Development of a noninvasive monitoring instrument for serum Indocyanine Green dye concentration

A noninvasive instrument to monitor serum Indocyanine Green (ICG) dye removal by the liver, which uses a new analytical method and an optical sensor, has been developed. The principal elements of the optical sensor are two light-emitting diodes at 810- and 940-nm wavelengths and a photodiode to detect light transmittance through the fingertip. A new analytical calibration method to compensate for the effect of blood volume variations has been developed. Thereby, only ICG concentration could be extracted. In addition, through clinical evaluation of hepatic disease patients, the correlation between serum ICG disappearance rates by this method and the conventional blood sampling method has been confirmed as evidence of its usefulness.