体外循环术中局部脑氧饱和度监测与其影响因素的分析

Influencing factors of regional cerebral oxygen saturation during cardiopulmonary bypass

目的探讨体外循环(CPB)术中影响局部脑氧饱和度(rScO_2)监测的因素,降低围CPB期rScO_2降低的发生率。方法选择在CPB下行心脏手术的患者60例,在术前(T_1)、入手术室至诱导前(T_2)、诱导至CPB开始期间(T__3)、CPB降温期间(T_4)、CPB降温末至CPB开始复温(T_5)、CPB开始复温至CPB停机(T_6)、CPB停机后30min(T_7)7个时间段,记录rScO_2、红细胞比容(Hct)、血红蛋白(Hb)、动脉血氧分压(paO_2)、动脉血二氧化碳分压(paCO_2)、血乳酸(Lac)、血液pH值、平均动脉压(MAP)和鼻咽温的平均值。rScO_2与各时间段各项指标的相关性分析采用多元线性回归分析。结果各时间段间rScO_2的差异有统计学意义(F=3.291,P=0.004),T_5和T_6时间段的rScO_2均显著低于其他时间段(P值均<0.05),其他时间段间rScO_2的差异均无统计学意义(P值均>0.05)。以rScO_2为y,影响因素Hct、Hb、血液pH值、paCO_2、paO_2、Lac、MAP和鼻咽温分别为x1、x2、x3、x4、x5、x6、x7、x8。在T_1和T_2时间段,rScO_2较平稳,线性回归方程分别为y=0.65±0.034和y=0.65±0.037,不存在对rScO_2有影响的相关因素(P值均>0.05)。在T_3时间段,仅鼻咽温与rScO_2呈正相关(β=0.385,P=0.002),线性回归方程为y=-0.554+0.033x8。在T_4时间段,MAP和鼻咽温均与rScO_2呈正相关(β=0.295、0.226,P=0.009),线性回归方程为y=0.373+0.001x7+0.008x8,鼻咽温的β值小于MAP,表明该时间段鼻咽温对rScO_2的影响小于MAP。在T_5时间段,paCO_2和Lac均与rScO_2呈正相关(β=0.268、0.465,P=0.001),线性回归方程为y=0.498+0.003x4+0.015x6,Lac的β值大于paCO_2,表明该时间段Lac对rScO_2的影响大于paCO_2。在T_6时间段,paCO_2和Lac均与rScO_2呈正相关(β=0.274、0.223,P=0.001),线性回归方程为y=0.550+0.002x4+0.004x6,Lac的β值小于paCO_2,表明该时间段Lac对rScO_2的影响小于paCO_2。在T_7时间段,仅鼻咽温与rScO_2呈正相关(β=0.285,P=0.001),线性回归方程为y=0.805+0.042x8。在各时间段Hct、Hb、血液pH值、paO_2与rScO_2均不相关(P值均>0.05)。结论CPB中对rScO_2有影响的因素是paCO_2、鼻咽温、Lac,MAP在降温阶段与rScO_2也有一定的相关性。本研究中患者在血液稀释后,Hct和Hb均有较大幅度的波动,但均与rScO_2的变化不相关。

Objective To explore the relative factors of regional cerebral oxygen saturation （rScO2） monitoring during cardiopulmonary bypass （CPB） so as to reduce the incidence of low rScO2. Methods Sixty patients undergoing elective cardiac surgery by CPB were enrolled in the study. The rSoO2, hematocrit （Hct）, hemoglobin （Hb）, arterial blood oxygen partial pressure （paO2）, arterial blood CO2 partial pressure （poCO2）, blood lactic acid （Lac）, pH value, mean arterial pressure （MAP） and nasopharynx temperature were recorded at the following time points： before surgery （T1）, before anesthesia induction （T2）, from induction to the beginning of CPB （T3）, from the beginning of CPB to the end of nose temperature cooling （T4）, from the end of nose temperature cooling to the beginning of warming （T5）, from the beginning of warming to the end of CPB （T6）,30 minutes after CPB （T7）. Multiple logistic regression analysis was used to evaluate the relationship between rScO2 and these parameters. Results There was significant difference in rSoO2 between different time points （F = 3. 291, P = 0. 004）, and rScO2 at Ts and Te were significantly lower than those at the other time points （all P〈 0.05）. Ify represented rScO2, x1, x2, x3, x4, x5, x6, x7 and x8 represented Hct, Hb, blood pH, paCO2, paO2, Lac, MAP and nasopharyngeal temperature, respectively, linear regression equation was y = 0.65 ± 0. 034 and y = 0.65±0. 037 at T1 and T2, respectively; there was no obvious change of rScO2 and no factors related to rSoO2 was found （all P〉0. 05）. Nasopharyngeal temperature was positively cor related with rScO2 （β = 0. 385, P = 0. 002） at T3, and the linear regression equation was y = - 0. 554 ＋ 0. 033x8. The MAP and nasopharyngeal temperature were positively correlated with rScO2 （β = 0. 295, 0. 226, P = 0. 009） at T4, and the linear regression equation was y= 0. 373 ＋ 0. 001x7 ±0. 008x8. The 13 value of nasopharyngeal temperature was less than that of MAP, which indicated that nasopharyngeal temperature had less influence on rSoO2 than MAP at T4. The paCO2 and Lac were positively correlated with rScO2 at Ts （β = 0. 268, 0. 465, P = 0. 001 ）, and the linear regression equation was y = 0. 498 ＋ 0. 003x4 ＋ 0. 015x6. The β value of Lac was greater than that of po CO2, showing that Lac had greater impact on rSoO2 than poCO2 at Ts. The pcCO2 and Lac were positively correlated with rScO2 （β = 0. 274, 0. 223, P = 0.001 ） at T6, and the linear regression equation was y = 0. 550 ＋ 0. 002x4 ＋ 0. 004x6. The β value of Lac was less than that of poCO2, indicating that Lac had less impact on rScO2 than poCO2 at T6. Only nasopharyngeal temperature was positively correlated with rScO2 （β = 0. 285, P = 0. 001 ） at T7, and the linear regression equation was y = 0. 805 ＋ 0. 042x8. Conclusion The paC02, nasopharynx temperature and Lac can affect rScO2 during CPB. The MAP in the cooling stage also has a certain correlation with rScO2. After hemodilution, both Hct and Hb have great changes, but they are not correlated with rScO2.