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

我们开发了一种使用近红外光谱（NIRS）的无创连续测量氧饱和度（St O_2）和血红蛋白绝对体积（Hb vol）的方法。为此设计了一种仪器（PSA-III N），用三种波长的红外光连续照射组织表面，并在距离被照射部位一定距离的组织表面上测量组织散射光。利用兰伯特-比尔定律推导出的方程，可以无创地从测量的吸光度中确定组织中的St O_2和Hb vol的绝对值。利用PSA-III n . n .的输出量可以测定组织耗氧量（Vt O_2），在运动过程中用PSA-III n .测量大腿股四头肌的Hb vol和Vt O_2，运动过程中St O_2和Vt O_2的变化随着负荷的增加而增加，而在较重的负荷下则趋于平稳。在类似的低气压条件下负荷运动实验中，St O_2和Vt O_2的响应明显受到抑制，运动后Vt O_2的恢复有所延迟。局部肌肉的反应通常与全身耗氧量的变化相对应。从这些结果，我们得出结论，该仪器（PSA-III N）提供了一种测量组织氧条件的手段，可能在基础和临床医学中非常有用。

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.