Dynamic continuous blood pressure monitoring system and method based on four-element electric network model

Abstract

The invention discloses a dynamic continuous blood pressure monitoring system and method based on a four-element electric network model. The dynamic continuous blood pressure monitoring system comprises a signal receiving and transmitting module, a data processing module, a cardiac impedance signal collecting module, an electrocardiosignal collecting module and a pulse wave signal collecting module. The cardiac impedance signal acquisition module, the electrocardiosignal acquisition module and the pulse wave signal acquisition module are respectively connected with a monitored object and the signal receiving and transmitting module; and the data processing module is connected with the signal receiving and transmitting module. When the first cardiac impedance signal, the first electrocardiosignal and the first pulse wave signal are received synchronously, the influence of the time synchronization problem on the precision in the blood pressure monitoring process is avoided, various physiological signals are obtained through collection, namely key parameters needed by the dynamic continuous blood pressure monitoring system are determined according to dynamic values, and the accuracy of the blood pressure monitoring system is improved. The accuracy of parameters needed when the blood pressure is predicted based on the Windkessel model is improved, and the accuracy and reliability of blood pressure monitoring are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of blood pressure monitoring, and in particular to a dynamic continuous blood pressure monitoring system and method based on a four-element electrical network model. Background Art

[0002] Blood pressure monitoring and cardiovascular parameter monitoring are of great significance in hypertension control and cardiovascular health management. Although traditional invasive blood pressure measurement is regarded as the gold standard, it has the risk of infection and causes great trauma to patients, so it is not suitable for use in non-critical care scenarios. In some non-critical care scenarios, non-invasive blood pressure monitoring methods are often used.

[0003] Among the non-invasive blood pressure monitoring methods, there are mainly blood pressure estimation methods based on pulse transit time (PTT), PPG (Photoplethysmography) feature extraction methods based on machine learning, and automatic feature extraction methods based on deep learning. Among them, the blood pressure estimation method based on pulse transit time uses the inverse relationship between blood pressure and pulse transit time to predict blood pressure through a regression model. The blood pressure estimation method based on pulse transit time requires at least two sensors, one placed at the proximal end (such as ECG (Electrocardiogram) sensor for collecting electrocardiogram signals) and one placed at the distal end (such as PPG sensor for collecting peripheral signals of the monitored object) to measure the time it takes for the pulse to propagate from the heart to the distal artery, thereby inferring blood pressure. Although this method has a certain degree of accuracy, it requires multiple sensors, the system is complex and prone to signal synchronization problems. The PPG feature extraction method based on machine learning extracts artificially designed features (such as waveform morphology features, pulse rate variation, etc.) from the PPG signal and combines it with a regression model to predict blood pressure. This method only requires one PPG sensor and is easier to integrate into wearable devices. It is suitable for daily health management, but its prediction accuracy may be affected by individual differences and environmental factors, and feature design relies on experience. The automatic feature extraction method based on deep learning can automatically extract deep features from the original PPG signal for blood pressure prediction, reducing the need for artificial feature design, and has high prediction potential, which is suitable for personalized and real-time monitoring. However, the deep learning model has high requirements for computing resources, and its physiological interpretability needs to be improved. Therefore, blood pressure monitoring based on the WK (elastic cavity, Windkessel) model has attracted widespread attention. The elastic cavity model can fully consider the dynamic changes of the cardiovascular system, which not only improves the accuracy of blood pressure measurement, but also can analyze the physiological mechanism of blood pressure changes, bringing a new research perspective to blood pressure monitoring. At present, the blood pressure monitoring system based on the Windkessel model usually only collects one or two physiological signals, and obtains some key parameters required for blood pressure monitoring through the collected physiological signals, while other key parameters depend on static preset values. However, the Windkessel model actually requires more physiological signals to accurately obtain complete dynamic key parameters. In the prior art, some of the key parameters required by many blood pressure monitoring systems rely on static preset values ​​rather than being determined based on physiological signals collected in real time. This shows that the existing blood pressure monitoring system fails to fully collect the necessary physiological signals required for blood pressure monitoring, resulting in inaccurate estimation of the parameters required for the Windkessel model to predict blood pressure, thereby affecting the accuracy and reliability of blood pressure monitoring.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a dynamic continuous blood pressure monitoring system and method based on a four-element electrical network model, so as to solve the problem that some key parameters required for the blood pressure monitoring system in the prior art depend on static preset values ​​rather than being determined based on physiological signals collected in real time. This shows that the existing blood pressure monitoring system fails to fully collect the necessary physiological signals required for blood pressure monitoring, resulting in inaccurate estimation of the parameters required for predicting blood pressure using the Windkessel model, thereby affecting the accuracy and reliability of blood pressure monitoring.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a dynamic continuous blood pressure monitoring system based on a four-element electrical network model, comprising: a signal receiving and transmitting module, a data processing module connected to the signal receiving and transmitting module, a cardiac impedance signal acquisition module, an electrocardiogram signal acquisition module and a pulse wave signal acquisition module; The cardiac impedance signal acquisition module, the electrocardiographic signal acquisition module and the pulse wave signal acquisition module are respectively connected to the monitored object and the signal receiving and transmitting module; The signal receiving and transmitting module is used to synchronously receive the first cardiac impedance signal output by the cardiac impedance signal acquisition module, the first electrocardiogram signal output by the electrocardiogram signal acquisition module, and the first pulse wave signal output by the pulse wave signal acquisition module in a continuous cycle, and convert the first cardiac impedance signal into a first digital signal, convert the first electrocardiogram signal into a second digital signal, and convert the first pulse wave signal into a third digital signal; The data processing module is used to receive the first digital signal, the second digital signal and the third digital signal, and restore the second cardiac impedance signal according to the first digital signal, restore the second electrocardiogram signal according to the second digital signal, and restore the second pulse wave signal according to the third digital signal, and is also used to extract the first feature point according to the second cardiac impedance signal, extract the second feature point according to the second electrocardiogram signal, and extract the third feature point according to the second pulse wave signal, and is also used to extract features of the first feature point, the second feature point and the third feature point to obtain a feature data set, and calculate cardiovascular parameters according to the feature data set and predict cardiac cycle blood pressure values ​​based on a four-element electrical network model; Among them, the feature data set includes left ventricular ejection time, the maximum value in the second cardiac impedance signal, the morphological characteristics in the second pulse wave signal, the statistical characteristics of the second pulse wave signal, the sequence characteristics of the second pulse wave signal and the heart rate.

[0007] According to a further configuration of the present invention, the first characteristic point includes point B, point C and point X in the second cardiac impedance signal; the second characteristic point includes the peak of the second pulse wave signal and the trough of the second pulse wave signal; and the third characteristic point includes the positive wave in the QRS complex wave in the second electrocardiographic signal.

[0008] According to a further configuration of the present invention, the signal receiving and transmitting module comprises: a transmission unit, an analog-to-digital conversion unit and a first control unit; The analog-to-digital conversion unit is connected to the cardiac impedance signal acquisition module, the electrocardiogram signal acquisition module and the pulse wave signal acquisition module, and the analog-to-digital conversion unit is used to convert the first cardiac impedance signal into the first digital signal, convert the first electrocardiogram signal into the second digital signal, and convert the first pulse wave signal into the third digital signal; The first control unit is connected to the transmission unit and the analog-to-digital conversion unit. The first control unit is used to control the analog-to-digital conversion unit to synchronously receive the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal in a continuous cycle; and is also used to control the transmission unit to transmit the first digital signal, the second digital signal and the third digital signal to the data processing module.

[0009] In a further configuration of the present invention, the cardiac impedance signal acquisition module comprises: a first electrode, a second electrode, a third electrode, a fourth electrode, a signal generator, a first constant current source, a first front-end amplification unit, a detection unit and a first filtering amplification unit; The first electrode and the second electrode are sequentially attached to the neck of the monitored object from top to bottom; The third electrode and the fourth electrode are sequentially attached to the outer side of the abdomen of the monitored object from top to bottom; The signal generator is connected to the first constant current source, and the signal generator is used to output a first voltage signal to the first constant current source; The output end of the first constant current source is connected to the first electrode, and the first constant current source is used to output a constant current excitation signal to the first electrode; The first front-end amplifying unit is connected to the second electrode and the third electrode, and is used for collecting and amplifying a third cardiac impedance signal through the second electrode and the third electrode to output a fourth cardiac impedance signal; The detection unit is connected to the first front-end amplification unit, and is used to receive the fourth cardiac impedance signal and modulate and demodulate and output a fifth cardiac impedance signal; The first filter amplification unit is connected to the detection unit and the analog-to-digital conversion unit, and is used for amplifying and filtering the fifth cardiac impedance signal to output the first cardiac impedance signal.

