Systems and methods for determining respiration information from a photoplethysmograph
First Claim
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1. A method for determining respiration information, the method comprising:
- receiving a photoplethysmograph (PPG) signal;
identifying, using a processor, a plurality of time domain fiducial points in the PPG signal;
generating, using the processor, a plurality of morphology metric signals from time domain portions of the PPG signal defined by the plurality of fiducial points, at least one of the plurality of morphology metric signals being selected from the group consisting of a down metric signal, a kurtosis signal of a derivative of the PPG signal, and a delta of second derivative of the PPG signal, wherein the down metric signal is based on a difference between an amplitude of a fiducial point defining a beginning of a time domain portion of the PPG signal and a minimum amplitude of the time domain portion of the PPG signal, and wherein the delta of second derivative of the PPG signal is based on a difference between a second derivative of a fiducial point of the PPG signal and a second derivative of another fiducial point of the PPG signal; and
processing, using the processor the plurality of morphology metric signals to determine a respiration rate from the plurality of morphology metric signals.
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Abstract
A patient monitoring system may receive a photoplethysmograph (PPG) signal including samples of a pulse waveform. The PPG signal may demonstrate morphology changes based on respiration. The system may calculate morphology metrics from the PPG signal, the first derivative of the PPG signal, the second derivative of the PPG signal, or any combination thereof. The morphology metrics may demonstrate amplitude modulation, baseline modulation, and frequency modulation of the PPG signal that is related to respiration. Morphology metric signals generated from the morphology metrics may be used to determine respiration information such as respiration rate.
179 Citations
12 Claims
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1. A method for determining respiration information, the method comprising:
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receiving a photoplethysmograph (PPG) signal; identifying, using a processor, a plurality of time domain fiducial points in the PPG signal; generating, using the processor, a plurality of morphology metric signals from time domain portions of the PPG signal defined by the plurality of fiducial points, at least one of the plurality of morphology metric signals being selected from the group consisting of a down metric signal, a kurtosis signal of a derivative of the PPG signal, and a delta of second derivative of the PPG signal, wherein the down metric signal is based on a difference between an amplitude of a fiducial point defining a beginning of a time domain portion of the PPG signal and a minimum amplitude of the time domain portion of the PPG signal, and wherein the delta of second derivative of the PPG signal is based on a difference between a second derivative of a fiducial point of the PPG signal and a second derivative of another fiducial point of the PPG signal; and processing, using the processor the plurality of morphology metric signals to determine a respiration rate from the plurality of morphology metric signals. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system comprising:
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an interface configured to receive a photoplethysmograph (PPG) signal; a processor configured to; identify a plurality of time domain fiducial points in the PPG signal; generate a plurality of morphology metric signals from time domain portions of the PPG signal defined by the plurality of fiducial points, at least one of the plurality of morphology metric signals being selected from the group consisting of a down metric signal, a kurtosis signal of a derivative of the PPG signal, and a delta of second derivative of the PPG signal, wherein the down metric signal is based on a difference between an amplitude of a fiducial point defining a beginning of a time domain portion of the PPG signal and a minimum amplitude of the time domain portion of the PPG signal, and wherein the delta of second derivative of the PPG signal is based on a difference between a second derivative of a fiducial point of the PPG signal and a second derivative of another fiducial point of the PPG signal; and process the plurality of morphology metric signals to determine a respiration rate from the plurality of morphology metric signals. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification