Signal processing apparatus and method
First Claim
1. A method of determining an indication of blood oxygen saturation comprising the steps of:
- transmitting light of at least first and second wavelengths through body tissue carrying blood to a light-sensitive detector to generate first and second measured intensity signals;
filtering at least one of said first and second intensity signals with an adaptive canceler to provide at least one output signal; and
calculating oxygen saturation based upon said at least one output signal.
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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 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 may be employed in conjunction with an adaptive noise canceler in physiological monitors wherein the know 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.
1270 Citations
32 Claims
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1. A method of determining an indication of blood oxygen saturation comprising the steps of:
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transmitting light of at least first and second wavelengths through body tissue carrying blood to a light-sensitive detector to generate first and second measured intensity signals; filtering at least one of said first and second intensity signals with an adaptive canceler to provide at least one output signal; and calculating oxygen saturation based upon said at least one output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A pulse oximeter which measures the oxygen saturation of blood in body tissue, said pulse oximeter comprising:
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a light emitter adapted to emit light of at least first and second wavelengths; a light detector responsive to light from said light emitter which has passed through body tissue having blood, said light detector providing intensity signals; an adaptive filter responsive to said intensity signals to provide at least one filtered signal; and a oxygen saturation module responsive to at least said filtered signal to calculate oxygen saturation of said blood. - View Dependent Claims (17, 19, 20, 21, 22, 23, 24, 25)
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18. The pulse oximeter of clam 16, wherein said adaptive canceler comprises a first predetermined filter and adaptive correlation canceler.
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26. A pulse oximeter which measures the oxygen saturation of blood in body tissue, said pulse oximeter comprising:
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a light emitter adapted to emit light of at least first and second wavelengths; a light detector responsive to light from said light emitter which has passed through body tissue having blood, said light detector providing intensity signals; a digital to analog converter which digitizes the intensity signals from said light detector; a multiple notch filter responsive to said intensity signals after conversion with said digital to analog converter to provide at least one filtered signal; and an oxygen saturation module responsive to at least said filtered signal to calculate oxygen saturation of said blood. - View Dependent Claims (27)
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28. A pule oximeter which measures the oxygen saturation of blood in body tissue, said pulse oximeter comprising:
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a light emitter adapted to emit light of at least first and second wavelengths; a light detector responsive to light from said light emitter which has passed through body tissue having blood, said light detector providing intensity signals having desired and undesired signal portions; a digital to analog converter which digitizes the intensity signals from said light detector; an adaptive signal processor responsive to said intensity signals to adaptively filter said intensity signals; and an oxygen saturation module responsive to at least said at least one signal to calculate oxygen saturation of said blood. - View Dependent Claims (29, 30, 31, 32)
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Specification