CN112674750B - Method for calculating human body hemodynamics parameters - Google Patents
Method for calculating human body hemodynamics parameters Download PDFInfo
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- CN112674750B CN112674750B CN202011579644.2A CN202011579644A CN112674750B CN 112674750 B CN112674750 B CN 112674750B CN 202011579644 A CN202011579644 A CN 202011579644A CN 112674750 B CN112674750 B CN 112674750B
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Abstract
The invention discloses a method for calculating human body hemodynamics parameters, which belongs to the field of medical measurement, and comprises the following steps of S01, generating and outputting an electric signal with certain frequency; s03, transmitting the electric signal with certain frequency to human body and measuring the frequency of the input signal; s05, measuring and obtaining the resonance frequency of the human body current loop of the signal at each time point by sensing the frequency of the electric signal with certain frequency input into the human body and the frequency conversion frequency of the output signal; and S07, determining the resonant frequency of the current loop, and calculating the basic parameter of the human heart, namely stroke volume, reflecting the cardiac function by using the change rate of the resonant frequency of the current loop. The invention measures the stroke volume through the change rate of the resonant frequency, and has small influence of interference and high accuracy.
Description
Technical Field
The invention relates to the field of measurement of human body electric signals, in particular to a method for calculating human body hemodynamics parameters.
Background
In the field of biomedical electrics, a human body is mostly simulated by using an analog circuit based on a resistor R, an inductor L and a capacitor C, and particularly, the human body is generally researched by using a series circuit and a parallel circuit which are composed of the resistor, the inductor and the capacitor.
Methods based on impedance calculations, etc. are used to calculate hemodynamic parameters. In a real human body, the resistance R, the inductance L and the capacitance C are constantly changing. Whether in a series or parallel circuit of resistor R, inductor L and capacitor C, any variation in these variables will cause the resonant condition of the loop to vary, giving the loop an infinite number of resonant frequency points.
In the series model, when the resistance R, the inductance L and the capacitance C loop resonate, the loop reactance is 0, which is the minimum loop impedance value. And the current value of the loop reaches a maximum value. The frequency of resonance can be obtained from the maximum value of the calculated current. The series resonant circuit features a minimum total impedance, a maximum current at a given supply voltage, a resistive circuit, and a higher voltage on the capacitor or inductor than the supply voltage.
In parallel circuits, the voltage across the capacitor is at a maximum when resonance occurs. The resistance R, the inductance L and the capacitance C are constantly changed, so that an infinite number of resonant frequencies can be obtained by testing different voltage maximum points. When the voltage is constant, the current is minimum when the resonance occurs. The total impedance is the largest, the circuit is resistive, and the branch current may be greater than the total current.
The existing bio-impedance measurement method uses a method of dividing voltage by current to calculate, so that errors exist when a human body is analyzed, and the analysis of the cardiac output of the human body by using a phase difference is more accurate.
The human body impedance is not constant all the time, and when the heart performs the relaxation exercise, the human body impedance changes along with the time, and the human body impedance is equivalent to a constant resistor, so that the activity condition of the human body cannot be well reflected.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention is directed to a non-impedance blood flow output measurement method.
To achieve the above object, the present invention provides a method for calculating hemodynamic parameters of a human body, comprising
S01, generating and outputting an electric signal with a certain frequency;
s03, transmitting the electric signal with certain frequency to human body and measuring the frequency of the input signal;
s05, measuring and obtaining the resonance frequency of the human body current loop through which the signal passes at each time point by sensing the frequency of the electric signal with a certain frequency input into the human body and the frequency conversion frequency of the output signal;
and S07, determining the resonant frequency of the current loop, and calculating the basic parameter of the human heart, namely stroke volume, reflecting the cardiac function by using the change rate of the resonant frequency of the current loop.
Further, said calculating of the resonance frequency comprises using a functional relationship between said resonance frequency and the blood flow.
Further, the proportionality coefficient of the linear relationship includes systolic ejection time of the subject.
Further, the method comprises reducing or eliminating the modulation of the frequency of the input signal of the current loop to provide a stable frequency input signal.
Further, the method includes calculating at least one of stroke volume, cardiac output, cerebral intra-luminal blood volume, or arterial blood flow using the rate of change of the resonant frequency of the current loop.
Further, said wherein said arterial blood flow is selected from the group consisting of: cardiac aorta, pulmonary aorta, radial artery, femoral artery, finger artery, external carotid blood flow, internal carotid blood flow, ulnar blood flow, radial artery blood flow, brachial artery blood flow, common iliac artery blood flow, external iliac artery blood flow, posterior tibial blood flow, anterior tibial blood flow, fibular blood flow, lateral plantar artery blood flow, medial plantar artery blood flow, and deep plantar artery blood flow.
