Frietsch T, Lenz C, Kuschinsky W, Waschke K E
Faculty of Clinical Medicine Mannheim, Department of Anesthesiology and Critical Care Medicine, University of Heidelberg, Germany.
Eur J Anaesthesiol. 2004 Jan;21(1):53-9. doi: 10.1017/s0265021504001097.
Acute isovolaemic haemodilution increases local and mean cerebral blood flow. It is not known whether a single haemodilution has a short-term effect only or whether it affects cerebral perfusion over a longer time period. In the present study, local and mean cerebral blood flow were determined in conscious rats after a 4, 24 and 48 h period following one-time haemodilution.
Thirty-six rats were randomized to three untreated sham groups and three groups of haemodilution (4, 24 or 48 h, n = 6 for each group). Isovolaemic haemodilution with albumin 5% aimed to a target haematocrit of 0.2. Local cerebral blood flow was measured in 38 brain regions by the iodo-[14C]antipyrine method in conscious normothermic rats.
Isovolaemic haemodilution reduced haematocrit from 0.44 to 0.20. During the following 24 and 48 h periods, haematocrit remained low (0.22 and 0.21). Mean cerebral blood flow was similar in untreated sham groups (88 +/- 12 after 4 h, 92 +/- 11 after 24 h, 96 +/- 10 mL 100 g(-1) min(-1) after 48 h). Haemodilution increased mean cerebral blood flow after 4h (184 +/- 11 mL 100 g(-1) min(-1)), after 24h (153 +/- 13 mL 100 g(-1) min(-1)) and 48h (149 +/- 15 mL 100 g(-1) min(-1)) (P < or = 0.05). Local cerebral blood flow increased in all 38 structures after 4h haemodilution but decreased with time in six of 38 brain structures after 24h and in 15 regions after 48 h (P < or = 0.05).
A single one-time haemodilution increased mean cerebral blood flow for 2 days. However, local adaptation of cerebral blood flow to a chronic low haematocrit occurred but was heterogeneous within the brain.
急性等容性血液稀释可增加局部和平均脑血流量。目前尚不清楚单次血液稀释是否仅具有短期效应，还是会在更长时间段内影响脑灌注。在本研究中，测定了一次性血液稀释后4小时、24小时和48小时清醒大鼠的局部和平均脑血流量。
将36只大鼠随机分为3个未处理的假手术组和3个血液稀释组（4小时、24小时或48小时，每组n = 6）。用5%白蛋白进行等容性血液稀释，目标血细胞比容为0.2。采用碘代[14C]安替比林法在清醒的正常体温大鼠的38个脑区测量局部脑血流量。
等容性血液稀释使血细胞比容从0.44降至0.20。在随后的24小时和48小时内，血细胞比容保持在较低水平（0.22和0.21）。未处理的假手术组的平均脑血流量相似（4小时后为88±12，24小时后为92±11，48小时后为96±10 mL 100 g-1 min-1）。血液稀释后4小时（184±11 mL 100 g-1 min-1）、24小时（153±13 mL 100 g-1 min-1）和48小时（149±15 mL 100 g-1 min-1）平均脑血流量增加（P≤0.05）。血液稀释4小时后，所有38个结构的局部脑血流量均增加，但24小时后38个脑结构中有6个随时间减少，48小时后在15个区域减少（P≤0.05）。
单次一次性血液稀释使平均脑血流量增加2天。然而，脑血流量对慢性低血细胞比容发生了局部适应性变化，但在脑内是异质性的。
