我们感谢圣保罗研究基金会 （FAPESP） 通过第 2012/02500-8 （RM）、2014/25486-6 （RF） 和 2013/07559-3 号文件提供的支持。资助者在研究设计、数据收集和分析、发表决定或手稿准备方面没有任何作用。

该协议由坎皮纳斯大学地方委员会批准（协议号56602516.2.0000.5404）。在测量之前，从患者或法定代表人那里获得了书面知情同意。我们监测了坎皮纳斯大学诊所医院收治的患者，诊断为缺血性中风或影响前循环的蛛网膜下腔出血。影响后循环的缺血性中风患者，由于颅内压升高而导致减压性颅骨切除术的患者和其他神经退行性疾病（痴呆，帕金森氏症或任何其他可能与皮质萎缩相关的疾病）的患者被排除在研究方案之外。
1. 将系统移至重症监护室之前的准备工作
<ol><li>将所有光纤连接到相关的激光器和检测器，并确保它们正确连接到光学探头（图1B）。</li>
	<li>检查光学探头是否用黑布覆盖，以避免激光照射在房间内。</li>
	<li>将系统电源开关转到"ON"位置。系统通电后，等待30秒，然后将DCS激光钥匙开关转到"ON"位置。FD-DOS激光器在系统通电时自动打开。</li>
	<li>在准备系统时，请征得参与者或法定代表人的同意。获得同意后，将推车带到患者房间。 注意:由于混合动力系统具有可持续使用长达 45 分钟的内置电池，因此在运输过程中无需关闭。</li>
</ol>2. DOS系统的校准和增益设置
<ol><li>到达ICU后，通过将钥匙切换到"OFF"位置来关闭DCS激光器。</li>
	<li>从标有"校准"的固体模型开始，按照以下步骤在FD-DOS软件（BOXY，ISS）上运行校准过程。<ol><li>在"文件"菜单上，通过单击"加载设置文件"选项，为正在使用的探头加载相应的设置文件。</li>
		<li>将探头放在模型的弯曲侧，确保与表面良好接触，然后单击FD-DOS软件中的"优化所有探测器" 按钮来优化PMT偏置电压。</li>
		<li>通过单击"计算波形校准"选项，运行多个源检测器分离的校准。光学道具的值。和"校准" 菜单中的多个距离"。</li>
		<li>从"文本星期一"菜单中打开"用户定义的计算"选项，以检查测量的光学属性是否与预先指定的值（写在实体模型中）匹配，以及拟合 R2 是否接近 1。</li>
	</ol></li>
	<li>重复上述步骤（步骤2.2.3除外）以测量标记为"检查" 的模型的光学特性，以确保校准充分。测量的光学特性应在 10% 以内与模型中指定的值匹配。 注意:确保每次移动探头时都关闭PMT（通过单击"所有探测器关闭"按钮），以避免由于环境光的直接照明而损坏PMT。</li>
	<li>如果校准不充分，请重新运行校准过程（步骤 2.2 和 2.3）。确保FD-DOS系统的良好校准对于FD-DOS测量的有效性至关重要。</li>
</ol>3. 参与者在床边的准备
<ol><li>使用消毒湿巾清洁探头和患者额头。</li>
	<li>将双面胶带放在探头上（图1B），确保胶带不与光纤尖端直接接触。</li>
	<li>在主题上放置激光安全谷歌。</li>
	<li>将探针放在感兴趣区域（ROI）上，并将松紧带缠绕在受试者的头部。虽然FD-DOS和DCS并非绝对必要，但建议用黑布或黑色绷带覆盖光学探头，以减少环境光引起的噪音。 注意:重要的是要确保弹性带既不太紧也不太松。如果带子太紧，可能会给患者带来明显的不适，如果带子太松，可能会导致数据质量差，因为双面带的强度不足以将探头固定到位。</li>
	<li>将探头正确固定在患者的额头上后，通过将钥匙切换到"ON"位置来打开DCS激光器。 注意:DCS系统使用3B类激光，这对眼睛暴露是危险的。只有当探头正确连接到患者的额头上时，才打开激光非常重要。</li>
</ol>4. 数据质量评估
<ol><li>在开始使用GUI获取数据之前，请在GUI的"设置" 选项卡中编写DCS源检测器分离。 注意:DCS系统不需要校准步骤，但实时分析需要正确输入源探测器分离（详见 补充材料 ）。</li>
	<li>按GUI中的"开始" 按钮启动采集软件，并在FD-DOS软件中检查DOS信号:<ol><li>单击FD-DOS软件中的"优化所有检测器" 按钮以优化PMT偏置电压。</li>
		<li>在"文本星期一"菜单中的"用户定义计算"选项中检查光学特性和DOS拟合的R2。R2系数应接近单位，根据经验，人类患者的吸收系数应在0.05和0.2cm-1范围内，而散射系数应在6和13cm-113范围内。</li>
	</ol></li>
	<li>在GUI的"相关曲线"选项卡中检查DCS信号。<ol><li>通过将开关转到"ON" 位置来打开DCS探测器。</li>
		<li>确保每个DCS探测器测量的光强度都足够。根据经验，需要超过 10 kHz。</li>
		<li>如果测量强度高于800 kHz，请使用中性密度滤光片减少光子计数，以免损坏探测器。对于较短（< 1 cm）的源检测器分离，这通常是一个问题。 注意:除了可能损坏DCS探测器外，高于800 kHz的光子计数也可能由于探测器中的非线性效应而带来误差。</li>
		<li>检查自相关曲线以确保良好的皮肤耦合（参见 代表性结果 和 图2）， 并在必要时重新定位光学探头。</li>
		<li>如果在上一步中需要重新定位探头，请重复步骤 4.2 和 4.3。这些步骤可能需要重复多次。 注意:每次移动探头时，必须关闭DCS和FD-DOS探测器。要关闭DCS探测器，请手动将开关移动到"关闭"位置。通过单击FD-DOS软件中的"所有探测器关闭"按钮，将关闭FD-DOS探测器。</li>
	</ol></li>
	<li>当探头和皮肤之间实现良好接触时，通过单击 GUI 中的"停止"按钮停止数据收集。然后，在"文件夹"文本框中设置实验和患者标识符，并在"文件名"文本框中写入ROI名称。</li>
	<li>按GUI中的"开始"按钮开始数据采集。</li>
	<li>在协议要求的情况下，在第一个ROI中收集数据。如有必要，将探头移动到其他ROI并重复测量。 注意:监测期可能因研究目标而异。</li>
</ol>5. 测量过程中对实验者的考虑
<ol><li>开始测量后，在GUI的"实验信息"选项卡中写下相关的患者信息（例如，损伤的类型和位置，正在服用的药物，年龄，性别等）。</li>
	<li>确保通过单击 GUI 上的"标记"按钮来标记在监控期间发生的任何相关事件。每次标记后，请确保在 GUI 的"实验信息"选项卡中编写事件描述。</li>
</ol>6. 停止数据收集
<ol><li>通过按 GUI 中的"停止"按钮停止数据收集。</li>
	<li>通过按下FD-DOS软件中表示为两个红色方块的停止数据采集和记录按钮来停止FD-DOS软件。</li>
	<li>通过将开关翻转到"关闭"位置来关闭DCS探测器，通过将钥匙转到"关闭" 位置来关闭DCS激光器。</li>
	<li>通过单击"所有探测器关闭"按钮关闭FD-DOS模块的PMT。</li>
	<li>从患者头部取下探头，然后从探头上取下双面胶带。然后，用消毒湿巾清洁探头。</li>
	<li>尽快重复测量每个固体模型的光学特性，以确保在整个监测过程中校准保持充分（参见步骤4.2.2）。 注意:理想情况下，校准步骤应在从患者头部取下光学探头后立即完成（步骤6.6）。但是，由于时间问题，在下一节中介绍的示例中，这是在存储设施中完成的。</li>
	<li>用消毒湿巾清洁系统及其附件。</li>
	<li>将推车推回储藏室。</li>
</ol>

