Near Infrared Spectroscopy (NIRS)
Near infrared spectroscopy (NIRS) uses specific, calibrated wavelengths of near infrared light to noninvasively illuminate the tissue below a sensor placed on the skin. These wavelengths of light scatter in the tissue and are absorbed differently dependent on the amount of oxygen attached to hemoglobin in the microcirculation. Light that is not absorbed is returned as an optical signal and analyzed to produce a ratio of oxygenated hemoglobin to total hemoglobin, expressed as percent StO2.
In practice, near infrared light penetrates tissues such as skin, bone, muscle and soft tissue where it is absorbed by chromophores (hemoglobin and myoglobin) that have absorption wavelengths in the near infrared region (approximately 700-1000nm). These chromophores vary in their absorbance of NIRS light, depending on changes in oxygenation. Complex algorithms built into the InSpectra™ StO2 Tissue Oxygenation Monitor differentiate the absorbance contribution of the individual chromophores.
Hutchinson Technology's InSpectra StO2 Tissue Oxygenation Monitor uniquely measures hemoglobin oxygen saturation in the microcirculation, where oxygen is exchanged with tissue.