Tu Y K, Liu H M
Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital (Taipei).
Stroke. 1996 Mar;27(3):441-5. doi: 10.1161/01.str.27.3.441.
To verify the hemorheological effects of isovolemic hemodilution on hemodynamics and cerebral perfusion of normal humans, we tested the efficacy of isovolemic hemodilution in systemic hemodynamics and cerebral bood flow augmentation and its influences in vascular reserve.
Isovolemic hemodilution was studied in a total of 13 normal healthy subjects. Regional cerebral blood flow was measured by the xenon-enhanced CT method. Cerebral vascular activity was measured by acetazolamide challenge. These measurements, in association with hemorheological and hemodynamic monitoring, were analyzed before and after isovolemic hemodilution with low-molecular-weight dextran.
Our results showed significant change in hemodynamic parameters after isovolemic hemodilution, including tachycardia, a 24% increase of cardiac index, and decrease of peripheral vascular resistance. Both left and right heart work index increased as a consequence of increased cardiac index. Regional cerebral blood flow increased 35.0 +/- 2.5% at 3 hours after hemodilution and 20.2 +/- 3.9% at 1 week after hemodilution. Cerebral vascular reactivity decreased from 32.1 +/- 4.1% to 25.3 +/- 4.0% after hemodilution, implicating a certain degree of vasodilation in the process of hemodilution. The whole procedure of hemodilution was completed in 52 +/- 6 minutes, and the subjects did not report discomfort during the procedure.
Isovolemic hemodilution in subjects with normal cerebral perfusion can augment cerebral blood flow efficiently in a rapid fashion, and this effect can last for at least a week. The mechanism of flow augmentation may be partially attributed to vasodilation, which could be manifested as tachycardia, increased cardiac output, and decreased cerebral vascular reactivity.
为验证等容血液稀释对正常人体血流动力学及脑灌注的血液流变学效应，我们测试了等容血液稀释在增加全身血流动力学和脑血流量方面的功效及其对血管储备的影响。
对总共13名正常健康受试者进行等容血液稀释研究。采用氙增强CT法测量局部脑血流量。通过乙酰唑胺激发试验测量脑血管活性。在使用低分子右旋糖酐进行等容血液稀释前后，结合血液流变学和血流动力学监测对这些测量结果进行分析。
我们的结果显示等容血液稀释后血流动力学参数有显著变化，包括心动过速、心脏指数增加24%以及外周血管阻力降低。由于心脏指数增加，左右心做功指数均升高。血液稀释后3小时局部脑血流量增加35.0±2.5%，血液稀释后1周增加20.2±3.9%。血液稀释后脑血管反应性从32.1±4.1%降至25.3±4.0%，这意味着在血液稀释过程中有一定程度的血管扩张。血液稀释的整个过程在52±6分钟内完成，受试者在过程中未报告不适。
在脑灌注正常的受试者中，等容血液稀释可快速有效地增加脑血流量，且这种效应可持续至少一周。血流量增加的机制可能部分归因于血管扩张，表现为心动过速、心输出量增加和脑血管反应性降低。
