深低温体外循环期间pH管理对脑氧合的影响：α稳态与pH稳态。
Effects of pH management during deep hypothermic bypass on cerebral oxygenation: alpha-stat versus pH-stat.
作者信息
Li Zhi-jun, Yin Xiao-mei, Ye Jian
机构信息
Department of Cardiothoracic Surgery, Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou 310016, China.
出版信息
J Zhejiang Univ Sci. 2004 Oct;5(10):1290-7. doi: 10.1631/jzus.2004.1290.
OBJECTIVE
There is a remarkable lack of scientific evidence to support the option to use alpha-stat or pH-stat management, as to which is more beneficial to brain protection during deep hypothermic CPB. This study examined cortical blood flow (CBF), cerebral oxygenation, and brain oxygen consumption in relation to deep hypothermic CPB with alpha-stat or pH-stat management.
METHODS
Twenty-two pigs were cooled with alpha-stat or pH-stat during CPB to 15 degrees C esophageal temperature. CBF and cerebral oxygenation were measured continuously with a laser flowmeter and near-infrared spectroscopy, respectively. Brain oxygen consumption was measured with standard laboratory techniques.
RESULTS
During CPB cooling, CBF was significantly decreased, about 52.2%+/-6.3% (P<0.01 vs 92.6%+/-6.5% of pH-stat) at 15 degrees C in alpha-stat, whereas there were no significant changes in CBF in pH-stat. While cooling down, brain oxygen extraction (OER) progressively decreased, about 9.5%+/-0.9% and 10.9%+/-1.5% at 15 degrees C in alpha-stat and pH-stat, respectively. At 31 degrees C the decreased value in pH-stat was lower than in alpha-stat (29.9%+/-2.7% vs 22.5%+/-1.9%; P<0.05). The ratio of CBF/OER were 2.0+/-0.3 in alpha-stat and pH-stat, respectively; it was kept in constant level in alpha-stat, and significantly increased by 19 degrees C to 15 degrees C in pH-stat (4.9+/-0.9 vs 2.3+/-0.4; P<0.01). In mild hypothermia, cerebral oxyhemoglobin and oxygen saturation in alpha-stat were greater than that in pH-stat (102.5%+/-1.4% vs 99.1%+/-0.7%; P<0.05). In deep hypothermia, brain oxygen saturation in pH-stat was greater than that in alpha-stat (99.2%+/-1.0% vs 93.8%+/-1.0%; P<0.01), and deoxyhemoglobin in pH-stat decreased more greatly than that in alpha-stat (28.7%+/-6.8% vs 54.1%+/-4.7%; P<0.05).
CONCLUSIONS
In mild hypothermic CPB, brain tissue oxygen saturation was greater in alpha-stat than in pH-stat. However, cerebral oxygenation and brain tissue oxygen saturation were better in pH-stat than in alpha-stat during profound hypothermia. PH-stat strategy provided much more oxygen to brain tissue before deep hypothermic circulatory arrest.
目的
目前显著缺乏科学证据来支持在深度低温体外循环期间使用α稳态或pH稳态管理哪种对脑保护更有益。本研究探讨了与采用α稳态或pH稳态管理的深度低温体外循环相关的皮质血流量（CBF）、脑氧合和脑氧消耗。
方法
22头猪在体外循环期间采用α稳态或pH稳态冷却至食管温度15℃。分别用激光流量计和近红外光谱法连续测量CBF和脑氧合。用标准实验室技术测量脑氧消耗。
结果
在体外循环冷却期间，CBF显著降低，α稳态在15℃时约为52.2%±6.3%（与pH稳态的92.6%±6.5%相比，P<0.01），而pH稳态下CBF无显著变化。在降温过程中，脑氧摄取率（OER）逐渐降低，α稳态和pH稳态在15℃时分别约为9.5%±0.9%和10.9%±1.5%。在31℃时，pH稳态下的降低值低于α稳态（29.9%±2.7%对22.5%±1.9%；P<0.05）。α稳态和pH稳态下CBF/OER的比值分别为2.0±0.3；α稳态下该比值保持恒定，而pH稳态下从31℃降至15℃时显著增加（4.9±0.9对2.3±0.4；P<0.01）。在轻度低温时，α稳态下的脑氧合血红蛋白和氧饱和度高于pH稳态（102.5%±1.4%对99.1%±0.7%；P<0.05）。在深度低温时，pH稳态下的脑氧饱和度高于α稳态（99.2%±1.0%对93.8%±1.0%；P<0.01），且pH稳态下的脱氧血红蛋白降低幅度大于α稳态（28.7%±6.8%对54.1%±4.7%；P<0.05）。
结论
在轻度低温体外循环中，α稳态下的脑组织氧饱和度高于pH稳态。然而，在深度低温时，pH稳态下的脑氧合和脑组织氧饱和度优于α稳态。pH稳态策略在深度低温循环停止前为脑组织提供了更多的氧。
Zotero 插件