Klaesner J W, Pou N A, Parker R E, Finney C, Roselli R J
Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA.
J Appl Physiol (1985). 1998 Apr;84(4):1381-7. doi: 10.1152/jappl.1998.84.4.1381.
In this study, lung filtration coefficient (Kfc) was measured in eight isolated canine lung preparations by using three methods: standard gravimetric (Std), blood-corrected gravimetric (BC), and optical. The lungs were held in zone III conditions and were subjected to an average venous pressure increase of 8.79 +/- 0.93 (mean +/- SD) cmH2O. The permeability of the lungs was increased with an infusion of alloxan (75 mg/kg). The resulting Kfc values (in milliliters . min-1 . cmH2O-1 . 100 g dry lung weight-1) measured by using Std and BC gravimetric techniques before vs. after alloxan infusion were statistically different: Std, 0.527 +/- 0.290 vs. 1. 966 +/- 0.283; BC, 0.313 +/- 0.290 vs. 1.384 +/- 0.290. However, the optical technique did not show any statistical difference between pre- and postinjury with alloxan, 0.280 +/- 0.305 vs. 0.483 +/- 0. 297, respectively. The alloxan injury, quantified by using multiple-indicator techniques, showed an increase in permeability and a corresponding decrease in reflection coefficient for albumin (sigmaf). Because the optical method measures the product of Kfc and sigmaf, this study shows that albumin should not be used as an intravascular optical filtration marker when permeability is elevated. However, the optical technique, along with another means of measuring Kfc (such as BC), can be used to calculate the sigmaf of a tracer (in this study, sigmaf of 0.894 at baseline and 0.348 after injury). Another important finding of this study was that the ratio of baseline-to-injury Kfc values was not statistically different for Std and BC techniques, indicating that the percent contribution of slow blood-volume increases does not change because of injury.
在本研究中，采用三种方法在八个离体犬肺标本中测量肺滤过系数（Kfc）：标准重量法（Std）、血液校正重量法（BC）和光学法。肺处于Ⅲ区条件下，平均静脉压升高8.79±0.93（均值±标准差）cmH₂O。用四氧嘧啶（75mg/kg）灌注使肺的通透性增加。在四氧嘧啶灌注前后，采用Std和BC重量法测得的Kfc值（单位为毫升·分钟⁻¹·cmH₂O⁻¹·100克干肺重量⁻¹）在统计学上有差异：Std法，0.527±0.290对比1.966±0.283；BC法，0.313±0.290对比1.384±0.290。然而，光学法在四氧嘧啶损伤前后未显示出任何统计学差异，分别为0.280±0.305对比0.483±0.297。用多种指标技术量化的四氧嘧啶损伤显示通透性增加，白蛋白反射系数（σf）相应降低。由于光学法测量的是Kfc与σf的乘积，本研究表明当通透性升高时，白蛋白不应用作血管内光学滤过标记物。然而，光学技术与另一种测量Kfc的方法（如BC法）一起，可用于计算示踪剂的σf（在本研究中，基线时σf为0.894，损伤后为0.348）。本研究的另一个重要发现是，Std法和BC法的基线与损伤后Kfc值之比在统计学上无差异，表明缓慢血容量增加的百分比贡献不会因损伤而改变。
