Monitoring respiration based on plethysmographic heart rate signal
First Claim
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1. A method for use in monitoring a patient, comprising the steps of:
- obtaining a photoplethysmographic (“
pleth”
) signal that is modulated based on interaction of a transmitted optical signal having at least two wavelength cannels with a patient'"'"'s blood;
first processing at least a first portion of said pleth signal to obtain a blood oxygen related value associated with said patient'"'"'s blood;
based on said blood oxygen related value, selecting at least one of said wavelength channels of said pleth signal for additional processing;
second processing at least a second portion of said at least one wavelength channel of said pleth signal to obtain heart rate information regarding a heart rate of said patient; and
third processing said heart rate information to obtain respiration information regarding respiration of said patient.
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Abstract
A pleth signal is analyzed to identify a heart rate variability parameter associated with respiration rate. In one embodiment, an associated process involves obtaining a photoplethysmograpic signal, processing the pleth signal to obtain heart rate samples, monitoring the heart rate sample to identify a heart rate variability associated with respiration, and determining a respiration rate based on the heart rate variability. The photoplethysmographic signal may be based on one or more channel signals of a conventional pulse oximeter. The invention thus allows for noninvasive monitoring of respiration rate and expands the functionality of pulse oximeters.
353 Citations
38 Claims
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1. A method for use in monitoring a patient, comprising the steps of:
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obtaining a photoplethysmographic (“
pleth”
) signal that is modulated based on interaction of a transmitted optical signal having at least two wavelength cannels with a patient'"'"'s blood;
first processing at least a first portion of said pleth signal to obtain a blood oxygen related value associated with said patient'"'"'s blood;
based on said blood oxygen related value, selecting at least one of said wavelength channels of said pleth signal for additional processing;
second processing at least a second portion of said at least one wavelength channel of said pleth signal to obtain heart rate information regarding a heart rate of said patient; and
third processing said heart rate information to obtain respiration information regarding respiration of said patient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 23)
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14. A method for use in monitoring a patient, comprising the steps of:
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obtaining a time-based photoplethysmographic (“
pleth”
) signal that is modulated based on interaction of a transmitted optical signal with a patient'"'"'s blood;
transforming a selected portion of said time-based pleth signal to into a frequency domain pleth signal;
obtaining a heart rate signal, from said frequency domain pleth signal, reflecting a time series of heart rate values for said patient processing said heart rate signal using at least one filter to distinguish a signal component of interest having a frequency corresponding to a respiration rate of said patient from a potentially interfering signal component; and
providing an output indicative of said respiration rate of said patient based on said signal component of interest. - View Dependent Claims (15, 16, 24, 25)
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17. An apparatus for use in monitoring a patient, comprising:
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a port for receiving a photoplethysmograph (“
pleth”
) signal that is modulated based on interaction of a transmitted optical signal with a patient'"'"'s blood; and
a processor operative for;
first processing said pleth signal to determine a blood oxygen level associated with said patient'"'"'s blood;
based on said blood oxygen level, second processing a selected portion said pleth signal to obtain heart rate information regarding a heart rate of said patient; and
third processing said heart rate information to obtain respiration information regarding respiration of said patient. - View Dependent Claims (18, 19, 20, 21, 22)
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26. A method for use in monitoring a patient, comprising the steps of:
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obtaining a photoplethysmographic (“
pleth”
) signal that is modulated based on interaction of a transmitted optical signal with a patient'"'"'s blood, said pleth signal being in the time domain;
first performing a transform on said time domain pleth signal to obtain spectral information, said spectral information being in the frequency domain;
second performing a transform based on said spectral information to obtain transformed information; and
identifying a physiological parameter of interest based on said transformed information. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
processing said pleth signal to obtain a blood oxygen value associated with said patient'"'"'s blood; and
based on said blood oxygen level, selecting at least one of said wavelength channels of said pleth signal for additional processing.
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29. The method of claim 26, further comprising;
prior to said second performing step processing said spectral information to obtain a power pleth spectrum signal.
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30. The method of claim 29, wherein said step of processing comprises identifying a spectral peak associated with a heart rate of said patient.
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31. The method of claim 30, wherein said step of identifying further comprises generating a time series of heart rate values for said patient.
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32. The method of claim 31, wherein said second performing step comprise transforming said time series of heart rate values to obtain respiratory information, said respiratory information being in the frequency domain.
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33. The method of claim 32, wherein a spectral peak of said respiratory information in said frequency domain is associated with respiration.
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34. A method for use in monitoring a patient, comprising the steps of:
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obtaining a time-based photoplethysmographic (“
pleth”
) signal that is modulated based on interaction of a transmitted optical signal having at least two wavelength channels with a patient'"'"'s blood;
first processing an AC component of at least one of said wavelength channels to obtain a heart rate signal reflecting a time series of heart rate values for said patient;
second processing said heart rate information to obtain respiration information regarding respiration of said patient. - View Dependent Claims (35, 36, 37, 38)
processing at least a first portion of said pleth signal to obtain a blood oxygen related value associated with said patient'"'"'s blood;
and based on said blood oxygen related value, selecting at least one of said wavelength channels of said pleth signal for said first processing step.
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36. The method of claim 34, wherein said first processing step includes:
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transforming said time-based pleth signal into spectral information;
identifying a spectral peak associated with a heart rate of said patient; and
using a plurality of temporally distinct spectral peaks associated with said heart rate to generate said heart rate signal, wherein said heart rate signal is a time-based signal.
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37. The method of claim 34, wherein said second processing step comprises transforming said heart rate signal into a frequency-based signal.
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38. The method of claim 37, further comprising identifying a spectral peak in said frequency-based signal associated with a respiration rate of said patient.
Specification