Apparatus and method for measuring blood oxygen saturation
First Claim
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1. An apparatus for measuring a selected parameter of a blood sample, comprising:
- a first radiation source of a first wavelength;
a second radiation source of a second wavelength;
means for positioning said radiation sources to irradiate said sample;
sensor means responsive to radiation from said sources, having an electrical output and positioned to receive radiation from said sources after reflection from said sample and reject other radiation;
means for selectively and adjustably energizing said first radiation source such that the amount of its radiation reflected from said sample and received by said sensor means remains substantially constant regardless of the reflectivity of said sample;
means for selectively and adjustably energizing said second radiation source such that its radiant output is related to the radiant output of said first radiation source;
circuit means for developing a signal related to the ratio of the reflected radiation received by said sensor means from said first and second radiation sources;
circuit means responsive to said signal for producing a resultant signal representative of said selected parameter.
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Abstract
A device and method for measuring blood characteristics and parameters, especially arterial, venous, or differential blood oxygen saturation levels uses one or two probes containing a unique configuration of light emitters of two different wavelengths, and sensors which alternately illuminate and read reflected light from blood passing through a specially-designed cuvette. Electronic comparison of reflected radiation received by the probes produces a voltage which is linearly related to blood oxygen saturation level. An opto-electronic feedback network compensates for differences in blood optical density.
109 Citations
33 Claims
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1. An apparatus for measuring a selected parameter of a blood sample, comprising:
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a first radiation source of a first wavelength; a second radiation source of a second wavelength; means for positioning said radiation sources to irradiate said sample; sensor means responsive to radiation from said sources, having an electrical output and positioned to receive radiation from said sources after reflection from said sample and reject other radiation; means for selectively and adjustably energizing said first radiation source such that the amount of its radiation reflected from said sample and received by said sensor means remains substantially constant regardless of the reflectivity of said sample; means for selectively and adjustably energizing said second radiation source such that its radiant output is related to the radiant output of said first radiation source; circuit means for developing a signal related to the ratio of the reflected radiation received by said sensor means from said first and second radiation sources; circuit means responsive to said signal for producing a resultant signal representative of said selected parameter. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 19, 20, 21, 22, 23, 24, 25, 26)
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2. An apparatus for measuring a selected parameter of a blood sample, comprising:
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a first radiation source of a first wavelength; a second radiation source of a second wavelength; means for positioning said radiation sources to irradiate said sample; sensor means responsive to radiation from said sources, having an electrical output and positioned to receive radiation from said sources after transmission through said sample and reject other radiation; means for selectively and adjustably energizing said first radiation source such that the amount of its radiation transmitted through said sample and received by said sensor means remains substantially constant regardless of the transparency of said sample; means for selectively and adjustably energizing said second radiation source such that its radiant output is related to the radiant output of said first radiation source; circuit means for developing a signal related to the ratio of the transmitted radiation received by said sensor means for said first and second radiation sources; circuit means responsive to said signal for producing a resultant signal representative of said selected parameter.
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11. An apparatus for determining the level of oxygen saturation in extracorporeally circulating blood comprising:
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a cuvette interposed in the flow path of said blood, having a substantially flat, optically clear window area; a first radiation source of a first wavelength located proximately to said window; a second radiation source of a second wavelength located proximately to said window; sensor means located proximately to said window and responsive to radiation from said first and second radiation sources; means for selectively and adjustably energizing said first radiation source such that the amount of its radiation reflected from said blood and received by said sensor means remains substantially constant regardless of the reflectivity of said blood; means for selectively and adjustably energizing said second radiation source such that its radiant output is related to the radiant output of said first radiation source; circuit means for developing a signal related to the ratio of the reflected radiation received by said sensor means from said first and second radiation sources; and circuit means responsive to said signal for producing a resultant signal representative of said level of oxygen saturation. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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27. In a blood oxygen saturation meter of the opto-electronic type, including first and second selectively and adjustably energizable light sources of two different wavelengths;
- sensor means for receiving light emitted by said sensors and transmitted through a blood sample;
means for adjusting the output level of this second one of said light sources such that its radiant output is related to the radiant output of the first one of said light sources; and
means for determining the ratio of the signals received by said sensor from said light sources;
the improvement comprising;means for selectively and adjustably energizing said first light source such that the amount of its light transmitted through said blood and received by said sensor means remains substantially constant regardless of the transmissibility of said blood.
