US 5,690,104 AGranted

Apparatus and method for measuring oxygen saturation in blood and apparatus and method for measuring concentration of light-absorbing materials in blood

AssigneeNihon Kohden Corporation

InventorsMichio Kanemoto, Naoki Kobayashi, Takuo Aoyagi

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Abstract

Intensities of light of two different wavelengths transmitted through a tissue of a living body are measured during a first time period. A data processor determines a first regression line using logarithmically processed data corresponding to the light intensities measured during the first time period. An operator injects a dye into the living body and measurements of intensities of light at the two different wavelengths are made during a later time period. The data processor determines a second regression line using logarithmically processed data corresponding to the light intensities measured during the later time period. The data processor finds an intersection of the two regression lines and uses the intersection to determine a bloodless level point. The processor then forms a dye dilution curve incorporating the bloodless level point data.

Claims4

Dependent claims

An apparatus for measuring the concentration of light-absorbing materials in blood comprising:

light generating means for projecting light beams of two different wavelengths to a living body;
photo sensing means for receiving light beams transmitted through the living body and for converting received light beams into electrical signals;
regression line computing means for forming at least two regression lines for at least two periods, using values, at a plurality of time points, of said electrical signals output from said photo sensing means, wherein coordinates of points on said at least two regression lines refer to an ordinate and an abscissa which represent the magnitudes of said electrical signals;
bloodless level computing means for computing a bloodless level of said received light beams using intersections of extensions of said at least two regression lines;
absorbance calculating means for computing a blood absorbance of said received light beams of different wavelengths by using said bloodless level computed by said bloodless level computing means and said electrical signals;
and
concentration computing means for computing the concentration of light absorbing materials in blood using said absorbance computed by said absorbance calculating means.

4 more elements

Dependencies are inferred from the claim text.