新生児脳内の近赤外領域拡散スペクトルの研究

为了预防和处理新生儿缺氧缺血性脑病，正确、实时地测定脑组织中Hb的氧合状态、血氧饱和度(SbO2)、细胞色素C氧化酶的氧化还原状态和脑血容量是非常重要的。利用多点连续近红外光谱(CNIRS)方法，我们将平坦和非线性扩散光谱转换为非平坦光谱和线性光谱，并对各个光谱之间不同的光程长度进行了归一化处理。通过计算特定生物材料光路中各发色团组分的摩尔比，可在活体条件下测定脑组织中氧合血红蛋白、脱氧血红蛋白、SbO2和细胞色素C氧化酶的氧化还原状态。将头皮测量结果与直接测量结果进行比较，间接和直接测量结果吻合较好。对足月儿和早产儿的血红蛋白氧合和细胞色素C氧化酶的氧化还原状态进行了研究。足月儿SBO_2为60~70%，早产儿为50~75%。窒息新生儿总Hb和SBO2明显高于正常新生儿。在呼吸暂停期间，SBO2后细胞色素c氧化酶的氧化态减少，提示床边连续监测脑血红蛋白氧合和细胞色素c氧化酶的氧化还原状态可能成为评价脑血流动力学和能量状态的有用指标。

In order to prevent and manage hypoxic-ischemic encephalopathy in neonates, it is very important to determine the oxygenated state of Hb, oxygen saturation (SbO_2), the redox state of cytochrome c oxidase, and cerebral blood volume in the cerebral tissue correctly and at real time. Using continuous near infrared spectroscopy (cNIRS) with multi-point method, we converted both the flattened and nonlinear diffusion spectra to both the non flattened and linear spectra and normalized different light pathlengths between respective spectra. Upon calculation of molar ratios of individual chromophore components existing in the light path of a given biological material, it was feasible to determine oxyhemoglobin, deoxyhemoglobin, SbO_2, and the redox state of cytochrome c oxidase in the cerebral tissue in vivo.Comparing the results measured on the scalp with the result measured directly on the dura of the piglets, a close agreement was proven to exist between the results of indirect and direct measurements. We studied the oxygenation of hemoglobin and the redox state of cytochrome c oxidase in full term and premature infants. SbO_2 was 60-70% in normal term infants and 50-75% in premature infants. The asphyxiated infant had a significantly higher total Hb and SbO_2 than the normal neonates controls. In apneic spell, the oxidized form of cytochrome c oxidase decreased after SbO_2.Thus, this study demonstrates that continuous bedside monitoring of cerebral hemoglobin oxygenation and the redox state of cytochrome c oxidase might become a useful index for evaluating cerebral hemodynamics and energy state.