作者声明了与本文的研究、作者身份和/或出版有关的以下潜在利益冲突:RC Mesquita 有一项待决专利申请和与这项工作相关的另外两项专利（美国专利 10，342，488 和 10，064，554）。目前没有作者从这些专利中获得版税或付款。

本文提出了一种混合光学系统，该系统可以在旁边提供神经危重症患者的脑血流、脑氧合和脑氧代谢的实时信息。弥漫光学技术的使用以前曾被认为是临床情况下非侵入性床旁监测的潜在标志物。之前的一项研究通过病例报告9重点关注神经ICU住院期间光学监测的临床方面和可行性。这项工作的重点是详细说明与漫反射光学实时监测相关的相关和创新方面。具体来说，本文提出了一种实时GUI，为临床医生提供清晰有用的信息。GUI允许轻松比较不同的时间段，这对于解释临床相关数据非常重要。这里介绍的GUI实现可以很容易地转换为基于软件相关器的DCS系统，但需要注意的是，实时显示频率必须限制在~20 Hz。 自相关曲线的实时平均可用于下采样更快的采集速率。将来，拟议方案提供的实时信息可用于指导治疗，从而可能改善神经危重患者的临床结果。
这项工作还建议使用可定制的光学探头，该探头可以解决不同的设置，因此适合临床医生的不同目的和需求。正确选择源-检测器分离是最大化漫反射光学器件大脑灵敏度的关键步骤。在大多数情况下，成人DCS测量的最佳探头应至少具有短（<1厘米）和长（>2.5厘米）源-检测器分离。长源-检测器分离在信噪比（SNR）和脑灵敏度之间提供了最佳折衷方案12，14，16，而短分离主要对脑外组织敏感，有助于区分脑外变化和脑变化12，16.对于FD-DOS，一种在成人SNR和大脑敏感性之间提供合理折衷的简单探针包含4种源检测器分离（1.5，2.0，2.5和3.0cm）58。FD-DOS测量最关键的步骤是比较不同光纤的交流和相位变化所必需的校准程序（协议第2节）。FD-DOS系统的校准不良会导致组织光学特性的检索值出现较大误差，这将影响脑氧合和脑血流量值的准确性。重要的是，本研究中提出的协议侧重于包含单个PMT和多个光源的FD-DOS光学探针。对于使用多个检测器的实验，需要修改此处描述的校准程序。对于使用多个检测器的研究，PMT的偏置电压不应在校准过程中改变，因此需要仔细选择校准模型的光学特性。
除了脑氧合测量外，DOS模块还改进了CBF的计算，因为DCS模型还取决于组织的光学特性。本研究采用具有单一调制频率的商用FD-DOS系统来恢复光学特性和脑氧合。然而，还有其他替代方法可以提供更准确的信息，例如时域DOS或多频FD-DOS系统59，60，61，62，63，64。这些系统可以降低实验复杂性，因为它们需要单个源探测器分离来恢复大脑生理，而这里采用的传统FD-DOS需要多个源探测器分离，因此多个纤维连接到头部。此外，由于该协议的主要兴趣是脑生理学的长期趋势，因此本研究选择进行交错的DOS和DCS测量。将来，为了避免交叉污染并提高采样频率，可以通过在DOS和DCS探测器上安装陷波滤波器来同时获取DOS和DCS测量。
当前协议的一个限制是探头放置在前额的限制。截至目前，很难通过头发获得DCS测量值。对于覆盖大脑大部分的侮辱来说，这不是一个问题，就像神经ICU中最常见的情况一样。但是，例如，额头上的测量可能对小的MCA或PCA中风不敏感。随着光学探头的进一步改进，可以通过头发进行测量，并且通过将系统与神经导航设备相结合，可以在较小的局部ROI上进行测量。通过将详细的空间信息收集到光学信息上，我们期望弥漫光学器件对局灶性脑血管疾病引起的血流动力学损伤的敏感性显着提高。
最后，重要的是要提到漫反射光学技术的一些局限性。首先，漫反射光学器件本质上对脑外组织敏感，可能需要对数据进行更好的建模，以正确解释脑外和脑生理学的差异65，66，67，68，69，70。此外，CBF的DCS测量对光学探针对组织的外部压力很敏感。例如，通过增加探头压力，我们减少了外部组织中的血流量，这也将减少DCS71，72，73测量的CBF。但请注意，尽管由于探头压力增加，CBF降低，但CBF的心率脉动性保持不变72。有趣的是，由于外部探头压力，可以使用CBF中的这些变化来分离脑外和脑生理73。最后，光学衍生的CBF具有物理单位（即cm2 / s），而不是更常见的临床单位（即ml / 100g组织/分钟）。一些作者建议使用吲哚菁绿（ICG）从DOS中回收绝对CBF，并将CBF指数从DCS校准到绝对临床单位74，75，76，77，78。然而，由于脑外伤后宏观和微循环的异常，ICG校准因子的准确性可能无法直接转化为不同的情况。

