Neurocognitive Function and Cerebral Perfusion in Cardiac Surgery

描述(申请人提供)：心脏手术后的神经认知功能障碍是一种公认的并发症，约50%的患者在出院时受到影响。脑是体外循环(CPB)期间最容易因灌注不足而受损的器官，但也是手术中监测最少的器官，因为缺乏一种可行的方法来监测术中脑灌注。该项目的主要目标是将近红外光谱(NIRS)断层扫描技术应用于术中监测。近红外断层成像提供了脑血流的时间和空间的实时测量，空间分辨率与功能磁共振相当，但时间分辨率要好得多。除了在传统的简化框架内分析数据(分别考虑氧合血红蛋白、脱氧血红蛋白和总血红蛋白)外，还将应用一种新的对比增强方法，该方法基于将每种形式的血红蛋白分解为对诱发性氧债务敏感的六类，以进一步细化脑血流灌注模式的时空特征。该项目的最终目标是在可逆阶段确定后续神经认知功能障碍的术中生物标志物。该项目将招募至少50名心脏手术患者和25名不涉及体外循环的开胸手术患者(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。术中将进行脑血流NIRS成像，并进行分析，以确定缺氧区，以及低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，以确定这些操作中哪些与缺氧事件有关，并预测随后的神经功能障碍。将对已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，这些共同特征建议在手术期间采取适当的对策来逆转或预防脑灌注不良。这些研究的结果将为辨别心脏手术期间的循证脑保护方案提供基础。此外，基于实时近红外成像，可以做出改进的术中管理决策，以提醒临床医生注意低灌注率的罪魁祸首模式，并评估救援操作的有效性。 公共卫生相关性：神经认知功能障碍是心脏手术后的常见并发症。该项目旨在利用近红外光学断层扫描在术中环境中监测脑血流灌注。收集到的信息将帮助外科医生和麻醉师对患者进行适当的管理，以防止神经系统并发症。

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.