CN112263249A - A method and device for enhancing blood oxygen saturation monitoring based on ECG - Google Patents
A method and device for enhancing blood oxygen saturation monitoring based on ECG Download PDFInfo
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Abstract
The invention relates to a method and a device for strengthening blood oxygen saturation monitoring based on ECG. The invention synchronously acquires the ECG signal and the PPG signal of an individual, designs the real-time personalized filter based on the individual of a subject through the ECG signal, and compared with the traditional filter, the filter can be more targeted on specific scene application, effectively inhibits noise and strengthens the heart rate signal characteristics. The PPG signal processed by the ECG real-time personalized filter is used for monitoring the blood oxygen saturation, so that the stability and the robustness of measurement can be enhanced.
Description
Technical Field
The invention relates to the field of physiological data monitoring, in particular to a method and a device for strengthening blood oxygen saturation monitoring based on ECG.
Background
Photoplethysmography (PPG) reflects important information of a human body, contains abundant microcirculation physiological and pathological information, and is an important information source for researching a human body circulatory system. The application field of the method is developed from a human body circulatory system to a respiratory system, and the method has good application prospect in noninvasive detection of human body blood pressure, blood flow, blood oxygen, cerebral oxygen, muscular oxygen, blood sugar, pulse rate, respiratory capacity and the like.
Extracting the features of blood oxygen saturation from PPG signals has become the most prominent way to non-invasively measure blood oxygen saturation at present. The principle of the PPG signal for measuring blood oxygen saturation is: the absorption intensity of different oxygen contents of hemoglobin on the spectrum is different, for example, when the oxygen content of arterial blood is reduced, the absorption of hemoglobin on red light is enhanced, and the absorption of infrared light is weakened. Therefore, the blood oxygen saturation can be calculated and calibrated through the amplitude change of the red light and infrared light two-channel signals. However, PPG has the disadvantage of being quite sensitive to ambient noise (including body motion, ambient light variations, etc.). The amplitude variation of the PPG signal, once disturbed by noise, is difficult to use for the calculation of the blood oxygen saturation.
Finger oximeter is a relatively mature wearable physiological monitoring product on the market at present, and monitors heart rate and blood oxygen saturation through red and infrared dual-band. However, as mentioned above, because the optical signal is sensitive to environmental noise (body motion, ambient light variation, etc.), the stability and robustness of PPG monitoring are low.
The prior art discloses methods for improving the accuracy of the detection of blood oxygen saturation. For example, patent document CN109044323A, published japanese patent No. 20181221, discloses a heart rate and blood oxygen saturation measurement device based on deep learning and PPG signals, which uses two lights to obtain two PPG signals, and processes the PPG signals by means of a deep learning network model in the device, so as to predict the heart rate and blood oxygen saturation of a human body. The device has good tolerance to noise, and can accurately measure heart rate and blood oxygen in a resting state and a moving state. For another example, patent document CN109247944A, published japanese patent No. 20190122, discloses a non-contact type blood oxygen saturation detection method based on a low-end color camera, which is implemented by the following steps: (1) controlling a camera to collect a video facing a human face for 12 s; (2) carrying out face detection on the collected video to obtain a stable face video; (3) extracting better pulse wave signals from the face video by using a self-adaptive noise cancellation technology; (4) calculating a direct current component IDC and an alternating current component IAC of the pulse wave signal; (5) the blood oxygen saturation is estimated by the two-wavelength method through the lambert-beer law and the light scattering theory. The invention eliminates the interference caused by head shaking and illumination change through the self-adaptive noise cancellation technology, and then carries out the blood oxygen saturation estimation of the dual-wavelength method, thereby improving the accuracy of the detection of the blood oxygen saturation, and being applicable to the non-contact type detection of the blood oxygen saturation in the realistic scene of cooperation and non-cooperation. However, there is still a need to develop new methods to improve the accuracy of monitoring the blood oxygen saturation of human body, especially in the exercise state.