An erratum was issued for:&#160;<a href="https://www-jove-com.remotexs.ntu.edu.sg/t/61608">Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies</a>. The Authors section was updated from:
Rodrigo Menezes Forti1,2 
Marilise Katsurayama2,3 
Lenise Valler2,3 
Andr&#233;s Quiroga1,2 
Luiz Simioni1 
Julien Menko4 
Antonio L. E. Falc&#227;o3 
Li Min Li2,5 
Rickson C. Mesquita1,2 
1Institute of Physics, University of Campinas 
2Brazilian Institute of Neuroscience and Neurotechnology 
3Clinical Hospital, University of Campinas 
4Department of Emergency Medicine, Albert Einstein College of Medicine 
5School of Medical Sciences, University of Campinas
to:
Rodrigo Menezes Forti1,2 
Marilise Katsurayama2,3 
Giovani Grisotti Martins1 
Lenise Valler2,3 
Andr&#233;s Quiroga1,2 
Luiz Simioni1 
Julien Menko4 
Antonio L. E. Falc&#227;o3 
Li Min Li2,5 
Rickson C. Mesquita1,2 
1Institute of Physics, University of Campinas 
2Brazilian Institute of Neuroscience and Neurotechnology 
3Clinical Hospital, University of Campinas 
4Department of Emergency Medicine, Albert Einstein College of Medicine 
5School of Medical Sciences, University of Campinas

An erratum was issued for:&#160;<a href="https://www-jove-com.remotexs.ntu.edu.sg/t/61608">Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies</a>. The Authors section was updated.

Erratum: Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies

导致危重神经系统患者预后不良的大多数并发症与脑血流动力学损伤引起的继发性损伤有关。因此，监测这些患者的脑生理可能直接影响发病率和死亡率1，2，3，4，5，6，7。然而，目前还没有成熟的临床工具用于在床边对神经危重患者的脑生理进行连续实时无创监测。在潜在的候选者中，漫反射光学技术最近被提出作为填补这一空白的有前途的工具8，9，10，11。通过测量来自头皮的漫射近红外光（~650-900 nm）的缓慢变化（即数十到数百毫秒），漫反射光谱（DOS）可以测量大脑中主要发色团的浓度，例如脑氧（HbO）和脱氧血红蛋白（HbR）12，13。此外，可以通过量化光强度的快速波动（即从几μs到几毫秒）来测量脑血流量（CBF）10，14，15，16，17。当结合时，DOS和DCS还可以提供大脑代谢率的估计值（CMRO2）18，19，20。
已经探索了DOS和DCS的组合，以在几种临床前和临床情况下监测患者。例如，漫反射光学已被证明可以为危重新生儿提供相关的临床信息 21，22，23，24，包括在心脏手术期间治疗心脏缺陷 23，25，26，27，28.此外，几位作者还探索了在不同脑血管介入治疗过程中使用漫反射光学来评估脑血流动力学，例如颈动脉内膜切除术29、30、31、中风溶栓治疗32、床头操作33、34、35、心肺复苏36 和其他 37，38，39.当连续血压监测也可用时，漫反射光学器件可用于监测健康和危重受试者的大脑自动调节11，40，41，42，以及评估脑循环的临界闭合压力43。几位作者已经根据不同的金标准CBF测量18验证了DCS的CBF测量结果，而使用漫反射光学器件测量的CMRO2已被证明是神经关键监测的有用参数8，18，23，24，28，43，44，45.此外，先前的研究已经验证了光学衍生的脑血流动力学参数用于长期监测神经危重症患者8，9，10，11，包括用于预测缺氧46，47，48和缺血事件8。
漫反射光学技术在纵向测量和临床干预期间提供有价值的实时信息的可靠性在很大程度上仍未得到解决。以前将独立DOS系统的使用与侵入性脑组织氧张力监测仪进行比较，并且DOS被认为没有足够的敏感性来取代侵入性监测仪。然而，除了使用相对较小的人群外，侵入性和非侵入性监测仪的直接比较可能会被误导，因为每种技术探测包含大脑脉管系统不同部分的不同体积。尽管这些研究最终得出结论，漫反射光学器件不能替代侵入性监视器，但在这两项研究中，DOS都达到了中等到良好的精度，这对于没有侵入性监视器的情况和/或地方可能足够了。
相对于其他方法，漫反射光学器件的主要优点是它能够使用便携式仪器在床边无创（连续）同时测量血流和组织血氧合。与经颅多普勒超声（TCD）相比，DCS还有一个额外的优势:它在组织水平上测量灌注，而TCD测量大脑底部大动脉的脑血流速度。在评估近端大动脉血流和软脑膜侧支均有助于灌注的狭窄闭塞性疾病时，这种区别可能尤为重要。与其他传统成像模式（如正电子发射断层扫描（PET）和磁共振成像（MRI））相比，光学技术也具有优势。除了同时提供CBF和HbO/HbR浓度的直接测量（单独使用MRI或PET无法实现）外，光学监测还提供了明显更好的时间分辨率，例如，允许评估动态脑自动调节40，41，42和评估动态演变的血流动力学变化。此外，与PET和MRI相比，漫射光学仪器价格低廉且便于携带，鉴于中低收入国家血管疾病的高负担，这是一个关键优势。
这里提出的协议是对重症监护病房（ICU）的患者进行实时床边神经监测的环境。该方案使用混合光学设备以及临床友好的图形用户界面（GUI）和定制的光学传感器来探测患者（图1）。用于展示该协议的混合系统结合了来自独立模块的两个漫反射光谱:商用频域（FD-）DOS模块和自制DCS模块（图1A）。FD-DOS 模块49，50 由 4 个光电倍增管 （PMT） 和 32 个以四种不同波长（690、704、750 和 850 nm）发射的激光二极管组成。DCS 模块由一个发射 785 nm 的长相干激光器、16 个作为探测器的单光子计数器和一个相关器板组成。FD-DOS模块的采样频率为10 Hz，DCS模块的最大采样频率为3 Hz。为了集成FD-DOS和DCS模块，在我们的控制软件中编程了一个微控制器，以便在每个模块之间自动切换。微控制器负责打开和关闭FD-DOS和DCS激光器，以及FD-DOS探测器，以允许对每个模块进行交错测量。总的来说，所提出的系统可以每0.5至5秒收集一个FD-DOS和DCS组合样本，具体取决于信噪比（SNR）要求（收集时间越长，SNR越好）。为了将光耦合到额头，我们开发了一种3D打印的光学探头，可以为每个患者定制（图1B），源检测器的间隔在0.8到4.0厘米之间变化。此处示例中使用的标准源检测器分离对于DCS为2.5 cm，对于FD-DOS为1.5、2.0、2.5和3.0 cm。
本研究中提出的协议的主要特征是开发了一个实时界面，既可以使用友好的GUI控制硬件，又可以在不同的时间窗口下实时显示主要的大脑生理参数（图1C）。在所提出的GUI中开发的实时分析管道速度快，计算光学参数所需的时间不到50 ms（有关更多详细信息，请参阅 补充材料 ）。GUI的灵感来自神经ICU现有的临床仪器，并在将系统转换为神经ICU期间，通过临床用户的广泛反馈进行了调整。因此，实时GUI可以促进常规医院工作人员（如神经重症监护医生和护士）采用光学系统。漫反射光学作为临床研究工具的广泛采用有可能增强其监测生理上有意义的数据的能力，并最终证明漫反射光学是实时无创监测神经关键患者的良好选择。

