Tsai A G, Arfors K E, Intaglietta M
Department of AMES-Bioengineering, University of California, San Diego, La Jolla 92093-0412.
Int J Microcirc Clin Exp. 1991 Nov;10(4):317-34.
The effect of extreme hemodilution on single capillary red blood cell (RBC) distribution and microcirculatory hemodynamic parameters was studied in the resting rabbit tenuissimus muscle. Systematic hematocrit was progressively reduced to 26 +/- 3% of control by isovolemic hemodilution with a 6% dextran solution (70,000 MW). Heart rate and mean arterial pressure were monitored and noted to be constant throughout the procedure to ensure isovolemic exchange. Hemodilution induced an increase in the median spatial distance between RBCs within a capillary segment and a broadening of the range. Comparison of histograms constructed from normalized RBC spacing data relative to the median at each dilution level showed no statistical deviation from control, suggesting that spatial RBC distribution during capillary transit is independent of hematocrit reduction. Thus progressive hemodilution, while reducing capillary hematocrit and increasing the median spacing, did not alter the relative spatial distribution of RBCs within a vessel. The hemodynamic parameters analyzed were capillary hematocrit (HCTc), RBC flux (RBCf), and RBC velocity (VRBC). The reduction of the systemic hematocrit (HCTs) was not followed by a proportional fall in HCTc, implying a Hctc regulation. RBCf was maintained by an overall increase in VRBC which reached 101 +/- 61% of the control level at an average HCTs of 11 +/- 1.4%. The relative pattern of RBC spacing remained fixed, despite the change in cell number and modification of velocity. During extreme hemodilution, the potential supply of oxygen to the tissue remained constant and the pattern of RBC delivery pass the tissue was unchanged.
在静息状态的兔缝匠肌中，研究了极度血液稀释对单个毛细血管红细胞（RBC）分布及微循环血流动力学参数的影响。通过用6%葡聚糖溶液（分子量70,000）进行等容血液稀释，将系统血细胞比容逐渐降至对照值的26±3%。在整个过程中监测心率和平均动脉压，并注意到其保持恒定，以确保等容交换。血液稀释导致毛细血管段内红细胞之间的中位空间距离增加，范围变宽。对在每个稀释水平相对于中位值的标准化红细胞间距数据构建的直方图进行比较，结果显示与对照无统计学偏差，这表明毛细血管内红细胞的空间分布与血细胞比容降低无关。因此，渐进性血液稀释虽然降低了毛细血管血细胞比容并增加了中位间距，但并未改变血管内红细胞的相对空间分布。所分析的血流动力学参数为毛细血管血细胞比容（HCTc）、红细胞通量（RBCf）和红细胞速度（VRBC）。系统血细胞比容（HCTs）降低后，HCTc并未成比例下降，这意味着存在Hctc调节。RBCf通过VRBC的总体增加得以维持，在平均HCTs为11±1.4%时，VRBC达到对照水平的101±61%。尽管细胞数量改变且速度发生变化，但红细胞间距的相对模式保持不变。在极度血液稀释期间，组织的潜在氧气供应保持恒定，且红细胞通过组织的输送模式未改变。
