Development and application of a method for non-invasive measurements of local oxygen consumption by near-infrared spectroscopy

本文介绍了一种利用近红外光谱技术（NIRS）无创连续测量血氧饱和度（StO_2）和血红蛋白绝对体积（Hbvol）的方法。一个仪器（PSA-Ⅲ N）已被设计用于这种方法的使用，使组织表面可以用三种波长的红外光连续照射，并从组织的散射光可以在组织表面上的一个点上测量一定距离远离照射部位。利用朗伯-比尔定律推导出的公式，可以从测量的吸光度无创地确定组织中的St O_2和Hb vol的绝对值。用PSA-Ⅲ N测定运动过程中股四头肌的St O_2、Hb vol和Vt O_2。运动过程中St O_2和Vt O_2的变化在中等负荷以下随负荷增加而增加，在较大负荷时趋于平稳。在低气压条件下的类似负荷运动实验中，St O_2和Vt O_2的反应明显受到抑制，运动后Vt O_2的恢复延迟。局部肌肉的反应一般与全身耗氧量的变化相对应，由此我们得出结论：PSA-Ⅲ N仪器提供了一种测量组织氧状况的手段，在基础医学和临床医学上可能是非常有用的。

We have developed a method of non-invasive and continuous measurements of oxygen saturation (St O_2) and absolute volumes of hemoglobin (Hb vol) using near-infrated spectroscopy (NIRS). An instrument (PSA-III N) has been designed for the use of this method so that the tissue surface can be irradiated successively with infrared light of three wavelengths, and the scattered light from the tissue can be measured on the tissue Surface at a point a certain distance away from the irradiated site. St O_2 and absolute values of Hb vol in tissues can be non-invasively determined from the measured absorbance using equations derived from Lambert-beer's law. Oxygen consumption in the tissue (Vt O_2) can then be determined based on the output of PSA-III N.St O_2, Hb vol and Vt O_2 of quadriceps muscles of thigh were measured during exercise using PSA-III N.Changes in St O_2 and Vt O_2 during exercise increased with the load up to a moderate load, while they leveled off at heavier loads. In similar experiments of loaded exercise under conditions of low atmospheric pressure, responses of St O_2 and Vt O_2 were clearly suppressed, and the recovery of Vt O_2 after exercise was delayd. Responses of local muscles generally corresponded to changes in oxygen consumption of the entire body.From these results, we concluded that the instrument (PSA-III N) offers a means of measuring oxygen conditions of tissues, and may be very useful in basic and clinical medicine.