CN116098601A

CN116098601A - Verification method and equipment for noninvasive cardiac output parameters

Info

Publication number: CN116098601A
Application number: CN202310102419.7A
Authority: CN
Inventors: 刘金惠
Original assignee: Shandong Elfa Intelligent Medical Technology Co ltd
Current assignee: Shandong Elfa Intelligent Medical Technology Co ltd
Priority date: 2023-02-09
Filing date: 2023-02-09
Publication date: 2023-05-12
Anticipated expiration: 2043-02-09
Also published as: CN116098601B

Abstract

The application discloses a verification method and equipment for noninvasive cardiac output parameters, which are used for solving the following technical problems: how to directly verify the accuracy of the cardiac output parameters without adding additional cost. The method comprises the following steps: acquiring a first signal wave and a second signal wave of a human body model through cardiac output preset parameters; calculating a cardiac output prediction parameter corresponding to the human body model by using the first signal wave and the second signal wave; and comparing the cardiac output prediction parameter with the cardiac output preset parameter. The cardiac output prediction parameters are compared with the cardiac output preset parameters, so that accuracy verification is directly performed on the cardiac output parameters, and meanwhile, human body related signal waves are collected through a human body model, so that verification cost is saved.

Description

Verification method and equipment for noninvasive cardiac output parameters

Technical Field

The application relates to the technical field of cardiac output monitoring, in particular to a method and equipment for verifying noninvasive cardiac output parameters.

Background

Most of noninvasive cardiac output devices use body surface physiological impedance methods to calculate parameters in terms of hemodynamics, i.e., cardiac output parameters. The body surface physiological impedance method is to send weak current to the body surface through electrodes attached to the human body, measure potential difference at the acquisition end, then obtain resistance value through a resistance formula, and finally obtain an impedance wave signal. The impedance wave signal obtained by the method has correlation with the electrocardiographic waveform, and can change along with the change of one cardiac cycle, so that the cardiac output parameter can be calculated by analyzing the form of the impedance wave signal.

Currently, the verification methods for the accuracy of the acquired cardiac output parameters mainly comprise an impedance verification method and a human body simulation method. The impedance verification method is to load rated resistance on an impedance acquisition electrode, then read the acquired impedance data to compare accuracy, the human body simulation method is to simulate a human body by using a dummy, a simulated blood circulation system is added in the dummy to simulate blood flow, then an impedance wave signal is acquired through an electrode on the surface of the dummy, and finally the finally calculated cardiac output parameter is compared with the parameter set by the dummy to verify the accuracy of the cardiac output parameter. However, the impedance verification method can only verify the basic principle of measurement, but cannot verify the accuracy of the actually measured cardiac output parameters, and the simulation human body method can additionally increase the input cost due to equipment cost and maintenance difficulty, so that the method is not suitable for being used in factories of a general scale.

Disclosure of Invention

The embodiment of the application provides a verification method and verification equipment for noninvasive cardiac output parameters, which are used for solving the following technical problems: how to directly verify the accuracy of the cardiac output parameters without adding additional cost.

In one aspect, embodiments of the present application provide a method for verifying a noninvasive cardiac output parameter, the method comprising: acquiring a first signal wave and a second signal wave of a human body model through cardiac output preset parameters; calculating a cardiac output prediction parameter corresponding to the human body model by using the first signal wave and the second signal wave; and comparing the cardiac output prediction parameter with the cardiac output preset parameter.

In one or more embodiments of the present specification, before the acquisition of the first signal wave and the second signal wave of the manikin by the cardiac output preset parameters, the method further comprises: a phantom containing the parameter body surface area BSA is built.

In one or more embodiments of the present specification, after establishing the mannequin including the body surface area BSA, the method further includes: establishing an impedance wave model, an electrocardio wave model and a signal simulation circuit; the cardiac output preset parameters comprise parameters in the impedance wave model and parameters in the electrocardio wave model, the first signal wave is an impedance wave signal, and the second signal wave is an electrocardio wave signal.

In one or more embodiments of the present application, the acquiring the first signal wave and the second signal wave of the manikin by the cardiac output preset parameter specifically includes: acquiring an impedance wave signal corresponding to the human body model through the signal simulation circuit based on parameters in the impedance wave model; based on parameters in the electrocardiograph wave model, electrocardiograph wave signals corresponding to the human body model are acquired through the signal simulation circuit.

In one or more embodiments of the present specification, the parameters in the impedance wave model include a heart contraction index CTI; parameters in the electrocardiographic wave model include heart rate HR and ventricular ejection time VET.