[0010] According to a further configuration of the present invention, the first constant current source comprises: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first operational amplifier and a second operational amplifier; One end of the first resistor is grounded, the other end of the first resistor and one end of the second resistor are connected to the inverting input of the first operational amplifier, the other end of the second resistor is connected to the output of the first operational amplifier, one end of the third resistor is connected to the signal generator, the other end of the third resistor and one end of the fourth resistor are connected to the non-inverting input of the first operational amplifier, the other end of the fourth resistor is connected to the output and the inverting input of the second operational amplifier, the output of the first operational amplifier is connected to one end of the fifth resistor, the positive power supply of the first operational amplifier is connected to the first power supply, the negative power supply of the first operational amplifier is connected to the second power supply, the positive power supply of the second operational amplifier is connected to the first power supply, the negative power supply of the second operational amplifier is connected to the second power supply, the other end of the fifth resistor is connected to one end of the sixth resistor and the non-inverting input of the second operational amplifier, and the other end of the sixth resistor is connected to the first electrode; The detection unit includes a seventh resistor, an eighth resistor, a first voltage-stabilizing diode, a second voltage-stabilizing diode, a third operational amplifier, a first power supply, and a second power supply; One end of the seventh resistor is connected to the first front-end amplifier unit, the other end of the seventh resistor, one end of the eighth resistor and the positive electrode of the first voltage-stabilizing diode are connected to the inverting input terminal of the third operational amplifier, the negative electrode of the first voltage-stabilizing diode and the positive electrode of the second voltage-stabilizing diode are connected to the output terminal of the third operational amplifier, the negative electrode of the second voltage-stabilizing diode and the other end of the eighth resistor are connected to the first filtering amplifier unit, the non-inverting input terminal of the third operational amplifier is grounded, the positive power supply terminal of the third operational amplifier is connected to the third power supply terminal, and the negative power supply terminal of the third operational amplifier is connected to the fourth power supply terminal.

[0011] In a further configuration of the present invention, the ECG signal acquisition module includes: a fifth electrode, a sixth electrode, a second front-end amplification unit, a second filtering amplification unit, and a right leg driving unit; The fifth electrode is attached to the chest of the monitored object; The sixth electrode is attached to the lower abdomen of the monitored object; The second front-end amplifying unit is connected to the third electrode, and the second front-end amplifying unit is used to collect and amplify the third electrocardiogram signal to output a fourth electrocardiogram signal; The right leg driving unit is connected to the third electrode, the fifth electrode and the sixth electrode, and the right leg driving unit is used to suppress power frequency interference in the first electrocardiogram signal; The second filtering and amplifying unit is connected to the second front-end amplifying unit and the analog-to-digital conversion unit, and the second filtering and amplifying unit is used to amplify and filter the fourth electrocardiographic signal to output the first electrocardiographic signal.

[0012] According to a further configuration of the present invention, the right leg driving unit includes: a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a first capacitor, a fourth operational amplifier, and a fifth operational amplifier; One end of the ninth resistor is connected to the fifth electrode, one end of the tenth resistor is connected to the sixth electrode, the other end of the ninth resistor and the other end of the tenth resistor are connected to the positive phase input terminal of the fourth operational amplifier, the inverting input terminal and the output terminal of the fourth operational amplifier are connected, one end of the eleventh resistor is connected to the output terminal of the fourth operational amplifier, the other end of the eleventh resistor, one end of the twelfth resistor and one end of the eleventh resistor are connected to the inverting input terminal of the fifth operational amplifier, the other end of the first capacitor and the other end of the twelfth resistor are connected to the output terminal of the fifth operational amplifier, the other end of the thirteenth resistor is connected to the positive phase input terminal of the fifth operational amplifier, the other end of the thirteenth resistor is grounded, and the other end of the first capacitor and the other end of the twelfth resistor are also connected to the third electrode.

[0013] In a further configuration of the present invention, the pulse wave signal acquisition module includes: a blood oxygen finger clip, a light source driving unit, a transimpedance amplification unit and a third filtering amplification unit; The blood oxygen finger clip is connected to the monitored object and is used to output a blood volume change signal; The light source driving unit is connected to the blood oxygen finger clip, and the light source driving unit is used to drive the light source in the blood oxygen finger clip; The transimpedance amplification unit is connected to the blood oxygen finger clip, and the transimpedance amplification unit is used to receive the blood volume change signal and output a third pulse wave signal according to the blood volume change signal; The third filtering and amplifying unit is connected to the transimpedance amplifying unit, and is used for amplifying and filtering the third pulse wave signal to output the first pulse wave signal.

[0014] According to a further configuration of the present invention, the transimpedance amplification unit includes: a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor and a first chip; One end of the fourteenth resistor is connected to the blood oxygen finger clip, and the other end of the fourteenth resistor is connected to the second pin of the first chip, one end of the fifteenth resistor is connected to the blood oxygen finger clip, and the other end of the fifteenth resistor is connected to the third pin of the first chip, one end of the sixteenth resistor is connected to the third pin of the first chip, and the other end of the sixteenth resistor is grounded, the fourth pin of the first chip is connected to the sixth power supply terminal, and the seventh pin of the first chip is connected to the sixth power supply terminal, one end of the seventeenth resistor is connected to the second pin of the first chip, and the other end of the seventeenth resistor is connected to the sixth pin of the first chip and the third filtering amplification unit, the seventh pin of the first chip is connected to the sixth power supply terminal, and the fourth pin of the first chip is connected to the fifth power supply terminal.

[0015] The present invention also provides a method for applying the dynamic continuous blood pressure monitoring system based on the four-element electrical network model as described above, the method comprising: Synchronously receiving the first cardiac impedance signal output by the cardiac impedance signal acquisition module, the first electrocardiogram signal output by the electrocardiogram signal acquisition module, and the first pulse wave signal output by the pulse wave signal acquisition module in a continuous cycle; converting the first cardiac impedance signal into a first digital signal; Converting the first electrocardiogram signal into a second digital signal; converting the first pulse wave signal into a third digital signal; receiving the first digital signal, the second digital signal and the third digital signal, and restoring a second cardiac impedance signal according to the first digital signal, a second electrocardiogram signal according to the second digital signal, and a second pulse wave signal according to the third digital signal; extracting a first feature point according to the second cardiac impedance signal, extracting a second feature point according to the second electrocardiogram signal, and extracting a third feature point according to the second pulse wave signal; Extracting features from the first feature point, the second feature point, and the third feature point to obtain a feature data set, and calculating cardiovascular parameters according to the feature data set and predicting cardiac cycle blood pressure values ​​based on a four-element electrical network model; Among them, the feature data set includes left ventricular ejection time, the maximum value in the second cardiac impedance signal, the morphological characteristics in the second pulse wave signal, the statistical characteristics of the second pulse wave signal, the sequence characteristics of the second pulse wave signal and the heart rate.

[0016] The beneficial effects of the present invention are: The dynamic continuous blood pressure monitoring system based on the four-element electrical network model can monitor cardiovascular parameters and cardiac cycle blood pressure values ​​through the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal, and when receiving the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal, they are received synchronously, avoiding the influence of time synchronization problems on the accuracy of the blood pressure monitoring process, and a variety of physiological signals are obtained through collection, that is, the key parameters required by the dynamic continuous blood pressure monitoring system are determined according to dynamic values, which improves the accuracy of the parameters required for predicting blood pressure based on the Windkessel model, so that the accuracy and reliability of blood pressure monitoring are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary personnel in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0018] Figure 1 It is a principle block diagram of the dynamic continuous blood pressure monitoring system based on the four-element electrical network model of the present invention.