The present inventors have extensively and intensively studied and found that ECG is more robust to noise disturbances (e.g. motion disturbances) than PPG, as ECG has been well-established for use in fitness products (Polar belt, ECG chest strap) to monitor the heart rate of a person while running. But the ECG electrical signal cannot measure the blood oxygen saturation because its principle does not allow. And the method is a feasible method for enhancing the stability and robustness of the PPG for measuring the blood oxygen saturation by combining the advantages of the ECG on the heart rate monitoring. Some solutions for integrating ECG and PPG into a single device are disclosed, such as patent document CN108514409A, published japanese 20180911, which discloses a multi-parameter human body detection device, comprising: the system comprises a body fat rate detection system, a blood pressure and pulse rate detection system, a blood oxygen saturation detection system, a respiratory rate detection system, an electrocardio and heart rate detection system, a body temperature detection system, a step counting system, a fingerprint identification system and an auxiliary circuit system. However, such devices are still limited to measuring different physiological signals by using ECG and PPG, respectively, and the stability and robustness of measuring the blood oxygen saturation by PPG are not improved.
Disclosure of Invention
The invention aims to provide a PPG signal denoising method aiming at the defects in the prior art.
It is a further object of this invention to provide a method for enhanced ECG-based blood oxygen saturation monitoring.
It is another object of the present invention to provide an ECG enhanced blood oxygen saturation monitoring device.
In order to achieve the first purpose, the invention adopts the technical scheme that:
a PPG signal denoising method comprises the following steps:
s1, synchronously acquiring an ECG signal and a PPG signal of the individual;
s2, obtaining an ECG frequency spectrum through the collected ECG signals;
s3, designing an ECG personalized real-time filter with the heart rate characteristics of the individual through an ECG frequency spectrum, wherein the ECG personalized real-time filter changes or optimizes filter parameters according to the real-time heart rate change of the individual so as to suppress PPG signal noise to the maximum extent and strengthen the heart rate characteristics.
Preferably, the specific algorithm of the PPG signal denoising method is as follows:
setting Pred and Pir as a double-channel PPG signal, wherein Pred is a red waveband signal and Pir is an infrared waveband signal; let E be the ECG signal;
firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
where fft () is a fourier transform, converting the input time domain signal to the frequency domain.
Calculating the frequency max _ idx corresponding to the maximum value spectrum value or energy value of the ECG signal in the frequency domain:
wherein abs () takes the absolute value of the input value; max () takes the maximum value of the input vector.
Let max _ idx be the current heart rate value to set the adaptive filter band:
wherein n is the range of heart rate variability allowed in the period;
and filtering Fred and Fir (performing frequency truncation) by taking HR _ range as a heart rate wave band, and converting the filtered PPG signal into a time domain:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))
where ifft () is an inverse fourier transform, converting the input frequency domain signal to the time domain.
In order to achieve the second object, the invention adopts the technical scheme that:
a method for ECG-based enhanced blood oxygen saturation monitoring, comprising the steps of:
s1, synchronously acquiring an ECG signal and a PPG signal of the individual;
s2, obtaining an ECG frequency spectrum through the collected ECG signals;
s3, designing an ECG personalized real-time filter with heart rate characteristics of an individual through an ECG frequency spectrum, wherein the ECG personalized real-time filter changes or optimizes filter parameters according to real-time heart rate changes of the individual so as to suppress PPG signal noise to the maximum extent and strengthen the heart rate characteristics;
s4, applying the ECG individualized real-time filter adjusted in real time to a PPG signal to suppress noise;
s5, calculating the blood oxygen saturation of the individual based on the PPG signal denoised by the ECG personalized real-time filter.
Preferably, the specific algorithm of the ECG-based enhanced blood oxygen saturation monitoring method is as follows:
setting Pred and Pir as a double-channel PPG signal, wherein Pred is a red waveband signal and Pir is an infrared waveband signal; let E be the ECG signal;
firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
where fft () is a fourier transform, converting the input time domain signal to the frequency domain.
Calculating the frequency max _ idx corresponding to the maximum value spectrum value or energy value of the ECG signal in the frequency domain:
wherein abs () takes the absolute value of the input value; max () takes the maximum value of the input vector.
Let max _ idx be the current heart rate value to set the adaptive filter band:
wherein n is the range of heart rate variability allowed in the period;
and filtering Fred and Fir (performing frequency truncation) by taking HR _ range as a heart rate wave band, and converting the filtered PPG signal into a time domain:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))
where ifft () is an inverse fourier transform, converting the input frequency domain signal to the time domain.
In order to achieve the third object, the invention adopts the technical scheme that:
an ECG-enhanced blood oxygen saturation monitoring device is characterized in that the ECG-enhanced blood oxygen saturation monitoring device is provided with an ECG sensor, a dual-channel PPG sensor and an arithmetic chip; the ECG sensor is used for acquiring an ECG signal of an individual; the two-channel PPG sensor is used for acquiring PPG signals of an individual; the operation chip comprises an ECG frequency spectrum acquisition module, an ECG individualized real-time filter parameter design module, an ECG individualized real-time filter and a blood oxygen signal calculation module; the ECG frequency spectrum acquisition module is used for deriving an ECG frequency spectrum based on an ECG signal acquired by an ECG sensor; the ECG individualized real-time filter design module is used for designing an ECG individualized real-time filter with the heart rate characteristics of an individual through an ECG frequency spectrum; the ECG individualized real-time filter is applied to a PPG signal (time domain or frequency domain), strengthens heart rate characteristics and inhibits noise; the blood oxygen signal calculation module is used for calculating the blood oxygen saturation of the individual according to the PPG signal denoised by the ECG personalized real-time filter.
Preferably, the specific algorithm of the operation chip is as follows:
setting Pred and Pir as a double-channel PPG signal, wherein Pred is a red waveband signal and Pir is an infrared waveband signal; let E be the ECG signal;
firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
where fft () is a fourier transform, converting the input time domain signal to the frequency domain.
Calculating the frequency max _ idx corresponding to the maximum value spectrum value or energy value of the ECG signal in the frequency domain:
wherein abs () takes the absolute value of the input value; max () takes the maximum value of the input vector.
Let max _ idx be the current heart rate value to set the adaptive filter band:
wherein n is the range of heart rate variability allowed in the period;
and filtering Fred and Fir (performing frequency truncation) by taking HR _ range as a heart rate wave band, and converting the filtered PPG signal into a time domain:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))
where ifft () is an inverse fourier transform, converting the input frequency domain signal to the time domain.
Preferably, the ECG enhanced blood oxygen saturation monitoring device is also provided with an alarm; the operation chip is also provided with an early warning module which is used for comparing and analyzing the actually measured blood oxygen saturation with a set standard blood oxygen saturation range and giving an alarm when the blood oxygen saturation is reduced or continues to be at a low level.
Preferably, the alarm is used for sending an alarm prompt to the individual to be tested for blood oxygen saturation or a monitoring worker, and is specifically an acoustic alarm or an optical alarm or a combination of the two.
Preferably, the arithmetic chip further judges and eliminates the artifact in the PPG signal through other denoising algorithms.
Preferably, the ECG-enhanced blood oxygen saturation monitoring device is a professional medical grade device, a home healthcare device or a portable wearable device.
The invention has the advantages that:
the PPG is easily influenced by environmental noise on signal monitoring, the real-time personalized filter based on the individual subject is designed through the ECG, and compared with the traditional filter, the real-time personalized filter can be more targeted on specific scene application, effectively inhibits noise and strengthens the heart rate signal characteristics. The PPG signal processed by the ECG real-time personalized filter is used for monitoring the blood oxygen saturation, so that the stability and the robustness of measurement can be enhanced. The invention can be applied to the following scenarios:
(1) professional medical grade equipment: long-term continuous physiological monitoring and reporting is performed for certain types of patients, such as cardiovascular disease, cardiopulmonary dysfunction/rehabilitation, sleep apnea syndrome (obstructive, central nervous, mixed), Intensive Care Unit (ICU), cardiopathy unit (CCU), postoperative care, and the like.