In one or more embodiments of the present specification, the cardiac output prediction parameters include: heart contractility index CTI, heart rate HR, and ventricular ejection time VET.

In one or more embodiments of the present specification, the signal simulation circuit includes: the master control module is used for outputting a digital signal corresponding to the impedance wave signal and a digital signal corresponding to the electrocardio wave signal; the D/A conversion and analog output module is used for converting the digital signal corresponding to the impedance wave signal into an analog signal and converting the digital signal corresponding to the electrocardio wave signal into an analog signal and outputting the analog signal; and the power supply module is used for supplying power to the master control module and the D/A conversion and analog output module.

In one or more embodiments of the present specification, before the acquisition of the first signal wave and the second signal wave of the manikin by the cardiac output preset parameters, the method further comprises: applying a first signal wave acquisition electrode to subcutaneous tissue of the human body model; and a second signal wave acquisition electrode acts on subcutaneous tissue of the human body model.

In one or more embodiments of the present specification, after acquiring the first signal wave and the second signal wave of the manikin by the cardiac output preset parameters, the method further comprises: calculating human body sign parameters corresponding to the human body model according to the first signal wave and the second signal wave; and correcting the acquired first signal wave and second signal wave according to the human body physical sign parameters.

In another aspect, an embodiment of the present application further provides a verification device for a non-invasive cardiac output parameter, the device including: a processor; and a memory having stored thereon executable instructions that, when executed, cause the processor to perform a method of verification of a non-invasive cardiac output parameter as described above.

The verification method and the verification equipment for the noninvasive cardiac output parameters have the following beneficial effects: the impedance wave signal and the electrocardio wave signal of the human body model are output through the signal simulation circuit, then the cardiac output prediction parameter is measured according to the two signals, and is compared with the initial cardiac output preset parameter, so that the direct verification of the accuracy of the cardiac output parameter can be realized.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:

FIG. 1 is a flowchart of a method for verifying noninvasive cardiac output parameters according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a cardiac cycle provided in an embodiment of the present application;

FIG. 3 is a diagram showing a comparison between an impedance wave signal and an electrocardiographic wave signal according to an embodiment of the present disclosure;

fig. 4 is a schematic diagram of an electrode placement of the collection electrode according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram of a power supply module of a signal analog circuit according to an embodiment of the present application;

fig. 6 is a schematic diagram of a general control module of a signal analog circuit according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a D/A conversion and analog output module of a signal analog circuit according to an embodiment of the present disclosure;

fig. 8 is a structural diagram of a verification device for noninvasive cardiac output parameters according to an embodiment of the present application.

Detailed Description

For the purposes, technical solutions and advantages of the present application, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

The non-invasive cardiac output monitoring technology includes the steps of sending weak current to human body surface via attached collecting electrode, measuring potential difference at the collecting end, and finally, measuring the potential difference via resistance formula

And obtaining a resistance value and finally obtaining an impedance wave signal. The impedance wave signal obtained by the non-invasive cardiac output monitoring technology has a correlation with the electrocardiographic waveform, and the impedance wave signal changes along with the change of one cardiac cycle, and can be specifically shown in fig. 2 and 3. By morphological analysis of the impedance wave, parameters in terms of hemodynamics, i.e. heart, can be calculatedOutput parameters.

Verification of cardiac output parameters obtained using non-invasive cardiac output monitoring techniques may provide a channel of electrical electrocardiographic waveform signals, and a channel of impedance signals that may be correlated with the electrical electrocardiographic waveforms.

Since the data provided by the non-invasive cardiac output monitoring technology are parameters in terms of hemodynamics, the data can be obtained by calculating the obtained impedance value, and the body surface area of the tester is also related to the parameters, the verification process of the non-invasive cardiac output device needs to set human parameters (height, weight) for calculating and modeling the parameters. The setting parameter is a fixed value and cannot be changed.

The non-invasive cardiac output monitoring technology mostly adopts a body surface physiological impedance method to calculate parameters in the aspect of blood flow dynamics. Thus, the following 2 methods are currently used for verification of such technologies:

1) Impedance verification method

And loading rated resistance on the impedance acquisition electrode, and then reading the acquired impedance data to compare the accuracy. Using this method, the provided hemodynamic parameters are not verified, but rather the parameter accuracy is demonstrated by verifying the impedance accuracy.

This method is relatively simple, but does not directly prove the accuracy of the parameter values. The noninvasive cardiac output monitoring technology is not only related to impedance, but also related to the acquired electrocardiographic waveform and the human body parameters when measuring and calculating the hemodynamic parameters, so that the accuracy of the cardiac output parameters cannot be directly verified by the method.

