Signal processing apparatus
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Abstract
A signal processor which acquires a first signal, including a first primary signal portion and a first secondary signal portion, and a second signal, including a second primary signal portion and a second secondary signal portion, wherein the first and second primary signal portions are correlated. The signals may be acquired by propagating energy through a medium and measuring an attenuated signal after transmission or reflection. Alternatively, the signals may be acquired by measuring energy generated by the medium. A processor of the present invention generates a primary or secondary reference signal which is a combination, respectively, of only the primary or secondary signal portions. The secondary reference signal is then used to remove the secondary portion of each of the first and second measured signals via a correlation canceler, such as an adaptive noise canceler, preferably of the joint process estimator type. The primary reference signal is used to remove the primary portion of each of the first and second measured signals via a correlation canceler. The processor of the present invention may be employed in conjunction with a correlation canceler in physiological monitors wherein the known properties of energy attenuation through a medium are used to determine physiological characteristics of the medium. Many physiological conditions, such as the pulse, or blood pressure of a patient or the concentration of a constituent in a medium, can be determined from the primary or secondary portions of the signal after other signal portion is removed.
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Citations
85 Claims
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1-38. -38. (Cancelled).
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39. An apparatus for computing arterial and venous signals in living tissue, said apparatus comprising:
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a detector configured to receive a first signal which travels along a first propagation path and a second signal which travels along a second propagation path, at least a portion of said first and second propagation paths being located in a propagation medium, wherein said first signal has an arterial signal portion that is indicative of arterial blood and another signal portion that is indicative of venous blood, and said second signal has an arterial signal portion that is indicative of arterial blood and another signal portion that is indicative of venous blood; and
a signal processor responsive to representations of the first signal and the second signal to generate a signal having a significant component which is a function of said arterial portions of said first and said second signal. - View Dependent Claims (40)
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41. A method determining a value of blood oxygen saturation of pulsing blood, the method comprising:
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receiving three or more intensity signals from at least one light-sensitive detector which detects light attenuated by body tissue carrying pulsing blood, wherein the three or more intensity signals correspond to detection of at least three wavelengths of the light; and
determining a value of oxygen saturation using the three or more intensity signals, wherein the three or more intensity signals include motion induced noise. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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56. A method of reducing an effect of motion induced noise on a plurality of intensity signals during the determination of a parameter of pulsing blood, the method comprising:
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receiving a plurality of intensity signals from at least one light−
sensitive detector which detects light of a plurality of wavelengths attenuated by body tissue carrying pulsing blood; and
processing one of the plurality of intensity signals using data from an additional intensity signal other than the plurality of intensity signals, the additional intensity signal corresponding to an additional wavelength of light, wherein the processing determines a value of blood oxygen saturation of the pulsing blood during motion induced noise, wherein the data from the extra wavelength is used to reduce an effect of the motion induced noise. - View Dependent Claims (57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67)
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68. A physiological monitor for determining a physiological parameter of a patient, the physiological monitor comprising:
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an input which receives three or more intensity signals from at least one light-sensitive detector which detects light attenuated by body tissue carrying pulsing blood, wherein the three or more intensity signals correspond to detection of at least three wavelengths of the light; and
a processor which determines a value of oxygen saturation using the three or more intensity signals, wherein the three or more intensity signals include motion induced noise. - View Dependent Claims (69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82)
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83. A method of determining blood oxygen saturation, the method comprising:
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receiving a plurality of intensity signals representative of light of at least three wavelengths attenuated by body tissue carrying pulsing blood;
processing ratiometric data related to the plurality of intensity signals to reduce an effect of motion induced noise in at least one of the plurality of intensity signals;
determining a value of oxygen saturation from the at least one of the plurality of intensity signals. - View Dependent Claims (84, 85)
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Specification