ABSTRACT
Tissue oximeters using near-infrared spectroscopy (NIRS) have been applied for evaluating the viability of cerebral tissue in surgery and for monitoring muscle oxygenation in sport medicine and rehabilitation. It outlined the principle of oximetry, its medical device development, and its applications. However, ear oximeters did not have sufficient measurement stability for continuous monitoring of oxygen saturation because the calibration procedures were based on many assumptions. In 1974, Aoyagi et al. presented a new idea called pulse oximetry, which utilizes the pulsation of arteries. Pulse oximetry is now used in clinical medicine throughout the world. In near-infrared spectroscopy, tissue oxygenation is determined by analyzing the reflected or transmitted light intensity. In CWS, scattered light is detected at a distance from the light source, and tissue oxygenation is determined from the change in absorption coefficients of a tissue using the basic equations of conventional oximetry. Oximetry is the colorimetric measurement of the degree of oxygen saturation.