[0019] Figure 2 It is a specific connection block diagram of a dynamic continuous blood pressure monitoring system based on a four-element electrical network model in one embodiment of the present invention.

[0020] Figure 3 4 is a circuit diagram of a first constant current source in one embodiment of the present invention.

[0021] Figure 4 1 is a circuit diagram of a detection unit in one embodiment of the present invention.

[0022] Figure 5 1 is a circuit diagram of a right leg driving unit in one embodiment of the present invention.

[0023] Figure 6 is a circuit structure diagram of a transimpedance amplifier unit in one embodiment of the present invention.

[0024] Figure 7 4 is a waveform diagram of the second cardiac impedance signal in one embodiment of the present invention.

[0025] Figure 8 4 is a waveform diagram of a second pulse wave signal in one embodiment of the present invention.

[0026] Fig. 9 It is a waveform diagram of a second electrocardiogram signal in one embodiment of the present invention.

[0027] Fig.10 It is a monitoring platform of a dynamic continuous blood pressure monitoring system based on a four-element electrical network model in one embodiment of the present invention.

[0028] Fig.11 It is a circuit structure diagram of the four-element electrical network model.

[0029] Fig.12 It is a schematic diagram of a monitoring object attached with a first electrode, a second electrode, a third electrode, a fourth electrode, a fifth electrode and a sixth electrode in one embodiment of the present invention.

[0030] Fig.13 It is a flow chart of the dynamic continuous blood pressure monitoring method of the present invention. DETAILED DESCRIPTION

[0031] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0032] At present, blood pressure monitoring based on the WK (elastic cavity, Windkessel) model has attracted widespread attention. The elastic cavity model is a mathematical model used to describe the blood flow characteristics in the cardiovascular system. It is mainly used to quantitatively analyze the relationship between volume pulse blood flow and microcirculation. The elastic cavity model can fully consider the dynamic changes of the cardiovascular system, which not only improves the accuracy of blood pressure measurement, but also can analyze the physiological mechanism of blood pressure changes, bringing a new research perspective to blood pressure monitoring. In the WK model, the time window is divided by the ECG signal and the heart rate characteristics are provided. The resistance and capacitance parameters required by the WK model are obtained by the pulse wave signal. The cardiac impedance signal can obtain the pulse volume SV and then obtain the current parameters required by the WK model. The obtained resistance, capacitance, current and other parameters are substituted into the WK model state equation to obtain the WK model voltage (corresponding to the blood pressure of the monitored object). At present, the blood pressure monitoring system based on the Windkessel model usually only collects one or two physiological signals, and obtains some key parameters required for blood pressure monitoring through the collected physiological signals, while other key parameters depend on static preset values. However, the Windkessel model actually requires more physiological signals to accurately obtain complete dynamic key parameters. However, in the prior art, some of the key parameters required by many blood pressure monitoring systems rely on static preset values ​​rather than being determined based on physiological signals collected in real time. This indicates that the existing blood pressure monitoring systems fail to fully collect the necessary physiological signals required for blood pressure monitoring, resulting in inaccurate estimation of the parameters required for predicting blood pressure using the Windkessel model, thereby affecting the accuracy and reliability of blood pressure monitoring.

[0033] Based on the above problems, the present invention provides a dynamic continuous blood pressure monitoring system based on a four-element electrical network model. The dynamic continuous blood pressure monitoring system based on a four-element electrical network model monitors cardiovascular parameters and cardiac cycle blood pressure values ​​based on a four-element electrical network model.

[0034] Among them, the four-element electrical network model is a form of the WK model (the WK model has many forms), such as Fig.11As shown, it is a circuit diagram of a four-component electrical network model, wherein the four-component electrical network model includes an eighteenth resistor R18, a nineteenth resistor R19, a second capacitor C2 and a first inductor L1, wherein one end of the eighteenth resistor R18 is connected to one end of the first inductor L1, the other end of the eighteenth resistor R18 is connected to the other end of the first inductor L1, one end of the second capacitor C2 and one end of the nineteenth resistor R19 are connected to the other end of the eighteenth resistor R18, and the other end of the second capacitor C2 is connected to the other end of the nineteenth resistor R19, wherein, in the four-component electrical network model, the total peripheral resistance is analogous to the nineteenth resistor R19, the arterial compliance is analogous to the second capacitor C2, the arterial inertia is analogous to the first inductor L1, the aortic resistance is analogous to the eighteenth resistor R18, the blood flow from the ventricle to the artery is analogous to the current that varies with time, and the arterial pressure wave (aortic blood pressure) is analogous to the voltage that varies with time.

[0035] In some embodiments, Figure 1 As shown, the dynamic continuous blood pressure monitoring system based on the four-element electrical network model may include a cardiac impedance signal acquisition module 100 , an electrocardiogram signal acquisition module 200 , a pulse wave signal acquisition module 300 , a signal receiving and transmitting module 400 , and a data processing module 500 .

[0036] Among them, the cardiac impedance signal acquisition module 100, the electrocardiographic signal acquisition module 200 and the pulse wave signal acquisition module 300 are respectively connected to the monitoring object 600 and the signal receiving and transmitting module 400, the cardiac impedance signal acquisition module 100 is used to output the first cardiac impedance signal, the electrocardiographic signal acquisition module 200 is used to output the first electrocardiographic signal, and the pulse wave signal acquisition module 300 is used to output the first pulse wave signal.

[0037] The signal receiving and transmitting module 400 is used to synchronously receive the first cardiac impedance signal output by the cardiac impedance signal acquisition module 100, the first electrocardiogram signal output by the electrocardiogram signal acquisition module 200, and the first pulse wave signal output by the pulse wave signal acquisition module 300 in a continuous cycle, and convert the first cardiac impedance signal into a first digital signal, convert the first electrocardiogram signal into a second digital signal, and convert the first pulse wave signal into a third digital signal.

[0038] The data processing module 500 is used to receive a first digital signal, a second digital signal and a third digital signal, and to restore a second cardiac impedance signal according to the first digital signal, to restore a second electrocardiogram signal according to the second digital signal, and to restore a second pulse wave signal according to the third digital signal. The data processing module 500 is also used to extract a first feature point according to the second cardiac impedance signal, to extract a second feature point according to the second electrocardiogram signal, and to extract a third feature point according to the second pulse wave signal. The data processing module 500 is also used to extract features from the first feature point, the second feature point and the third feature point to obtain a feature data set, and to calculate cardiovascular parameters according to the feature data set and to predict cardiac cycle blood pressure values ​​based on a four-element electrical network model.

[0039] Specifically, the monitoring object 600 refers to a person whose blood pressure and cardiovascular parameters are to be monitored by the dynamic continuous blood pressure monitoring system based on the four-element electrical network model. Cardiovascular parameters may include the heart rate (HR), stroke volume (SV), cardiac output (CO) and left ventricular ejection time (LVET) of the monitoring object 600. The blood pressure values ​​of the cardiac cycle include diastolic blood pressure (DBP) and systolic blood pressure (SBP).

[0040] Among them, the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal are all analog signals. The signal receiving and transmitting module 400 receives the first cardiac impedance signal and converts it into a first digital signal and outputs it to the data processing module 500; similarly, the first electrocardiogram signal is received and converted into a second digital signal and outputs it to the data processing module 500, and the first cardiac impedance signal is received and converted into a third digital signal and outputs it to the data processing module 500. When calculating cardiovascular parameters and predicting cardiac cycle blood pressure values ​​based on a four-element electrical network model, it is necessary to process based on analog signals. Therefore, after receiving the first digital signal, the data processing module 500 restores the second cardiac impedance signal through the first digital signal, restores the second electrocardiogram signal through the second digital signal after receiving the second digital signal, and restores the second pulse wave signal through the third digital signal after receiving the third digital signal.

[0041] Furthermore, the data processing module 500 will perform a bandpass filter and a 50Hz notch process on the second cardiac impedance signal, the second electrocardiogram signal and the second pulse wave signal to extract the first feature point, the second feature point and the third feature point; thereafter, feature extraction is performed based on the first feature point, the second feature point and the third feature point to obtain a feature data set, and cardiovascular parameters are calculated based on the feature data set, and the blood pressure value of the cardiac cycle is predicted based on the four-element electrical network model.