(2) Household healthcare equipment: providing physiological monitoring for a particular group of people or under specific circumstances, such as the elderly, infants, snorers, or groups with related needs.
Based on the invention, portable wearable equipment can be developed, ECG and PPG are integrated on one equipment, wearable continuous noninvasive blood oxygen saturation monitoring (7 days/24 hours) is realized, the blood oxygen saturation is stably monitored in real time through ECG and dual-channel PPG signals, a data basis is provided for doctor diagnosis and treatment, and clinical significance is provided. An intelligent diagnostic and early warning function can also be added to give an alarm when the blood oxygen saturation is reduced or continues to be low (such as lower than 95%).
Drawings
FIG. 1 is a block diagram of an ECG-enhanced blood oxygen saturation monitoring device of the present invention.
FIG. 2 is a flow chart of a method of ECG-based enhanced blood oxygen saturation monitoring of the present invention.
Fig. 3 is an example of the ECG-based enhanced blood oxygen saturation monitoring method of the present invention.
FIG. 4 is a block diagram of another ECG enhanced blood oxygen saturation monitoring device in accordance with the present invention.
Detailed Description
The following detailed description of the present invention will be made with reference to the accompanying drawings.
The reference numerals and components referred to in the drawings are as follows:
3. Operation chip 21.LED light source
22. Photodetector 31 ECG frequency spectrum acquisition Module
ECG personalized real-time Filter parameter design Module 33 ECG personalized real-time Filter
34. Blood oxygen signal calculation module 35, early warning module
4. Alarm device
Referring to fig. 1, fig. 1 is a block diagram of an ECG-enhanced blood oxygen saturation monitoring apparatus according to the present invention. The ECG-enhanced blood oxygen saturation monitoring device is provided with an ECG sensor 1, a dual-channel PPG sensor 2 and an operation chip 3.
The ECG sensor 1 is used to acquire an ECG signal of an individual. Preferably, the skin potential variation is measured by attaching electrodes at different positions on the surface of the human body, and the potential difference between the electrodes is traced. More preferably, the ECG sensor 1 is used to sense the action potential waveforms of cells in different areas of the heart and convert them into usable ECG signals.
The two-channel PPG sensor 2 is used to acquire a PPG signal, which contains the necessary elements to measure the blood oxygen saturation based on the PPG signal. Typically, the necessary elements include an LED light source 21, which includes both red and infrared light sources, and a photodetector 22.
The operation chip 3 comprises an ECG frequency spectrum acquisition module 31, an ECG personalized real-time filter parameter design module 32, an ECG personalized real-time filter 33 and a blood oxygen signal calculation module 34. The ECG frequency spectrum acquisition module 31 is configured to derive an ECG frequency spectrum based on the ECG signals acquired by the ECG sensor. The ECG personalized real-time filter design module 32 is used to design an ECG personalized real-time filter with heart rate characteristics of an individual by an ECG frequency spectrum. The ECG personalized real-time filter 33 is used for applying to the PPG signal (time domain or frequency domain), enhancing heart rate characteristics, and suppressing noise. The blood oxygen signal calculating module 34 is configured to calculate the blood oxygen saturation of the individual according to the PPG signal denoised by the ECG personalized real-time filter. The specific algorithm of the operation chip 3 is as follows:
let Pred, Pir be the two-channel PPG signal, where Pred is the red band signal and Pir is the infrared band signal. Let E be the ECG signal. Firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
where fft () is a fourier transform, converting the input time domain signal to the frequency domain.
Calculating the frequency max _ idx corresponding to the maximum value spectrum value (or energy value) of the ECG signal in the frequency domain, as follows:
wherein abs () takes the absolute value of the input value; max () takes the maximum value of the input vector.
Let max _ idx be the current heart rate value to set the adaptive filtering band, such as:
where "3 bpm" is the range (settable) allowed for the heart rate variability over that period. And filtering Fred and Fir (performing frequency truncation) by taking HR _ range as a heart rate wave band, and converting the filtered PPG signal into a time domain, such as:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))
where ifft () is an inverse fourier transform, converting the input frequency domain signal to the time domain.