<table><tbody><tr><td>3D Printer</td><td>Sethi3D</td><td>S2</td><td>3D-printer used to print the customizable probes</td></tr><tr><td>Arduino UNO</td><td>Arduino</td><td>UNO REV3</td><td>Microcontroller responsible to interleave the DCS and FD-DOS measurements</td></tr><tr><td>DCS Correlator</td><td>Correlator.com</td><td>Flex11-16ch</td><td>Component of the DCS module</td></tr><tr><td>DCS Dectectors IO Boards</td><td>Excelitas Technology</td><td>SPCM-AQ4C-IO</td><td>Component of the DCS module</td></tr><tr><td>DCS Detectors</td><td>Excelitas Technology</td><td>SPCM-AQ4C</td><td>Component of the DCS module</td></tr><tr><td>DCS Laser</td><td>CrystaLaser</td><td>DL785-120-SO</td><td>Component of the DCS module</td></tr><tr><td>DCS Power supply</td><td>Artesyn</td><td>UMP10T-S2A-S2A-S2A-S2A-IES-00-A</td><td>Component of the DCS module (power supply for the DCS detecto; 2, 5 and 30V)</td></tr><tr><td>FD-DOS fibers</td><td>ISS</td><td>Imagent supplies</td><td>The fibers used for FD-DOS detection and illumination are provived by ISS</td></tr><tr><td>Flexible 3D printer material</td><td>Sethi3D</td><td>NinjaFlex</td><td>Material used to print the flexible customizable probes</td></tr><tr><td>Imagent</td><td>ISS</td><td>Imagent</td><td>FD-DOS module</td></tr><tr><td>Laser safety googles</td><td>Thorlabs</td><td>LG9</td><td></td></tr><tr><td>Multi-mode fiber</td><td>Thorlabs</td><td>FT400EMT</td><td>Multi-mode fiber used for DCS illumination</td></tr><tr><td>Neutral density filter 1.0 OD</td><td>Edmund Optics</td><td>53-705</td><td>Neutral density filter for the short source detector separations</td></tr><tr><td>Single-mode optical fiber</td><td>Thorlabs</td><td>780HP</td><td>Single-mode optical fiber used for the DCS detectors</td></tr><tr><td>System battery</td><td>SMS</td><td>NET4</td><td>System battery used for transportation</td></tr></tbody></table>

real-time monitoring of neurocritical patients with diffuse optical spectroscopies

神经生理学监测是神经危重症患者治疗的一个重要目标，因为它可以预防继发性损伤并直接影响发病率和死亡率。然而，目前缺乏合适的非侵入性实时技术来连续监测床边的脑生理。弥漫光学技术已被提出作为神经危重患者床旁测量脑血流量和脑氧合的潜在工具。以前已经探索过漫反射光谱法，以监测从新生儿监测到成人脑血管介入治疗等多种临床场景的患者。然而，该技术通过在床边提供实时信息来帮助临床医生的可行性在很大程度上仍未得到解决。在这里，我们报告了漫反射光学系统的翻译，用于在重症监护期间连续实时监测脑血流量，脑氧合和脑氧代谢。该仪器的实时功能可以实现基于患者特定脑生理学的治疗策略，而不是依赖于替代指标，例如动脉血压。通过使用相对便宜和便携式的仪器在不同时间尺度上提供有关脑循环的实时信息，这种方法在低预算医院、偏远地区和开放领域（例如国防和体育）的监测中可能特别有用。