Further, the frequency of the electric signal of a certain frequency input into the human body and the frequency of the frequency conversion of the output signal are measured by connecting a plurality of electrodes to the body of the object, and the resonance frequency of the human body current loop through which the signal passes at each time point is obtained through measurement.
Further wherein the number of said plurality of electrodes is selected to substantially separate the frequency of said input signal from at least one influence selected from the group consisting of posture change effects, respiration effects, and motion effects, and effects of other surrounding instruments or objects.
Further wherein the plurality of electrodes comprises two electrodes.
Further wherein the plurality of electrodes comprises three electrodes.
In a preferred embodiment of the present invention, the inaccuracy of the impedance method is overcome by measuring and calculating the rate of change of resonance to obtain data on blood flow.
The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, the features and the effects of the present invention.
Drawings
FIG. 1 is a flow chart of a method in accordance with a preferred embodiment of the present invention.
Detailed Description
The technical contents of the preferred embodiments of the present invention will be more clearly and easily understood by referring to the drawings attached to the specification. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.
In the drawings, structurally identical elements are represented by like reference numerals, and structurally or functionally similar elements are represented by like reference numerals throughout the several views. The size and thickness of each component shown in the drawings are arbitrarily illustrated, and the present invention is not limited to the size and thickness of each component. The thickness of the components may be exaggerated where appropriate in the figures to improve clarity.
As can be seen in the figures,
a method of calculating hemodynamic parameters of a human body, comprising
S01, generating and outputting an electric signal with a certain frequency;
s03, transmitting the electric signal with certain frequency to human body and measuring the frequency of the input signal;
s05, measuring and obtaining the resonance frequency of the human body current loop through which the signal passes at each time point by sensing the frequency of the electric signal with a certain frequency input into the human body and the variable frequency of the output signal;
and S07, determining the resonant frequency of the current loop, and calculating the stroke volume of the basic parameter of the human heart reflecting the cardiac function by using the change rate of the resonant frequency of the current loop. The calculation of the resonance frequency includes the functional relationship between the resonance frequency and the blood flow used. The scaling factor of the linear relationship includes the systolic ejection time of the subject. Including reducing or eliminating modulation of the frequency of the input signal to the current loop to provide a stable frequency input signal. The calculation of the rate of change of the resonant frequency of the current loop including use includes at least one quantity of stroke volume, cardiac output, cerebral intracavity blood volume, or arterial blood flow.
Wherein the arterial blood flow is selected from the group consisting of: cardiac aorta, pulmonary aorta, radial artery, femoral artery, finger artery, external carotid blood flow, internal carotid blood flow, ulnar blood flow, radial artery blood flow, brachial artery blood flow, common iliac artery blood flow, external iliac artery blood flow, posterior tibial blood flow, anterior tibial blood flow, fibular blood flow, lateral plantar artery blood flow, medial plantar artery blood flow, and deep plantar artery blood flow.
The resonance frequency of a human body current loop through which a signal passes at each time point is measured and obtained by sensing the frequency of a plurality of electric signals input into a human body at a certain frequency and the frequency of corresponding output signal frequency conversion by connecting a plurality of electrodes to the body of a subject.
Wherein the number of the plurality of electrodes is selected to substantially separate the frequency of the input signal from at least one influence selected from the group consisting of a posture change influence, a respiration influence, and a motion influence, and influence of other surrounding instruments or objects. The plurality of electrodes includes two electrodes. The plurality of electrodes includes three electrodes. The plurality of electrodes includes four electrodes.
Wherein the plurality of electrodes are connected to have a substantially constant sensitivity to electrical signals transmitted through the electrodes regardless of the orientation of the electrodes on the subject.
Wherein at least a portion of the plurality of electrodes comprises at least one elongated conductive material designed and configured to adhere to at least a portion of an external organ of the test subject to have a substantially constant sensitivity to electrical signals transmitted through the electrodes regardless of an orientation of the electrodes on the external organ.
Wherein the external organ is selected from the group consisting of chest, hip, thigh, neck, head, arm, forearm, abdomen, gluteus, leg, hand and foot.
The linear relationship between the resonant frequency and blood flow comprises a functional relationship between the slope of the change in resonant frequency and blood flow.
