Neurocognitive Function and Cerebral Perfusion in Cardiac Surgery

描述（由申请人提供）：心脏手术后神经认知功能障碍是公认的并发症，约50%的患者在出院时受到影响。在体外循环（CPB，即心肺机）中，脑是最容易受到灌注不足损伤的器官，但由于缺乏可行的术中脑灌注监测方式，它也是手术中监测最少的器官。该项目的主要目的是将近红外光谱（NIRS）断层扫描应用于术中监测。近红外层析成像提供了大脑时空灌注的实时测量，其空间分辨率与功能性MRI相当，但时间分辨率明显更好。除了在传统的还原框架内分析数据（分别考虑含氧血红蛋白，脱氧血红蛋白和总血红蛋白），一种新的对比度增强方法，基于将每种形式的血红蛋白分解为六种对诱导氧债敏感的类别，将应用于进一步细化脑灌注模式的空间和时间特征。该项目的最终目标是在可逆阶段确定随后的神经认知功能障碍的术中生物标志物。本项目将招募至少50例心脏手术患者和25例不涉及CPB的开胸手术患者（对照组）。他们将在手术前后接受一系列标准的神经认知测试。术中对脑灌注进行近红外成像分析，以确定缺氧区域，以及缺氧应激的持续时间和程度。将与神经认知测试结果以及外科医生、麻醉师和灌注师的术中操作记录进行比较，以确定哪些与缺氧事件共同变化，并预测随后的神经功能障碍。将对确定的事件进行研究，以确定在受影响的受试者组中是否存在共同特征，这些特征提示在手术中采取适当的对策来逆转或预防脑灌注不良。这些研究结果将为在心脏手术中制定基于证据的脑保护方案提供依据。此外，基于实时近红外光谱成像，可以改进术中管理决策，提醒临床医生注意灌注不足的罪魁祸首特征模式，并评估救援操作的有效性。

DESCRIPTION (provided by applicant): Neurocognitive dysfunction after cardiac surgery is a well-recognized complication that affects about 50% of patients at discharge. The brain is the organ most susceptible to damage from inadequate perfusion during cardiopulmonary bypass (CPB, i.e. heart-lung machine), but it is also the organ least monitored during surgery, due to the absence of a feasible modality for monitoring intraoperative cerebral perfusion. The broad aim of this project is to adapt near-infrared spectroscopic (NIRS) tomography to intraoperative monitoring. NIRS tomography provides real-time measures of the temporal and spatial cerebral perfusion, with spatial resolution comparable to functional MRI, but with significantly better temporal resolution. In addition to analysis of data within a conventional reductionistic framework (oxyhemoglobin, deoxyhemoglobin, and total hemoglobin considered separately), a novel contrast-enhancement method, based on resolving each form of hemoglobin into six categories that are sensitive to induced oxygen debt, will be applied to further refine spatial and temporal features of cerebral perfusion patterns. The ultimate goal of this project is to identify intraoperative biomarkers of subsequent neurocognitive dysfunction at a reversible stage. A minimum of 50 cardiac surgical patients, and 25 patients undergoing open chest surgery not involving CPB (control group), will be recruited for this project. They will undergo a standard battery of neurocognitive tests before and after surgery. Intraoperative NIRS imaging of cerebral perfusion will be performed and analyzed to identify areas of hypoxia, as well as the duration and magnitude of hypoxic stress. Comparison will be made to neurocognitive test results, as well as to records of intraoperative maneuvers by surgeons, anesthesiologists, and perfusionists, to determine which of these co-vary with the hypoxic events and are predictive of subsequent neurological deficit. Identified events will be studied to determine whether common features exist within the affected subject group that is suggestive of appropriate countermeasures during surgery to reverse or forestall cerebral malperfusion. Results from these studies will provide a basis for discerning an evidence-based cerebral protection protocol during cardiac surgery. Furthermore, improved intraoperative management decisions can be made, based on real-time NIRS imaging, to alert clinicians to culprit signature patterns of hypoperfusion and to assess the effectiveness of rescue maneuvers. PUBLIC HEALTH RELEVANCE: Neurocognitive dysfunction is a common complication after cardiac surgery. This project aims to utilize near- infrared optical tomography to monitor cerebral perfusion in intraoperative settings. The information gathered will help surgeons and anesthesiologists manage patients appropriately to prevent neurological complications.