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

尽管心肺转流术（CPB）技术取得了进步。以及在手术和麻醉方法中，心脏外科文献继续报道。在现代心脏外科实践中，脑功能障碍是一个主要的持续性问题，其术后发病率不可接受。关于脑功能障碍。一个主要因素是CPB期间脑灌注水平不足以满足脑代谢需求。与这起并发症有关因此，在CPB期间维持足够的脑灌注。不是脑血流量本身的水平。但脑灌注和脑耗氧量之间的适当平衡可能是重要的。在这项研究中，我们使用近红外光谱（NIRS）评价了CPB术后脑损伤的新脑保护。<METHODS>16只犬麻醉后，机械通气线索调整为k ...更多信息 保持PaCO 2在35到40 mmHg之间。在研究期间测量颈静脉血氧饱和度（SjvO 2）。通过左颈内静脉逆行插管插入5 Fr导管。超声渡越时间血流探头放置在左侧颈动脉（CA）周围，连续测量脑血流（CBF）的变化。采用近红外光谱法（NIRS）测定脑氧合，将一对光纤光管直接连接于左侧颅骨，光管间距3cm。分别在25℃和15℃下深低温停循环60 min，观察SjvO 2、CNF、cyt. ox氧化还原行为、和s-100β蛋白的表达。此外，我们还评估了术后神经功能预后。<RESULTS>25℃组和15℃组DHCA时、后SjvO 2、CBF和s-100β蛋白值差异无统计学意义。另一方面，25℃组的细胞色素氧化酶比15℃组显著降低。术后15℃组动物均恢复正常，无神经系统并发症，25℃组动物出现瘫痪或惊厥，死亡。<DISCUSSION>在昏迷或脑死亡的患者中曾报告过颈内静脉血的高氧;这被认为是因为颈外动脉区域接受了“过度灌注”，导致从脑外组织返回的静脉血的高氧。因此，脑缺氧的程度不能仅通过SjvO 2或CBF来判断。最近体外循环期间血清中出现的S-100β蛋白大多数可能来源于脑外。然而，我们的数据表明，cyt. ox的reolox行为。(as通过NIRS测量）可以提供关于与相当广泛的缺氧和/或缺血相关的脑氧代谢危机的直接实时信息，并且获得这些信息使得我们能够评估脑损伤的可能程度并预测术后脑结果。少

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