Ohtaki M, Tranmer B I
Department of Clinical Neurosciences, University of Calgary, Alberta, Canada.
Surg Neurol. 1993 Sep;40(3):196-206. doi: 10.1016/0090-3019(93)90068-c.
This study was designed to better define a protocol for hypervolemic hemodilution in acute cerebral ischemia and investigate the mechanism of action of this therapy. Anesthetized rats (n = 40) were subjected to 6 h of middle cerebral artery (MCA) occlusion. At 45 min after MCA occlusion, each rat received one of the following treatment modalities: (1) control, (2) isovolemic hemodilution, (3) hypervolemic nonhemodilution (whole blood), (4) hypervolemic hemodilution (normal saline), and (5) hypervolemic hemodilution (hetastarch). Local cerebral blood flow (CBF) was determined with hydrogen clearance technique, and cardiac output was assessed by measuring the descending aorta blood flow (DAF). Infarction volume was estimated by 2,3,5-triphenyltetrazolium chloride staining method. Hetastarch infusion increased both DAF and local CBF more than the other treatments, by 98% and by 89%, respectively. Hetastarch also reduced infarction volume the most to 71 +/- 19 mm3 (p < 0.01 versus control 117 +/- 32 mm3). A significant correlation between percent (%) changes in local CBF and % changes in DAF existed in ischemic brain regions, and the hetastarch infusion improved local CBF more prominently in profoundly ischemic regions in contrast to isovolemic hemodilution. These data demonstrated the superiority of hypervolemic hemodilution with hetastarch as compared to other similar treatment modalities for acute cerebral ischemia, and indicate that cardiac output augmentation may be more responsible than decreased blood viscosity for the beneficial effect of hypervolemic hemodilution on local CBF in profoundly ischemic regions, as such ischemic brain tissue can severely lose its regulatory control of CBF to alterations in cardiac output.
本研究旨在更好地确定急性脑缺血中高容量血液稀释的方案，并研究该疗法的作用机制。将麻醉大鼠（n = 40）进行大脑中动脉（MCA）闭塞6小时。在MCA闭塞后45分钟，每只大鼠接受以下治疗方式之一：（1）对照组，（2）等容量血液稀释，（3）高容量非血液稀释（全血），（4）高容量血液稀释（生理盐水），以及（5）高容量血液稀释（羟乙基淀粉）。用氢清除技术测定局部脑血流量（CBF），通过测量降主动脉血流量（DAF）评估心输出量。采用2,3,5-三苯基四氮唑氯化物染色法估计梗死体积。与其他治疗相比，输注羟乙基淀粉使DAF和局部CBF分别增加得更多，分别增加了98%和89%。羟乙基淀粉还使梗死体积减少最多，降至71±19 mm³（与对照组117±32 mm³相比，p < 0.01）。缺血脑区局部CBF的百分比变化与DAF的百分比变化之间存在显著相关性，与等容量血液稀释相比，羟乙基淀粉输注在严重缺血区域更显著地改善了局部CBF。这些数据表明，与急性脑缺血的其他类似治疗方式相比，高容量血液稀释联合羟乙基淀粉具有优越性，并表明心输出量增加可能比血液粘度降低更能解释高容量血液稀释对严重缺血区域局部CBF的有益作用，因为这样的缺血脑组织对心输出量变化的CBF调节控制可能严重丧失。
