Method and apparatus for discriminating between valid and artifactual pulse waveforms in pulse oximetry
First Claim
1. A method for discriminating between artifactual and non-artifactual pulse waveforms generated by a pulse oximeter for validating indicated arterial oxygen saturation levels of a subject also generated by the pulse oximeter, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the method comprising:
- selecting a predetermined range of a first parameter indicative of a correct pulse waveform, said first parameter being selected from the group consisting of systolic upstroke times and diastolic times;
receiving from the pulse oximeter, in a first receiving step, pulse waveforms;
receiving from the pulse oximeter, in a second receiving step, signals indicative of the arterial oxygen saturation level of the subject;
measuring said first parameter of the received pulse waveforms, wherein said measuring step comprises measuring the systolic upstroke times corresponding to received pulse waveforms;
comparing the measured systolic upstroke times to a predetermined range of, systolic upstroke times;
rejecting as artifactual any of the pulse waveforms having a systolic upstroke time outside said predetermined range of systolic upstroke times; and
determining the arterial oxygen saturation levels indicated by the received signals corresponding temporally to the non-rejected pulse waveforms.
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Accused Products
Abstract
A method and apparatus for use in pulse oximetry for discriminating between valid pulse waveforms and artifactual pulse waveforms. Systolic upstroke times for valid pulse waveforms are in a consistent, narrow range which varies only slightly from subject to subject. This narrow range, which may be defined empirically for each subject or established by a default setting applicable to all subjects, defines a predetermined range of systolic upstroke times indicative of valid pulse waveforms. The systolic upstroke time of each pulse waveform is compared against the predetermined range, and pulse waveforms are deemed valid only if their systolic upstroke times are within the predetermined range. Only arterial oxygen saturation levels based on validated pulse waveforms are accepted. The present invention may also be used to validate the heart rate and/or R-R, intervals of an ECG, and for discriminating between sleep and wakefulness in a monitored subject.
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Citations
29 Claims
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1. A method for discriminating between artifactual and non-artifactual pulse waveforms generated by a pulse oximeter for validating indicated arterial oxygen saturation levels of a subject also generated by the pulse oximeter, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the method comprising:
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selecting a predetermined range of a first parameter indicative of a correct pulse waveform, said first parameter being selected from the group consisting of systolic upstroke times and diastolic times; receiving from the pulse oximeter, in a first receiving step, pulse waveforms; receiving from the pulse oximeter, in a second receiving step, signals indicative of the arterial oxygen saturation level of the subject; measuring said first parameter of the received pulse waveforms, wherein said measuring step comprises measuring the systolic upstroke times corresponding to received pulse waveforms; comparing the measured systolic upstroke times to a predetermined range of, systolic upstroke times; rejecting as artifactual any of the pulse waveforms having a systolic upstroke time outside said predetermined range of systolic upstroke times; and determining the arterial oxygen saturation levels indicated by the received signals corresponding temporally to the non-rejected pulse waveforms. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for discriminating between artifactual and non-artifactual pulse waveforms for validating indicated arterial oxygen saturation levels of a subject, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the method comprising:
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receiving pulse waveforms; measuring, in a first measuring step, a first parameter of the received pulse waveforms selected from the group consisting of the systolic upstroke times and diastolic times; comparing the measured first parameter to a predetermined range of the first parameter indicative of a correct pulse waveform; rejecting as artifactual any of the received pulse waveforms having a said measured first parameter outside said predetermined range of the first parameter; measuring, in a second measuring step, the first parameter for as plurality of pulse waveforms generated prior to said first measuring step; and determining said predetermined range from selected first parameter values measured during said second measuring step, wherein said step of determining said predetermined range comprises; determining a second parameter selected from a mean and median of the selected first parameter for said plurality of pulse waveforms of said second measuring step, and establishing said predetermined range as within a predetermined time interval having a minimum less than said second parameter and a maximum greater than said second parameter. - View Dependent Claims (9)
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10. A method for discriminating between artifactual and non-artifactual pulse waveforms for validating indicated arterial oxygen saturation levels of a subject, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the method comprising:
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receiving pulse waveforms; measuring a first parameter of the received pulse waveforms selected from the group consisting of the systolic upstroke times and diastolic times; comparing the measured first parameter to a predetermined range of the first parameter indicative of a correct pulse waveform; rejecting as artifactual any of the pulse waveforms having a said measured first parameter outside said predetermined range of the first parameter; and determining whether said subject is asleep or awake by classifying said subject as awake during time intervals corresponding to rejected pulse waveforms and as asleep during time intervals corresponding to non-rejected pulse waveforms. - View Dependent Claims (11)
