Flick M R, Perel A, Kageler W, Staub N C
J Appl Physiol Respir Environ Exerc Physiol. 1979 May;46(5):932-6. doi: 10.1152/jappl.1979.46.5.932.
We measured the regional distribution of pulmonary extravascular water to test our prediction that, because of higher vascular hydrostatic pressure in more dependent zones, the bottom of the lung would tend to be wetter than the top. We injected eight normal sheep under halothane anesthesia with 125I-labeled albumin and killed them 5 min later. We suspended the sheep in the prone position and froze them solid in dry ice. We sawed the thorax into horizontal slices, chipped the frozen lung from each, and determined extravascular lung water and hematocrit. Hematocrit was calculated from separately measured red blood cell (tissue hemoglobin) and plasma (125I-albumin) masses. We found regional extravascular water was constant throughout the lung. Regional hematocrit was significantly higher at the lung base than at the apex in these slowly frozen sheep after death. Calculation of extravascular water using a single blood mass marker (hemoglobin) underestimated lung water, more so at the base than at the apex, because blood mass was overestimated. Accurate measurement of blood mass is critical in the calculation of regional lung water.
我们测量了肺血管外水的区域分布，以检验我们的预测，即由于更依赖区域的血管静水压较高，肺底部会比顶部更湿。我们在氟烷麻醉下给八只正常绵羊注射了125I标记的白蛋白，并在5分钟后将它们处死。我们将绵羊俯卧位悬吊，在干冰中冻实。我们将胸腔锯成水平切片，从每个切片中取出冷冻的肺，测定肺血管外水和血细胞比容。血细胞比容由分别测量的红细胞（组织血红蛋白）和血浆（125I-白蛋白）质量计算得出。我们发现整个肺的区域血管外水是恒定的。在这些死后缓慢冷冻的绵羊中，肺底部的区域血细胞比容显著高于肺尖。使用单一血容量标记物（血红蛋白）计算血管外水会低估肺水，在肺底部比在肺尖更明显，因为血容量被高估了。准确测量血容量在区域肺水的计算中至关重要。
