Cyanotic infant sensor
First Claim
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1. A pulse oximetry sensor comprising:
- a plurality of emitters configured to transmit light into a fleshy medium, wherein a first subset of said plurality of emitters are matched to transmit light at a first wavelength and a second subset of said plurality of emitters are matched to transmit light at a second wavelength, and wherein said plurality of emitters are configured such that an emitted DC intensity ratio is matched to a first predetermined constant, wherein said emitted DC intensity ratio is a ratio of an intensity of the light emitted at the first wavelength to an intensity of the light emitted at the second wavelength for given DC drive currents; and
a detector responsive to said light after absorption by constituents of pulsatile blood flowing within said medium so as to generate a plurality of intensity signals, said detector configured such that a DC response ratio is matched to a second predetermined constant;
wherein said matching of said emitters to said first and second wavelengths, said matching of said emitted DC intensity ratio to said first predetermined constant, and said matching of said DC response ratio to said second predetermined constant reduces variations in a mean pathlength ratio of said light traveling through said fleshy medium between said plurality of emitters and said detector.
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Abstract
A pulse oximetry sensor comprises emitters configured to transmit light having a plurality of wavelengths into a fleshy medium. A detector is responsive to the emitted light after absorption by constituents of pulsatile blood flowing within the medium so as to generate intensity signals. A sensor head has a light absorbing surface adapted to be disposed proximate the medium. The emitters and the detector are disposed proximate the sensor head. A detector window is defined by the sensor head and configured so as to limit the field-of-view of the detector.
739 Citations
11 Claims
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1. A pulse oximetry sensor comprising:
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a plurality of emitters configured to transmit light into a fleshy medium, wherein a first subset of said plurality of emitters are matched to transmit light at a first wavelength and a second subset of said plurality of emitters are matched to transmit light at a second wavelength, and wherein said plurality of emitters are configured such that an emitted DC intensity ratio is matched to a first predetermined constant, wherein said emitted DC intensity ratio is a ratio of an intensity of the light emitted at the first wavelength to an intensity of the light emitted at the second wavelength for given DC drive currents; and a detector responsive to said light after absorption by constituents of pulsatile blood flowing within said medium so as to generate a plurality of intensity signals, said detector configured such that a DC response ratio is matched to a second predetermined constant; wherein said matching of said emitters to said first and second wavelengths, said matching of said emitted DC intensity ratio to said first predetermined constant, and said matching of said DC response ratio to said second predetermined constant reduces variations in a mean pathlength ratio of said light traveling through said fleshy medium between said plurality of emitters and said detector. - View Dependent Claims (2, 3, 4, 5)
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6. A pulse oximetry method comprising the steps of:
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providing a plurality of emitters, wherein a first subset of the plurality of emitters have been matched to transmit light at a first wavelength and a second subset of the plurality of emitters have been matched to transmit light at a second wavelength, and wherein an emitted DC intensity ratio of said plurality of emitters has been matched to a first predetermined constant, and wherein said emitted DC intensity ratio is a ratio of an intensity of the light emitted at the first wavelength to an intensity of the light emitted at the second wavelength for given DC drive currents; transmitting light from said emitters into a fleshy medium; detecting said transmitted light with detectors, said light detected after absorption by constituents of pulsatile blood flowing within said medium so as to generate a corresponding plurality of intensity signals, a DC response ratio of said detectors matched to a second predetermined constant; and wherein said matching of said emitters to said first and second wavelengths, said matching of said emitted DC intensity ratio to said first predetermined constant, and said matching of said DC response ratio to said second predetermined constant reduces variations in a mean pathlength ratio. - View Dependent Claims (7, 8, 9, 10)
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11. A pulse oximeter comprising a noninvasive sensor outputting a signal indicative of light attenuated by body tissue;
- and a processor configured to process said signal and determine whether a cyanotic condition is occurring in a monitored infant, wherein determining whether a cyanotic condition is occurring comprises matching an emitted DC intensity ratio of emitters used for outputting said signal to a first predetermined constant, wherein said emitted DC intensity ratio is a ratio of an intensity of the light emitted at the first wavelength to an intensity of the light emitted at the second wavelength for given DC drive currents, matching a DC response ratio of detectors used for detecting said signal to a second predetermined constant, using said first predetermined constant and said second predetermined constant to calculate and calibrate a mean pathlength ratio, and using said mean pathlength ratio to calculate oxygen saturation values.
Specification