Dept. of Internal Medicine, Univ. of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA.
J Appl Physiol (1985). 2009 Nov;107(5):1569-78. doi: 10.1152/japplphysiol.00503.2009. Epub 2009 Sep 3.
To quantify the in vivo magnitude and distribution of regional compensatory lung growth following extensive lung resection, we performed high-resolution computed tomography at 15- and 30-cmH(2)O transpulmonary pressures and measured air and tissue (including microvascular blood) volumes within and among lobes in six adult male foxhounds, before and after balanced 65% lung resection ( approximately 32% removed from each side). Each lobe was identified from lobar fissures. Intralobar gradients in air and tissue volumes were expressed along standardized x,y,z-coordinate axes. Fractional tissue volume (FTV) was calculated as the volume ratio of tissue/(tissue + air). Following resection compared with before, lobar air and tissue volumes increased 1.8- to 3.5-fold, and whole lung air and tissue volumes were 67 and 90% of normal, respectively. Lobar-specific compliance doubled post-resection, and whole lung-specific compliance normalized. These results are consistent with vigorous compensatory growth in all remaining lobes. Compared with pre-resection, post-resection interlobar heterogeneity of FTV, assessed from the coefficient of variation, decreased at submaximal inflation, but was unchanged at maximal inflation. The coefficient of variation of intralobar FTV gradients changed variably due to the patchy development of thickened pleura and alveolar septa, with elevated alveolar septal density and connective tissue content in posterior-caudal and peripheral regions of the remaining lobes; these areas likely experienced disproportional mechanical stress. We conclude that HRCT can noninvasively and quantitatively assess the magnitude and spatial distribution of compensatory lung growth. Following extensive resection, heterogeneous regional mechanical lung strain may exceed the level that could be sustained solely by existing connective tissue elements.
为了量化广泛肺切除术后活体区域代偿性肺生长的幅度和分布，我们在 15 和 30cmH2O 跨肺压力下进行了高分辨率 CT，并测量了 6 只成年雄性猎狐犬肺切除术前和术后每个肺叶内和之间的空气和组织（包括微血管血液）体积，肺切除平衡为 65%（每侧切除约 32%）。每个肺叶均由叶裂识别。空气和组织体积的叶内梯度沿标准化的 x、y、z 坐标表示。组织分数体积（FTV）计算为组织/（组织+空气）的体积比。与术前相比，术后肺叶空气和组织体积增加了 1.8-3.5 倍，全肺空气和组织体积分别为正常的 67%和 90%。肺叶特定顺应性术后增加了一倍，全肺特定顺应性正常化。这些结果与所有剩余肺叶的剧烈代偿性生长一致。与术前相比，术后 FTV 的叶间异质性（通过变异系数评估）在亚最大充气时降低，但在最大充气时保持不变。由于增厚的胸膜和肺泡隔的斑片状发育，以及后-尾侧和外周区域剩余肺叶的肺泡隔密度和结缔组织含量升高，导致叶内 FTV 梯度的变异系数发生变化；这些区域可能经历了不成比例的机械应力。我们得出结论，HRCT 可以无创和定量评估代偿性肺生长的幅度和空间分布。广泛切除后，不均匀的区域机械性肺应变可能超过仅由现有结缔组织元素维持的水平。
