, the compliance of the unsubmerged part when it was inflated with air. Cr/Cr' was linearly related to the degree of immersion: as immersion increased Cr/Cr' fell; so when lobes were 80% immersed Cr/Cr' was 0.3--0.5, indicating that compressing the lower part of the lung made the upper easier to expand. This behavior could be explained if with immersion lung units moved from the submerged part to the unsubmerged part and this shift increased with the degree of immersion. We demonstrated that when one part of a lobe was compressed lung units moved away from the compressive force and that this movement could occur without similar movement of the pleural surace. Tissue movement probably accounted at least in part for our results.
当一个孤立的肺叶部分被淹没时，气体容积会从被淹没部分转移到未被淹没部分。我们将已知重量和容积的孤立犬肺叶部分淹没，并测量气道压力，通过排水法测量被淹没部分的容积。然后将肺叶风干，并在水线处切片，分别称取每一部分的重量。用肺叶容积乘以被淹没部分的重量分数，可得出淹没前被淹没部分的容积，从而得出因淹没导致转移到未被淹没部分的容积。用该容积转移量除以因淹没引起的气道压力变化，可得出未被淹没部分的顺应性（Cr'）。将Cr'与未被淹没部分充气时的顺应性Cr进行比较。Cr/Cr'与淹没程度呈线性相关：随着淹没程度增加，Cr/Cr'下降；因此当肺叶80%被淹没时，Cr/Cr'为0.3 - 0.5，这表明压缩肺的下部会使上部更易于扩张。如果随着淹没，肺单位从被淹没部分转移到未被淹没部分，且这种转移随淹没程度增加，那么这种现象就可以得到解释。我们证明，当肺叶的一部分受到压缩时，肺单位会远离压缩力，并且这种移动可以在胸膜表面没有类似移动的情况下发生。组织移动可能至少部分地解释了我们的结果。
