体外循环中苯肾上腺素和灌注流量对脑氧代谢的影响

Influence of phenylephrine and perfusion flow rate on cerebral oxygen metabolism during cardiopulmonary bypass

目的观察体外循环(CPB)低血压期间,使用苯肾上腺素和提高灌注流量两种方法对术中脑氧代谢和术后认知功能、肾功能的影响。方法列入拟研究对象的择期CPB下心脏瓣膜手术的成年患者共50例,CPB开始后5 min内流量达2.6 L/(min·m2)仍不能使平均动脉压(MAP)≥50 mm Hg者随机分为D组(n=25)和F组(n=25),分别给予苯肾上腺素和提高流量处理。观察处理前后的MAP,脑组织氧饱和度(r Sc O2),全身氧供(DO2),上腔静脉血氧饱和度(Ssv O2)变化以及血神经胶质细胞酸性蛋白(GFAP)变化,观察术后血尿素氮(BUN)和肌酐(Cr),并行认知功能问卷评估。结果两组患者的一般情况及基础临床参数无统计学差异。对低血压给予处理后,两组MAP都有显著提高,但D组提高更多。F组的提高流量措施使r Sc O2、DO2及Ssv O2显著提高,而D组的药物处理没有影响r Sc O2、DO2及Ssv O2。在给予干预措施后,F组r Sc O2、DO2及Ssv O2显著高于D组。两组患者术后GFAP、BUN、Cr水平及认知功能评分无差异。结论 CPB中发生低血压时,提高灌注流量比使用苯肾上腺素更有利于脑灌注;通过近红外光谱脑氧监测r Sc O2具有重要的参考价值。

Objective To evaluate the impact of phenylephrine and perfusion flow rate on cerebral oxygenation metabolism during cardiopulmonary bypass（ CPB）. The influences on post-operative cognitive function and renal function were also observed. Methods Patients undergoing elective cardiac valve surgery were ready to be included in the study. Patients whose mean blood pressure（ MAP） lower than 50 mm Hg during the initial 5 min of CPB with a flow rate of 2.6 L/min/m2 were actually enrolled in the study and randomized to Group D（ n = 25） or Group F（ n = 25）. Patients of Group D were treated by phenylephrine infusion while Group F were treated by increasing flow rate. Variables before and after the treatments were observed,including MAP,regional cerebral oxygen saturation（ r Sc O2）,oxygen delivery（ DO2）,superior vena cava blood oxygen saturation（ Ssv O2）,blood glial fibrillary acid protein（ GFAP） concentration,blood urea nitrogen（ BUN） and creatinine（ Cr） concentration. Post-operative cognitive test was also performed. Results Baseline values did not differ between the two groups. MAP of both groups elevated after the treatments,but Group D showed a higher value. DO2,r Sc O2 and Ssv O2 increased significantly after treatment in Group F,but not in Group D. The value of r Sc O2,DO2 and Ssv O2 after treatment were significantly higher in Group F than in Group D. Post-operative GFAP,BUN,Cr and cognitive test scores showed no significant differences between the two groups. Conclusion Changes in perfusion flow rate affect cerebral oxygenation greater than phenylephrine,and r Sc O2 offers important information about cerebral perfusion.