Ford G T, Bradley C A, Anthonisen N R
J Appl Physiol Respir Environ Exerc Physiol. 1980 Jan;48(1):29-33. doi: 10.1152/jappl.1980.48.1.29.
When an excised lung lobe undergoes atelectasis, its shape differs from that observed when lobar atelectasis occurs in an intact animal: the chest wall deforms the collapsing lobe. In eight anesthetized dogs in the left lateral position we measured lung volume and transpulmonary pressure during the development of atelectasis. We then induced atelectasis of the left lower lobe with the rest of the lung maintained at FRC and measured lobar volume and "translobar" (lobar minus esophageal) pressure. Lung and lobar volumes were measured by prebreathing the animal with 88% O2-12% N2, occluding the airway and observing the increase in lung or lobar N2 concentration. When the left lower lobe alone collapsed, translobar pressures were more negative than transpulmonary pressure at the same relative volume when the whole lung collapsed. This pressure difference, which represents the deforming force applied to the lobe minus the pressure costs of deformation, averaged 3 cmH2O at 50% FRC. Infusion of 25 ml of normal saline into the pleural space sharply reduced the difference pulmonary pressure during lung collapse: this difference was abolished at 80% FRC and halved at 50% FRC. The large effect of the small volume of fluid suggested that deforming forces were largely generated in relatively local areas, such as regions of the chest wall with sharp angulation.
当切除的肺叶发生肺不张时，其形状与完整动物发生肺叶性肺不张时观察到的形状不同：胸壁会使塌陷的肺叶变形。我们对8只处于左侧卧位的麻醉犬在肺不张形成过程中测量了肺容积和跨肺压。然后，在其余肺维持在功能残气量（FRC）的情况下，诱导左下叶肺不张，并测量肺叶容积和“跨肺叶”（肺叶压力减去食管压力）压力。通过让动物预呼吸88% O₂ - 12% N₂、闭塞气道并观察肺或肺叶N₂浓度的增加来测量肺和肺叶容积。当单独左下叶塌陷时，在相同相对容积下，与整个肺塌陷时相比，跨肺叶压力更负。这种压力差代表施加于肺叶的变形力减去变形的压力消耗，在功能残气量为50%时平均为3 cmH₂O。向胸腔内注入25 ml生理盐水会显著降低肺塌陷期间的跨肺压力差：在功能残气量为80%时这种差异消失，在功能残气量为50%时减半。少量液体产生的巨大影响表明，变形力主要在相对局部的区域产生，如胸壁有锐角的区域。
