深度低温体外循环期间脑血流量和氧消耗与灌注流速的关系。一项实验研究。

Relationship of brain blood flow and oxygen consumption to perfusion flow rate during profoundly hypothermic cardiopulmonary bypass. An experimental study.

作者信息

Fox L S, Blackstone E H, Kirklin J W, Bishop S P, Bergdahl L A, Bradley E L

出版信息

J Thorac Cardiovasc Surg. 1984 May;87(5):658-64.

Abstract

A study was made of the relation of brain blood flow and oxygen consumption to changes in perfusion flow rate during cardiopulmonary bypass at 20 degrees C in nine cynomolgus monkeys. Four perfusion flow rates varying from 0.25 to 1.75 L X min-1 X m-2 were randomly instituted, each for a 10 minute period. At the end of each period, brain arteriovenous oxygen content difference was measured and 15 mu radioactive microspheres were injected into the arterial perfusion line. The brain was then removed and section into anatomic regions and radioactivity was counted. Regional and total brain blood flows were calculated, as was whole brain oxygen consumption. Brain perfusion continued in all areas at all perfusion flow rates. Whole brain blood flow decreased (p less than 0.0001) as perfusion flow rate was reduced (45 +/- 6.5, 41 +/- 7.9, and 23 +/- 2.8 ml X min-1 X 100 gm-1 at 1.5, 1.0, and 0.5 L X min-1 X m-2, respectively). The proportion of the total perfusion delivered to the brain increased (p = 0.003) with decreasing perfusion flow rates (5.4% +/- 0.78%, 7.1% +/- 1.24%, and 8.2% +/- 1.11% at 1.5, 1.0, and 0.5 L X min-1 X m-2, respectively). Brain blood flow resistance remained unchanged (p = 0.4) while that of the remaining body increased (p less than 0.0001). There was a greater reduction of blood flow in the cortical white matter (p = 0.01) than in other regions of the brain. Brain oxygen consumption was the same (p = 0.5) at all perfusion flow rates, related to an increasing percent oxygen extraction with decreasing perfusion flow rate (p less than 0.0001). The data indicate that all areas of the brain remain perfused, even at low perfusion flow rates, during profoundly hypothermic cardiopulmonary bypass, and that brain oxygen consumption is maintained in part by increased oxygen extraction and in part by redistribution of the perfusate from the remaining body to the brain.

摘要

对9只食蟹猴在20℃体外循环期间脑血流量、氧耗与灌注流速变化之间的关系进行了研究。随机设定4种灌注流速，范围从0.25至1.75L·min⁻¹·m⁻²，每种流速持续10分钟。在每个时间段结束时，测量脑动静脉氧含量差，并将15个微居里放射性微球注入动脉灌注管路。然后取出大脑，切成解剖区域并计算放射性。计算区域脑血流量和全脑血流量以及全脑氧耗。在所有灌注流速下所有区域的脑灌注均持续。随着灌注流速降低，全脑血流量减少（p<0.0001）（在1.5、1.0和0.5L·min⁻¹·m⁻²时分别为45±6.5、41±7.9和23±2.8ml·min⁻¹·100g⁻¹）。随着灌注流速降低，输送至大脑的总灌注比例增加（p = 0.003）（在1.5、1.0和0.5L·min⁻¹·m⁻²时分别为5.4%±0.78%、7.1%±1.24%和8.2%±1.11%）。脑血流阻力保持不变（p = 0.4），而身体其他部位的血流阻力增加（p<0.0001）。皮质白质的血流减少幅度大于脑的其他区域（p = 0.01）。在所有灌注流速下脑氧耗相同（p = 0.5），这与随着灌注流速降低氧摄取百分比增加有关（p<0.0001）。数据表明，在深度低温体外循环期间，即使在低灌注流速下，脑的所有区域仍保持灌注，并且脑氧耗部分通过增加氧摄取以及部分通过灌注液从身体其他部位重新分布至大脑来维持。