Menke J, Stöcker H, Sibrowski W
Department of Transfusion Medicine, University Hospital, 48149 Münster, Germany.
Transfusion. 2004 Mar;44(3):414-21. doi: 10.1111/j.1537-2995.2003.00663.x.
Blood donation is a safe human model for acute blood loss. This study investigated associated changes in regional cerebral oxygenation and cerebral blood volume (CBV) by near-infrared spectroscopy (NIRS).
Fifty healthy blood donors donated 450 mL of whole blood within 4 to 9 minutes. Changes in regional cerebral oxygen saturation (rSO2) and cerebral tissue Hb concentration (HbT) were semiquantitatively measured by NIRS. Venous Hb concentration was measured before and after blood donation. The predonation and postdonation CBV was estimated from HbT and venous Hb concentration. Differences between pre- and postdonation study parameters were analyzed by paired t tests (p < 0.05).
Within the study group, rSO2 decreased by 0.44 sat percent (p < 0.01) on average during blood donation, which is still within the range of individual physiologic baseline variation. The average venous Hb concentration decreased significantly by 4.6 percent, whereas HbT increased significantly by 2.5 percent and CBV increased even by 7.5 percent on average.
The increase in CBV indicates cerebral vasodilation, which seems to be the major compensation mechanism during acute blood loss. The decrease in rSO2 was relatively small, indicating that cerebral oxygenation was maintained within the physiologic range.
献血是急性失血的一种安全人体模型。本研究通过近红外光谱（NIRS）研究了局部脑氧合和脑血容量（CBV）的相关变化。
50名健康献血者在4至9分钟内捐献450毫升全血。通过NIRS半定量测量局部脑氧饱和度（rSO2）和脑组织血红蛋白浓度（HbT）。在献血前后测量静脉血红蛋白浓度。根据HbT和静脉血红蛋白浓度估算献血前和献血后的CBV。采用配对t检验分析献血前后研究参数的差异（p < 0.05）。
在研究组中，献血期间rSO2平均下降0.44饱和度百分比（p < 0.01），仍在个体生理基线变化范围内。静脉血红蛋白浓度平均显著下降4.6%，而HbT平均显著增加2.5%，CBV平均甚至增加7.5%。
CBV的增加表明脑血管扩张，这似乎是急性失血期间的主要代偿机制。rSO2的下降相对较小，表明脑氧合维持在生理范围内。
