您当前的位置:首页 > 主题内容 > 临床麻醉 > 基础与临床研究

脑表面降温可行性的实验研究

时间:2010-08-24 11:32:29  来源:  作者:

Experimental Research on the Feasibility of Brain Surface Cooling<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

肖圣华,何荣芝,谢长春,卢振和,高崇荣
广州医学院第二附属医院麻醉科,广州510260
Sheng-hua Xiao, Rong-zhi He, Chang-chun Xie, Zhen-he Lu, Chong-rong Gao
Department of Anesthesiology, Second Affiliated Hospital, Guangzhou Medical College, Guangzhou 510260, China

ABSTRACT

Objective: To evaluate the effects of normal saline with different temperatures on brain surface cooling.
Methods: 48 rabbits were randomly divided into three groups. A small piece of cranial bone was opened in all rabbits. In Group A (controlled group, n=16), no measures of brain surface cooling were given. 22-23
normal saline in Group B (n=16) and 4 normal saline in Group C (n=16) were used to drip on the brain surface. Brain temperature in the third ventricle (Tb1) and at a depth of 5mm beneath brain surface (Tb2) and esophageal temperature (Teso) were continually monitored. Times when Tb1 reached 33 were recorded. Brain tissue was taken to observe the histopathological characteristics with electric microscope at the end of experiment.
Results: Times when Tb1 reached 33 were 300.5±4.2min in Group A, 41.5±1.2min in Group B and 32.4±1.3min in Group C, respectively. Temperatures in Tb2 at this time were 32.8±0.5 in Group A, 31.5±0.4 in Group B and 25.3±0.6 in Group C. Teso in three groups did not change significantly during the whole procedure. Temperature of normal saline, duration of brain opened and room temperature are the three main determinants of brain temperature. Electric microscopy showed normal brain structure.
Conclusion: Normal saline dripping at the temperature of either 4
or 22 can reduce the brain temperature of rabbits to moderate hypothermia. The effect of colder normal saline is better. Both normal salines are harmless to the brain tissue.
Key words: Brain surface cooling; Moderate hypothermia
Corresponding author: Zhen-he Lu; E-mail: luzhh@126.com

  颅脑手术中,经常用生理盐水冲洗术野及脑表面,以保持术野的干净,并降低电凝时产生的高温。生理盐水冲洗能否降低脑组织的温度,以及不同温度的生理盐水降温的效果如何?本研究通过动物实验来探讨脑表面降温的可行性。<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

材料与方法

  48只成年雄性新西兰大白兔随机分为三组,每组16只。兔用10%水合氯醛腹腔注射麻醉,并行气管切开,用动物呼吸机控制呼吸,打开一小块颅骨,露出面积大小为1.5x2.0cm的硬脑膜。对照组(A组)脑只暴露在室温空气下,脑表面不滴注生理盐水;室温生理盐水组(B组),脑表面滴注2223℃生理盐水;低温生理盐水组(C组)脑表面滴注4℃生理盐水。24G针状测温探头一个放在兔脑的第三脑室内,另一个放在顶叶皮层下5.0mm的地方,点式测温探头放在食管内,探头导线连接测温仪持续监测三处的温度,分别用Tb1,Tb2Teso表示。每10分钟记录一次温度,观察Tb1到达33℃各组所需时间。实验结束时,用10%氯化钾处死动物,取少量皮层脑组织,大小为1 mm 1 mm 1 mm,制成病理切片,电镜下检查脑组织形态学变化。
统计学处理:数据处理采用spss11.0统计软件,实验结果以均数±标准差(χ±s)表示,组间比较采用方差分析,多个变量相关性研究采用多元线性回归分析,P<0.05为差异有显著性。