Finally, PFred and PFir may be used to calculate the blood oxygen saturation.
Embodiment 2 a method for strengthening blood oxygen saturation monitoring based on ECG
Referring to fig. 2, fig. 2 is a flowchart illustrating a method for enhanced ECG-based blood oxygen saturation monitoring according to the present invention. The method for strengthening the blood oxygen saturation monitoring based on the ECG comprises the following steps:
and S1, synchronously acquiring the ECG signal and the PPG signal of the individual.
S2, an ECG frequency spectrum is derived from the acquired ECG signal.
S3, since the ECG has more heart rate waveform features (such as QRS waves) and harmonic features than the PPG, this step designs an ECG personalized real-time filter with individual heart rate features through the ECG frequency spectrum. The ECG personalized real-time filter is distinguished from the conventional filter by the following features: the parameters of the conventional filter are fixed and do not take into account the specific situation of a single individual, such as assuming a heart rate fluctuation interval of 30-240 times/min, while the ECG-personalized real-time filter can change (or optimize) the filter parameters according to the real-time heart rate variation of different individuals (such as 150 times/min of the infant) to suppress noise to the maximum extent, enhancing the heart rate characteristics. Even for a single individual, the ECG personalized real-time filter can set different filter parameters (such as the heart rate rising after a meal or during exercise) according to the heart rate of the individual in different time periods, so as to achieve real-time optimization.
S4, applying the ECG personalized real-time filter adjusted in real-time on the PPG signal (time domain or frequency domain) to suppress noise.
S5, calculating the blood oxygen saturation of the individual based on the PPG signal denoised by the ECG personalized real-time filter.
The specific algorithm of the above steps is as follows:
let Pred, Pir be the two-channel PPG signal, where Pred is the red band signal and Pir is the infrared band signal. Let E be the ECG signal. Firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
where fft () is a fourier transform, converting the input time domain signal to the frequency domain.
Calculating the frequency max _ idx corresponding to the maximum value spectrum value (or energy value) of the ECG signal in the frequency domain, as follows:
wherein abs () takes the absolute value of the input value; max () takes the maximum value of the input vector.
Let max _ idx be the current heart rate value to set the adaptive filtering band, such as:
where "3 bpm" is the range (settable) allowed for the heart rate variability over that period. And filtering Fred and Fir (performing frequency truncation) by taking HR _ range as a heart rate wave band, and converting the filtered PPG signal into a time domain, such as:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))
where ifft () is an inverse fourier transform, converting the input frequency domain signal to the time domain.
Finally, PFred and PFir may be used to calculate the blood oxygen saturation.
Fig. 3 is an example of a method of ECG-based enhanced blood oxygen saturation monitoring.
EXAMPLE 3 Another ECG-enhanced oximetry device of the present invention
Referring to fig. 4, fig. 4 is a block diagram of another ECG enhanced blood oxygen saturation monitoring apparatus according to the present invention. The ECG-enhanced blood oxygen saturation monitoring device is provided with an ECG sensor 1, a dual-channel PPG sensor 2, an operation chip 3 and an alarm 4.
The ECG sensor 1 is used to acquire an ECG signal of an individual. Preferably, the skin potential variation is measured by attaching electrodes at different positions on the surface of the human body, and the potential difference between the electrodes is traced. More preferably, the ECG sensor 1 is used to sense the action potential waveforms of cells in different areas of the heart and convert them into usable ECG signals.
The two-channel PPG sensor 2 is used to acquire an ECG signal, which contains the necessary elements to measure the blood oxygen saturation based on the PPG signal. Typically, the necessary elements include an LED light source 21, which includes both red and infrared light sources, and a photodetector 22.