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12. A method for discriminating between artifactual and non-artifactual pulse waveforms for validating a heart rate of a subject, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the method comprising:
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receiving pulse waveforms; measuring a first parameter of the received pulse waveforms selected from the group consisting of the systolic upstroke times and diastolic times; comparing the measured first parameter to a predetermined range of the first parameter indicative of a correct pulse waveform; rejecting as artifactual any of the pulse waveforms having a said measured first parameter outside said predetermined range of the first parameter; monitoring said subject with an ECG for generating a signal indicative of the heart rate of the subject; determining a pulse rate from pulse waveforms not rejected at said rejecting step; and validating the heart rate of the subject only when the pulse rate of the non-rejected pulse waveforms is approximately equal to the heart rate. - View Dependent Claims (13, 14, 15)
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16. An apparatus for discriminating between artifactual and non-artifactual pulse waveforms for validating indicated arterial oxygen saturation levels of a subject, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the apparatus comprising:
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means for selecting a predetermined range of a first parameter indicative of a correct pulse waveform, said selecting means selecting said first parameter from the group consisting of systolic upstroke times and diastolic times; first means for receiving pulse waveforms; second means for receiving signals indicative of the arterial oxygen saturation level of the subject; means for measuring said first parameter of the pulse waveforms received by said first receiving means, wherein said means for measuring is operative to measure systolic upstroke times of the received pulse waveforms; means for comparing the measured systolic upstroke times to the predetermined range of systolic upstroke times selected by said selecting means; means for rejecting as artifactual any of the received pulse waveforms corresponding to measured systolic upstroke times outside said predetermined range of systolic upstroke times; and means for determining the arterial oxygen saturation levels indicated by the received signals corresponding temporarily to the non-rejected pulse waveforms. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. An apparatus for discriminating between artifactual and non-artifactual pulse waveforms for validating indicated arterial oxygen saturation levels of a subject the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the apparatus comprising:
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means for receiving pulse waveforms; first means for measuring a first parameter of said received pulse waveforms, said measured first parameter being selected from the group consisting of the systolic upstroke times and diastolic times; second means for measuring the first parameter for a plurality of waveforms generated prior to the pulse waveforms received by said first means for receiving; means for determining a predetermined range of the first parameter indicative of a correct pulse waveform from said measured first parameter of said pulse waveforms, wherein said means for determining said predetermined range is operative to determine one of a mean and median of said selected one of said systolic upstroke times and diastolic times for said prior generated plurality of pulse waveforms and to establish as said predetermined range a predetermined time interval having a minimum less than one of said mean and median and a maximum greater than one of said mean and median; means for comparing the measured first parameter of said pulse waveforms to said predetermined range of the first parameter; and means for rejecting as artifactual any of the received pulse waveforms having a said measured first parameter outside said predetermined range of the first parameter. - View Dependent Claims (24)
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25. An apparatus for discriminating between artifactual and nonartifactual pulse waveforms for validating indicated arterial oxygen saturation levels of a subject, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the apparatus comprising:
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means for receiving pulse waveforms; means for measuring a first parameter of said received pulse waveforms, said measured first parameter being selected from the group consisting of the systolic upstroke times and diastolic times; means for comparing the measured first parameters to a predetermined range of the first parameter indicative of a correct pulse waveform; means for rejecting as artifactual any of the received pulse waveforms having a said measured first parameter outside the predetermined range of the first parameter; and means for classifying said subject as awake during first time intervals corresponding to rejected pulse waveforms and as asleep during second time intervals corresponding to non-rejected pulse waveforms. - View Dependent Claims (26, 27, 28)
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29. An apparatus for discriminating between artifactual and non-artifactual pulse waveforms for validating a heart rate of a subject, the pulse waveforms each being defined, at least partially, by a systolic upstroke time and a diastolic time, the apparatus comprising:
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means for receiving the pulse waveforms corresponding to pulse signals output by a pulse oximeter; means for measuring a first parameter of said received pulse waveforms selected from the group consisting of the systolic upstroke times and diastolic times; means for comparing the measured first parameter to a redetermined range of the first parameter indicative of a correct pulse waveform; means for rejecting as artifactual any of the received pulse waveforms having a said measured first parameter outside said predetermined range of the first parameter; an ECG for generating a signal indicative of a heart rate of the subject; means for determining a pulse rate from the pulse waveforms generated by the pulse oximeter; and means for indicating that the pulse rate of non-rejected pulse waveforms is approximately equal to the heart rate.
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Specification