Two-wavelength oximetry of tissue microcirculation based on sidestream dark-field imaging

Monitoring oxygen saturation ([Formula: see text]) in microcirculation is effective for understanding disease dynamics. We have developed an [Formula: see text] estimation method, sidestream dark-field (SDF) oximetry, based on SDF imaging. SDF imaging is a noninvasive and clinically applicable technique to observe microcirculation. We report the first in vivo experiment observing the changes in [Formula: see text] of microcirculation using SDF oximetry. First, heat from the light-emitting diodes used for the SDF imaging might affect hemodynamics in microcirculation, hence, we performed an experiment to evaluate the influence of that on the SDF oximetry. The result suggested that SDF oximetry had enough stability for long-term experiments. Then, to evaluate the sensitivity of SDF oximetry to alterations in the hemodynamics of the microcirculation, we observed the time-lapsed [Formula: see text] changes in the dermis microcirculation of rats under hypoxic stimulation. We confirmed that the [Formula: see text] estimated by SDF oximetry was in accordance with changes in the fraction of inspired oxygen ([Formula: see text]). Thus, SDF oximetry is considered to be able to observe [Formula: see text] changes that occur in accordance with alteration of the microcirculation.