System for prefiltering a plethysmographic signal
First Claim
1. A method for use in pulse oximetry, comprising the steps of:
- receiving an electronic signal reflective of one or more optical signals incident on a detector of a pulse oximeter, wherein said electronic signal includes a first temporal portion that is potentially corrupted by artifact;
processing said electronic signal such that an amplitude associated with said first temporal portion of said electronic signal is reduced in relation to less than an amplitude of a second temporal portion of said electronic signal determined to generally correspond to a clean waveform, thereby providing a processed signal; and
after the processing, using said processed signal to obtain physiological information regarding a patient.
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Accused Products
Abstract
A detector signal in a pulse oximeter is prefiltered, prior to processing so as to determine a physiological parameter value, so as to reduce the effects of artifact in the signal. An exemplary prefilter multiplies signal amplitude values by a quantitude that is inversely proportional to a substantially current amplitude so as to reduce the amplitude of large amplitude sections typically associated with artifact. In one implementation, the quantity is a ratio of an amplitude associated with a clean section of the signal by some exponential factor of a substantially current amplitude. In this manner, artifact affected portions of the signal are deemphasized in subsequent analyses.
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Citations
19 Claims
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1. A method for use in pulse oximetry, comprising the steps of:
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receiving an electronic signal reflective of one or more optical signals incident on a detector of a pulse oximeter, wherein said electronic signal includes a first temporal portion that is potentially corrupted by artifact; processing said electronic signal such that an amplitude associated with said first temporal portion of said electronic signal is reduced in relation to less than an amplitude of a second temporal portion of said electronic signal determined to generally correspond to a clean waveform, thereby providing a processed signal; and after the processing, using said processed signal to obtain physiological information regarding a patient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for use in pulse oximetry, comprising the steps of:
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receiving a time-based signal reflective of one or more optical signals incident on a detector of a pulse oximeter; performing a correction with respect to a portion of said received time-based signal to reduce an effect of artifact, thereby providing a processed time-based signal; performing a transform on said processed time-based signal to obtain transformed information relative to a second domain; and processing the transformed information to obtain physiological information regarding a patient; wherein said step of performing a correction comprises prefiltering said received time based signal to reduce an amplitude of a portion of said signal determined to be affected by an artifact to a value less than an amplitude of a portion of the signal determined to be clean with reference to the artifact. - View Dependent Claims (11)
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12. An apparatus for use in pulse oximetry, comprising:
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a port for receiving an electronic signal reflective of one or more optical signals incident on a detector of a pulse oximeter; a prefilter for filtering said signal such that an amplitude associated with an artifact affected portion of said signal is reduced in relation to a magnitude less than an amplitude associated with a second portion of said signal that is determined to be associated with a clean waveform, thereby providing a processed signal; and a processor for processing said processed signal after the processing by the prefilter to obtain physiological information regarding a patient. - View Dependent Claims (13, 14, 15, 16)
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17. A method for prefiltering a plethysmographic signal, comprising:
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receiving a detector signal; removing a carrier wave and DC portion from the detector signal to generate a pulsatile signal; providing an amplitude for a clean portion of the pulsatile signal characterized by a relatively well-defined phethysmographic waveform; processing the pulsatile signal to generate a prefiltered signal by determining an amplitude of a plurality of temporal portions of the pulsatile signal and applying a transfer function to the determined amplitude, wherein the transfer function comprises a ratio of the amplitude of the clean portion to each of the amplitudes of the temporal portions; and after the processing, performing spectral processing of the prefiltered signal to obtain physiological information. - View Dependent Claims (18, 19)
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Specification