选择性脑灌注期间泵流量对脑血流动力学和代谢的影响。

Impact of pump flow rate during selective cerebral perfusion on cerebral hemodynamics and metabolism.

机构信息

Department of Cardiothoracic Surgery, University of Cologne, Cologne, Germany.

出版信息

Ann Thorac Surg. 2010 Dec;90(6):1975-84. doi: 10.1016/j.athoracsur.2010.06.111.

DOI:10.1016/j.athoracsur.2010.06.111

PMID:21095348

Abstract

BACKGROUND

Although hypothermic selective cerebral perfusion (SCP) is widely used for cerebral protection during aortic surgery, little is known about the ideal pump-flow management during this procedure. This study explored cerebral hemodynamics and metabolism at two different flow rates.

METHODS

Fourteen pigs (33 to 38 kg) were cooled on cardiopulmonary bypass to 25°C. After 10 minutes of hypothermic circulatory arrest, the animals were randomly assigned to 60 minutes of SCP at two different pump flow rates: 8 mL·kg(-1)·min(-1) (n = 7) and 18 mL·kg(-1)·min(-1) (n = 7). Microspheres were injected at baseline, coolest temperature, and at 5, 15, 25, and 60 minutes of SCP to calculate cerebral blood flow, cerebral vascular resistance, metabolic rate, and intracranial pressure.

RESULTS

Cerebral blood flow decreased during cooling to 41% of the baseline value (from 57 ± 10 to 23 ± 4 mL·min(-1)·100 g(-1)). It recovered during the initial 15 minutes of SCP, showing a significantly higher increase (p = 0.017) at high-flow versus low-flow perfusion (139 ± 41 versus 75 ± 22 mL·min(-1)·100 g(-1)). After 60 minutes of SCP the cerebral blood flow almost returned to baseline values in the low-flow group (43 ± 25 mL·min(-1)·100 g(-1)), but showed an unexpected decrease (30 ± 7 mL·min(-1)·100 g(-1)) in the high-flow group. The highest regional cerebral blood flow was seen in the cortex (66 ± 12 mL·min(-1)·100 g(-1)), followed by the cerebellum (63 ± 12 mL·min(-1)·100 g(-1)), the pons (51 ± 17 mL·min(-1)·100 g(-1)), and the hippocampus (36 ± 9 mL·min(-1)·100 g(-1)). Intracranial pressure increased from 11 ± 3 to 13 ± 5 mm Hg during cooling on cardiopulmonary bypass. During low-flow SCP, it stayed stable at baseline values, whereas high-flow perfusion resulted in significantly higher intracranial pressures (17 ± 3 mm Hg; p = 0.001). Changes in cerebral vascular resistance and metabolic rate showed no significant differences between the groups.

CONCLUSIONS

High-flow SCP provides no benefit during long-term SCP at 25°C. Higher cerebral blood flow during the initial SCP period leads to cerebral edema, with no profit in metabolic rate.

摘要

背景

虽然低温选择性脑灌注（SCP）在主动脉手术期间被广泛用于脑保护，但对于该过程中理想的泵流量管理知之甚少。本研究探讨了两种不同流速下的脑血流动力学和代谢情况。

方法

14 头（33 至 38 公斤）猪在心肺转流下冷却至 25°C。低温循环停止 10 分钟后，动物随机分为两组，在两种不同的泵流量下进行 SCP 60 分钟：8 mL·kg(-1)·min(-1)（n = 7）和 18 mL·kg(-1)·min(-1)（n = 7）。在基线、最冷温度以及 SCP 的 5、15、25 和 60 分钟时注射微球，以计算脑血流量、脑血管阻力、代谢率和颅内压。

结果

在冷却至 41%基线值（从 57 ± 10 降至 23 ± 4 mL·min(-1)·100 g(-1)）期间，脑血流减少。在 SCP 的初始 15 分钟内，高流量（p = 0.017）比低流量（139 ± 41 比 75 ± 22 mL·min(-1)·100 g(-1)）灌注时的恢复程度更高。在 SCP 60 分钟后，低流量组的脑血流几乎恢复到基线值（43 ± 25 mL·min(-1)·100 g(-1)），但高流量组却出现了意外的下降（30 ± 7 mL·min(-1)·100 g(-1)）。皮质（66 ± 12 mL·min(-1)·100 g(-1)）的局部脑血流最高，其次是小脑（63 ± 12 mL·min(-1)·100 g(-1)）、脑桥（51 ± 17 mL·min(-1)·100 g(-1)）和海马（36 ± 9 mL·min(-1)·100 g(-1)）。在心肺转流的冷却过程中，颅内压从 11 ± 3 升高至 13 ± 5 mm Hg。在低流量 SCP 期间，它保持在基线值稳定，而高流量灌注导致颅内压显著升高（17 ± 3 mm Hg；p = 0.001）。两组之间的脑血管阻力和代谢率变化无显著差异。