2) Human body simulation method

In this method, a dummy is used to simulate a human body, and a simulated blood circulation system is added to the dummy to simulate blood flow. Parameters inside the dummy can be controlled by software, such as ejection volume, ejection speed, heart beat, etc. The noninvasive cardiac output monitoring technology collects impedance wave signals through electrodes on the surface of the dummy, and compares the finally measured hemodynamic parameters with the set parameters of the dummy to verify the accuracy of the hemodynamic parameters.

Although a comparatively intuitive parameter comparison can be obtained by this method, the cost of the dummy is too high and the comparison takes up space, which additionally increases the investment cost. The simulated blood circulation system for simulating the human body is complex, a large number of parameter settings are needed before verification is carried out, the system is difficult to maintain, and the stability of the parameters is difficult to confirm.

Therefore, both of the above commonly used device verification methods have problems in verifying the accuracy of the cardiac output parameters. The impedance verification method can only verify the basic principle of measurement, but cannot verify the accuracy of actually obtained parameters, and the simulation human body method is not suitable for being used in factories with a common scale due to the cost of a system and a dummy and the difficulty of maintenance.

Therefore, in order to more intuitively verify the cardiac output parameters obtained by the noninvasive cardiac output monitoring technology and to perform the verification in a general factory environment, the embodiment of the application provides a special verification method, by using the verification method, the required impedance wave signal can be deduced by setting the parameters of the blood flow dynamics, then the blood flow dynamics parameters are calculated by the impedance wave signal and the electrocardio wave signal, and the acquired parameters are compared with the set parameters, so that the accuracy of the cardiac output parameters is verified.

The following describes in detail the technical solution proposed in the embodiments of the present application through the accompanying drawings.

Fig. 1 is a flowchart of a method for verifying a noninvasive cardiac output parameter according to an embodiment of the present application. As shown in fig. 1, the cardiac output parameter verification method in the embodiment of the present application at least includes the following execution steps:

step 101, acquiring a first signal wave and a second signal wave of a human body model through cardiac output preset parameters.

The cardiac output preset parameters may be parameters related to hemodynamics set in advance, and then the first signal wave and the second signal wave of the human body model are acquired based on the set parameters. The first signal wave and the second signal wave are here both signal waves which are related to the physical parameters of the human body model.

And 102, calculating a cardiac output prediction parameter corresponding to the human body model by using the first signal wave and the second signal wave.

After the first signal wave and the second signal wave are acquired, measuring and calculating the cardiac output prediction parameters corresponding to the human body model through the parameters in the two signal waves, wherein the cardiac output prediction parameters are calculated in the actual measurement process.

And step 103, comparing the cardiac output prediction parameter with the cardiac output preset parameter.

And comparing the cardiac output prediction parameter with the cardiac output preset parameter to realize the direct verification of the accuracy of the cardiac output parameter.

In one or more possible implementations of the embodiments of the present application, the first signal wave is an impedance wave signal of the mannequin, and the second signal wave is an electrocardiographic wave signal of the mannequin, for both signals, an impedance wave model and an electrocardiographic wave model need to be built before acquisition, so that parameters in the impedance wave model and parameters in the electrocardiographic wave model form preset parameters of cardiac output. In one example of the present application, the parameters in the impedance wave model include a heart contraction index CTI, and the parameters in the electrocardiographic wave model include a heart rate HR and a ventricular ejection time VET; thus, cardiac output prediction parameters include: heart contractility index CTI, heart rate HR, and ventricular ejection time VET.

Therefore, the first signal wave and the second signal wave of the human body model are collected through the cardiac output preset parameters, specifically, based on the parameters in the impedance wave model, the impedance wave signals corresponding to the human body model are collected through the signal simulation circuit, and based on the parameters in the electrocardio wave model, the electrocardio wave signals corresponding to the human body model are collected through the signal simulation circuit.

It should be noted that, the signal simulation circuit is also constructed before the signal wave of the human body model is collected, and the signal simulation circuit in the embodiment of the application includes: the master control module is used for outputting digital signals corresponding to the impedance wave signals and digital signals corresponding to the electrocardio wave signals; the D/A conversion and analog output module is used for converting a digital signal corresponding to the impedance wave signal into an analog signal and converting a digital signal corresponding to the electrocardio wave signal into an analog signal and outputting the analog signal; and the power supply module is used for supplying power to the master control module and the D/A conversion and analog output module.

Furthermore, before the first signal wave and the second signal wave of the human body model are acquired, the human body model needs to be constructed, so that in order to save cost, the human body model in the embodiment of the application can be used without using a dummy model in a traditional sense, and only needs to contain the parameter of the human body surface area BSA.

In order to describe the verification method in the embodiment of the application in a clearer and more detailed manner, the embodiment of the application is further described in the following supplementary description.

1) Cardiac cycle

The heart contracts and expands once, constituting a mechanical active cycle, called the cardiac cycle. The cardiac cycle of both the atrium and the ventricle includes systole and diastole. Since the ventricles play a major role in cardiac pumping activity, the cardiac cycle is generally referred to as the active cycle of the ventricles. The normal heart's activity is composed of a series of cardiac cycles, and therefore the cardiac cycles can be used as the basis for analyzing the mechanical activity of the heart.

Fig. 2 is a schematic diagram of a cardiac cycle according to an embodiment of the present application. The duration of the cardiac cycle is related to the heart beat frequency. The adult heart rate averages 75 beats per minute, with each cardiac cycle lasting 0.8s. In one cardiac cycle, the two atria contract first for 0.1s, followed by atrial diastole for 0.7s. When the atrium contracts, the ventricle is in diastole, and shortly after the atrium enters diastole, the ventricle starts to contract for 0.3s, then enters diastole for 0.5s. For normal people, if the heart rate increases or slows, the diastole and systole of the atria and ventricles will also change, but the corresponding cycle ratio will not change.

The physiological impedance acquired by non-invasive cardiac output techniques may also vary at different phases of the cardiac cycle. In the isovolumetric systolic phase, the physiological impedance is smaller; during the ejection phase, the physiological impedance increases and a maximum occurs; the physiological impedance begins to decrease during isovolumetric diastole; during the rapid filling period, the physiological impedance continues to decrease; during the slow filling period, the physiological impedance maintains a small change; during atrial systole, the physiological impedance continues to decrease, returning to the original level.

2) Description of noninvasive cardiac output monitoring techniques

The noninvasive cardiac output monitoring technology is a method for calculating the hemodynamic changes of a human body by measuring the physiological impedance changes of the body surface of the human body. The method comprises the steps of sending weak constant current to the ground through one electrode to calculate the voltage of the current flowing through each electrode, and finally, calculating the formula through impedance

An impedance value is calculated. The body surface impedance value of the human body is related to the ejection speed and ejection volume of each heart beat, so that the cardiac output parameter can be calculated through monitoring the body surface impedance.

The body surface impedance changes continuously along with the beating of the heart, and the speed and quantity of each beat of the blood can influence the impedance. Thus, the impedance values monitored using non-invasive cardiac output monitoring techniques are a trend graph of changes and will follow the generation of a continuous waveform of the electrocardiographic waveform.

The body surface impedance is related to cardiac ejection parameters and also related to other parameters, such as respiration, so that the non-invasive cardiac output monitoring technology is used for impedance measurement and calculation, and other unnecessary interference needs to be removed, so that a special scheme is adopted for non-invasive cardiac output acquisition in the embodiment of the application.

When the current with different frequencies is input into a human body, the current can act on different cortex (epidermis, dermis or subcutaneous), and the body surface impedance is easy to be interfered by factors such as respiration, static electricity and the like, so in the embodiment of the application, the current with certain frequency acts on other cortex of the human body to calculate the corresponding change of the impedance, so that the calculation of the hemodynamic parameters can be realized by the following formula:

wherein SV is stroke volume (unit: ml); p is the blood resistivity (unit: ohm/cm); l is the distance (in cm) between the two electrodes; z0 is chest impedance (units: ohm); dZ/dtmax is the heart contraction index, i.e., CTI, (unit: ohm/s), where Z is the physiological impedance acquired and tmax is one complete cardiac cycle; t is the ventricular ejection time, i.e., VET, (unit: s).

In one example of the present application, the aforementioned constant current may be applied to subcutaneous tissue of a human body, and in this cortex, fat, ungulate tissue and blood vessels are included, and fat and ungulate tissue are poor conductors, weak current hardly flows therein, and blood in the blood vessels is an excellent conductor, so that the flow and measurement of current are facilitated, so that the embodiments of the present application have better accuracy in measuring cardiac output parameters.