理想情况下，使用DCS模块获得的归一化自相关曲线在零延迟时间外推（使用单模光纤14时）应约为1.5，并且在较长的延迟时间下，曲线应衰减至1。曲线应该是平滑的，对于较长的源-检测器分离，它应该具有更快的衰减。 图2A显示了良好自相关的示例。 图2B 显示了不良自相关曲线的示例;在本例中，无法区分不同源检测器分离的曲线。 图2C 显示了另一个不良自相关曲线的例子，其中曲线的尾部与使用的模型不匹配。两条曲线中的问题（图2B，C）都与探针与皮肤的不良耦合有关，或者与光源直接泄漏到较短的光源-检测器分离中有关。
作为在不同时间窗口显示神经生理学以正确解释在将变化与临床行为相关联之前实时看到的变化的重要性的一个例子， 图 3 显示了来自镇静卒中患者的监测会话的时间序列，如重症监护人员在 GUI 上看到的那样。在部分监测过程中，临床医生正在抽吸患者的支气管和口腔分泌物（由 图3中的阴影区域表示）。干预引起的患者运动明显干扰光信号，导致光学参数出现非生理性尖峰;因此，很难将这些变化赋予任何生理意义。干预后不久，血流动力学参数恢复到干预前大致相同的值，与稳定患者的预期一样。这个例子说明了神经ICU中实时系统的稳定性，以及在不同时间窗口分析患者血流动力学的重要性。
为了说明混合漫反射光学装置在神经ICU中提供有意义信息的可行性，我们介绍了一名患有糖尿病，高血压和充血性心力衰竭病史的50岁女性的案例，她因左侧轻偏瘫入院，并被发现由于右侧MCA闭塞而患有缺血性中风（NIH卒中量表= 11）。图4显示了住院后第13天的平均光学衍生参数和CT扫描，同时患者管和镇静。在本次监测期间，同病灶前额的CBF和CMRO2远低于对称区域的对病参数。这一结果与灌注不足和随后由大血管缺血引起的组织坏死一致。值得注意的是，尽管同侧病变半球的CBF较低，但在两个半球均发现较高的OEF。这可能与痛苦灌注的想法一致，尽管CBF很低（但非零），但这种状态仍存在高耗氧量（高OEF），因为组织试图促进恢复8，51，52。目前，痛苦灌注在神经ICU中很难诊断。尽管需要对急性缺血性卒中患者进行更大规模的研究来评估漫反射光谱检测痛苦灌注的灵敏度，但这个例子证明了漫反射光学系统实时评估临床重要信息的潜力。
最后，我们介绍了一名 62 岁女性的纵向结果，该女性因严重的右大脑中动脉 （MCA） 动脉瘤性蛛网膜下腔出血而入住神经 ICU，Hunt & Hess 量表为 V 级（即预测结果不佳且生存可能性低）53 和 Fisher 量表的 III 级（即 血管痉挛的低至高风险）54.该患者在整个住院期间均接受监测，所有脑血流动力学参数与患者病情的临床演变一致。我们向感兴趣的读者推荐最近发表的病例报告，其中包含该病例的完整描述9.为了说明在不同日期进行测量的可行性， 图5 显示了对上述病例住院期间使用系统收集的数据的离线分析，并在文献9中详细介绍。在这里，每个生理参数的偏侧指数（LI）计算如下:
<img alt="Equation 1" src="/files/ftp_upload/61608/61608equ01v2.jpg">
其中X表示测量的变量（即CBF，OEF，CMRO2），下标表示大脑半球。使用LI，可以直接比较整个住院期间每个半球的差异。偏侧指数已被证明对不同的临床情况非常有用52，55，56，57，并且可以通过顺序测量两个半球的对称区域来使用此处提出的协议轻松评估。平均动脉压（MAP）是用神经ICU中可用的独立仪器收集的，图5也显示了它以供参考。
对 图5 的仔细分析揭示了半球损伤的两个重要时期。第一个时期发生在住院后第一天和第三天之间，其中同病ROI中的所有神经生理学参数都比对称性对病ROI增加更多。住院后第三天LI的增加可能表明可能试图恢复受影响组织的代谢平衡。在第二个时期，从住院第三天开始，LI持续下降，这与患者病情恶化一致。在这种情况下，患者在住院9天后死亡。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61608/61608fig1v2.jpg"> 图 1:为监测重症监护病房内的患者而开发的光学环境。 （A）混合漫反射光学系统结合了频域漫反射光谱（DOS）模块和漫反射相关光谱（DCS）模块。（B）本研究中提出的可定制探头默认为DCS的4个源探测器分离（0.7，1.5，2.5和3.0厘米）和DOS的4个源探测器分离（1.5，2.0，2.5和3.0厘米）。为简单起见，此处介绍的示例仅对DCS使用了2.5 cm源-探测器分离。（C）实时图形用户界面（GUI）控制漫反射光学系统，并在5分钟时间窗口（左图）和2小时时间窗口（右图）内实时显示测量的脑血流量（CBF），氧气提取分数（OEF）和脑代谢率（CMRO2）。在GUI的底部，研究人员可以按下按钮开始和停止数据收集，获取基线期进行比较并标记任何相关干预措施。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61608/61608fig01large.jpg" target="_blank">请点击此处查看此图的大图。</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/61608/61608fig2v2.jpg"> 图 2:DCS 模块的代表性自相关曲线。 （A）一个良好的自相关示例，在零延迟时间外推时约为1.5，在较长的延迟时间时衰减为1。正如预期的那样，对于较长的源-检测器分离，自相关曲线衰减得更快。（B）一个糟糕的自相关曲线的例子，其中无法区分不同源检测器分离的曲线。（C）另一个不良自相关曲线的例子，其中曲线的尾部与使用的模型不匹配。（B）和（C）中的问题与探针与皮肤的不良耦合或光从光源直接泄漏到较短的源-检测器分离中有关。研究人员可以在GUI的"相关曲线"选项卡上查看曲线。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61608/61608fig02large.jpg" target="_blank">请点击此处查看此图的大图。</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/61608/61608fig3v2.jpg"> 图 3:来自镇静卒中患者的监测会话的脑生理学，如重症监护人员在 GUI 上看到的那样。 GUI实时显示（A）短（即5分钟）和（B）长（即2小时）时间窗口的脑血流量（CBF，红色），氧气提取分数（OEF，蓝色）和大脑氧气代谢率（CMRO2，绿色）以及过去5分钟的（C）平均值。在部分监测过程中，临床医生正在抽吸患者的支气管和口腔分泌物（由B中的阴影区域表示）。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61608/61608fig03large.jpg" target="_blank">请点击此处查看此图的大图。</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/61608/61608fig04.jpg"> 图4:住院后第13天右中动脉严重缺血性中风患者的神经生理学信息。 （A）在对位和同侧病变半球用漫反射光学系统测量的脑血流量（CBF），氧提取分数（OEF），脑代谢率（CMRO2）和总血红蛋白浓度（HbT）。（B）从患者的单日测量中获得的计算机断层扫描（CT）。CT图像中的红色区域表示假定的光学敏感区域，紫色椭圆表示大致的损伤位置。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61608/61608fig04large.jpg" target="_blank">请点击此处查看此图的大图。</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/61608/61608fig05.jpg"> 图 5:一名 62 岁女性患者在高级别动脉瘤性蛛网膜下腔出血 （aSAH） 后光学衍生生理参数的偏侧性指数的时间演变。 与对位病变ROI的变化相比，同病灶感兴趣区域（ROI）的变化显示在脑血流量（CBF，红色圆圈），氧气提取分数（OEF，蓝色菱形）和脑代谢率的左轴中。平均动脉压（MAP，灰色方块）的演变是独立收集的，并显示在右轴上进行比较。每个点的误差线表示每个参数在整个监视会话中的标准偏差。有些日子，标准差太小而无法显示。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61608/61608fig05large.jpg" target="_blank">请点击此处查看此图的大图。</a>
补充材料。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61608/Manuscript_JoVE_2020_SupplementaryMaterial.docx" target="_blank">请点击这里下载此文件。</a>

Watch this Scientific Journal Video about Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies at JoVE.com

Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies

这里介绍的是一种方案，用于使用漫反射光学器件实时和在床边实时无创监测神经危重患者的脑血流动力学。具体而言，该协议使用混合漫反射光学系统来检测和显示有关脑氧合，脑血流和脑代谢的实时信息。

使用漫反射光谱实时监测神经危重症患者

Neurophysiological monitoring is an important goal in the treatment of neurocritical patients, as it may prevent secondary damage and directly impact ...

real-time-monitoring-neurocritical-patients-with-diffuse-optical

Nanyang Technological University

Research

JoVE Journal

Medicine

2.0K 次观看.  University of Campinas. 这里介绍的是一种方案，用于使用漫反射光学器件实时和在床边实时无创监测神经危重患者的脑血流动力学。具体而言，该协议使用混合漫反射光学系统来检测和显示有关脑氧合，脑血流和脑代谢的实时信息。

视频: Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies

Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence

Monitoring of the spatiotemporal characteristics of cerebral blood and tissue oxygenation is crucial for better understanding of the 
neuro-metabolic-vascular relationship. Development of new pO2 measurement modalities with simultaneous monitoring of pO2 in larger fields of view with higher 
spatial and/or temporal resolution will enable greater insight into the functioning of the normal brain and will also have significant impact on diagnosis 
and treatment of neurovascular diseases such as stroke, Alzheimer's disease, and head injury.
Optical imaging modalities have shown a great potential to provide high spatiotemporal resolution and quantitative imaging of pO2 based on hemoglobin absorption in visible and near infrared range of optical spectrum. However, multispectral measurement of cerebral blood oxygenation relies on photon migration through the highly scattering brain tissue. Estimation and modeling of tissue optical parameters, which may undergo dynamic changes during the experiment, is typically required for accurate estimation of blood oxygenation. On the other hand, estimation of the partial pressure of oxygen (pO2) based on oxygen-dependent quenching of phosphorescence should not be significantly affected by the changes in the optical parameters of the tissue and provides an absolute measure of pO2. Experimental systems that utilize oxygen-sensitive dyes have been demonstrated in in vivo studies of the perfused tissue as well as for monitoring the oxygen content in tissue cultures, showing that phosphorescence quenching is a potent technology capable of accurate oxygen imaging in the physiological pO2 range. 
Here we demonstrate with two different imaging modalities how to perform measurement of pO2 in cortical vasculature based on phosphorescence lifetime imaging. In first demonstration we present wide field of view imaging of pO2 at the cortical surface of a rat. This imaging modality has relatively simple experimental setup based on a CCD camera and a pulsed green laser. An example of monitoring the cortical spreading depression based on phosphorescence lifetime of Oxyphor R3 dye was presented. In second demonstration we present a high resolution two-photon pO2 imaging in cortical micro vasculature of a mouse. The experimental setup includes a custom built 2-photon microscope with femtosecond laser, electro-optic modulator, and photon-counting photo multiplier tube. We present an example of imaging the pO2 heterogeneity in the cortical microvasculature including capillaries, using a novel PtP-C343 dye with enhanced 2-photon excitation cross section.
Click here to view the related article <a href="https://www-jove-com.remotexs.ntu.edu.sg/Details.php?ID=1731">Synthesis and Calibration of Phosphorescent Nanoprobes for Oxygen Imaging in Biological Systems.</a>

We present an experimental procedure for measuring the partial pressure of oxygen (pO2) in cerebral vasculature based on oxygen-dependent quenching of phosphorescence. Animal preparation and imaging procedures were outlined for both large field of view CCD-based imaging of pO2 in rats and 2-photon excitation based imaging of pO2 in mice.

脑血氧测量基于磷光氧依赖淬火

Monitoring of the spatiotemporal characteristics of cerebral blood and tissue oxygenation is crucial for better understanding of the 
...

科研

神经科学

Non-invasive Optical Measurement of Cerebral Metabolism and Hemodynamics in Infants

Perinatal brain injury remains a significant cause of infant mortality and morbidity, but there is not yet an effective bedside tool that can accurately screen for brain injury, monitor injury evolution, or assess response to therapy. The energy used by neurons is derived largely from tissue oxidative metabolism, and neural hyperactivity and cell death are reflected by corresponding changes in cerebral oxygen metabolism (CMRO2). Thus, measures of CMRO2 are reflective of neuronal viability and provide critical diagnostic information, making CMRO2 an ideal target for bedside measurement of brain health.
Brain-imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) yield measures of cerebral glucose and oxygen metabolism, but these techniques require the administration of radionucleotides, so they are used in only the most acute cases.
Continuous-wave near-infrared spectroscopy (CWNIRS) provides non-invasive and non-ionizing radiation measures of hemoglobin oxygen saturation (SO2) as a surrogate for cerebral oxygen consumption. However, SO2 is less than ideal as a surrogate for cerebral oxygen metabolism as it is influenced by both oxygen delivery and consumption. Furthermore, measurements of SO2 are not sensitive enough to detect brain injury hours after the insult 1,2, because oxygen consumption and delivery reach equilibrium after acute transients 3. We investigated the possibility of using more sophisticated NIRS optical methods to quantify cerebral oxygen metabolism at the bedside in healthy and brain-injured newborns. More specifically, we combined the frequency-domain NIRS (FDNIRS) measure of SO2 with the diffuse correlation spectroscopy (DCS) measure of blood flow index (CBFi) to yield an index of CMRO2 (CMRO2i) 4,5.
With the combined FDNIRS/DCS system we are able to quantify cerebral metabolism and hemodynamics. This represents an improvement over CWNIRS for detecting brain health, brain development, and response to therapy in neonates. Moreover, this method adheres to all neonatal intensive care unit (NICU) policies on infection control and institutional policies on laser safety. Future work will seek to integrate the two instruments to reduce acquisition time at the bedside and to implement real-time feedback on data quality to reduce the rate of data rejection.

We combined frequency-domain near-infrared spectroscopy measures of cerebral hemoglobin oxygenation with diffuse correlation spectroscopy measures of cerebral blood flow index to estimate an index of oxygen metabolism. We tested the utility of this measure as a bedside screening tool to evaluate the health and development of the newborn brain.

婴幼儿的脑代谢和血流动力学的非侵入式光学测量

Perinatal brain injury remains a significant cause of infant mortality  and morbidity, but there is not yet an effective bedside tool that can  accurately ...

