Monitoring Cerebral Oxygen Saturation Using Near Infrared Spectroscopy during Cardiopulmonary Bypass: Comparing with Monitoring Mixed Venous Oxygen Saturation

Teng Yichao,Gong Qingcheng,Ding Haishu,Huang Lan

doi:10.1109/iccme.2007.4381892

Abstract

Cerebral oxygenation can be monitored non-invasively by near infrared spectroscopy (NIRS), which is significantly important for clinical cerebral protection against hypoxia. Our group developed an NIRS oximeter, by which regional cerebral oxygen saturation (rSO 2 ) can be monitored non-invasively, continuously and in real time. Using it, we monitored cerebral rSO 2 of three children during cardiac surgery all with cardiopulmonary bypass (CPB). The mixed venous oxygen saturation of the vena cava (SvO 2 ) at the entrance of the artificial CPB pump was also measured at the same time by another monitor. The results indicated that there was statistical correlation between cerebral rSO 2 and mixed SvO 2 ( R =0.547, 0.465 and 0.695 respectively, and p all less than 0.01). But all the above R was not high, because cerebral rSO 2 was mainly reflected by cerebral venous oxygen saturation, which was generally not consistent with the SvO 2 . During CPB, when the perfusion rate or the body temperature was changed, the changes of the mixed SvO 2 were delayed for several minutes compared with the corresponding changes of cerebral rSO 2 . This was because cerebral venous blood flew relatively low, and it might take a period that the venous blood flew from the brain into the vena cava. Therefore, the mixed SvO 2 cannot trace the changes of cerebral oxygenation in real time during CPB, and monitoring cerebral rSO 2 using NIRS is of greatly advantages than the mixed SvO 2 .

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