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Method and system to identify motion artifacts and improve reliability of measurements and alarms in photoplethysmographic measurements

  • US 9,788,793 B2
  • Filed: 07/22/2013
  • Issued: 10/17/2017
  • Est. Priority Date: 08/01/2012
  • Status: Active Grant
First Claim
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1. A system for identifying motion artifacts, said system comprising:

  • a probe configured to sense a physiological parameter of an associated patient, the probe configured to be positioned on or proximate to the associated patient, the probe being configured to generate one or more physiological signals indicative of the sensed physiological parameter;

    an accelerometer configured to be positioned on, proximate to, or integrated with the probe, the accelerometer configured to generate one or more acceleration signals measuring acceleration;

    a first signal processing unit configured to process the one or more physiological signals from the probe to determine measurements of the physiological parameter;

    a second signal processing unit configured to process one or more acceleration signals from the accelerometer to determine motion characteristics, the processing of the second signal processing unit being performed in parallel, and independent of, the processing of the first signal processing unit; and

    a labeling unit configured to label measurement of the physiological parameter with temporally corresponding motion characteristics based on the determined motion characteristics; and

    a signal quality index (SQI) threshold unit configured to discard or down weight measurements of the physiological parameter with signal quality indices (SQI)s below a SQI threshold and passing a remaining or down weighted measurements of the physiological parameter to the labeling unit; and

    wherein the SQI threshold unit is configured to determine the SQI threshold by;

    determining whether there is motion based on the measured acceleration;

    in response to determining there is no motion, setting the SQI threshold to a predetermined value;

    in response to determining there is motion, determining whether the motion is correlated with a measured motion artifact of the one or more physiological signals that is generated by, and received from, the probe;

    in response to determining the motion is correlated, setting the SQI threshold to a first value using a correlated lookup function of a motion strength value; and

    in response to determining the motion is uncorrelated, setting the SQI threshold to a second value using an uncorrelated lookup function of the motion strength value.

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