医学

Simultaneous Evaluation of Cerebral Hemodynamics and Light Scattering Properties of the In Vivo Rat Brain Using Multispectral Diffuse Reflectance Imaging

The simultaneous evaluation of cerebral hemodynamics and the light scattering properties of in vivo rat brain tissue is demonstrated using a conventional multispectral diffuse reflectance imaging system. This system is constructed from a broadband white light source, a motorized filter wheel with a set of narrowband interference filters, a light guide, a collecting lens, a video zoom lens, and a monochromatic charged-coupled device (CCD) camera. An ellipsoidal cranial window is made in the skull bone of a rat under isoflurane anesthesia to capture in vivo multispectral diffuse reflectance images of the cortical surface. Regulation of the fraction of inspired oxygen using a gas mixture device enables the induction of different respiratory states such as normoxia, hyperoxia, and anoxia. A Monte Carlo simulation-based multiple regression analysis for the measured multispectral diffuse reflectance images at nine wavelengths (500, 520, 540, 560, 570, 580, 600, 730, and 760 nm) is then performed to visualize the two-dimensional maps of hemodynamics and the light scattering properties of the in vivo rat brain.

Simultaneous Evaluation of Cerebral Hemodynamics and Light Scattering Properties of the In Vivo Rat Brain Using Multispectral Diffuse Reflectance Imaging

The simultaneous evaluation of cerebral hemodynamics and the light scattering properties of in vivo rat brain tissue is demonstrated using a conventional multispectral diffuse reflectance imaging system.

脑血流动力学和的光散射特性的同步评估<em&gt;体内</em&gt;大鼠脑使用多光谱漫反射成像

The simultaneous evaluation of cerebral hemodynamics and the light scattering properties of in vivo rat brain tissue is demonstrated using a conventional ...

Cerebral Blood Flow-Based Resting State Functional Connectivity of the Human Brain using Optical Diffuse Correlation Spectroscopy

To obtain a comprehensive understanding of the human brain, utilization of cerebral blood flow (CBF) as a source of contrast is desired because it is a key hemodynamic parameter related to cerebral oxygen supply. Resting state low frequency fluctuations based on oxygenation contrast have been shown to provide correlations between functionally connected regions. The presented protocol uses optical diffuse correlation spectroscopy (DCS) to assess blood flow-based resting state functional connectivity (RSFC) in the human brain. Results of CBF-based RSFC in human frontal cortex indicate that intra-regional RSFC is significantly higher in the left and right cortices compared to inter-regional RSFC in both cortices. This protocol should be of interest to researchers who employ multi-modal imaging techniques to study human brain function, especially in the pediatric population.

This protocol demonstrates how to measure resting state functional connectivity in the human prefrontal cortex using a custom-made diffuse correlation spectroscopy instrument. The report also discuss practical aspects of the experiment as well as detailed steps for analyzing the data.

使用光学漫反射相关光谱，基于脑血流的休息状态功能连接

To obtain a comprehensive understanding of the human brain, utilization of cerebral blood flow (CBF) as a source of contrast is desired because it is a ...

生物工程

A Model to Simulate Clinically Relevant Hypoxia in Humans

In case of apnea, arterial partial pressure of oxygen (pO2) decreases, while partial pressure of carbon dioxide (pCO2) increases. To avoid damage to hypoxia sensitive organs such as the brain, compensatory circulatory mechanisms help to maintain an adequate oxygen supply. This is mainly achieved by increased cerebral blood flow. Intermittent hypoxia is a commonly seen phenomenon in patients with obstructive sleep apnea. Acute airway obstruction can also result in hypoxia and hypercapnia. Until now, no adequate model has been established to simulate these dynamics in humans. Previous investigations focusing on human hypoxia used inhaled hypoxic gas mixtures. However, the resulting hypoxia was combined with hyperventilation and is therefore more representative of high altitude environments than of apnea. Furthermore, the transferability of previously performed animal experiments to humans is limited and the pathophysiological background of apnea induced physiological changes is poorly understood. In this study, healthy human apneic divers were utilized to mimic clinically relevant hypoxia and hypercapnia during apnea. Additionally, pulse-oximetry and Near Infrared Spectroscopy (NIRS) were used to evaluate changes in cerebral and peripheral oxygen saturation before, during, and after apnea.

Hypoxia simulation in humans has usually been performed by inhaling hypoxic gas mixtures. For this study, apneic divers were used to simulate dynamic hypoxia in humans. Additionally, physiological changes in desaturation and re-saturation kinetics were evaluated with non-invasive tools such as Near-Infrared-Spectroscopy (NIRS) and peripheral oxygenation saturation (SpO2).

一个模型来模拟人类临床相关性缺氧

In case of apnea, arterial partial pressure of oxygen (pO2) decreases, while partial pressure of carbon dioxide (pCO2) increases. To avoid damage to ...

Standardized Hemorrhagic Shock Induction Guided by Cerebral Oximetry and Extended Hemodynamic Monitoring in Pigs

Hemorrhagic shock ranks among the main reasons for severe injury-related death. The loss of circulatory volume and oxygen carriers can lead to an insufficient oxygen supply and irreversible organ failure. The brain exerts only limited compensation capacities and is particularly at high risk of severe hypoxic damage.This article demonstrates the reproducible induction of life-threatening hemorrhagic shock in a porcine model by means of calculated blood withdrawal. We titrate shock induction guided by near-infrared spectroscopy&#160;and extended hemodynamic monitoring to display systemic circulatory failure, as well as cerebral microcirculatory oxygen depletion. In comparison to similar models that primarily focus on predefined removal volumes for shock induction, this approach highlights a titration by means of the resulting failure of macro- and microcirculation.

Hemorrhagic shock is a severe complication in seriously injured patients, which leads to life-threatening oxygen undersupply. We present a standardized method to induce hemorrhagic shock via blood withdrawal in pigs that is guided by hemodynamics and microcirculatory cerebral oxygenation.

由脑氧测量和猪期扩展血液动力学监测指导的标准化出血性休克诱导

Hemorrhagic shock ranks among the main reasons for severe injury-related death. The loss of circulatory volume and oxygen carriers can lead to an ...

