Evaluation of new ceerbral protection for postoperative brain injury after cardiopulmonary bypass using near-infrared spectroscopy

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Despite advances in the technology involved in cardiopulmonary bypass (CPB). as well as in surgical and anesthetic methods, the cardiac surgical literature has continued to report. cerebral dysfunction as a major continuing problem in modern cardiac surgical practice, with an unacceptale incidence of postoperative morbidity. Concerning on the cerebral dysfunction. one major factor, the presence of a level of cerebral perfusion that is inadequate for the cerebral metabolic demand during CPB. is incriminated in this complication. Consequently, to maintain an adequate cerebral perfusion during CPB. it is not, the level of cerebral blood flow per se. but an appropriate balance between cerebral perfusion and cerebral oxygen consumption that is likely to be important. In this study, we evaluated the new cerebral protection for postoperative brain injury after CPB using near-infrared spectroscopy (NIRS). <METHODS> 16 dogs were anesthetized, and mechanically ventilated clue to be adjusted to k … More eep PaCO2 within the range 35 to 40 mmHg. To measure the jugular venous oxygen saturation (SjvO2) during the study. 5 Fr catheter was inserted via retrograde cannulation of the left internal jugular, vein. Ultrasound transit-time flow probes was placed around the left carotid artery (CA) for continuous measurement of the changes in cerebral blood flow (CBF). To measure cerebral oxygenation by NIRS, a pair of fiberoptic optodes was attached to a leftsicle cranial bones directly with a distance of 3cm apart. Deep hypothermic circulatory arrest (DHCA) was induced for 60 min under 25℃ or 15℃ and evaluated the changes in the values of SjvO2, CNF, redox behavior of cyt.ox., and s-100β protein during and after DHCA. Furthermore, we evaluated the postoperative neurological prognosis.<RESULTS>The values of SjvO2, CBF and s-100β protein in the 25℃ group and 15℃ group during and after DHCA did not show the significant differences. On the other hand, cytochrome oxidase significantly reduced in the 25℃ group than 15℃ group. After operation, all animals in 15℃ group recovered without neurological complications, while those in the 25℃ group suffered From paralysis or convulsion resulted in died. <DISCUSSION> Hyperoxia of the internal jugular venous blood has been reported in patients who suffered coma or brain death ; this was thought to be because the external carotid regions had received "luxury perfusion", resulting in hyperoxia of the venous blood returning from the extracerebral tissues Thus, the degree of cerebral hypoxia cannot be judged by SjvO2 or CBF alone. Recently. it has been reported that most s-100β protein appearing in the serum during CPB may be of extracerebral origin. However, our data demonstrate that the reolox behavior of cyt.ox. (as measured by NIRS) can provide direct real-time information about crises in cerebral oxygen metabolism associated with fairly widespread hypoxia and/or ischeniia, and th at acquiring such information enables us both to assess the likely degree of cerebral damage and to predict the postoperative cerebral outcome. Less