Pulse oximeter with probe difference compensation

Abstract

A pulse oximeter of the present invention is to provide a greatly simplified in construction and a simplified procedure for performing arithmetic operations. The pulse oximeter of the present invention comprises a light-emitting diode which is provided in a probe and that illuminates a living tissue with red light of a reference wavelength, a light-emitting diode that illuminates the living tissue with infrared light, a light-receiving device that detects the optical output that remains after the living tissue absorbs the two wavelengths of red light and infrared light that have been issued from the light-emitting diodes, detectors which, on the basis of the detection output of the light-receiving device, compute the pulsating components of absorbances for the two wavelengths, a multiplier that multiplies the value from the detector by an appropriate coefficient in order to adjust that the value detected when using red light of a wavelength offset from the reference wavelength is gain-adjusted for correction to a known value obtained when using red light of the reference wavelength, a computing means that computes an absorbance ratio using both the value after gain adjustment that is delivered from the multiplier and the value from the detector, and a computing means that computes the oxygen saturation of arterial blood using the computed value. Information on the coefficient is provided by resistor which is built in the probe.