How to Administer Near-Infrared Spectroscopy in Critically ill Neonates, Infants, and Children

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated hemoglobin molecules. A probe placed on the skin emits light that is absorbed, scattered, and reflected by the underlying tissue. Detectors in the probe sense the amount of reflected light: this reflects the organ-specific ratio of oxygen supply and consumption - independent of pulsatile flow. Modern devices enable the simultaneous monitoring at different body sites. A rise or dip in the rSO2 curve visualizes changes in oxygen supply or demand before vital signs indicate them. The evolution of rSO2 values in relation to the starting point is more important for interpretation than are absolute values.
A routine clinical application of NIRS is the surveillance of somatic and cerebral oxygenation during and after cardiac surgery. It is also administered in preterm infants at risk for necrotizing enterocolitis, newborns with hypoxic ischemic encephalopathy and a potential risk of impaired tissue oxygenation. In the future, NIRS could be increasingly used in multimodal neuromonitoring, or applied to monitor patients with other conditions (e.g., after resuscitation or traumatic brain injury).

This protocol is designed to assist clinicians to measure regional tissue oxygenation at different body sites in infants and children. It can be used in situations where tissue oxygenation is potentially compromised, particularly during cardiopulmonary bypass, when using non-pulsatile cardiac-assist devices, and in critically ill neonates, infants and children.

如何管理危重新生儿、婴儿和儿童近红外光谱

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated ...

Simultaneous Data Collection of fMRI and fNIRS Measurements Using a Whole-Head Optode Array and Short-Distance Channels

Functional near-infrared spectroscopy (fNIRS) is a portable neuroimaging methodology, more robust to motion and more cost-effective than functional magnetic resonance imaging (fMRI), which makes it highly suitable for conducting naturalistic studies of brain function and for use with developmental and clinical populations. Both fNIRS and fMRI methodologies detect changes in cerebral blood oxygenation during functional brain activation, and prior studies have shown high spatial and temporal correspondence between the two signals. There is, however, no quantitative comparison of the two signals collected simultaneously from the same subjects with whole-head fNIRS coverage. This comparison is necessary to comprehensively validate area-level activations and functional connectivity against the fMRI gold standard, which in turn has the potential to facilitate comparisons of the two signals across the lifespan. We address this gap by describing a protocol for simultaneous data collection of fMRI&#160;and fNIRS signals that: i) provides whole-head fNIRS coverage; ii) includes short-distance measurements for regression of the non-cortical, systemic physiological signal; and iii) implements two different methods for optode-to-scalp co-registration of fNIRS measurements. fMRI and fNIRS data from three subjects are presented, and recommendations for adapting the protocol to test developmental and clinical populations are discussed. The current setup with adults allows scanning sessions for an average of approximately 40 min, which includes both functional and structural scans. The protocol outlines the steps required to adapt the fNIRS equipment for use in the magnetic resonance (MR) environment, provides recommendations for both data recording and optode-to-scalp co-registration, and discusses potential modifications of the protocol to fit the specifics of the available MR-safe fNIRS system. Representative subject-specific responses from a flashing-checkerboard task illustrate the feasibility of the protocol to measure whole-head fNIRS signals in the MR environment. This protocol will be particularly relevant for researchers interested in validating fNIRS signals against fMRI across the lifespan.

We present a method for simultaneously collecting fMRI and fNIRS signals from the same subjects with whole-head fNIRS coverage. The protocol has been tested with three young adults and can be adapted for data collection for developmental studies and clinical populations.

使用全头光电阵列和短距离通道同时收集 fMRI 和 fNIRS 测量数据

Functional near-infrared spectroscopy (fNIRS) is a portable neuroimaging methodology, more robust to motion and more cost-effective than functional ...

Non-Invasive Monitoring of Microvascular Oxygenation and Reactive Hyperemia using Hybrid, Near-Infrared Diffuse Optical Spectroscopy for Critical Care

The detection of levels of impairment in microvascular oxygen consumption and reactive hyperemia is vital in critical care. However, there are no practical means for a robust and quantitative evaluation. This paper describes a protocol to evaluate these impairments using a hybrid near-infrared diffuse optical device. The device contains modules for near-infrared time-resolved and diffuse correlation spectroscopies and pulse-oximetry. These modules allow the non-invasive, continuous, and real-time measurement of the absolute, microvascular blood/tissue oxygen saturation (StO2) and the blood flow index (BFI) along with the peripheral arterial oxygen saturation (SpO2). This device uses an integrated, computer-controlled tourniquet system to execute a standardized protocol with optical data acquisition from the brachioradialis muscle. The standardized vascular occlusion test (VOT) takes care of the variations in the occlusion duration and pressure reported in the literature, while the automation minimizes inter-operator differences. The protocol we describe focuses on a 3-min occlusion period but the details described in this paper can readily be adapted to other durations and cuff pressures, as well as other muscles. The inclusion of an extended baseline and post-occlusion recovery period measurement allows the quantification of the baseline values for all the parameters and the blood/tissue deoxygenation rate that corresponds to the metabolic rate of oxygen consumption. Once the cuff is released, we characterize the tissue reoxygenation rate, magnitude, and duration of the hyperemic response in BFI and StO2. These latter parameters correspond to the quantification of the reactive hyperemia, which provides information about the endothelial function. Furthermore, the above-mentioned measurements of the absolute concentration of oxygenated and deoxygenated hemoglobin, BFI, the derived metabolic rate of oxygen consumption, StO2, and SpO2 provide a yet-to-be-explored rich data set that can exhibit disease severity, personalized therapeutics, and management interventions.

We describe a protocol to non-invasively and continuously measure absolute microvascular blood flow index and blood oxygen saturation using a multi-modal device based on near-infrared diffuse optics. We then evaluate the metabolic rate of oxygen consumption and reactive hyperemia utilizing a vascular occlusion test.

使用混合近红外漫反射光谱对重症监护的微血管氧合和反应性充血进行无创监测

The detection of levels of impairment in microvascular oxygen consumption and reactive hyperemia is vital in critical care. However, there are no ...

Diffuse Correlation Spectroscopy to Assess Cerebral Blood Flow in a Mouse Model

Source: Brothers, R. O., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/61504">Systems Analysis of the Neuroinflammatory and Hemodynamic Response to Traumatic Brain Injury.</a> J. Vis. Exp. (2022)
In this video, we demonstrate the diffuse correlation spectroscopy technique to measure cerebral blood flow in a mouse model of mild traumatic brain injury.

弥散相关光谱评估小鼠模型中的脑血流

Source: Brothers, R. O., et al. Systems Analysis of the Neuroinflammatory and Hemodynamic Response to Traumatic Brain Injury. J. Vis. Exp. (2022)
In this ...