3) Electrode paste placement for noninvasive cardiac output monitoring technology

The electrode patch of the noninvasive cardiac output monitoring technology can be attached to a discharge electrode slice on a body surface in a mode of fig. 4, and is used for collecting physiological impedance wave signals and electrocardio wave signals. Wherein Z1 is a current emitter, Z2 is a measuring electrode 1, Z3 is a measuring electrode 2, Z4 is a grounding electrode, EKG1 is an electrocardio acquisition electrode, and EKG2 is an electrocardio reference electrode.

Noninvasive cardiac output monitoring techniques measure chest impedance wave signals through electrodes Z2 and Z3, typically at a distance of 35cm; the electrocardiographic wave signal is acquired by EKG 1.

4) Analysis of impedance wave signals and electrocardiographic wave signals

By morphological analysis of the electrocardiographic wave signal and the impedance wave signal, a basic relationship between the electrocardiographic waveform and the impedance waveform, and the first-order impedance waveform can be established, as shown in fig. 3. And then, the heart cycle chart (shown in fig. 2) of the electrocardiographic waveform is comprehensively analyzed, so that the following information can be obtained:

(1) the period of the impedance waveform is consistent with that of the electrocardiographic waveform;

(2) the PEP stage that the starting point of the Q wave to the ST segment of the electrocardio waveform is impedance wave;

(3) the ejection phase + isovolumetric diastole of the electrocardiographic waveform is the LEVT phase of the impedance wave.

Therefore, the time length of the above stage can be obtained by analyzing the electrocardiographic waveform. As can be seen from an analysis of the impedance wave, the parameters that determine the morphology of the impedance waveform include: z maximum, Z minimum, peak-to-peak of impedance wave; TFIF, the length of time from the peak of the first-order impedance wave to the first return to above baseline.

The above waveform is calculated to obtain the above parameters, and the formula can be used

To calculate hemodynamic parameters, i.e. cardiac output parameters.

5) Modeling

(1) A human body model is built, the body height is 160, the weight is 60kg, the BSA=1.64 m is calculated according to a human body surface area BSA formula ² 。

And then establishing an electrocardio wave model and an impedance wave model according to the human body model.

(2) An electrocardiographic wave model 1 is established, the set parameter heart rate HR is 60bpm, the ventricular ejection time VET is 300ms, and the TFIF is 300ms.

An impedance wave model 1 is established according to the relation between each phase of the cardiac cycle and the physiological impedance, and parameters are set: heart contraction index cti=2000, then z0max-z0min=dz=cti=dtmax=2000×0.3=600 according to the formula.

(3) An electrocardiographic wave model 2 was built, and parameters of 80bpm heart rate HR, 400ms ventricular ejection time VET and 400ms TFIF were set.

An impedance wave model 2 is established according to the relation between each phase of the cardiac cycle and the physiological impedance, and parameters are set: heart contraction index cti=3000, then z0max-z0min=dz=cti=dtmax=3000×0.4=1200 according to the formula.

(4) An electrocardiographic wave model 3 is established, the device parameter heart rate HR is 220bpm, the ventricular ejection time VET is 100ms, and the TFIF is 100ms.

An impedance wave model 2 is established according to the relation between each phase of the cardiac cycle and the physiological impedance, and parameters are set: the heart contraction index cti=1000, then z0max-z0min=dz=cti=dtmax=1000×0.1=100 according to the formula.

6) Construction circuit

And constructing each module of the signal simulation circuit. The power supply module is a power supply input of the signal simulation circuit, and can output voltages of 6V and 3.3V for other circuit modules, and the circuit diagram is shown in fig. 5; the master control module comprises a singlechip PIC16F876A, and outputs set signal waveforms (an electrocardiographic wave signal and an impedance wave signal) through a singlechip program, and the circuit diagram is shown in fig. 6; the D/A conversion and analog output module converts the digital signal generated by the singlechip into an analog signal and performs waveform processing, and the circuit diagram is shown in fig. 7.

As shown in fig. 5, the power supply module includes: the pin 1 of the interface J1 is connected with the voltage test point V1, the pin 2 is grounded, and the pin 3 is suspended; the pin 1 of the interface J1 is simultaneously connected with one end of a capacitor C1, and the other end of the capacitor C1 is grounded; the pin 1 of the interface J1 is also connected with the cathode of a diode D1, and the anode of the diode D1 is grounded; the pin 1 of the interface J1 is also connected with one end of a capacitor C2, and the other end of the capacitor C2 is grounded; the pin 1 of the interface J1 is also connected with one end of a capacitor C3, and the other end of the capacitor C3 is grounded; the pin 1 of the interface J1 is also connected with one end of a switch S1, the other end of the switch S1 is connected with the pin 3 of a voltage conversion chip U1, the pin 2 of the voltage conversion chip U1 is connected with one end of a capacitor C4 and simultaneously connected with one end of a capacitor C5, and simultaneously connected with one end of a capacitor C6, the other end of the capacitor C4 is grounded, the other end of the capacitor C5 is grounded, the other end of the capacitor C6 is grounded, and one end of the capacitor C6 is also connected with a voltage test point V2; the pin 1 of the voltage conversion chip U1 is grounded.

In the power supply module, 4 batteries with the number 5 are adopted to provide required electric quantity, after the 4 batteries are connected in series, an interface J1 is connected, and the voltage of the batteries can be measured at a voltage test point V1; the switch S1 can be used for controlling the starting of the power supply module, when the switch S1 is arranged at the 1 position, the power supply module is started, when the switch S1 is arranged at the 2 position, the power supply module is closed, the power supply module adopts 1117S_3.3V packaged by SOT-223 as a voltage conversion chip U1 to convert input voltage into 3.3V so as to supply power for other modules, and the voltage conversion chip U1 can constantly output 3.3V without being influenced by voltage change of an input end; at voltage test point V2, the voltage output by the power supply module may be measured.

As shown in fig. 6, the master control module includes: the general control chip U2, pin 1 of the general control chip U2 is connected with one end of a resistor R7, and the other end of the resistor R7 is connected with a voltage source V7; the pin 2 of the master control chip U2 is connected with one end of a resistor R1, and simultaneously connected with one end of a resistor R2, the other end of the resistor R1 is connected with a voltage test point V4, and the other end of the resistor R2 is grounded; the pin 3 of the master control chip U2 is connected with one end of a resistor R3, the pin 4 of the master control chip U2 is connected with one end of a resistor R4, and the other end of the resistor R3 is connected with the other end of the resistor R4 and then connected with a voltage source V5; the pin 3 and the pin 4 of the master control chip U2 are also connected with one end of the switch S2 at the same time, and the other end of the switch S2 is grounded; the pin 8 of the master control chip U2 is grounded; the pin 9 of the master control chip U2 is connected with one end of the crystal oscillator chip U3 and one end of the capacitor C9, the pin 10 of the master control chip U2 is connected with the other end of the crystal oscillator chip U3 and one end of the capacitor C8, and the other end of the capacitor C8 is grounded after being connected with the other end of the capacitor C9; pin 19 of the master control chip U2 is grounded; the 20 # pin of the master control chip U2 is connected with one end of the capacitor C7, and is simultaneously connected with the voltage input point V3, and the other end of the capacitor C7 is grounded; the 23 # pin of the master control chip U2 is connected with one end of a resistor R6, and the other end of the resistor R6 is grounded; the 25 # pin of the master control chip U2 is connected with the cathode of the light emitting diode D2, the anode of the light emitting diode D2 is connected with one end of the resistor R5, the other end of the resistor R5 is connected with the voltage source V8, and the 25 # pin of the master control chip U2 is also connected with the frequency test point V6.

In the master control module, the master control chip U2 is realized by adopting a singlechip PIC16F876A-ISP, and the 3.3V voltage output by the power supply module is connected to the No. 20 pin of the master control chip U2. The pin No. 2 of the total control chip U2 can be used for detecting electric quantity, and when the voltage is lower than 4.5V, the total control module is in a low-electric-quantity state and can not provide signals required by subsequent modules; the switch S2 can control the levels of a pin 3 and a pin 4 of the master control chip U2, when the switch S2 is placed at a position 29, the pin 3 is high, the pin 4 is low, the master control chip U2 outputs a signal A, when the switch S2 is placed at a position 30, the pin 3 is low, the pin 4 is high, the master control chip U2 outputs a signal B, when the switch S2 is placed at a position 31, the pin 3 and the pin 4 are both high, and the master control chip U2 outputs a signal C; meanwhile, the master control chip U2 uses a crystal oscillator of 44MHz to provide the required frequency; the pin 25 of the master control chip U2 is connected with a light emitting diode D2, and can be used for collecting the frequency of an output signal at a frequency test point V6; meanwhile, a 16-number pin and a 15-number pin of the master control chip U2 are respectively used as a signal input pin and an output pin.

As shown in fig. 7, the D/a conversion and analog output module includes: the pin 1 of the conversion chip U3 is connected with a voltage source C9 and is simultaneously connected with one end of a capacitor C12, and the other end of the capacitor C12 is grounded; the No. 2 pin and the No. 6 pin of the conversion chip U3 are connected with one end of a resistor R8, the other end of the resistor R8 is connected with one end of a capacitor C10, and the other end of the capacitor C10 is grounded; the pin 7 of the conversion chip U3 is grounded, the pin 8 of the conversion chip U3 is connected with one end of a resistor R17, the other end of the resistor R17 is connected with one end of a capacitor C11, and the other end of the capacitor C11 is grounded; the other end of the resistor R17 is simultaneously connected with a No. 3 pin of the amplifying chip U4, a No. 4 pin of the amplifying chip U4 is grounded, a No. 2 pin of the amplifying chip U4 is connected with a No. 1 pin of the amplifying chip U4, and a No. 1 pin of the amplifying chip U4 is connected with one end of the resistor R16; the pin 5 of the amplifying chip U4 is connected with a voltage source V10 and is simultaneously connected with one end of a capacitor C13, and the other end of the capacitor C13 is grounded; the other end of the resistor R16 is connected with one end of the capacitor C16, and is simultaneously connected with one end of the resistor R11 and the No. 5 pin of the interface J3; after the other end of the capacitor C16 is connected with the other end of the resistor R11, the pin 6 of the interface J3 is connected, and meanwhile, one end of the resistor R10 is connected, and the other end of the resistor R10 is grounded; and the No. 2 pin and the No. 3 pin of the interface J3 are connected with the No. 4 pin and then grounded.

Further, one end of the capacitor C10 is also connected with the first end of the variable resistor R9, the second end of the variable resistor R9 is grounded, the third end of the variable resistor R9 is connected with the No. 3 pin of the amplifying chip U5, the No. 2 pin of the amplifying chip U5 is connected with one end of the capacitor C15, meanwhile, one end of the resistor R12 is connected with the first end of the variable resistor R13, the other end of the capacitor C15 is connected with the second end of the variable resistor R13 after being connected with the other end of the resistor R12, and the third end of the variable resistor R13 is grounded after being connected with the second end of the variable resistor R13; the No. 1 pin of the amplifying chip U5 is connected with the base electrode of the triode Q, the emitter electrode of the triode Q is connected with one end of the resistor R12, the collector electrode of the triode Q is connected with the No. 2 pin of the filter chip U6, and meanwhile, the No. 3 pin of the filter chip U6 is connected; the pin 1 of the filter chip U6 is connected with a voltage source V11 and is simultaneously connected with one end of a capacitor C14, and the other end of the capacitor C14 is grounded; the No. 4 pin of filter chip U6 is grounded, the No. 5 pin is unsettled, the one end of 6 pin connecting resistor R15, the 5 pin of interface J2 is connected simultaneously, the one end of connecting resistor R14 simultaneously, the 4 pin of interface J2 is connected to the other end of resistor R15, the No. 1 pin of interface J2 is connected to the other end of resistor R14, the 2 pin of interface J2 is connected with the No. 3 pin back, the ground connection.

In the D/A conversion and analog output module, the digital-analog conversion chip U3 adopts the MCP4822-E_P chip to convert digital-analog signals, and the converted signals are filtered and amplified through the 2-level signals and are respectively connected to the binding post through the J2 interface and the J3 interface.

7) Verification procedure for cardiac output parameters

The non-invasive cardiac output parameter may complete the accuracy verification process according to the following procedure:

(1) a signal simulation circuit (simulator may also be used) is connected to the non-invasive cardiac output apparatus.

(2) Setting parameters HR to 60, VET to 300ms, CTI to 2000, and outputting waveform. And using noninvasive cardiac output equipment to read the electrocardio wave signals and the impedance wave signals, acquiring HR and VET according to the electrocardio wave signals, and acquiring a parameter CTI according to the variation of the impedance wave signals.

(3) And comparing the acquired parameters with the set parameters.

(4) The modification parameters HR is 80, VET is 400ms, CTI is 3000, and the waveform is output. And using noninvasive cardiac output equipment to read the electrocardio wave signals and the impedance wave signals, acquiring HR and VET according to the electrocardio wave signals, and acquiring a parameter CTI according to the variation of the impedance wave signals.

(5) And comparing the acquired parameters with the set parameters.

(6) The modification parameters HR is 220, VET is 100ms, CTI is 1000, and the waveform is output. And using noninvasive cardiac output equipment to read the electrocardio wave signals and the impedance wave signals, acquiring HR and VET according to the electrocardio wave signals, and acquiring a parameter CTI according to the variation of the impedance wave signals.

(7) And comparing the acquired parameters with the set parameters.

Thus, the accuracy verification process of the cardiac output parameter is completed.

The foregoing is a method embodiment in the embodiments of the present application, and based on the same inventive concept, the embodiments of the present application further provide a verification device for a noninvasive cardiac output parameter, where the structure of the verification device is shown in fig. 8.

Fig. 8 is a structural diagram of a verification device for noninvasive cardiac output parameters according to an embodiment of the present application. As shown in fig. 8, the apparatus includes: a processor; and a memory having stored thereon executable instructions that, when executed, cause the processor to perform a method of verification of a non-invasive cardiac output parameter as described above.

In one or more possible implementations of the embodiments of the present application, the processor is configured to collect, by the cardiac output preset parameter, a first signal wave and a second signal wave of the manikin; calculating a cardiac output prediction parameter corresponding to the human body model by using the first signal wave and the second signal wave; and comparing the cardiac output prediction parameter with the cardiac output preset parameter.

All embodiments in the application are described in a progressive manner, and identical and similar parts of all embodiments are mutually referred, so that each embodiment mainly describes differences from other embodiments. In particular, for the apparatus embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference is made to the description of the method embodiments in part.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and changes may be made to the present application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. which are within the spirit and principles of the present application are intended to be included within the scope of the claims of the present application.

Claims

1. A method of non-invasive cardiac output parameter verification, the method comprising:

acquiring a first signal wave and a second signal wave of a human body model through cardiac output preset parameters;

calculating a cardiac output prediction parameter corresponding to the human body model by using the first signal wave and the second signal wave;

and comparing the cardiac output prediction parameter with the cardiac output preset parameter.

2. A method of non-invasive cardiac output parameter verification according to claim 1, wherein prior to acquiring the first signal wave and the second signal wave of the manikin by cardiac output preset parameters, the method further comprises:

a phantom containing the parameter body surface area BSA is built.

3. A method of non-invasive cardiac output parameter verification according to claim 2, wherein after establishing the mannequin comprising body surface area BSA, the method further comprises:

establishing an impedance wave model, an electrocardio wave model and a signal simulation circuit;

the cardiac output preset parameters comprise parameters in the impedance wave model and parameters in the electrocardio wave model, the first signal wave is an impedance wave signal, and the second signal wave is an electrocardio wave signal.

4. A method for non-invasive cardiac output parameter verification according to claim 3, wherein the acquiring the first signal wave and the second signal wave of the manikin by the cardiac output preset parameter specifically comprises:

acquiring an impedance wave signal corresponding to the human body model through the signal simulation circuit based on parameters in the impedance wave model;

based on parameters in the electrocardiograph wave model, electrocardiograph wave signals corresponding to the human body model are acquired through the signal simulation circuit.

5. A method of non-invasive cardiac output parameter verification according to claim 4, wherein,

parameters in the impedance wave model include a heart contraction index CTI;

parameters in the electrocardiographic wave model include heart rate HR and ventricular ejection time VET.

6. A method of non-invasive cardiac output parameter verification according to claim 1, wherein,

the cardiac output prediction parameters include: heart contractility index CTI, heart rate HR, and ventricular ejection time VET.

7. A method of non-invasive cardiac output parameter verification according to claim 3, wherein the signal simulation circuit comprises:

the master control module is used for outputting a digital signal corresponding to the impedance wave signal and a digital signal corresponding to the electrocardio wave signal;

the D/A conversion and analog output module is used for converting the digital signal corresponding to the impedance wave signal into an analog signal and converting the digital signal corresponding to the electrocardio wave signal into an analog signal and outputting the analog signal;

and the power supply module is used for supplying power to the master control module and the D/A conversion and analog output module.

8. A method of non-invasive cardiac output parameter verification according to claim 1, wherein prior to acquiring the first signal wave and the second signal wave of the manikin by cardiac output preset parameters, the method further comprises:

applying a first signal wave acquisition electrode to subcutaneous tissue of the human body model;

and a second signal wave acquisition electrode acts on subcutaneous tissue of the human body model.

9. The method of non-invasive cardiac output parameter verification according to claim 8, wherein after acquiring the first signal wave and the second signal wave of the manikin by cardiac output preset parameters, the method further comprises:

calculating human body sign parameters corresponding to the human body model according to the first signal wave and the second signal wave;

and correcting the acquired first signal wave and second signal wave according to the human body physical sign parameters.

10. A verification device for non-invasive cardiac output parameters, the device comprising:

a processor; the method comprises the steps of,

a memory having stored thereon executable instructions which, when executed, cause the processor to perform a method of verification of a non-invasive cardiac output parameter as claimed in any of claims 1-9.