The operation chip 3 comprises an ECG frequency spectrum acquisition module 31, an ECG personalized real-time filter parameter design module 32, an ECG personalized real-time filter 33, a blood oxygen signal calculation module 34 and an early warning module 35. The ECG frequency spectrum acquisition module 31 is configured to derive an ECG frequency spectrum based on the ECG signals acquired by the ECG sensor. The ECG personalized real-time filter design module 32 is used to design an ECG personalized real-time filter with heart rate characteristics of an individual by an ECG frequency spectrum. The ECG personalized real-time filter 33 is used for applying to the PPG signal (time domain or frequency domain), enhancing heart rate characteristics, and suppressing noise. The blood oxygen signal calculating module 34 is configured to calculate the blood oxygen saturation of the individual according to the PPG signal denoised by the ECG personalized real-time filter. The early warning module 35 is used for comparing and analyzing the actually measured blood oxygen saturation with a set standard blood oxygen saturation range, and giving an alarm when the blood oxygen saturation is reduced or continues to be at a low level (e.g. lower than 95%). The specific algorithm of the operation chip 3 is as described in embodiment 1.
The alarm 4 is used for giving an alarm prompt to the individual to be measured for blood oxygen saturation or the staff for monitoring, and can be an acoustic alarm or an optical alarm or a combination of the two.
For the above embodiments, it should be further explained that the present invention designs the real-time personalized filter based on the individual subject through the ECG, which is more flexible and targeted than the conventional fixed parameter filter, and can automatically adjust the filter parameters according to the ECG signal according to different individuals (infants, adults, and the elderly) and different application scenarios (sleeping and moving), so as to achieve the PPG filtering range most suitable for the individual and the scenario. In the implementation process of the invention, the red light intensity signal and the infrared light intensity signal are required to be acquired at the same time so as to ensure that the value of the blood oxygen saturation is accurately calculated. The arithmetic chip 3 may further determine and eliminate artifacts in the PPG signal through other denoising algorithms, including but not limited to independent component analysis, singular value decomposition, wavelet transformation, empirical mode decomposition, and adaptive filter. The ECG-enhanced blood oxygen saturation monitoring device of the present invention may further comprise a storage module for storing the measurement data. When the portable wearable measuring device is used as a hospital monitoring device or a portable wearable measuring device, a display screen is preferably arranged on the device and used for displaying blood oxygen saturation data, a communication interface is arranged on the device, and measured related data are sent to an intelligent terminal through a wireless receiving module to be stored or sent to a remote hospital workstation through the internet when necessary. The device should also have a power supply for supplying power to components such as the ECG sensor, the dual channel PPG sensor and the computing chip.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.
Claims (10)
1. A PPG signal denoising method is characterized by comprising the following steps:
s1, synchronously acquiring an ECG signal and a PPG signal of the individual;
s2, obtaining an ECG frequency spectrum through the collected ECG signals;
s3, designing an ECG personalized real-time filter with the heart rate characteristics of the individual through an ECG frequency spectrum, wherein the ECG personalized real-time filter changes or optimizes filter parameters according to the real-time heart rate change of the individual so as to suppress PPG signal noise to the maximum extent and strengthen the heart rate characteristics.
2. The method for denoising the PPG signal according to claim 1, wherein the specific algorithm of the method for denoising the PPG signal is as follows:
setting Pred and Pir as a double-channel PPG signal, wherein Pred is a red waveband signal and Pir is an infrared waveband signal; let E be the ECG signal;
firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
calculating the frequency max _ idx corresponding to the maximum value spectrum value or energy value of the ECG signal in the frequency domain:
let max _ idx be the current heart rate value to set the adaptive filter band:
wherein n is the range of heart rate variability allowed in the period;
and filtering Fred and Fir by taking HR _ range as a heart rate wave band, and converting the PPG signal after filtering into a time domain:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))。
3. a method for enhanced ECG-based blood oxygen saturation monitoring, comprising the steps of:
s1, synchronously acquiring an ECG signal and a PPG signal of the individual;
s2, obtaining an ECG frequency spectrum through the collected ECG signals;
s3, designing an ECG personalized real-time filter with heart rate characteristics of an individual through an ECG frequency spectrum, wherein the ECG personalized real-time filter changes or optimizes filter parameters according to real-time heart rate changes of the individual so as to suppress PPG signal noise to the maximum extent and strengthen the heart rate characteristics;
s4, applying the ECG individualized real-time filter adjusted in real time to a PPG signal to suppress noise;
s5, calculating the blood oxygen saturation of the individual based on the PPG signal denoised by the ECG personalized real-time filter.
