NIRS FOR BRAIN MONITORING IN CARDIAC SURGERY

接受先天性心脏畸形手术修复的儿童在 脑损伤的重大风险。与成年人相比， 心脏手术中的脑损伤最常见的是固定或栓塞 动脉粥样硬化，在儿童中最常见的原因是全球性的 缺氧/缺血。在拟议的研究中要检验的第一个假设 全脑缺氧/缺血是由可定义的、叠加的 灌注参数的极端操作的相互作用， 在儿科心脏手术中使用，即极低程度的 灌注流量、低温、血液稀释和pH值变化，这可能导致 大脑线粒体供氧受损 近红外光谱技术是一种新的实时脑监测方法 它提供了检测即将发生的严重脑损伤的可能性， 缺氧/缺血。这种技术提供了明显的优势， 间接监测大脑功能的方法，因为它的能力， 定义通过以下方式向神经元线粒体成功输送氧气： 细胞色素AA 3的氧化还原状态的评估。本研究将定义一个 细胞色素aa 3还原的临界阈值 波近红外光谱脑损伤的阈值将 使用近红外光谱的新侵入性方法进行验证 测量血红蛋白和线粒体的绝对变化 氧合在研究的第一阶段确定了关键的 伤害阈值，研究的第二阶段将测试第二个 假设用近红外光谱法进行真实的实时监测可以 允许操纵灌注参数， 是避免的。这项研究将揭示流动的机制， 速率、温度、红细胞压积和pH相互作用， 氧气输送它还将展示近红外线的实用性 光谱学作为一种临床方法用于避免儿科手术中脑损伤 心脏手术

Children undergoing surgical repair of congenital cardiac anomalies are at significant risk of brain injury. In contrast to adults in whom the cause of brain injury during cardiac surgery is most commonly fixed or embolic atherosclerosis, in children the cause is most commonly global hypoxia/ischemia. The first hypothesis to be tested in the proposed study is that global cerebral hypoxia/ischemia results from definable, additive interactions of the extreme manipulations of perfusion parameters that are employed in pediatric cardiac surgery, namely extreme degrees of low perfusion flow, hypothermia, hemodilution and pH shifts, which can result in impaired oxygen delivery to cerebral mitochondria. Near infrared spectroscopy is a mew method of real-time brain monitoring that offers the potential to detect impending critical cerebral hypoxia/ischemia. This technique offers distinct advantages over current indirect methods of monitoring brain function because of its capacity to define successful delivery of oxygen to neuronal mitochondria through assessment of the redox state of cytochrome aa3. This study will define a critical threshold of cytochrome aa3 reduction using standard continuous wave near infrared spectroscopy. This threshold for cerebral injury will be validated using a novel invasive method of near infrared spectroscopy that measures absolute changes in both hemoglobin and mitochondrial oxygenation. After the first phase of the study has defined the critical threshold of injury, the second phase of the study will test the second hypothesis that real time monitoring with near infrared spectroscopy can allow manipulation of perfusion parameters such that neurological injury is avoided. The study will shed light on the mechanisms by which flow rate, temperature, hematocrit and pH interact to determine intraneuronal oxygen delivery. It also will demonstrate the utility of near infrared spectroscopy as a clinical method for avoid brain injury during pediatric cardiac surgery.