[0042] Among them, the four-element electrical network model is preset in the data processing module 500 in advance. When extracting features, the feature point extraction algorithm in the prior art is used to extract features from the first feature point; the feature point extraction algorithm in the prior art is used to extract features from the second feature point; and the feature point extraction algorithm in the prior art is used to extract features from the third feature point. The feature data set includes left ventricular ejection time, the maximum value in the second cardiac impedance signal, the morphological features in the second pulse wave signal, the statistical features of the second pulse wave signal, the sequence features of the second pulse wave signal, and the heart rate; wherein the morphological features of the second pulse wave signal specifically include the pulse wave conduction time parameter, the amplitude parameter of the second pulse wave signal, the area parameter of the second pulse wave signal, and the proportional relationship between the pulse wave conduction time parameter, the amplitude parameter of the second pulse wave signal, and the area parameter of the second pulse wave signal; the statistical features of the second pulse wave signal specifically include the mean, median, and standard deviation of the second pulse wave signal; the sequence features of the second pulse wave signal specifically include the change of heartbeat interval, the short-term and long-term scatter plot standard deviation based on Poincare map analysis, etc.

[0043] It can be seen that when predicting cardiovascular parameters and blood pressure values ​​of the cardiac cycle, the cardiovascular parameters and blood pressure values ​​of the cardiac cycle can be monitored through the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal, and when receiving the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal, they are received synchronously, avoiding the influence of time synchronization problems on the accuracy of the blood pressure monitoring process, and a variety of physiological signals are obtained through collection, that is, the key parameters required for the dynamic continuous blood pressure monitoring system are determined according to the dynamic values, which improves the accuracy of the parameters required for predicting blood pressure based on the Windkessel model, thereby improving the accuracy and reliability of blood pressure monitoring.

[0044] In some embodiments, the first characteristic point includes point B, point C, and point X in the second cardiac impedance signal. Figure 7 As shown in FIG. 1 , it is a waveform diagram of the second cardiac impedance signal. The second characteristic point includes the peak of the second pulse wave signal and the trough of the second pulse wave signal, such as Figure 8 The third characteristic point includes the positive wave in the QRS complex wave in the second electrocardiogram signal, such as Fig. 9, which is a waveform diagram of the second electrocardiogram signal.

[0045] In some embodiments, Figure 1 , Figure 2 As shown, the signal receiving and transmitting module 400 may include a transmitting unit 403 , an analog-to-digital conversion unit 401 and a first control unit 402 .

[0046] Among them, the analog-to-digital conversion unit 401 is connected to the cardiac impedance signal acquisition module 100, the electrocardiogram signal acquisition module 200 and the pulse wave signal acquisition module 300, and the analog-to-digital conversion unit 401 is used to convert the first cardiac impedance signal into a first digital signal, convert the first electrocardiogram signal into a second digital signal, and convert the first pulse wave signal into a third digital signal.

[0047] The first control unit 402 is connected to the transmission unit 403 and the analog-to-digital conversion unit 401. The first control unit 402 is used to control the analog-to-digital conversion unit 401 to synchronously receive the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal in a continuous period; the first control unit 402 is also used to control the transmission unit 403 to transmit the first digital signal, the second digital signal and the third digital signal to the data processing module 500.

[0048] Specifically, the analog-to-digital conversion unit 401 has three receiving interfaces, and the cardiac impedance signal acquisition module 100, the electrocardiographic signal acquisition module 200, and the pulse wave signal acquisition module 300 are respectively connected to a receiving interface, and the three receiving interfaces can receive data simultaneously, that is, the first control unit 402 can control the analog-to-digital conversion unit 401 to synchronously receive data at the three interfaces in a continuous cycle, and the data here refers to the first cardiac impedance signal, the first electrocardiographic signal, and the first pulse wave signal; and the analog-to-digital conversion unit 401 can perform analog-to-digital conversion on the first cardiac impedance signal to obtain a first digital signal, perform analog-to-digital conversion on the first electrocardiographic signal to obtain a second digital signal, and perform analog-to-digital conversion on the first pulse wave signal to obtain a third digital signal. After obtaining the first digital signal, the second digital signal, and the third digital signal, the first control unit 402 controls the transmission unit 403 to transmit the first digital signal, the second digital signal, and the third digital signal to the data processing module 500.

[0049] The transmission unit 403 may be a Bluetooth transmission unit, an infrared transmission unit, or a radio frequency transmission unit. Those skilled in the art may determine the transmission unit 403 according to actual needs, and no further limitation is made here.

[0050] The core chip in the analog-to-digital conversion unit 401 may be ADS1256. In the case where the analog-to-digital conversion unit 401 can realize the above functions, the specific circuit structure of the analog-to-digital conversion unit 401 is not limited too much.

[0051] When the first control unit 402 controls the analog-to-digital conversion unit 401, the analog-to-digital conversion unit 401 is triggered by the same timer at a fixed time interval to synchronously receive the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal, that is, the first control unit 402 controls the analog-to-digital conversion unit 401 to synchronously receive the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal in a continuous cycle. Among them, the time interval is preset in advance in the first control unit 402, and the time interval can be 4ms, 5ms, 10ms, etc., and those skilled in the art can determine the specific time interval according to actual needs, and synchronously receiving the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal avoids the influence of time asynchrony on the measurement accuracy. The core chip in the first control unit 402 can be a chip of the STM32 series, for example, the core chip can be STM32F103BCT6. When the first control unit 402 can realize the above functions, the specific circuit structure of the first control unit 402 is not too limited.

[0052] In some embodiments, Figure 2 , Fig.12 As shown, the cardiac impedance signal acquisition module 100 may include a first electrode 106, a second electrode 107, a third electrode 108, a fourth electrode 109, a signal generator 101, a first constant current source 102, a first front-end amplifier unit 103, a detection unit 104 and a first filter amplifier unit 105; the first electrode 106 and the second electrode 107 are sequentially attached to the neck of the monitored object 600 from top to bottom; the third electrode 108 and the fourth electrode 109 are sequentially attached to the outer side of the abdomen of the monitored object 600 from top to bottom; the signal generator 101 is connected to the first constant current source 102, and the signal generator 101 is used to output a first voltage signal to the first constant current source 102; the output end of the first constant current source 102 is connected to the first electrode 106, and the first constant current source 1 02 is used to output a constant current excitation signal to the first electrode 106; the first front-end amplifier unit 103 is connected to the second electrode 107 and the third electrode 108, and the first front-end amplifier unit 103 is used to collect the third cardiac impedance signal through the second electrode 107 and the third electrode 108, and amplify the third cardiac impedance signal to output a fourth cardiac impedance signal; the detection unit 104 is connected to the first front-end amplifier unit 103, and the detection unit 104 is used to receive the fourth cardiac impedance signal and modulate and demodulate the fourth cardiac impedance signal to output a fifth cardiac impedance signal; the first filter amplifier unit 105 is connected to the detection unit 104 and the analog-to-digital conversion unit 401, and the first filter amplifier unit 105 is used to amplify and filter the fifth cardiac impedance signal to output the first cardiac impedance signal.

[0053] Specifically, the signal generator 101 may be, but is not limited to, a signal generator 101 of model AD9833, which outputs a first voltage signal of a sine wave with a frequency of 50 KHz to the first constant current source 102. After receiving the voltage signal of the sine wave of 50 KHz, the first constant current source 102 outputs a constant current excitation signal of a sine wave with an effective value of 1 mA. The output end of the first constant current source 102 is connected to the first electrode 106 through an electrode lead wire, and the constant current excitation signal is injected into the monitoring object 600 through the first electrode 106. The fourth electrode 109 can be regarded as a ground terminal. After the constant current excitation signal is injected into the first electrode 106, the constant current excitation signal flows to the fourth electrode 109 through the first electrode 106, the second electrode 107, and the third electrode 108.

