Hirai K, Kobayashi T, Kubo K, Shibamoto T
First Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan.
J Appl Physiol (1985). 1988 Jan;64(1):243-8. doi: 10.1152/jappl.1988.64.1.243.
Effects of hypobaria on lung fluid balance were studied in five awake sheep with chronic lung lymph fistulas using a decompression chamber. Each sheep was exposed to three conditions of 6,600-m-simulated high altitude in random order as follows: 1) 6,600-m-simulated hypoxic hypobaria (barometric pressure 326 Torr, 21% inspired O2 fraction), 2) 6,600-m-simulated normoxic hypobaria (barometric pressure 326 Torr, 65% inspired O2 fraction), and 3) 6,600-m-simulated normoxic hypobaria (barometric pressure 326 Torr, 65% inspired O2 fraction) after pretreatment with a 2-h pure O2 inhalation (i.e., denitrogenation) to allow elimination of dissolved gases, especially N2, from the blood and tissues. We observed that under both hypoxic hypobaria and normoxic hypobaria, lung lymph flow (Qlym) significantly increased from the base-line values of 6.4 +/- 0.3 to 13.0 +/- 1.0 ml/h and 6.0 +/- 0.2 to 9.4 +/- 0.3 ml/h, respectively (P less than 0.05) and that the lymph-to-plasma protein concentration ratio remained unchanged. Moreover, pretreatment with a 2-h denitrogenation inhibited the increase in Qlym. These results suggest that rapid exposure to hypobaria causes an increase in pulmonary vascular permeability and that intravascular air bubble formation may account for this permeability change.
利用减压舱，对五只患有慢性肺淋巴瘘的清醒绵羊进行了低气压对肺液体平衡影响的研究。每只绵羊按随机顺序暴露于三种模拟6600米高海拔的条件下，具体如下：1）6600米模拟低氧低气压（气压326托，吸入氧分数21%），2）6600米模拟常氧低气压（气压326托，吸入氧分数65%），以及3）在吸入2小时纯氧（即去氮）预处理后进行的6600米模拟常氧低气压（气压326托，吸入氧分数65%），以允许从血液和组织中消除溶解气体，尤其是氮气。我们观察到，在低氧低气压和常氧低气压条件下，肺淋巴流量（Qlym）分别从基线值6.4±0.3显著增加到13.0±1.0毫升/小时和从6.0±0.2显著增加到9.4±0.3毫升/小时（P<0.05），并且淋巴与血浆蛋白浓度比保持不变。此外，2小时去氮预处理抑制了Qlym的增加。这些结果表明，快速暴露于低气压会导致肺血管通透性增加，并且血管内气泡形成可能是这种通透性变化的原因。
