Patent ID: 6397093
Filing Date: 2002-05-28
Classification: A61B

Abstract:
A non-invasive method for measuring the relative concentration or percentage of carboxyhemoglobin in a subject's blood, said method comprising the steps of:a. directing light at a first pair of two different wavelengths through tissue of the subject in which pulsatile flow of blood through an arterial blood vessel can be detected; b. directing light at a second pair of two different wavelengths through tissue of the subject in which pulsatile flow of blood through an arterial blood vessel can be detected, at least one of the wavelengths of the second pair differing from the wavelengths of the first pair; c. simultaneously determining the pulsatile changes in absorbance of the first and second pairs of wavelengths of light by the subject's arterial blood; d. determining the ratio of change in absorbance of each of the first and second pairs of wavelengths, and; e. calculating the concentration of carboxyhemoglobin in said subject's blood by comparing the results of a formula employing the ratios determined in step d as independent variables to the results of the same formula in subjects with known carboxyhemoglobin levels.