[0054] When the first electrode 106 and the second electrode 107 are set, they are set from top to bottom on the outside of the neck of the monitored object 600, roughly between the line connecting the ear and the shoulder; when the third electrode 108 and the fourth electrode 109 are set, they are set from top to bottom on the outer side of the abdomen of the monitored object 600, roughly between the line connecting the armpit and the leg. Among them, the first electrode 106 and the fourth electrode 109 are excitation electrodes, and a constant current excitation signal is injected through the first electrode 106. The constant current excitation signal is a high-frequency and low-amplitude current signal, and the fourth electrode 109 is regarded as grounded; the second electrode 107 and the third electrode 108 are response electrodes, and the third cardiac impedance signal is collected through the second electrode 107 and the third electrode 108, that is, the first front-end amplifier unit 103 can collect the third cardiac impedance signal through the second electrode 107 and the third electrode 108. The collected third cardiac impedance signal is weak, and the third cardiac impedance signal needs to be amplified by the first front-end amplifier unit 103 to output the fourth cardiac impedance signal. After receiving the fourth cardiac impedance signal, the detection unit 104 modulates and demodulates the fourth cardiac impedance signal to output a fifth cardiac impedance signal to the first filtering and amplifying unit 105. The first filtering and amplifying unit 105 further amplifies and filters the fifth cardiac impedance signal to filter out noise in the fifth cardiac impedance signal to obtain the first cardiac impedance signal.

[0055] In this embodiment, the first front-end amplifier unit 103 may be any circuit capable of collecting and amplifying the third cardiac impedance signal, and the specific circuit structure of the first front-end amplifier unit 103 is not limited in detail herein.

[0056] The first filtering and amplifying unit 105 is any circuit that can filter and amplify the fourth cardiac impedance signal. The specific circuit structure of the first filtering and amplifying unit 105 is not limited in detail herein.

[0057] During specific measurement, the constant current excitation signal is introduced into the chest through the electrode connection line and the first electrode 106, which will cause changes in the chest impedance during cardiac activity. This change can be monitored by the second electrode 107 and the third electrode 108; during cardiac systole, aortic ejection causes the chest and aortic volumes to increase, and the chest impedance decreases accordingly; during cardiac diastole, blood outflow decreases, the chest and aortic volumes decrease, and the chest impedance increases. The first cardiac impedance signal can be expressed as: .

[0058] Wherein, A is the overall gain of the cardiac impedance signal acquisition module 100; Vout is the first cardiac impedance signal; Ipeak is the amplitude of the constant current excitation signal; and Rheart is the first cardiac impedance signal in ohms.

[0059] In some embodiments, Figure 3 As shown, the first constant current source 102 may include a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first operational amplifier U1 and a second operational amplifier U2; wherein one end of the first resistor R1 is grounded, the other end of the first resistor R1 and one end of the second resistor R2 are connected to the inverting input terminal of the first operational amplifier U1, the other end of the second resistor R2 is connected to the output terminal of the first operational amplifier U1, one end of the third resistor R3 is connected to the signal generator 101, the other end of the third resistor R3 and one end of the fourth resistor R4 are connected to the non-inverting input terminal of the first operational amplifier U1, and the fourth resistor R4 is connected to the positive input terminal of the first operational amplifier U1. The other end is connected to the output end and the inverting input end of the second operational amplifier U2, the output end of the first operational amplifier U1 is connected to one end of the fifth resistor R5, the positive power supply end of the first operational amplifier U1 is connected to the first power supply end VDD1, the negative power supply end of the first operational amplifier U1 is connected to the second power supply end VDD2, the positive power supply end of the second operational amplifier U2 is connected to the first power supply end VDD1, the negative power supply end of the second operational amplifier U2 is connected to the second power supply end VDD2, the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6 and the non-inverting input end of the second operational amplifier U2, and the other end of the sixth resistor R6 is connected to the first electrode 106.

[0060] Specifically, one end of the third resistor R3 is the signal input end of the first constant current source 102, that is, the first voltage signal output by the signal generator 101 is output from one end of the third resistor R3 to the first constant current source 102. The constant current excitation signal output by the first constant current source 102 can be expressed as: .

[0061] Among them, I load (A) is the constant current excitation signal output by the first constant current source 102; G is the gain of the constant current excitation signal; Vp is the first voltage signal; V n is the ground voltage (in this embodiment, V n is 0); R s is the resistance value of the sixth resistor. The gain of the constant current excitation signal can be expressed as: .

[0062] It can be seen that the gain of the constant current excitation signal can be adjusted by adjusting the first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4.

[0063] Furthermore, the first power supply terminal VDD1 outputs a positive DC voltage, and the second power supply terminal VDD2 outputs a negative DC voltage. The specific voltage values ​​output by the first power supply terminal VDD1 and the second power supply terminal VDD2 are related to the first operational amplifier U1 and the second operational amplifier U2, that is, the output voltages of the first power supply terminal VDD1 and the second power supply terminal VDD2 need to meet the power supply requirements of the first operational amplifier U1 and the second operational amplifier U2, which will not be elaborated herein.

[0064] In this embodiment, the first constant current source 102 uses two operational amplifiers, namely, a first operational amplifier U1 and a second operational amplifier U2, so that the output impedance of the first constant current source 102 becomes high, thereby eliminating I feedback to I load The influence of I feedback with I load The location can be from Figure 3 It can be seen specifically in.

[0065] like Figure 4 As shown, the detection unit 104 may include a seventh resistor R7, an eighth resistor R8, a first voltage-stabilizing diode SD1, a second voltage-stabilizing diode SD2 and a third operational amplifier U3; one end of the seventh resistor R7 is connected to the first front-end amplifier unit 103, the other end of the seventh resistor R7, one end of the eighth resistor R8 and the positive electrode of the first voltage-stabilizing diode SD1 are connected to the inverting input terminal of the third operational amplifier U3, the negative electrode of the first voltage-stabilizing diode SD1 and the positive electrode of the second voltage-stabilizing diode SD2 are connected to the output terminal of the third operational amplifier U3, the negative electrode of the second voltage-stabilizing diode SD2 and the other end of the eighth resistor R8 are connected to the first filtering amplifier unit 105, the non-inverting input terminal of the third operational amplifier U3 is grounded, the positive power supply terminal of the third operational amplifier U3 is connected to the third power supply terminal VDD3, and the negative power supply terminal of the third operational amplifier U3 is connected to the fourth power supply terminal VDD4.

[0066] Specifically, the gain of the detection unit 104 can be expressed as: .

[0067] Among them, R f is the resistance value of the eighth resistor; R is the resistance value of the seventh resistor; Gain is the gain of the detection unit.

[0068] R f When selecting, R f The resistance value can be calculated using the following formula: .

[0069] Among them, R eq For R and R f The parallel combination resistance of nbb is the input voltage noise density of the third operational amplifier U3, in units of ; K b represents the Boltzmann constant, which is 1.381×10 -23 J / K; T represents absolute temperature, the unit is Kelvin K, here it is assumed that T is room temperature 298K.

[0070] It can be seen that when the third cardiac impedance signal is small, the detection unit 104 can still accurately demodulate without causing signal distortion due to the voltage drop of the first voltage zener diode SD1, effectively retaining the slight changes in the first cardiac impedance signal and ensuring monitoring accuracy.

[0071] In this embodiment, the third power supply terminal VDD3 outputs +2.5V DC, and the fourth power supply terminal VDD4 outputs -2.5V DC. Therefore, the third operational amplifier U3 is a dual-power operational amplifier. Specifically, the third operational amplifier U3 can be, but is not limited to, an operational amplifier of model OPA322.

[0072] In some embodiments, Figure 2 , Fig.12 As shown, the ECG signal acquisition module 200 may include a fifth electrode 204, a sixth electrode 205, a second front-end amplifier unit 201, a second filter amplifier unit 202 and a right leg drive unit 203; wherein the fifth electrode 204 is attached to the chest of the monitored object 600; the sixth electrode 205 is attached to the lower abdomen of the monitored object 600; the second front-end amplifier unit 201 is connected to the third electrode 108, and the second front-end amplifier unit 201 is used to collect the third ECG signal collected by the third electrode 108 and amplify it to output a fourth ECG signal; the right leg drive unit 203 is connected to the third electrode 108, the fifth electrode 204 and the sixth electrode 205, and the right leg drive unit 203 is used to suppress the power frequency interference in the first ECG signal; the second filter amplifier unit 202 is connected to the second front-end amplifier unit 201 and the analog-to-digital conversion unit 401, and the second filter amplifier unit 202 is used to amplify and filter the fourth ECG signal to output the first ECG signal.

