体外循环心脏手术中脑自身调节的变化

Continuous assessment of cerebral autoregulation in patients undergoing cardiac operation with cardiopulmonary bypass

目的 采用颈静脉球氧饱和度 (SjO2 )持续监测 ,以平均动脉压 (MAP)变化对SjO2 的影响及二者的相关关系作为评定脑自身调节的指标 ,对心脏手术病人术中脑自身调节功能进行估测。方法 2 4例心脏手术病人 ,男 16例 ,女 8例 ,ASA分级Ⅱ Ⅲ级 ,术前无神经系统病变、糖尿病及免疫系统疾病 ,术后无神经精神障碍表现。采用α stat原则维持血液酸碱平衡。采用计算机化麻醉监测记录系统持续监测SjO2 、MAP、体温、心率、肺动脉压、心排量等 ,采样间隔为 30s。分析CPB前、CPB中稳定低温期、CPB后血温下降期各 45 6 0minMAP与SjO2 的相关关系 ,并求出直线回归方程SjO2=b +aMAP。以斜率a为标准 ,a≥ 0 4为脑自身调节失常。结果 转流前无自身调节失常 ,转流后 4例 (16 7% )出现脑自身调节失常 ,其中 2例转流中即已存在。a值大小与主动脉阻断时间及CPB时间无关。 5例病人在不同的时间段内平均SjO2 低于 5 0 % ,但并未发生脑自身调节失常。结论 以MAP与SjO2 的相关性变化为标准对体外循环心脏手术中脑血管反应性进行持续观察发现 。

Objective The present study was designed to attempt a continuous assessment of cerebral autoregulation by continuously monitoring jugular venous bulb oxygen saturation (SjO 2) in patient undergoing cardiac operation. Methods Twenty-four patients undergoing cardiac surgery under cardiopulmonary bypass (CPB) were included. Among them 16 were male, 8 female. No neuropsychological deficit was found in any of them before or after operation. Patients had neither diabetes mellitus nor immunological diseases. Normocapnia was maintained during operation. SjO 2 and other routine parameters, such as blood pressure, temperature, heart rate, pulmonary atery pressure and cardiac output etc were monitored and recorded continuously via a computerized anesthetic recording system. The numerical data of SjO 2 and mean arterial pressure (MAP) were sampled every 30s. Correlation between SjO 2 and MAP was evaluated before, during and after CPB. According to the slope 'a' of the regression line 'SjO 2= b + a MAP', cerebral autoregulation was estimated. The cerebral autoregulation was taken as deteriorated if the two parameters were highly correlated with a ≥0.4, showed as dysautoregulation (+). Those with a < 0.4 (or correlation of the two parameters was not statistically significant) were taken as dysautoregulation (-).Results No dysautoregulation was found before CPB. Four patients (16.7%) suffered dysautoregulation (+) after CPB. Among them two had dysautoregulation (+) during CPB. There was no relationship between 'a' value and duration of CPB or aortic occlusion. Five patients who experienced averaged SjO 2 less than 50% did not suffer dysautoregulation (+).Conclusions By means of continuous assessment transient cerebral dysautoregulation was found during and after CPB in patient undergoing cardiac operations.