Pulse oximeter and sensor optimized for low saturation
First Claim
1. A method for measuring blood oxygen saturation, comprising the steps of:
- providing a sensor and a pulse oximeter;
selecting a light source and a light detector;
optimizing a wavelength spectrum of light received by said light detector from said light source for an oxygen saturation reading less than 80 percent;
placing said sensor on a patient; and
determining said blood oxygen saturation using said sensor and said pulse oximeter.
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Abstract
A pulse oximeter sensor with a light source optimized for low oxygen saturation ranges and for maximizing the immunity to perturbation induced artifact. Preferably, a red and an infrared light source are used, with the red light source having a mean wavelength between 700-790 nm. The infrared light source can have a mean wavelength as in prior art devices used on patients with high saturation. The sensor of the present invention is further optimized by arranging the spacing between the light emitter and light detectors to minimize the sensitivity to perturbation induced artifact. The present invention optimizes the chosen wavelengths to achieve a closer matching of the absorption and scattering coefficient products for the red and IR light sources. This optimization gives robust readings in the presence of perturbation artifacts including force variations, tissue variations and variations in the oxygen saturation itself.
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Citations
52 Claims
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1. A method for measuring blood oxygen saturation, comprising the steps of:
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providing a sensor and a pulse oximeter;
selecting a light source and a light detector;
optimizing a wavelength spectrum of light received by said light detector from said light source for an oxygen saturation reading less than 80 percent;
placing said sensor on a patient; and
determining said blood oxygen saturation using said sensor and said pulse oximeter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 20)
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17. A method for measuring blood oxygen saturation in a fetus, comprising the steps of:
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providing a sensor and a pulse oximeter;
selecting a light source and a light detector;
detecting light at said detector comprising red and infrared spectrums;
selecting the infrared spectrum so as to have a wavelength spectrum useful for measuring oxygen saturation in a patient with high saturation;
optimizing a wavelength spectrum of said red spectrum to a mean wavelength between 700 and 790 nanometers for an oxygen saturation reading between 15 and 65 percent, said optimizing increasing an immunity of a measurement of blood oxygen saturation to perturbation artifact;
placing said sensor on said fetus;
measuring an intensity of at least two light signals from said light source at said light detector after being scattered through a portion of said fetus; and
determining said blood oxygen saturation using said intensity and said pulse oximeter.
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19. A method for using a pulse oximeter to measure blood oxygen saturation in a patient, comprising the steps of:
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selecting a light source and a light detector for a sensor;
detecting light at said detector comprising first and second light spectrums, each of the light spectrums having an extinction and a scattering coefficient associated with blood perfused tissue;
optimizing said light spectrums by choosing wavelength spectrums whose product of their respective extinction and scattering coefficients form first and second values, a ratio between said first and second values being between 0.5 and 2 for a majority of the oxygen saturation reading range of 0 to 65 percent;
placing said sensor on said patient; and
determining said blood oxygen saturation using said sensor and said pulse oximeter.
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21. A method for measuring blood oxygen saturation in a fetus, comprising the steps of:
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providing a sensor and a pulse oximeter;
selecting a far red and infrared light source and a light detector;
detecting light at said detector including an infrared wavelength spectrum useful for measuring oxygen saturation in a patient with high saturation, the detected light including a far red wavelength spectrum which has a mean wavelength between 700 and 790 nanometers;
placing said light sources in a single encapsulated package and mounting said package on said sensor;
placing said sensor on said fetus;
measuring an intensity of light from said light source at said light detector after scattering through a portion of said fetus; and
determining said blood oxygen saturation using said intensity and said pulse oximeter. - View Dependent Claims (22, 24, 25, 26, 27, 28, 29, 30, 31)
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23. A fetal pulse oximeter sensor comprising:
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a housing;
at least one light source mounted in said housing;
at least one detector mounted in said housing;
means for detecting light subsequent to being scattered by fetal tissue, the light including an infrared light spectrum, said infrared spectrum having a range useful for measuring oxygen saturation in a patient with high saturation, the detected light also including a red light spectrum, said red light spectrum having a mean wavelength between 700 and 790 nanometers; and
said detector being mounted in said housing spaced from said light sources and positioned to detect light from said light sources.