- sensor means for receiving light emitted by said sensors and transmitted through a blood sample;
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28. In a blood oxygen saturation meter of the opto-electronic type, including first and second selectively and adjustably energizable light sources of two different wavelengths;
- sensor means for receiving light emitted by said sources and reflected from a blood sample;
means for adjusting the output level of the second one of said light sources such that its radiant output is related to the radiant output of the first one of said light sources; and
means for determining the ratio of the signals received by said sensor from said light sources, the improvement comprising;means for selectively and adjustably energizing said first light source such that the amount of its light reflected from said blood and received by said sensor means remains substantially constant regardless of the transmissibility or reflectivity of said blood.
- sensor means for receiving light emitted by said sources and reflected from a blood sample;
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29. In a blood oxygen saturation meter of the opto-electronic type, including first and second selectively and adjustably energizable light sources of two different wavelengths;
- sensor means for receiving light emitted by said sensors and transmitted through a blood sample;
means for adjusting the output level of this second one of said light sources such that its radiant output is related to the radiant output of the first one of said light sources; and
means for determining the ratio of the signals received by said sensor from said light sources;
the improvement comprising;means for selectively and adjustably energizing said first light source such that the amount of its light transmitted through said blood and received by said sensor means remains substantially constant regardless of the transmissibility of said blood; and said first and second light sources are comprised of a plurality of light emitters located around said sensor means.
- sensor means for receiving light emitted by said sensors and transmitted through a blood sample;
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30. In a blood oxygen saturation meter of the opto-electronic type, including first and second selectively and adjustably energizable light sources of two different wavelengths;
- sensor means for receiving light emitted by said sources and reflected from a blood sample;
means for adjusting the output level of the second one of said light sources such that its radiant output is related to the radiant output of the first one of said light sources; and
means for determining the ratio of the signals received by said sensor from said light sources;
the improvement comprising;means for selectively and adjustably energizing said first light source such that the amount of its light reflected from said blood and received by said sensor means remains substantially constant regardless of the reflectivity of said blood; and said first and second light sources are comprised of a plurality of light emitters located around said sensor means.
- sensor means for receiving light emitted by said sources and reflected from a blood sample;
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31. A method for measuring a selected parameter of a blood sample, comprising the steps of:
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positioning a first radiation source of a first wavelength and a second radiation source of a second wavelength proximately to said sample; positioning a sensor means, responsive to radiation from said sources and having an electrical output, proximately to said sample to receive radiation from said sources after reflection from said sample; selectively and adjustably energizing said first radiation source such that the amount of its radiation reflected from said sample and received by said sensor means remains substantially constant regardless of the reflectivity of said sample; selectively and adjustably energizing said second radiation source such that its radiant output is related to the radiant output of said first radiation source; developing a signal related to the ratio of the reflected radiation received by said sensor means from said first and second radiation sources; producing a resultant signal in response to said signal representative of said selected parameter. - View Dependent Claims (33)
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32. A method for measuring a selected parameter of a blood sample, comprising the steps of:
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positioning a first radiation source of a first wavelength and a second radiation source of a second wavelength proximately to said sample; positioning a sensor means, responsive to radiation from said sources and having an electrical output, proximately to said sample to receive radiation from said sources after transmission through said sample; selectively and adjustably energizing said first radiation source such that the amount of its radiation transmitted through said sample and received by said sensor means remains substantially constant regardless of the transparency of said sample; selectively and adjustably energizing said second radiation source such that its radiant output is related to the radiant output of said first radiation source; developing a signal related to the ratio of the transmitted radiation received by said sensor means from said first and second radiation sources; producing a resultant signal in response to said signal representative of said selected parameter.
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Specification