Noncontact tissue oxygenation measurement using near-infrared spectroscopy

Abstract

Here, we present a noncontact tissue oxygenation monitor that uses near-infrared spectroscopy (NIRS). We examined changes in sensitivity of tissue oxygenation measurement due to changes in the distance between the optical probe and the skin surface using a Monte Carlo simulation and in vivo tests. We also examined the effects of skin and fat layer thickness. Photon migration was analyzed in a model consisting of the skin, fat, and muscle layers. The relationship between measurement sensitivity and the probe-tissue distance was obtained from the results of the simulation and was used for correction of measurements. A noncontact tissue oximeter was used to perform the in vivo tests and measure oxygen consumption of the forearm muscle. The value of corrected oxygen consumption was 0.12±0.03ml∕(100gmin), which is consistent with previously reported values obtained using contact NIRS measurement and magnetic resonance spectroscopy. Quantitative measurement of oxygenation using noncontact NIRS is potentially useful for novel applications such as quantification of inflammation.