Health monitoring systems and methods
Systems, methods and devices for reducing noise in health monitoring including monitoring systems, methods and/or devices receiving a health signal and/or having at least one electrode or sensor for health monitoring.
1. A method for health monitoring comprising:
providing one or more ECG sensors to sense an ECG signal, and providing one or more PPG sensors to sense first and second PPG signals of first and second light wavelengths, all of the one or more ECG sensors and the one or more PPG sensors are configured to be disposed on a single health monitoring device configured to be disposed on a portion of a body;
sensing the ECG signal, the ECG signal including heartbeat information including information from one or more heartbeats; and sensing the first and second PPG signals corresponding to the first and second light wavelengths;
generating two or more PPG frames of the first and second PPG signals, the two or more PPG frames each being defined by the one or more heartbeats as included within the heartbeat information from the ECG signals and the first and second PPG signals, each of the two or more PPG frames including the first and second PPG signals occurring in an interval defined by the one or more heartbeats, the first and second PPG signals thereby being correlated with the one or more heartbeats;
constructing two or more time-concordance average frames from the two or more PPG frames; the two or more time-concordance average frames including a first time-concordance average frame corresponding to a first light wavelength selected from the first and second light wavelengths and a second time-concordance average frame corresponding to a second light wavelength selected from the first and second light wavelengths; the two or more time-concordance average frames being constructed by:
comparing a portion of the ECG signal and the first and second PPG signals in time concordance over the one or more heartbeats of the heartbeat information to determine a constant component value and a primary periodic component value of each of the first and second PPG signals; the portion of the ECG signal defining an interval within the one or more heartbeats corresponding with the two or more PPG frames, the constant component and primary periodic component values at concordant times within intervals averaged to calculate and define the first and second time-concordance average frames, the first and second time-concordance average frames reducing signal noise;
selecting a gain value,
multiplying the first time-concordance average frame by the selected gain value, and
determining a residual error with respect to the second time-concordance average frame of the second one of the first and second wavelengths of the first and second wavelengths; and,
calculating oxygen saturation from the first time-concordance average frame; from the constant component values and primary periodic component values of the first and second PPG signals; and from the residual error;
optionally, repeating one or more or all of the selecting, multiplying and determining operations for a number of gain values.
2. A method according to claim 1 further including finding one or more local minima and a global minimum of the first and second PPG signals; this finding further including determining from the global minimum a correlation caused by motion artifact, venous blood movement or another noise source, whereupon the global minimum is ignored, and from the one or more local minima a local minimum is selected instead.
3. A method according to claim 1 further comprising:
determining one or more of depth and/or rate of respiration.
4. A method according to claim 3 further comprising:
determining respiration rate and/or depth using one or more of ECG signal, the first and second PPG signals, pulse oximeter data and/or accelerometer data.
5. A method according to claim 4 including
generating a respiration waveform using the one or more of ECG signal, the first and second PPG signals, pulse oximeter data and/or accelerometer data.
6. A method according to claim 3 , the first and second light wavelengths being red or infrared (IR) values; including:
two or more red wavelengths, or
two or more IR wavelengths, or
one or more red wavelengths and one or more infrared (IR) wavelengths.
7. A method according to claim 3 , the PPG sensors including a photodiode; the method further including:
measuring IR or red reflection by the photodiode to estimate depth and/or rate of respiration.
8. A method according to claim 6 additionally determining one or both of:
maximum values of a curve or waveform of an IR or red PPG signal, and
minimum values of a curve or waveform of an IR or red PPG signal to represent the difference between respective maximum values of a curve or waveform of IR or red PPG signals and the minimum values of a curve or waveform of IR or red PPG signals related to one or both of:
a depth of breath in an individual being monitored, and/or,
a rate of respiration over time; evaluating said rate from a curve of maximum and minimum values over time.
9. A method according to claim 1 including
generating the two or more PPG frames in time concordance with the movement of the chest of the body expanding and contracting during breathing, and determining the presentation of the motion hereof as a wandering baseline artifact on one or both the first and second PPG signals.
10. A method according to claim 1 including
isolating a respiration signal by filtering one or both the first and second PPG signals to focus on the respiration signal.
11. A method according to claim 1 , the one or more PPG sensors being chest-mounted.
12. A method according to claim 3 the constructing including measuring one or more accelerometer signals by an accelerometer disposed on the single health monitoring device.
13. A method according to claim 12 including
measuring the one or more accelerometer signals in time concordance with the movement of one or both a chest of the body expanding and contracting, or a chest of the body accelerating up and down, as measured by the accelerometer.
14. A method according to claim 12 including
isolating a respiration signal by filtering one or more of the accelerometer signals to focus on the respiration signal.
15. A method according to claim 12 further including one or both:
chest-mounting the accelerometer and
lying the body of a user on his/her back.