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Catheter oximeter apparatus and method

  • US 4,114,604 A
  • Filed: 10/18/1976
  • Issued: 09/19/1978
  • Est. Priority Date: 10/18/1976
  • Status: Expired due to Term
First Claim
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1. Apparatus for determining oxygen saturation of blood comprising:

  • source means for producing electro-magnetic radiation at first, second and third radiation wavelengths;

    means coupled to the source means for supplying the radiation therefrom to blood under test with incident intensities at the respective wavelengths;

    detector means disposed to receive radiation from the blood under test altered from the incident intensities of the respective wavelengths by the optical properties of the blood under test for producing signals representative of the intensities of the radiation received thereby at the respective wavelengths;

    circuit means coupled to the detector means for producing a first output representative of the ratio of a first pair of the signals from said detector means, and for producing a second output representative of the ratio of a second pair of the signals from said detector means, the wavelengths of the radiation from said source means being such that the first ratio is independent of physiological changes of the sample blood other than oxygen saturation at a first oxygen saturation level and the second ratio is independent of physiological changes other than oxygen saturation at a second oxygen saturation level; and

    first means coupled to the circuit means for receiving the first and second outputs of said circuit means and applying selected coefficients thereto to minimize the effect of varying physiological characteristics of the blood under test other than oxygen saturation, said first means producing an output representative of the algebraic combination of selectively weighted first and second outputs of said circuit means; and

    second means coupled to the circuit means for receiving the first and second outputs of said circuit means and applying selected coefficients thereto to minimize the effect of varying physiological characteristics of the blood under test other than oxygen saturation, said second means producing an output representative of the algebraic combination of selectively weighted first and second outputs of said circuit means; and

    means coupled to the first and second means for receiving the outputs therefrom and producing an output manifestation of the ratio of the outputs from the first and second means.

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