大鼠轻、中度低温期间局部脑血流与代谢的关系。

Relationship between local cerebral blood flow and metabolism during mild and moderate hypothermia in rats.

作者信息

Frietsch T, Krafft P, Piepgras A, Lenz C, Kuschinsky W, Waschke K F

机构信息

Department of Anesthesiology and Critical Care Medicine, Faculty of Clinical Medicine Mannheim, Germany.

出版信息

Anesthesiology. 2000 Mar;92(3):754-63. doi: 10.1097/00000542-200003000-00019.

DOI:10.1097/00000542-200003000-00019

PMID:10719954

Abstract

BACKGROUND

Hypothermia may interfere with the relationship between cerebral blood flow (CBF) and metabolism. Because this conclusion was based on the analysis of global values, the question remains whether hypothermic CBF/metabolism uncoupling exists on a local cerebral level. This study investigated the effects of hypothermic anesthesia on local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU).

METHODS

Thirty-six rats were anesthetized with isoflurane (1 minimum alveolar concentration) and artificially ventilated to maintain normal arterial carbon dioxide partial pressure (pH-stat). Pericranial temperature was maintained as normothermic (37.5 degrees C, n = 12) or was reduced to 35 degrees C (n = 12) or 32 degrees C (n = 12). Pericranial temperature was maintained constant for 60 min until LCBF or LCGU were measured by autoradiography. Twelve conscious rats served as normothermic controls.

RESULTS

Compared with conscious animals, mean CBF remained unchanged during normothermic anesthesia. Mean CBF significantly increased during mild hypothermia but was unchanged during moderate hypothermia. During normothermic anesthesia, mean CGU was 45% lower than in conscious controls (P < 0.05). No further CGU reduction was found during mild hypothermia, whereas CGU further decreased during moderate hypothermia (48%; P < 0.05). Local analysis showed a linear LCBF/LCGU relationship in conscious (r = 0.94) and anesthetized (r = 0.94) normothermic animals, as well as in both hypothermic groups (35 degrees C: r = 0.92; 32 degrees C: r = 0.95; P < 0.05). The LCBF-to-LCGU ratio increased from 1.4 (conscious controls) to 2.4 (normothermic isoflurane) and 3.6 ml/micromol (mild and moderate hypothermia, P < 0.05).

CONCLUSIONS

Decrease of mean CGU at unchanged or increased mean CBF during hypothermic anesthesia may not indicate uncoupling. Local analysis shows a maintained linear relationship that is reset to a higher CBF/CGU ratio.

摘要

背景

体温过低可能会干扰脑血流量（CBF）与代谢之间的关系。由于这一结论是基于全局值的分析得出的，因此局部脑水平上是否存在低温性CBF/代谢解偶联的问题仍然存在。本研究调查了低温麻醉对局部脑血流量（LCBF）和局部脑葡萄糖利用（LCGU）的影响。

方法

36只大鼠用异氟醚（1个最低肺泡浓度）麻醉，并进行人工通气以维持正常动脉二氧化碳分压（pH稳态）。颅周温度维持在正常体温（37.5℃，n = 12），或降至35℃（n = 12）或32℃（n = 12）。颅周温度保持恒定60分钟，直到通过放射自显影法测量LCBF或LCGU。12只清醒大鼠作为正常体温对照。

结果

与清醒动物相比，正常体温麻醉期间平均CBF保持不变。轻度低温期间平均CBF显著增加，但中度低温期间保持不变。在正常体温麻醉期间，平均CGU比清醒对照低45%（P < 0.05）。轻度低温期间未发现CGU进一步降低，而中度低温期间CGU进一步降低（48%；P < 0.05）。局部分析显示，清醒（r = 0.94）和麻醉（r = 0.94）的正常体温动物以及两个低温组（35℃：r = 0.92；32℃：r = 0.95；P < 0.05）中，LCBF/LCGU呈线性关系。LCBF与LCGU的比值从1.4（清醒对照）增加到2.4（正常体温异氟醚麻醉）和3.6 ml/μmol（轻度和中度低温，P < 0.05）。