近红外光谱监测体外循环手术中脑组织氧合状况的研究

体外循环手术中，为防止因脑氧供需失衡导致脑缺氧，就要实时监测患者局部脑组织的氧合状况，以根据其变化调整生理参数或采取应急手段。用该研究小组自行研制的近红外仪器(使用一个双波长的近红外光源和两个近红外检测器)监测心脏手术中患者的脑氧，可以求出局部脑组织血红蛋白浓度的变化，并根据稳态空间分辨光谱(SRS)算法求出局部脑组织的氧饱和度(rSO₂)。体外循环中用监护仪监测患者的混合静脉血氧饱和度(SvO₂)等生理参数。测得的血红蛋白浓度变化容易受到干扰，而rSO₂的抗干扰性能较好。rSO₂在整个手术过程中都可以监测到，而SvO₂只能在体外循环过程中监测到。多数患者rSO₂和SvO₂存在正向相关性，但二者的相关系数并不很高。这是因为SvO₂是大静脉的血氧饱和度，而测得的rSO₂反映局部脑组织的氧合状况，二者的生理意义不同。实验结果表明，体外循环手术中rSO₂可以反映患者脑组织氧合状况的变化，而仅仅监测SvO₂是不够的。

Monitoring Cerebral Oxygenation Using Near Infrared Spectroscopy during Cardiopulmonary Bypass Surgery

To avoid cerebral hypoxia caused by the imbalance between cerebral oxygen supply and consumption, regional cerebral oxygenation of patients need to be monitored at real time during cardiopulmonary bypass (CPB) surgery, and the physiological parameters can be regulated and emergent treatment can be used according to it. Using the near infrared (NIR) instrument developed by our group, cerebral oxygenation of the patients under cardiac surgery was monitored. The instrument consists of a two-wavelength near infrared light source and two near infrared detectors. Hemoglobin concentration changes of regional cerebral tissue were calculated, and by steady-state spatially resolved spectroscopy (SRS) algorithm, regional cerebral oxygen saturation (rSO_2) was also calculated. Physiological parameters of patients, such as mixed venous oxygen saturation (SvO_2), were measured by another monitor during CPB. Hemoglobin concentration changes were easily disturbed, but the anti-disturbance ability of rSO_2 was good. The value of rSO_2 could be detected all over the surgeries, but SvO_2 could be detected only during CPB. There were positive correlations between rSO_2 and SvO_2 in most of the patients, but the correlation coefficients were not very high. This was because SvO_2 reflects the saturation of the main venous, but rSO_2 reflects regional cerebral oxygenation. So the physiological meaning of rSO_2 and SvO_2 is different. The results indicate that cerebral oxygenation of patients can be reflected by rSO_2 during CPB, while only monitoring SvO_2 is not enough.