Another preferred embodiment of the present invention discloses a method for calculating hemodynamic parameters of a human body, comprising S01 generating an electrical signal having a specific frequency;
s03, transmitting the electric signal to a specific part of the human body;
s05, sensing the output signal frequency of the specific part of the human body within a certain time;
and S07, determining the resonant frequency of the current loop corresponding to the specific part of the human body according to the output signal frequency of the specific part of the human body, and calculating the human body hemodynamic parameters by using the change rate of the resonant frequency of the current loop.
Preferably, the calculation in step S07 is based on a functional relationship between the resonance frequency and the blood flow.
Preferably, the coefficients of the functional relationship include factors of systolic ejection time of the subject.
Preferably, the method further comprises reducing or eliminating modulation of the frequency of the input signal to the current loop to provide a frequency stabilized input signal.
Preferably, the calculation of the rate of change of the resonant frequency of the current loop used comprises at least one of stroke volume, cardiac output, cerebral intracavity blood volume or arterial blood flow.
Preferably, the arterial blood flow is selected from the group consisting of: cardiac aorta, pulmonary aorta, radial artery, femoral artery, finger artery, external carotid blood flow, internal carotid blood flow, ulnar blood flow, radial artery blood flow, brachial artery blood flow, common iliac artery blood flow, external iliac artery blood flow, posterior tibial blood flow, anterior tibial blood flow, fibular blood flow, lateral plantar artery blood flow, medial plantar artery blood flow, and deep plantar artery blood flow.
Preferably, wherein the resonance frequency of the human body current loop through which the output signal passes at each point in time is measured by sensing the frequency of the plurality of electrical signals input into the human body and the corresponding output signal conversion frequency by connecting the plurality of electrodes to the body of the subject.
Preferably, the number of the plurality of electrodes is selected to substantially separate the frequency of the plurality of electrical signals input to the human body from at least one influence selected from the group consisting of a posture change influence, a respiration influence, a motion influence, and influence factors of other surrounding instruments or objects.
Preferably, the plurality of electrodes comprises two electrodes.
Preferably, the plurality of electrodes comprises three electrodes.
In a preferred embodiment of the present invention, the inaccuracy of the impedance method is overcome by measuring and calculating the rate of change of resonance to obtain data on blood flow.
The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.
Claims (8)
1. A method for calculating hemodynamic parameters of a human body, comprising
S01, generating an electrical signal having a specific frequency;
s03, transmitting the electric signal to a specific part of the human body;
s05, sensing the output signal frequency of the specific part of the human body within a certain time;
s07, connecting a plurality of electrodes to the body of the object, and measuring the resonance frequency of the human body current loop through which the output signal passes at each time point by sensing the frequency of a plurality of electric signals input into the human body and the corresponding frequency of the output signal; determining a resonant frequency of a current loop corresponding to the specific part of the human body according to the output signal frequency of the specific part of the human body, and calculating at least one quantity of stroke volume, cardiac output, cerebral blood volume or arterial blood flow by using the change rate of the resonant frequency of the current loop.
2. The method for calculating hemodynamic parameters of a human body of claim 1, wherein the calculating in S07 is based on a functional relationship between the resonant frequency and blood flow.
3. The method of calculating hemodynamic parameters of a subject of claim 2, wherein the coefficients of the functional relationship comprise factors of systolic ejection time of the subject.
4. The method of calculating a human hemodynamic parameter of claim 1, further comprising reducing or eliminating modulation of a frequency of an input signal to the current loop to provide a stable frequency input signal.
5. The method of calculating a human hemodynamic parameter of claim 1, wherein the arterial blood flow rate is selected from the group consisting of: cardiac aorta, pulmonary aorta, radial artery, femoral artery, finger artery, external carotid artery, internal carotid artery, ulnar artery, brachial artery, common iliac artery, external iliac artery, posterior tibial artery, anterior tibial artery, peroneal artery, lateral plantar artery, medial plantar artery, or deep plantar artery blood flow.
6. The method of claim 1, wherein the number of the plurality of electrodes is selected to separate the frequency of the plurality of electrical signals input to the body from at least one influence selected from the group consisting of a posture change influence, a respiration influence, a motion influence, and other surrounding objects.
7. The method of claim 6 wherein said plurality of electrodes comprises two electrodes.
8. The method of claim 6 wherein said plurality of electrodes comprises three electrodes.
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| WO2006087696A2 (en) * | 2005-02-15 | 2006-08-24 | Cheetah Medical Ltd. | System, method and apparatus for measuring blood flow and blood volume |
| US20110208071A1 (en) * | 2010-02-24 | 2011-08-25 | National Taiwan University | SMART NON-INVASIVE ARRAY-BASED HEMODYNAMIC MONITORING SYSTEM on CHIP AND METHOD THEREOF |
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