Van der Linden P, Gilbart E, Paques P, Simon C, Vincent J L
Department of Anesthesiology, Erasme University Hospital, Free University of Brussels, Belgium.
Am J Physiol. 1993 Jun;264(6 Pt 2):H1942-7. doi: 10.1152/ajpheart.1993.264.6.H1942.
This study was performed to test the hypothesis that tissue O2 extraction capabilities during hemorrhage may be greater when hematocrit (Hct) is initially reduced. Twenty-four anesthetized and splenectomized dogs were randomly assigned in three groups of eight dogs each: group 1 (Hct 40), 40-45% Hct; group 2 (Hct 30), 30-35% Hct; and group 3 (Hct 20), 20-25% Hct. In each animal, the desired Hct was obtained by normovolemic hemodilution using hydroxyethyl starch 450/0.7 and maintained throughout the experiment. O2 delivery (DO2) was progressively reduced by hemorrhage. At each step, DO2 and O2 consumption (VO2) were measured separately. Critical DO2 obtained from a plot of VO2 vs. DO2 was lower in the Hct 30 and Hct 20 groups than in the Hct 40 group [(in ml.min-1.kg-1) Hct 30, 7.9 +/- 2.2; Hct 20, 7.8 +/- 1.0; Hct 40, 10.4 +/- 1.1; P < 0.05]. Critical DO2 obtained from blood lactate levels was also significantly lower in the Hct 30 and Hct20 groups than in the Hct 40 group. Critical O2 extraction ratio was also greater in the Hct 30 and Hct 20 groups than in the Hct 40 group (Hct 30, 73.0 +/- 13.9%; Hct 20, 70.1 +/- 9.6%; Hct 40, 57.1 +/- 11.5%; P < 0.05). In the conditions of our study, moderate hemodilution was associated with an improvement of the O2 extraction capabilities of the body, probably related to the reduction in blood viscosity.
当初始血细胞比容（Hct）降低时，出血期间组织的氧提取能力可能更强。24只麻醉并脾切除的犬被随机分为三组，每组8只：第1组（Hct 40），Hct为40 - 45%；第2组（Hct 30），Hct为30 - 35%；第3组（Hct 20），Hct为20 - 25%。在每只动物中，通过使用羟乙基淀粉450/0.7进行等容血液稀释获得所需的Hct，并在整个实验过程中维持该水平。通过出血使氧输送（DO2）逐渐降低。在每个步骤中，分别测量DO2和氧消耗（VO2）。从VO2与DO2关系图获得的临界DO2在Hct 30组和Hct 20组中低于Hct 40组[（以ml·min⁻¹·kg⁻¹计）Hct 30组为7.9 ± 2.2；Hct 20组为7.8 ± 1.0；Hct 40组为10.4 ± 1.1；P < 0.05]。从血乳酸水平获得的临界DO2在Hct 30组和Hct 20组中也显著低于Hct 40组。临界氧提取率在Hct 30组和Hct 20组中也高于Hct 40组（Hct 30组为73.0 ± 13.9%；Hct 20组为70.1 ± 9.6%；Hct 40组为57.1 ± 11.5%；P < 0.05）。在我们的研究条件下，中度血液稀释与机体氧提取能力的改善相关，这可能与血液粘度降低有关。
