Tsai Amy G, Hofmann Axel, Cabrales Pedro, Intaglietta Marcos
Department of Bioengineering, University of California, San Diego, CA 92093-0412, USA.
Transfus Apher Sci. 2010 Aug;43(1):69-78. doi: 10.1016/j.transci.2010.05.011. Epub 2010 Jun 19.
We review the experimental evidence showing systemic and microvascular effects of blood transfusions instituted to support the organism in extreme hemodilution and hemorrhagic shock, focusing on the use of fresh vs. stored blood as a variable. The question: "What does a blood transfusion remedy?" was analyzed in experimental models addressing systemic and microvascular effects showing that oxygen delivery is not the only function that must be addressed. In extreme hemodilution and hemorrhagic shock blood transfusions simultaneously restore blood viscosity and oxygen carrying capacity, the former being critically needed for re-establishing a functional mechanical environment of the microcirculation, necessary for obtaining adequate capillary blood perfusion. Increased oxygen affinity due to 2,3 DPG depletion is shown to have either no effect or a positive oxygenation effect, when the transfused red blood cells (RBCs) do not cause additional flow impairment due to structural malfunctions including increased rigidity and release of hemoglobin. It is concluded that fresh RBCs are shown to be superior to stored RBCs in transfusion, however increased oxygen affinity may be a positive factor in hemorrhagic shock resuscitation. Although experimental studies seldom reproduce emergency and clinical conditions, nonetheless they serve to explore fundamental physiological mechanisms in the microcirculation that cannot be directly studied in humans.
我们回顾了相关实验证据，这些证据表明在极度血液稀释和失血性休克中为维持机体功能而进行输血所产生的全身和微血管效应，重点关注新鲜血液与库存血液作为一个变量的使用情况。在针对全身和微血管效应的实验模型中分析了“输血能补救什么？”这一问题，结果表明氧输送并非唯一需要解决的功能。在极度血液稀释和失血性休克中，输血可同时恢复血液粘度和氧携带能力，前者对于重建微循环的功能性力学环境至关重要，而这是获得充足毛细血管血液灌注所必需的。当输注的红细胞（RBC）不会因包括刚性增加和血红蛋白释放在内的结构故障而导致额外的血流障碍时，由于2,3 -二磷酸甘油酸（2,3 DPG）消耗导致的氧亲和力增加显示出要么没有影响，要么具有积极的氧合作用。得出的结论是，在输血方面，新鲜红细胞显示出优于库存红细胞，然而增加的氧亲和力可能是失血性休克复苏中的一个积极因素。尽管实验研究很少能重现紧急情况和临床状况，但它们有助于探索在人体中无法直接研究的微循环基本生理机制。
