低温心肺转流期间干扰脑氧平衡主要因素的探讨

The Main Factor Affecting Cerebral Oxygen Balance during Hypothermie Cardiopulmonary Bypass

为了探讨低温心肺转流（ＣＰＢ）期间干扰脑氧平衡的主要因素，本研究对１６例心脏瓣膜置换术患者，在６个时点同步测定脑氧饱和度（ｒＳＯ２）、颈静脉球血氧饱和度（ＳｊＯ２）、鼻咽温（ＮＰＴ）、血红蛋白（Ｈｂ）浓度及其他脑氧合参数、血流动力学和血气指标，并比较了ｒＳＯ２和ＳｊＯ２的相关性。结果表明，ｒＳＯ２与ＳｊＯ２有良好的相关性（ｒ＝０．８１，Ｐ＜０．００１），提示两种方法的观察效果是一致的。ＮＰＴ变化与ｒＳＯ２和ＳｊＯ２变化显著相关（Ｆ＝１５．８７，Ｐ＜０．００１）。ＭＡＰ、Ｈｂ、ＣＯ或Ｐｆ、ＰａＣＯ２在６个不同时点虽然有显著变化，但是与ｒＳＯ２和ＳｊＯ２变化无关。在同一时点，降温期脑氧耗下降幅度大于脑氧供（Ｐ＜０．０１），而复温期脑氧耗的上升幅度远远超过脑氧供（Ｐ＜０．００１），加快复温速度有脑脱氧合发生。说明低温ＣＰＢ期间，体温变化是干扰脑氧平衡的主要因素，复温期是发生脑脱氧合的危险阶段，复温速度过快则加重脑血流－代谢偶联失调。

In ordcr to investigate the main factor affecting cercbral oxygen saturation, rSO 2 was continuously measured by noninvasive cerebral oxygen saturation monitor in 16 adult patients undergoing open heart surgery.Blood samples were taken from jugular bulb catheter to measure jugular venous oxygen saturation (SjO 2)as a contro1.Nasopharyngeal temperature(NPT),Hb, cerebral oxygenation parameters, hemodynamic parameters and blood gas analysis valucs were rccorded before CPB,at begining of CPB, during CPB at 32℃ and 25 27℃,rewarming to 32℃and after CPB.Results show that there was a significent relationship between rSO 2 and SjO 2(r=0 81,P<0 01),suggesting that using rSO 2 and SjO 2 to evaluate cerebral oxygen balance was of same value.Changs of NPT correlated closely with those of rSO 2(F=15 87,P<0 001).Although MAP、Hb、CO、Pf and PCO 2 changed significantly at 6 time points ,there was no any correlation between rSO 2 and SjO 2.The decrease of cerebral oxygen consumpion was highter than that of cerebral oxygen delivery during hypothermic period(P<0 01).The increase of cerebral oxygen consumption was much higher than that of cerebral oxygen delivery during rewarming period(P<0 001). Bascd on these results we suppose that change of body temperature is the main factor affecting cerebral oxygen balance. Rewarmig period is critical for O 2 dcsatuation of the brain.A rapid rcwarming would significantly delay the control of flow metabolism coupling.