Monitoring of brain oxygen status using near-infrared spectroscopy

尽管细胞色素氧合酶(Cyt.(公牛)经近红外光谱分析(NIRS)可作为细胞内缺氧的有用指标。奥克斯。信号只占总变化的一小部分，因此很容易受到伪影的影响。最近有报道称，Cyt。奥克斯。近红外光谱测量的信号高度依赖于红细胞压积。我们开发了一种测量细胞色素T的新方法。奥克斯。在大脑中使用我们的新算法。在这项研究中，我们使用NIRS设备和我们的算法来检查当血液稀释发生变化时细胞色素和Hb信号之间可能存在的串扰。在另一项实验中，分别在25℃和15℃下诱导深低温停循环60min，以评价细胞色素T氧化还原行为之间的关系。奥克斯。深低温停循环期间及术后神经学预后。犬体外循环(CPB)后，用氰化钠解离Hb中的细胞色素。然后通过血液稀释将红细胞压积从35%降至5%。在本研究中，NIRS装置计算的Hb浓度与血液稀释过程中的红细胞压积呈显著正相关。但红细胞压积与细胞比容之间无相关性。奥克斯。信号，这表明细胞。奥克斯。用我们最近开发的算法计算的信号受红细胞压积的影响不大。此外，细胞色素T的氧化还原行为之间有很好的相关性。奥克斯。在深低温停循环期间的脑组织和术后脑损伤。总而言之，Cyt.奥克斯。近红外光谱测量的信号取决于所采用的算法。因此，只要采用一种准确的算法，就可以进行细胞周期测试。奥克斯。即使在红细胞压积和/或低温的各种变化下，近红外光谱测量的信号也应该为我们提供重要的信息。

Although the signal obtained for cytochrome oxydase (cyt. ox.) by near-infrared spectroscopy (NIRS) should be a useful indicator of intracellular hypoxia, the cyt. ox. signal represents a small component of the total change, and is therefore vulnerable to artifact. Recently it has been reported that cyt. ox. signal measured by NIRS is highly dependent on hematocrit. We have developed a new approach to the measurement of cyt. ox. in the brain involving the use of our new algorithm. In this study, we used NIRS device with our algorithm to examine possible cross-talk between the cytochrome and Hb signals while a change was occurring in the hemodilution. In another experiments, deep hypothermic circulatory arrest (DHCA) was induced for 60 min under 25℃ or 15℃ and evaluated the relationship between the redox behavior of cyt. ox. during DHCA and postoperative neurological prognosis. After institution of cardiopulmonary bypass (CPB), dogs received sodium cyanide to uncouple cytochrome from Hb. The hematocrit was then decreased from 35 to 5% by hemodilution. In this study, the Hb concentration calculated by NIRS device showed a strong positive correlation with hematocrit values in the blood during hemodilution. However, there was no correlation between the hematocrit and the cyt. ox. signal, which indicate that the cyt. ox. signal calculated using our recently developed algorithm was not much influenced by hematocrit. Furthermore, there was a good correlation between the redox behavior of cyt. ox. in the brain during DHCA and postoperative brain injury. In conclusion, the cyt. ox. signal measured by NIRS is dependent on the algorithm employed. Therefore, provided an accurate algorithm is employed the cyt. ox. signal measured by NIRS should provide us with important information even under various changes in hematocrit and/or hypothermia.