4. The method for ECG-based enhanced blood oxygen saturation monitoring according to claim 3, wherein the specific algorithm of the method for ECG-based enhanced blood oxygen saturation monitoring is as follows:
setting Pred and Pir as a double-channel PPG signal, wherein Pred is a red waveband signal and Pir is an infrared waveband signal; let E be the ECG signal;
firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
calculating the frequency max _ idx corresponding to the maximum value spectrum value or energy value of the ECG signal in the frequency domain:
let max _ idx be the current heart rate value to set the adaptive filter band:
wherein n is the range of heart rate variability allowed in the period;
and filtering Fred and Fir by taking HR _ range as a heart rate wave band, and converting the PPG signal after filtering into a time domain:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))。
5. an ECG-enhanced blood oxygen saturation monitoring device is characterized in that the ECG-enhanced blood oxygen saturation monitoring device is provided with an ECG sensor, a dual-channel PPG sensor and an arithmetic chip; the ECG sensor is used for acquiring an ECG signal of an individual; the two-channel PPG sensor is used for acquiring PPG signals of an individual; the operation chip comprises an ECG frequency spectrum acquisition module, an ECG individualized real-time filter parameter design module, an ECG individualized real-time filter and a blood oxygen signal calculation module; the ECG frequency spectrum acquisition module is used for deriving an ECG frequency spectrum based on an ECG signal acquired by an ECG sensor; the ECG individualized real-time filter design module is used for designing an ECG individualized real-time filter with the heart rate characteristics of an individual through an ECG frequency spectrum; the ECG individualized real-time filter is applied to a PPG signal, strengthens heart rate characteristics and inhibits noise; the blood oxygen signal calculation module is used for calculating the blood oxygen saturation of the individual according to the PPG signal denoised by the ECG personalized real-time filter.
6. The ECG enhanced blood oxygen saturation monitoring device according to claim 5, wherein the specific algorithm of the arithmetic chip is as follows:
setting Pred and Pir as a double-channel PPG signal, wherein Pred is a red waveband signal and Pir is an infrared waveband signal; let E be the ECG signal;
firstly, Fourier transform is carried out on three signals of Pred, Pir and E to convert the signals from a time domain to a frequency domain:
Fred＝fft(Pred)
Fir＝fft(Pir)
Fe＝fft(E)
calculating the frequency max _ idx corresponding to the maximum value spectrum value or energy value of the ECG signal in the frequency domain:
let max _ idx be the current heart rate value to set the adaptive filter band:
wherein n is the range of heart rate variability allowed in the period;
and filtering Fred and Fir by taking HR _ range as a heart rate wave band, and converting the PPG signal after filtering into a time domain:
PFred＝ifft(Fred(HRrange))
PFir＝ifft(Fir(HRrange))。
7. the ECG enhanced blood oxygen saturation monitoring device according to claim 5, wherein the ECG enhanced blood oxygen saturation monitoring device is further provided with an alarm; the operation chip is also provided with an early warning module which is used for comparing and analyzing the actually measured blood oxygen saturation with a set standard blood oxygen saturation range and giving an alarm when the blood oxygen saturation is reduced or continues to be at a low level.
8. The ECG enhanced blood oxygen saturation monitoring device according to claim 7, wherein the alarm is used for giving an alarm prompt to the individual whose blood oxygen saturation is measured or the staff who monitors, in particular an audible alarm or a light alarm or a combination of the two.
9. The ECG enhanced blood oxygen saturation monitoring device according to claim 5, wherein said arithmetic chip further determines and eliminates artifacts in the PPG signal by other denoising algorithms.
10. The ECG enhanced blood oxygen saturation monitoring device according to claim 5, wherein said ECG enhanced blood oxygen saturation monitoring device is a professional medical grade device, a home healthcare device or a portable wearable device.
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