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32. A sensor for a pulse oximeter for measuring blood oxygen saturation, comprising:
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a light source;
a light detector;
one of said light source and light detector including means for providing light comprising first and second spectrums, each of the spectrums being optimized for the products of their respective extinction and scattering coefficients in blood perfused tissue, the products forming first and second values, a ratio between said first and second values being between 0.5 and 2 for a majority of the oxygen saturations less than 80 percent. - View Dependent Claims (33, 34, 36, 37, 38, 39)
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35. A sensor for a pulse oximeter for measuring blood oxygen saturation in a fetus, comprising:
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a radiation source;
a radiation detector;
at least one of said source and detector being optimized for reducing the sensitivity of a blood oxygen saturation measurement to perturbation induced artifact for saturations less than 65 percent.
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40. A sensor for measuring blood oxygen saturation in a fetus, comprising:
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an infrared light source having a wavelength spectrum useful for measuring oxygen saturation in a patient with high saturation;
a deep red light source having a mean wavelength between 700 and 790 nanometers; and
a single encapsulated package enclosing said red and infrared light sources, said package being mounted on said sensor.
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41. A method of using a pulse oximeter, comprising the steps of:
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receiving at least first and second signals from a sensor obtained by scattering light through tissue, the light having at least first and second wavelength spectrums, the first and second spectrums being optimized for an oxygen saturation reading less than 80%; and
calculating the oxygen saturation using coefficients suitable for the first and second optimized spectrums.
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42. A method for measuring blood oxygen saturation in a fetus, comprising the steps of:
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providing a sensor and a pulse oximeter;
selecting a light source and a far red and infrared light detector;
detecting light at said detector including an infrared light wavelength spectrum useful for measuring oxygen saturation in a patient with high saturation, the detected light including a far red wavelength spectrum which has a mean wavelength between 700 and 790 nanometers;
placing said light detectors in a single encapsulated package and mounting said package on said sensor;
placing said sensor on said fetus;
measuring an intensity of light from said light source at said light detectors after scattering through a portion of said fetus; and
determining said blood oxygen saturation using said intensity and said pulse oximeter. - View Dependent Claims (43)
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44. A pulse oximeter comprising:
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an input connector for receiving at least first and second signals from a sensor obtained by scattering light through tissue, the light having at least first and second wavelength spectrums;
a memory storing coefficients suitable for said first and second spectrums, the spectrums being optimized for an oxygen saturation reading less than 80%; and
a processor, coupled to said memory and said input connector, for calculating the oxygen saturation using said coefficients. - View Dependent Claims (45, 46, 47, 48, 50)
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49. A fetal pulse oximeter comprising:
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an input connector for receiving at least first and second signals from a sensor obtained by scattering light through tissue of a fetus, the light having at least red and infrared spectrums;
a memory storing coefficients suitable for said infrared spectrum having a range useful for measuring oxygen saturation in a patient with high saturation and said red light spectrum having a mean wavelength between 700 and 790 nanometers; and
a processor, coupled to said memory and said input connector, for calculating the oxygen saturation of said fetus using said coefficients.
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51. A pulse oximeter, comprising:
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an input connector for receiving at least first and second signals from a sensor obtained by scattering light through tissue, the light having at least red and infrared spectrums;
a memory storing coefficients suitable for said spectrums, each of the spectrums being optimized for the products of their respective extinction and scattering coefficients in blood perfused tissue, the products forming first and second values, a ratio between said first and second values being between 0.5 and 2 for a majority of oxygen saturations less than 80 percent; and
a processor, coupled to said memory, for calculating the oxygen saturation using said coefficients.
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52. A pulse oximeter for measuring blood oxygen saturation in a fetus, comprising:
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an input connector for receiving at least first and second signals from a sensor obtained by detecting light having at least red and infrared spectrums, the light being scattered from tissue;
a memory storing coefficients suitable for said spectrums being optimized for reducing the sensitivity of a blood oxygen saturation measurement to perturbation induced artifact for saturations less than 65 percent; and
a processor, coupled to said memory, for calculating the oxygen saturation using said coefficients.
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Specification