[0073] Specifically, the fifth electrode 204 is an ECG electrode, which can be attached to the right chest of the monitored object 600, approximately 3 cm above the right chest nipple; the sixth electrode 205 is a right leg driving electrode, which is attached to the right lower abdomen of the monitored object 600; the third electrode 108 is also an ECG electrode, that is, the third electrode 108 is a common electrode when measuring electrocardiogram and cardiac impedance; the electrical activity of the heart is monitored by the fifth electrode 204, the sixth electrode 205 and the third electrode 108.

[0074] In this embodiment, the right leg driving unit 203 is used to suppress the power frequency interference in the first ECG signal, improve the signal common mode rejection ratio, and reduce the interference signal in the output first ECG signal.

[0075] In some embodiments, Figure 5 As shown, the right leg driving unit 203 may include a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a first capacitor C1, a fourth operational amplifier U4 and a fifth operational amplifier U5; wherein one end of the ninth resistor R9 is connected to the fifth electrode 204, one end of the tenth resistor R10 is connected to the sixth electrode 205, the other end of the ninth resistor R9 and the other end of the tenth resistor R10 are connected to the non-inverting input terminal of the fourth operational amplifier U4, the inverting input terminal and the output terminal of the fourth operational amplifier U4 are connected, and the eleventh resistor R11 is connected to the fourth operational amplifier U4. One end of the resistor R11 is connected to the output end of the fourth operational amplifier U4, the other end of the eleventh resistor R11, one end of the twelfth resistor R12 and one end of the first resistor R1 are commonly connected to the inverting input end of the fifth operational amplifier U5, the other end of the first capacitor C1 and the other end of the twelfth resistor R12 are commonly connected to the output end of the fifth operational amplifier U5, the other end of the thirteenth resistor R13 is connected to the non-inverting input end of the fifth operational amplifier U5, the other end of the thirteenth resistor R13 is grounded, and the other end of the first capacitor C1 and the other end of the twelfth resistor R12 are also commonly connected to the third electrode 108.

[0076] Specifically, the gain of the fourth operational amplifier U4 can be adjusted through the ninth resistor R9 and the tenth resistor R10. The gain of the fifth operational amplifier U5 can be adjusted through the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13 and the first capacitor C1.

[0077] In some embodiments, Figure 2As shown, the pulse wave signal acquisition module 300 may include a blood oxygen finger clip 303, a light source driving unit 304, a transimpedance amplification unit 301 and a third filtering and amplifying unit 302; wherein the blood oxygen finger clip 303 is clamped on the finger of the monitored object 600, and is used to output a blood volume change signal; the light source driving unit 304 is connected to the blood oxygen finger clip 303, and the light source driving unit 304 is used to drive the light source in the blood oxygen finger clip 303; the transimpedance amplification unit 301 is connected to the blood oxygen finger clip 303, and the transimpedance amplification unit 301 is used to receive the blood volume change signal, and output the third pulse wave signal according to the blood volume change signal; the third filtering and amplifying unit 302 is connected to the transimpedance amplification unit 301, and the third filtering and amplifying unit 302 is used to amplify and filter the third pulse wave signal to output the first pulse wave signal.

[0078] In this embodiment, the blood oxygen finger clip 303 can be, but is not limited to, a sensor of model DS100-ADB9-7. The light source in the blood oxygen finger clip 303 emits red light, infrared light, and green light, respectively, and the red light, infrared light, and green light can be independently controlled. The blood oxygen finger clip 303 uses a reflective principle differential method to obtain a blood oxygen value. However, since the focus of the present invention is to obtain a pulse wave waveform rather than a blood oxygen value, only the red light in the blood oxygen finger clip 303 is used to collect a blood volume change signal. It can be seen that the light source driving unit 304 can be any LED (Light Emitting Diode) driving circuit that can drive the blood oxygen finger clip 303 to emit red light. Those skilled in the art can determine the specific circuit of the light source driving unit 304 according to actual needs, and no excessive restrictions are made here. For example, the core chip in the LED driving circuit can be BCR421.

[0079] Specifically, under the action of the heart pumping blood, blood flows through the blood vessels periodically, causing periodic changes in the volume of the blood vessels; wherein, during the cardiac systole, the arterial blood flow increases, and the blood volume in the blood vessels increases. At this time, the blood absorbs more light, which reduces the amount of transmitted light. Due to the reduction in the amount of transmitted light, the light signal received by the photodetector in the blood oxygen finger clip 303 is weakened, and the photocurrent generated by the photodiode in the blood oxygen finger clip 303 decreases accordingly, and the first pulse wave signal decreases; on the contrary, during the cardiac diastole, the arterial blood flow decreases, the blood volume in the blood vessels decreases, and the amount of light transmitted back increases. The photodetector in the blood oxygen finger clip 303 receives a stronger light signal, and the photocurrent generated increases accordingly, and the first pulse wave signal increases; this change in light transmission caused by the heart beating forms a first pulse wave signal with a pulse waveform.

[0080] In this embodiment, the blood volume change signal is a changing current signal.

[0081] In some embodiments, Figure 6As shown, the transimpedance amplifier unit 301 may include a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17 and a first chip U6; wherein, one end of the fourteenth resistor R14 is connected to the blood oxygen finger clip 303, the other end of the fourteenth resistor R14 is connected to the second pin of the first chip U6, one end of the fifteenth resistor R15 is connected to the blood oxygen finger clip 303, the other end of the fifteenth resistor R15 is connected to the third pin of the first chip U6, one end of the sixteenth resistor R16 is connected to the third pin of the first chip U6, the other end of the sixteenth resistor R16 is grounded, the fourth pin of the first chip U6 is connected to the fifth power supply terminal VDD5, the seventh pin of the first chip U6 is connected to the sixth power supply terminal VDD6, one end of the seventeenth resistor R17 is connected to the second pin of the first chip U6, and the other end of the seventeenth resistor R17 is connected to the sixth pin of the first chip U6 and the third filtering amplifier unit 302.

[0082] Specifically, the first chip U6 may be, but is not limited to, a chip of model OPA1921DR, wherein one of the two current signals output by the blood oxygen finger clip 303 is input to the first chip U6 via one end of the fourteenth resistor R14, and the other current signal is input to the first chip U6 via one end of the fifteenth resistor R15. The fifth power supply terminal VDD5 is a voltage output port capable of outputting +5V direct current, and the eighth terminal is a voltage output port capable of outputting -5V direct current. The third pulse wave signal is output from the connection end between the sixth pin of the first chip U6 and the seventeenth resistor R17.

[0083] In this embodiment, the overall gain of the transimpedance amplifier unit 301 is related to the fourteenth resistor R14, the fifteenth resistor R15, the sixteenth resistor R16 and the seventeenth resistor R17, and the overall gain of the transimpedance amplifier unit 301 can be adjusted by the fourteenth resistor R14, the fifteenth resistor R15, the sixteenth resistor R16 and the seventeenth resistor R17.

[0084] In some embodiments, the first filter-amplifier unit 105 , the second filter-amplifier unit 202 , and the third filter-amplifier unit 302 may all be circuit structures constructed with the OPA4192 chip as the core chip, and the specific circuit structure is not limited in detail herein.

[0085] In some embodiments, the first electrode 106, the second electrode 107, the third electrode 108, the fourth electrode 109, the fifth electrode 204 and the sixth electrode 205 are disposable silver chloride electrodes. The first front-end amplifier unit 103, the signal generator 101, the first constant current source 102, the first filter amplifier unit 105, the detection unit 104, the second front-end amplifier unit 201, the second filter amplifier unit 202, the right leg driving unit 203, the light source driving unit 304, the transimpedance amplifier unit 301, the third filter amplifier unit 302, and the signal receiving and transmitting module 400 are arranged on the same board. The board is provided with electrode interfaces corresponding to the first electrode 106, the second electrode 107, the third electrode 108, the fourth electrode 109, the fifth electrode 204 and the sixth electrode 205, that is, after the first electrode 106, the second electrode 107, the third electrode 108, the fourth electrode 109, the fifth electrode 204 and the sixth electrode 205 are connected to the corresponding electrode interfaces through electrode lead wires, the first electrode 106 can be connected to the first constant current source 102, the second electrode 107 and the third electrode 108 can be connected to the first front-end amplifier unit 103, the fourth electrode 109 is grounded, the third electrode 108 can be connected to the second front-end amplifier unit 201 and the right leg drive unit 203, and the third electrode 108, the fifth electrode 204 and the sixth electrode 205 can be connected to the right leg drive unit 203; the board is also provided with a blood oxygen interface, through which the blood oxygen finger clip 303 is connected.

