Interference Suppression in Spectral Plethysmography
First Claim
1. A method for assessing a blood related parameter of a subject, the method comprising:
- obtaining at least one blood related signal from a subject;
deriving a power spectrum for at least one of the at least one blood related signal, thereby to obtain at least one power spectrum;
identifying at least one interference frequency of at least one interference source causing unwanted modulation in the at least one blood related signal;
determining a weight function in which the relative weight of at least one frequency is dampened, the at least one frequency depending on the at least one interference frequency identified;
applying the weight function to at least one of the at least one power spectrum, thereby to obtain at least one weighted power spectrum; and
defining the blood related parameter based on the at least one weighted power spectrum.
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Accused Products
Abstract
The invention relates to a patient monitoring device, especially to a pulse oximeter. For suppressing the effects of an interference source causing adverse modulation in one or more blood related signals input to the device, a power spectrum is derived for each blood related signal and the frequency of an interference source causing unwanted modulation in the blood related signal(s) is identified. A weight function is determined, in which the relative weight of at least one frequency is dampened, the at least one frequency depending on the identified frequency. The weight function is applied to the power spectrum(s), thereby to obtain at least one weighted power spectrum. A blood related parameter of the subject is defined based on the at least one weighted power spectrum.
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Citations
29 Claims
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1. A method for assessing a blood related parameter of a subject, the method comprising:
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obtaining at least one blood related signal from a subject; deriving a power spectrum for at least one of the at least one blood related signal, thereby to obtain at least one power spectrum; identifying at least one interference frequency of at least one interference source causing unwanted modulation in the at least one blood related signal; determining a weight function in which the relative weight of at least one frequency is dampened, the at least one frequency depending on the at least one interference frequency identified; applying the weight function to at least one of the at least one power spectrum, thereby to obtain at least one weighted power spectrum; and defining the blood related parameter based on the at least one weighted power spectrum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for assessing a blood related parameter of a subject, the apparatus comprising:
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a measurement unit configured to measure at least one blood related signal from a subject; a transform unit configured to derive a power spectrum for at least one of the at least one blood related signal, thereby to obtain at least one power spectrum; a frequency identification unit configured to identify at least one interference frequency of at least one interference source causing unwanted modulation in the at least one blood related signal; a first calculation unit configured to determine a weight function in which the relative weight of at least one frequency is dampened, the at least one frequency depending on the at least one interference frequency; a weighting unit configured to apply the weight function to at least one of the at least one power spectnjm, thereby to obtain at least one weighted power spectrum; and a second calculation unit configured to define the blood related parameter based on the at least one weighted power spectrum. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An apparatus for assessing a blood related parameter of a subject, the apparatus comprising:
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measurement means for measuring at least one blood related signal from a subject; transform means for deriving a power spectrum for at least one of the at least one blood related signal, thereby to obtain at least one power spectrum; frequency identification means for identifying at least one interference frequency of at least one interference source causing unwanted modulation in the at least one blood related signal; first calculation means for determining a weight function in which the relative weight of at least one frequency is dampened, the at least one frequency depending on the at least one interference frequency; weighting means for applying the weight function to at least one of the at least one power spectrum, thereby to obtain at least one weighted power spectrum; and second calculation means for defining the blood related parameter based on the at least one weighted power spectrum.
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28. A computer program product for an apparatus configured to assess a blood related parameter of a subject, the computer program product comprising:
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a first program code portion configured to determine a weight function in which the relative weight of at least one frequency is dampened, the at least one frequency depending on at least one frequency of an interference source causing unwanted modulation in at least one blood related signal; and a second program code portion configured to apply the weight function to at least one power spectrum of the at least one blood related signal, thereby to obtain at least one weighted power spectrum. - View Dependent Claims (29)
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Specification