Noninvasive Fast Analysis of Hemoglobin Levels in Blood Using a Fiber Optic Spectrophotometer

We have developed a method for online monitoring of blood levels of oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, methemoglobin, and sulfhemoglobin using the diffuse reflectance spectrum of the mucosa of the lip or tongue of the patient, measured at a distance from the area to which the exciting radiation is delivered. The method is based on simple analytical expressions approximating the dependence of the diffuse light signals on the absorption coefficient, the transport scattering coefficient, the scattering anisotropy factor, and the refractive index of the mucosa. We have estimated the uncertainties in the method when there is a priori uncertainty in the optical parameters of the tissue. We have analyzed the experimental diffuse reflectance spectra of the mucosa of the lip, demonstrating that the hemoglobin composition of the studied tissue corresponds to normal physiological data.