Method and apparatus for noninvasive monitoring of arterial blood oxygen saturation
First Claim
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1. A blood oxygen saturation monitoring system comprising:
- a first source of electromagnetic radiation at a first wavelength;
a second source of electromagnetic radiation at a second wavelength;
means for positioning said first and second sources of electromagnetic radiation to illuminate a sample of blood;
sensing means for receiving electromagnetic radiation reflected by said sample of blood, said reflected electromagnetic radiation comprising an AC component and a DC component, said sensing means producing an output signal corresponding only to the AC components of the reflected portions of said first and second electromagnetic radiation;
means for producing a quotient of said AC voltage components; and
means for calculating blood oxygen saturation by correlating said quotient of said AC voltage components with an oxygen saturation reference curve, said reference curve being uniquely representative of the blood oxygen saturation characteristics of a particular individual.
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Abstract
A noninvasive optical oximeter for measuring oxygen saturation of arterial blood. A sample of blood is illuminated with light at two different wavelengths. Light reflected by the blood is sensed by a photodetector and an output signal is created in response thereto. The output signal is processed to form a quotient representing the AC components of the reflected light at each wavelength. The oxygen saturation of the blood is calculated by correlating this quotient with an oxygen saturation reference curve uniquely representative of the blood oxygen saturation characteristics of a particular individual.
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Citations
17 Claims
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1. A blood oxygen saturation monitoring system comprising:
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a first source of electromagnetic radiation at a first wavelength; a second source of electromagnetic radiation at a second wavelength; means for positioning said first and second sources of electromagnetic radiation to illuminate a sample of blood; sensing means for receiving electromagnetic radiation reflected by said sample of blood, said reflected electromagnetic radiation comprising an AC component and a DC component, said sensing means producing an output signal corresponding only to the AC components of the reflected portions of said first and second electromagnetic radiation; means for producing a quotient of said AC voltage components; and means for calculating blood oxygen saturation by correlating said quotient of said AC voltage components with an oxygen saturation reference curve, said reference curve being uniquely representative of the blood oxygen saturation characteristics of a particular individual. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A blood oxygen saturation monitoring system comprising:
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a first light emitting diode for producing light at a first wavelength; a second light emitting diode for producing light at a second wavelength; means for positioning said first and second light emitting diodes to illuminate a sample of blood; sensing means for receiving light reflected by said sample of blood, said reflected light comprising an AC component and a DC component, said sensing means producing an output signal corresponding only to the AC components of said reflected light at said first and second wavelengths means for producing a quotient of said AC voltage components; and means for calculating blood oxygen saturation by correlating said quotient of said AC voltage components with an oxygen saturation reference curve, said reference curve being defined by a linear relationship between first and second data points, said first data point corresponding to a quotient of absorption coefficients of blood for light at said first wavelength, said second data point being a unique blood oxygen saturation point for a particular individual. - View Dependent Claims (8, 9, 10, 11)
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12. A method for determining the oxygen saturation of arterial blood, comprising the steps of:
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illuminating a sample of said blood with electromagnetic radiation at a first wavelength; illuminating said sample of blood with electromagnetic radiation at a second wavelength; collecting electromagnetic radiation reflected by said sample of blood, said reflected radiation comprising an AC component and a DC component, and developing therefrom an electrical signal representing only the AC components of said reflected radiation at said first and second wavelengths; processing said electronic signal to form a quotient corresponding to a voltage amplitude ratio of the alternating current components of said reflected radiation at said first and second wavelengths; and calculating the percent of oxygen saturation of said sample of blood by correlating said voltage amplitude ratio with an oxygen saturation reference curve, said reference curve being uniquely representative of the blood oxygen saturation characteristics of a particular individual. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification