Liver function testing apparatus

Abstract

In a liver function testing apparatus, light sources (11, 12) expose vital tissue (15) to first light of a wavelength capable of being absorbed by a specific dye dosed into blood of the vital tissue to be taken in and removed by the liver, and second light of a wavelength not capable of being absorbed by the specific dye. Optical pulses obtained from the vital tissue are received by a light receiving element (13), the output of which is sampled by an A/D converter (30) for converting the analog output signals into digital signals. A biocalibration is preformed on the basis of variable components in the blood. For this purpose a CPU (34) determines coefficients for first and second regression line expressions before and after an injection of the specific dye. The coefficients are provided by first and second photoelectric conversion signals. A value correlated with a specific dye concentration in the blood is processed on the basis of sampling signals during a prescribed period after injecton of the specific dye to provide the coefficients for the regression line expressions. The obtained coefficients are processed by using the method of least squares for obtaining a blood plasma disappearance rate of the specific dye and a retention rate for a prescribed length of time following an injection.