Signal processing apparatus and method
First Claim
1. A pulse oximeter comprising:
- at least first and second light emitting devices;
at least one light detector configured to receive light attenuated by transmission through a body tissue with pulsing blood, the at least one light detector acquiring a first signal based on light from the first light emitting device comprising a first desired signal portion and a first undesired signal portion and a second signal based on light from the second light emitting device comprising a second desired signal portion and a second undesired signal portion; and
a closed loop adaptive system responsive to said first and second signals to provide at least first and second output signals for use in calculating oxygen saturation of said blood.
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Accused Products
Abstract
A signal processor which acquires a first signal, including a first desired signal portion and a first undesired signal portion, and a second signal, including a second desired signal portion and a second undesired signal portion, wherein the first and second desired 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 noise reference signal which is a combination of only the undesired signal portions and is correlated to both the first and second undesired signal portions. The noise reference signal is then used to remove the undesired portion of each of the first and second measured signals via an adaptive noise canceler, preferably of the joint process estimator type. The processor of the present invention may be employed in conjunction with an adaptive noise 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 of a patient or the concentration of a constituent in a medium, can be determined from the desired portion of the signal after undesired signal portions, such as those caused by erratic motion, are removed.
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Citations
160 Claims
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1. A pulse oximeter comprising:
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at least first and second light emitting devices;
at least one light detector configured to receive light attenuated by transmission through a body tissue with pulsing blood, the at least one light detector acquiring a first signal based on light from the first light emitting device comprising a first desired signal portion and a first undesired signal portion and a second signal based on light from the second light emitting device comprising a second desired signal portion and a second undesired signal portion; and
a closed loop adaptive system responsive to said first and second signals to provide at least first and second output signals for use in calculating oxygen saturation of said blood. - View Dependent Claims (2, 3, 4, 5)
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6. A pulse oximeter comprising:
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at least first and second light emitting devices;
at least one light detector configured to receive light attenuated by transmission through body tissue with pulsing blood, the at least one light detector generating a first signal based on light transmitted from the first light emitting device and a second signal based on light transmitted from the second light emitting device; and
a processor that effects signals representing the first and second signals to provide at least one output signal, wherein the processor adjusts itself to optimize the at least one output signal for use in calculating oxygen saturation. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method of calculating blood oxygen saturation comprising:
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transmitting light of at least first and second wavelengths through body tissue carrying pulsing blood to a light-sensitive detector to generate first and second intensity signals;
digitizing the first and second intensity signals; and
processing the first and the second digitized intensity signals to provide first and second processed output signals, wherein the processing comprises monitoring an output of the processing, and in response, adjusting the processing to optimize at least one of said first or second processed output signals; and
calculating oxygen saturation based upon said first and second processed output signals. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A pulse oximeter comprising:
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at least one light detector configured to receive light of at least first and second wavelengths attenuated by transmission through a body tissue with pulsing blood, the at least one light detector generating a first signal based on light of the first wavelength and a second signal based on light of the second wavelength;
an analog to digital converter that digitizes the first and the second signals to produce digitized first and second signals; and
a processor that employs an adaptive algorithm to effect the digitized first and second signals for use in calculating oxygen saturation. - View Dependent Claims (19, 20, 21, 22)
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23. A pulse oximeter comprising:
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at least one light detector configured to receive light of at least first and second wavelengths attenuated by transmission through a body tissue with pulsing blood, the at least one light detector generating a first signal based on light of the first wavelength and a second signal based on light of the second wavelength;
an analog to digital converter that digitizes the first and the second signals to produce first and second digitized signals; and
a microprocessor that has a routine that executes a least squares algorithm to effect the first and the second digitized signals to produce first and second output signals, the first and second output signals for use in calculating oxygen saturation. - View Dependent Claims (24, 25, 26)
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27. A method of determining blood oxygen saturation comprising:
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transmitting light of at least first and second wavelengths through body tissue carrying pulsing blood to a light-sensitive detector to generate at least one intensity signal;
processing the at least one intensity signal using a closed loop adaptive algorithm to provide at least one output signal; and
calculating oxygen saturation based upon the at least one output signal. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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50. A pulse oximeter comprising:
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light emitters that transmit light of at least first and second wavelengths through body tissue carrying pulsing blood to a light-sensitive detector to generate at least one intensity signal; and
a processor that executes an adaptive algorithm to have an effect on the at least one intensity signal, wherein the at least one intensity signal, once effected by the adaptive algorithm, is used in calculating oxygen saturation. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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- 70. In a pulse oximeter wherein the improvement comprises effecting intensity signals resulting from light of first and second wavelengths attenuated by body tissue carrying pulsing blood by the operation of a least squares algorithm, which intensity signals, once effected, are used in the calculation of oxygen saturation.
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84. A method of determining blood oxygen saturation comprising:
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transmitting light of at least first and second wavelengths through body tissue carrying pulsing blood to a light-sensitive detector to generate at least one intensity signal;
processing the at least one intensity signal using a least squares algorithm to provide at least one output signal; and
calculating oxygen saturation based upon the at least one output signal. - View Dependent Claims (85, 86, 87, 88, 89, 90, 91, 92, 93, 94)
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95. A method of determining blood oxygen saturation comprising:
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transmitting light of at least first and second wavelengths through body tissue carrying pulsing blood to a light-sensitive detector to generate first and second intensity signals;
digitizing the first and second intensity signals to produce first and second digitized intensity signals;
processing the first and second digitized intensity signals to provide first and second output signals, wherein the processing adjusts itself to optimize at least one of the first and second output signals; and
calculating oxygen saturation based upon the first and second output signals. - View Dependent Claims (96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114)
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115. A method of determining blood oxygen saturation comprising:
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transmitting light of at least first and second wavelengths through body tissue carrying pulsing blood to a light-sensitive detector to generate first and second intensity signals;
digitizing the first and second intensity signals to produce first and second digitized intensity signals;
processing the first and second digitized intensity signals to provide first and second processed intensity signals, wherein the processing employs a predetermined algorithm that adjusts coefficients applied to the first and second digitized intensity signals, based on an output of the processing, in order to optimize at least one of the first and second processed intensity signals; and
determining blood oxygen saturation from the first and second processed intensity signals. - View Dependent Claims (116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130)
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- 131. In a pulse oximeter wherein the improvement comprises effecting intensity signals resulting from light of first and second wavelengths attenuated by pulsing blood by operation of an algorithm that responds to at least one error signal, wherein the intensity signals, after being effected, are used in the calculation of oxygen saturation.
- 145. In a pulse oximeter wherein the improvement comprises, comparing a signal and an estimate of the signal in order to produce an effect on intensity signals resulting from light of first and second wavelengths attenuated by pulsing blood, which intensity signals are then used in the calculation of oxygen saturation.
- 154. In a pulse oximeter, wherein the improvement comprises a processor that adjusts its own transfer function using a least squares algorithm to effect intensity signals resulting from light of first and second wavelengths attenuated by pulsing blood in a patient.
Specification