结  果

  当Tb1下降至33℃时,各组所需降温时间分别是:A300.5±4.2分钟,B41.5±1.2分钟,C32.4±1.3分钟,C组与B组和A组相比均有显著差异(P0.05=。此时各组Tb2分别是A32.8±0.5B31.5±0.4C25.3±0.6C组与B组和A组相比均有显著差异(P<0.05)。
  通过多元线性回归分析以及A组打开颅骨时和实验结束时Tb1Tb2的比较显示脑表面降温的生理盐水的温度、颅骨开放时间和室温是决定脑内温度的主要因素,相关系数分别是0.9780.9470.953P<0.01

皮层脑组织切片电镜检查示脑组织结构正常。

讨  论

  大量的实验和临床研究表明,全身亚低温对缺血、缺氧性脑损伤有一定的保护作用,并成为近年来脑保护作用的研究热点之一。由于实施全身亚低温的技术要求较高,并且操作较复杂,所需配套设施较多费用也较高。因此,近年来一些学者提出了“选择性脑部降温”(selective head cooling, SHC)的概念[1],即通过某种方法进行脑部的降温,一般使脑部达到亚低温水平(3035℃),而保持身体其它部位的温度不变或轻微降低。动物实验和临床观察显示,选择性脑部亚低温同样能显著减少脑缺血、缺氧及实验性脑损伤动物的继发性脑损害和脑水肿,保护神经功能,减少有害物质的生成,提高成活率,且相对全身亚低温来说,副作用少,操作相对简单[2]。既往实施选择性脑部亚低温的方法有头部冰水浸浴、头戴冰帽等[3],这些措施在神经外科手术中应用时有以下缺点:
1)降温仪器影响头部手术操作;
2)降温缓慢,可控性欠佳;
3)术后需缓慢复温,不利于患者意识及神经功能的观察;
4)仍有操作复杂之嫌。
  因此,本实验从方便神经外科手术角度着想,设想术中脑表面用低温盐水滴注的方法行脑直接降温,脑表面滴注的低温生理盐水可通过热的传导而降低脑温,本实验中,两种温度生理盐水均可使脑温降到亚低温水平,但4℃生理盐水使第三脑室温度更快地达到预定的水平,且此时,皮层下的脑温更低,显然更有利于颅脑手术中的脑保护。室温对开颅后的脑温有一定的影响,但难以在短时间内将脑温降低到理想的水平。生理盐水的温度越低,脑表面滴注时降温的效果越好,但低温盐水本身对脑组织有无损伤,如冻伤等?本实验的结果正好回答了一部分神经外科医师的疑问,即低温生理盐水对脑组织没有损伤,因此,为了更好地减轻手术操作如电凝、脑压板等对脑组织的损伤[4],可使用较低温度的生理盐水如4℃生理盐水。由于实验中使用的是大白兔,它的脑的重量占全身的重量较小,如果是人脑,能否在短时间内降低到亚低温水平,仍有待进一步研究。

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

01. Thoresen M, Simmonds M, Satas S, et al. Effective selective head cooling during posthypoxic hypothermia in newborn piglets. Pediatric Research, 2001,49:594-595.

02. Noguchi Y, Nishio S, Kawauchi M, et al. A new method of inducing selective brain hypothermia with saline perfusion into the subdural space: effects on transient cerebral ischemia in cats. Acta Medica Okayama,2002,56:279-286.

03. Keller E, Imhof HG, Gasser S, et al. Endovascular cooling with heat exchange catheters:a new method to induce and maintain hypothermia. Intensive Care Med, 2003, 29: 939-943.

04. Zhong J, Dujovny M, Perlin AR, et al. Brain retraction injury. Neurol Res, 2003,25:831-838.

 

  作者简介:肖圣华,男,34岁,主治医师,广州医学院第二附属医院麻醉学硕士研究生,现在广东省东莞市厚街医院从事临床麻醉工作。研究方向:麻醉与脑保护。

来顶一下
返回首页
返回首页

本周热点文章

站内搜索: 高级搜索
关于我们 | 主编信箱 | 广告查询 | 联系我们 | 网站地图 |