Abstract
Schuster's scattering theory was applied to a blood model and a theoretical formula of the blood optical attenuation change for unit blood thickness change was obtained. Several factors affecting the optical attenuation of blood were investigated in vitro and the blood optical attenuation change for unit blood thickness change was measured in vitro for 600-1, 300nm. With an increase of the size of the transmittance window, and with an increase of the thickness of the blood, the blood optical attenuation for unit blood thickness change decreased to a certain limit. In the condition of this limit, it was able to select a suitable value for the scattering constant for each hematocrit so that the theoretical blood optical attenuance agreed with the measured value. As hematocrit increased, in low hematocrit range, the scattering constant increased almost proportionally to hematocrit, and after certain hematocrit value, the scattering constant decreased. These theory and experimental observations can be used to refine and improve the technology of pulse oximetry.
