In this paper, we present a series of measurements made with a portable frequency-domain near-infrared tissue spectrometer (OMNIA). This is the first application of the OMNIA in a clinical setting. All of the measurements presented here were taken in vivo, most were on human subjects. We report the results of three experiments: (1) A simple ischemia/plethysmography experiment, which indicates ability of the instrument to noninvasively, continuously monitor the hemoglobin saturation of a limb. (2) A survey of hemoglobin saturation in patients with peripheral vascular disease. (3) An animal experiment to demonstrate the correlation of our instrument readings with results from established techniques for measuring hemoglobin saturation. We measured the absorption and reduced scattering coefficients of the tissue at two wavelengths (715 nm and 850 nm). From the absorption coefficients, we calculated the concentrations of oxygenated and deoxygenated hemoglobin ([HbO2] and [Hb]), which immediately yield the hemoglobin saturation (Y) and the total blood volume (T) in the tissue. Our preliminary results indicate some of the potential of the instrument and the areas for future improvement of it.
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