Blind source separation of pulse oximetry signals
First Claim
1. A computer useable medium having computer readable code, the computer readable code comprising:
- code configured to process a plurality of signals to obtain a plurality of principal components, wherein the plurality of signals corresponds to sensed optical energies from a plurality of wavelengths and wherein each of the plurality of signals comprises a source component corresponding to a physiological parameter and an interference component;
code configured to process the plurality of principal components to obtain a plurality of independent components, wherein a matrix of the plurality of signals corresponds to a matrix product of a matrix of the plurality of independent components and a matrix of mixing coefficients, and wherein the code configured to process the plurality of principal components comprisescode configured to separate the source component from the interference component; and
code configured to obtain a ratio of mixing coefficients from the matrix of mixing coefficients, wherein the ratio corresponds to a ratio of modulation ratios of red to infrared wavelengths of the plurality of wavelengths; and
code configured to extract a first measure of the physiological parameter corresponding to the source component from one of the plurality of independent components.
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Abstract
A method and apparatus for the application of Blind Source Separation (BSS), specifically independent Component Analysis (ICA) to mixture signals obtained by a pulse oximeter sensor. In pulse oximetry, the signals measured at different wavelengths represent the mixture signals, while the plethysmographic signal, motion artifact, respiratory artifact and instrumental noise represent the source components. The BSS is carried out by a two-step method including an ICA. In the first step, the method uses Principal Component Analysis (PCA) as a preprocessing step, and the Principal Components are then used to derive sat and the Independent Components, where the Independent Components are determined in a second step. In one embodiment, the independent components are obtained by high-order decorrelation of the principal components, achieved by maximizing the sum of the squares of the higher-order cumulants of the plurality of mixture signals.
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Citations
31 Claims
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1. A computer useable medium having computer readable code, the computer readable code comprising:
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code configured to process a plurality of signals to obtain a plurality of principal components, wherein the plurality of signals corresponds to sensed optical energies from a plurality of wavelengths and wherein each of the plurality of signals comprises a source component corresponding to a physiological parameter and an interference component; code configured to process the plurality of principal components to obtain a plurality of independent components, wherein a matrix of the plurality of signals corresponds to a matrix product of a matrix of the plurality of independent components and a matrix of mixing coefficients, and wherein the code configured to process the plurality of principal components comprises code configured to separate the source component from the interference component; and code configured to obtain a ratio of mixing coefficients from the matrix of mixing coefficients, wherein the ratio corresponds to a ratio of modulation ratios of red to infrared wavelengths of the plurality of wavelengths; and code configured to extract a first measure of the physiological parameter corresponding to the source component from one of the plurality of independent components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A pulse oximeter, comprising:
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a processor configured to; process a plurality of signals to obtain a plurality of principal components, wherein each of the plurality of signals comprises a source component corresponding to a physiological parameter and an interference component; process the plurality of principal components to obtain a plurality of independent components, wherein a matrix of the plurality of signals corresponds to a matrix product of a matrix of the plurality of independent components and a matrix of mixing coefficients; and extract a first measure of the physiological parameter corresponding to the source component from one of the plurality of independent components, wherein the physiological parameter comprises a pulse rate.
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13. A pulse oximeter, comprising:
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a processor configured to; process the plurality of signals to obtain a plurality of principal components, wherein each of the plurality of signals comprises a source component corresponding to a physiological parameter and an interference component; process the plurality of principal components to obtain a plurality of independent components, wherein a matrix of the plurality of signals corresponds to a matrix product of a matrix of the plurality of independent components and a matrix of mixing coefficients; and extract a first measure of the physiological parameter corresponding to the source component from one of the plurality of independent components, wherein the plurality of signals corresponds to sensed optical energies from a plurality of wavelengths. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A pulse oximeter, comprising:
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a processor configured to; process a plurality of signals to obtain a plurality of principal components, wherein each of the plurality of signals comprises a source component corresponding to a physiological parameter and an interference component; process a plurality of principal components to obtain a plurality of independent components, wherein a matrix of the plurality of signals corresponds to a matrix product of a matrix of the plurality of independent components and a matrix of mixing coefficients; and extract a first measure of the physiological parameter corresponding to the source component from one of the plurality of independent components, wherein the plurality of signals corresponds to sensed optical energies from a plurality of wavelengths from different times.
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Specification