[0086] Furthermore, the data processing module 500 may be a terminal device such as a computer or a laptop. In a specific embodiment, the data processing module 500 is a computer. When the dynamic continuous blood pressure monitoring system based on the four-element electrical network model is specifically applied, the following steps may be included: Step 1: attach the first electrode 106, the second electrode 107, the third electrode 108, the third electrode 108, the fourth electrode 109, the fifth electrode 204 and the sixth electrode 205 to the specified positions on the monitored object 600, and connect the first electrode 106, the second electrode 107, the third electrode 108, the fourth electrode 109 and the fifth electrode 204 to the corresponding electrode interfaces to ensure the correct collection of physiological signals.

[0087] Step 2: Place the middle finger of the monitored subject 600 in the blood oxygen finger clip 303, and connect the blood oxygen finger clip 303 to the blood oxygen interface.

[0088] Step 3: Enter the basic information of the monitored object 600 into the computer. The basic information may be parameters such as height, age, weight, etc., to provide a personalized reference for subsequent blood pressure prediction, and connect the computer to the transmission unit 403 for communication.

[0089] Step 4: Start monitoring. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model displays the collected waveform signals (the second cardiac impedance signal, the second electrocardiogram signal, and the second pulse wave signal) in real time. The computer extracts the first characteristic point, the second characteristic point, and the third characteristic point according to the waveform signal, and performs feature extraction according to the first characteristic point, the second characteristic point, and the third characteristic point to form a feature data set. Finally, the cardiovascular parameters are determined according to the feature data set, and the cardiac cycle blood pressure value is predicted based on the four-element electrical network model, such as Fig.10 As shown, it is a display platform of the dynamic continuous blood pressure monitoring system based on the four-element electrical network model on the computer. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model realizes non-invasive and continuous blood pressure monitoring of the human body, simplifies the operation process, and provides stable and accurate blood pressure measurement results. When transmitting the first digital signal, the second digital signal and the third digital signal, the transmission unit 403 packages the first digital signal, the second digital signal and the third digital signal and transmits them to the host computer.

[0090] In some embodiments, Fig.13 As shown, the present invention also provides a method for applying the dynamic continuous blood pressure monitoring system based on the four-element electrical network model as described above, the method comprising the steps of: S100, the signal receiving and transmitting module synchronously receives the first cardiac impedance signal output by the cardiac impedance signal acquisition module, the first electrocardiogram signal output by the electrocardiogram signal acquisition module, and the first pulse wave signal output by the pulse wave signal acquisition module in a continuous cycle; S200, the signal receiving and transmitting module converts the first cardiac impedance signal into a first digital signal; S300, the signal receiving and transmitting module converts the first electrocardiogram signal into a second digital signal; S400, the signal receiving and transmitting module converts the first pulse wave signal into a third digital signal; S500, the data processing module receives the first digital signal, the second digital signal and the third digital signal, and restores the second cardiac impedance signal according to the first digital signal, restores the second electrocardiogram signal according to the second digital signal, and restores the second pulse wave signal according to the third digital signal; S600, the data processing module extracts a first feature point according to the second cardiac impedance signal, extracts a second feature point according to the second electrocardiogram signal, and extracts a third feature point according to the second pulse wave signal; S700, the data processing module extracts features from the first feature point, the second feature point and the third feature point to obtain a feature data set, and calculates cardiovascular parameters based on the feature data set and predicts the blood pressure value of the cardiac cycle based on the four-element electrical network model, wherein the feature data set includes left ventricular ejection time, the maximum value in the second cardiac impedance signal, the morphological features in the second pulse wave signal, the statistical features of the second pulse wave signal, the sequence features of the second pulse wave signal and the heart rate.

[0091] Here, it should be pointed out that the description of the above embodiment of the dynamic continuous blood pressure monitoring method is similar to the description of the embodiment of the dynamic continuous blood pressure monitoring system based on the four-element electrical network model, and has similar beneficial effects as the above embodiment of the dynamic continuous blood pressure monitoring system based on the four-element electrical network model. For technical details not disclosed in the embodiment of the dynamic continuous blood pressure monitoring method, please refer to the description of the embodiment of the dynamic continuous blood pressure monitoring system based on the four-element electrical network model of the present invention for understanding.

[0092] In summary, the present invention provides a dynamic continuous blood pressure monitoring system and method based on a four-element electrical network model, which has the following beneficial effects: When predicting cardiovascular parameters and blood pressure values ​​of the cardiac cycle, the cardiovascular parameters and blood pressure values ​​of the cardiac cycle can be monitored through the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal, and when receiving the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal, they are received synchronously, avoiding the influence of time synchronization problems on the accuracy of the blood pressure monitoring process, and a variety of physiological signals are obtained through collection, that is, the key parameters required for the dynamic continuous blood pressure monitoring system are determined according to the dynamic values, which improves the accuracy of the parameters required for predicting blood pressure based on the Windkessel model, thereby improving the accuracy and reliability of blood pressure monitoring.

[0093] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A dynamic continuous blood pressure monitoring system based on a four-element electrical network model, characterized in that: include: A signal receiving and transmitting module, a data processing module connected to the signal receiving and transmitting module, a cardiac impedance signal acquisition module, an electrocardiographic signal acquisition module and a pulse wave signal acquisition module; The cardiac impedance signal acquisition module, the electrocardiographic signal acquisition module and the pulse wave signal acquisition module are respectively connected to the monitored object and the signal receiving and transmitting module; The signal receiving and transmitting module is used to synchronously receive the first cardiac impedance signal output by the cardiac impedance signal acquisition module, the first electrocardiogram signal output by the electrocardiogram signal acquisition module, and the first pulse wave signal output by the pulse wave signal acquisition module in a continuous cycle, and convert the first cardiac impedance signal into a first digital signal, convert the first electrocardiogram signal into a second digital signal, and convert the first pulse wave signal into a third digital signal; The data processing module is used to receive the first digital signal, the second digital signal and the third digital signal, and restore the second cardiac impedance signal according to the first digital signal, restore the second electrocardiogram signal according to the second digital signal, and restore the second pulse wave signal according to the third digital signal, and is also used to extract the first feature point according to the second cardiac impedance signal, extract the second feature point according to the second electrocardiogram signal, and extract the third feature point according to the second pulse wave signal, and is also used to extract features of the first feature point, the second feature point and the third feature point to obtain a feature data set, and calculate cardiovascular parameters according to the feature data set and predict cardiac cycle blood pressure values ​​based on a four-element electrical network model; Among them, the feature data set includes left ventricular ejection time, the maximum value in the second cardiac impedance signal, the morphological characteristics in the second pulse wave signal, the statistical characteristics of the second pulse wave signal, the sequence characteristics of the second pulse wave signal and the heart rate.

2. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 1 is characterized in that: The first characteristic point includes point B, point C and point X in the second cardiac impedance signal; the second characteristic point includes the peak of the second pulse wave signal and the trough of the second pulse wave signal; the third characteristic point includes the positive wave in the QRS complex wave in the second electrocardiogram signal.

3. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 2 is characterized in that: The signal receiving and transmitting module comprises: a transmission unit, an analog-to-digital conversion unit and a first control unit; The analog-to-digital conversion unit is connected to the cardiac impedance signal acquisition module, the electrocardiogram signal acquisition module and the pulse wave signal acquisition module, and the analog-to-digital conversion unit is used to convert the first cardiac impedance signal into the first digital signal, convert the first electrocardiogram signal into the second digital signal, and convert the first pulse wave signal into the third digital signal; The first control unit is connected to the transmission unit and the analog-to-digital conversion unit. The first control unit is used to control the analog-to-digital conversion unit to synchronously receive the first cardiac impedance signal, the first electrocardiogram signal and the first pulse wave signal in a continuous cycle; and is also used to control the transmission unit to transmit the first digital signal, the second digital signal and the third digital signal to the data processing module.

4. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 3 is characterized in that: The cardiac impedance signal acquisition module includes: a first electrode, a second electrode, a third electrode, a fourth electrode, a signal generator, a first constant current source, a first front-end amplification unit, a detection unit and a first filtering amplification unit; The first electrode and the second electrode are sequentially attached to the neck of the monitored object from top to bottom; The third electrode and the fourth electrode are sequentially attached to the outer side of the abdomen of the monitored object from top to bottom; The signal generator is connected to the first constant current source, and the signal generator is used to output a first voltage signal to the first constant current source; The output end of the first constant current source is connected to the first electrode, and the first constant current source is used to output a constant current excitation signal to the first electrode; The first front-end amplifying unit is connected to the second electrode and the third electrode, and is used for collecting and amplifying the third cardiac impedance signal through the second electrode and the third electrode to output a fourth cardiac impedance signal; The detection unit is connected to the first front-end amplification unit, and is used to receive the fourth cardiac impedance signal and modulate and demodulate and output a fifth cardiac impedance signal; The first filter amplification unit is connected to the detection unit and the analog-to-digital conversion unit, and is used for amplifying and filtering the fifth cardiac impedance signal to output the first cardiac impedance signal.

5. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 4 is characterized in that: The first constant current source includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first operational amplifier and a second operational amplifier; One end of the first resistor is grounded, the other end of the first resistor and one end of the second resistor are connected to the inverting input of the first operational amplifier, the other end of the second resistor is connected to the output of the first operational amplifier, one end of the third resistor is connected to the signal generator, the other end of the third resistor and one end of the fourth resistor are connected to the non-inverting input of the first operational amplifier, the other end of the fourth resistor is connected to the output and the inverting input of the second operational amplifier, the output of the first operational amplifier is connected to one end of the fifth resistor, the positive power supply of the first operational amplifier is connected to the first power supply, the negative power supply of the first operational amplifier is connected to the second power supply, the positive power supply of the second operational amplifier is connected to the first power supply, the negative power supply of the second operational amplifier is connected to the second power supply, the other end of the fifth resistor is connected to one end of the sixth resistor and the non-inverting input of the second operational amplifier, and the other end of the sixth resistor is connected to the first electrode; The detection unit includes a seventh resistor, an eighth resistor, a first voltage-stabilizing diode, a second voltage-stabilizing diode, a third operational amplifier, a first power supply, and a second power supply; One end of the seventh resistor is connected to the first front-end amplifier unit, the other end of the seventh resistor, one end of the eighth resistor and the positive electrode of the first voltage-stabilizing diode are connected to the inverting input terminal of the third operational amplifier, the negative electrode of the first voltage-stabilizing diode and the positive electrode of the second voltage-stabilizing diode are connected to the output terminal of the third operational amplifier, the negative electrode of the second voltage-stabilizing diode and the other end of the eighth resistor are connected to the first filtering amplifier unit, the non-inverting input terminal of the third operational amplifier is grounded, the positive power supply terminal of the third operational amplifier is connected to the third power supply terminal, and the negative power supply terminal of the third operational amplifier is connected to the fourth power supply terminal.

6. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 4, characterized in that: The electrocardiogram signal acquisition module includes: a fifth electrode, a sixth electrode, a second front-end amplification unit, a second filtering amplification unit and a right leg driving unit; The fifth electrode is attached to the chest of the monitored object; The sixth electrode is attached to the lower abdomen of the monitored object; The second front-end amplifying unit is connected to the third electrode, and the second front-end amplifying unit is used to collect and amplify the third electrocardiogram signal to output a fourth electrocardiogram signal; The right leg driving unit is connected to the third electrode, the fifth electrode and the sixth electrode, and the right leg driving unit is used to suppress power frequency interference in the first electrocardiogram signal; The second filtering and amplifying unit is connected to the second front-end amplifying unit and the analog-to-digital conversion unit, and the second filtering and amplifying unit is used to amplify and filter the fourth electrocardiographic signal to output the first electrocardiographic signal.

7. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 6, characterized in that: The right leg driving unit includes: a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a first capacitor, a fourth operational amplifier and a fifth operational amplifier; One end of the ninth resistor is connected to the fifth electrode, one end of the tenth resistor is connected to the sixth electrode, the other end of the ninth resistor and the other end of the tenth resistor are connected to the positive phase input terminal of the fourth operational amplifier, the inverting input terminal and the output terminal of the fourth operational amplifier are connected, one end of the eleventh resistor is connected to the output terminal of the fourth operational amplifier, the other end of the eleventh resistor, one end of the twelfth resistor and one end of the eleventh resistor are connected to the inverting input terminal of the fifth operational amplifier, the other end of the first capacitor and the other end of the twelfth resistor are connected to the output terminal of the fifth operational amplifier, the other end of the thirteenth resistor is connected to the positive phase input terminal of the fifth operational amplifier, the other end of the thirteenth resistor is grounded, and the other end of the first capacitor and the other end of the twelfth resistor are also connected to the third electrode.

8. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 3, characterized in that: The pulse wave signal acquisition module includes: a blood oxygen finger clip, a light source driving unit, a transimpedance amplifier unit and a third filter amplifier unit; The blood oxygen finger clip is connected to the monitored object and is used to output a blood volume change signal; The light source driving unit is connected to the blood oxygen finger clip, and the light source driving unit is used to drive the light source in the blood oxygen finger clip; The transimpedance amplification unit is connected to the blood oxygen finger clip, and the transimpedance amplification unit is used to receive the blood volume change signal and output a third pulse wave signal according to the blood volume change signal; The third filtering and amplifying unit is connected to the transimpedance amplifying unit, and is used for amplifying and filtering the third pulse wave signal to output the first pulse wave signal.

9. The dynamic continuous blood pressure monitoring system based on the four-element electrical network model according to claim 8, characterized in that: The transimpedance amplification unit includes: a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor and a first chip; One end of the fourteenth resistor is connected to the blood oxygen finger clip, and the other end of the fourteenth resistor is connected to the second pin of the first chip, one end of the fifteenth resistor is connected to the blood oxygen finger clip, and the other end of the fifteenth resistor is connected to the third pin of the first chip, one end of the sixteenth resistor is connected to the third pin of the first chip, and the other end of the sixteenth resistor is grounded, the fourth pin of the first chip is connected to the sixth power supply terminal, and the seventh pin of the first chip is connected to the sixth power supply terminal, one end of the seventeenth resistor is connected to the second pin of the first chip, and the other end of the seventeenth resistor is connected to the sixth pin of the first chip and the third filtering amplification unit, the seventh pin of the first chip is connected to the sixth power supply terminal, and the fourth pin of the first chip is connected to the fifth power supply terminal.

10. A method for using the dynamic continuous blood pressure monitoring system based on the four-element electrical network model as described in any one of claims 1 to 9, characterized in that: The method comprises: Synchronously receiving the first cardiac impedance signal output by the cardiac impedance signal acquisition module, the first electrocardiogram signal output by the electrocardiogram signal acquisition module, and the first pulse wave signal output by the pulse wave signal acquisition module in a continuous cycle; converting the first cardiac impedance signal into a first digital signal; Converting the first electrocardiogram signal into a second digital signal; converting the first pulse wave signal into a third digital signal; receiving the first digital signal, the second digital signal and the third digital signal, and restoring a second cardiac impedance signal according to the first digital signal, a second electrocardiogram signal according to the second digital signal, and a second pulse wave signal according to the third digital signal; extracting a first feature point according to the second cardiac impedance signal, extracting a second feature point according to the second electrocardiogram signal, and extracting a third feature point according to the second pulse wave signal; Feature extraction is performed on the first feature point, the second feature point and the third feature point to obtain a feature data set, and cardiovascular parameters are calculated based on the feature data set, and cardiac cycle blood pressure values ​​are predicted based on a four-element electrical network model, wherein the feature data set includes left ventricular ejection time, the maximum value in the second cardiac impedance signal, morphological features in the second pulse wave signal, statistical features of the second pulse wave signal, sequence features of the second pulse wave signal, and heart rate.

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