CN115886767A - Hemodynamics platform measuring method - Google Patents

Abstract

A hemodynamics platform measuring method is characterized in that a pulse wave of a person to be measured is measured by keeping a constant pressure on a measuring platform with the pressure of a blood pressure belt of an electronic sphygmomanometer in a range of 55-70 mm Hg, at least one pulse wave is captured from a plurality of measured pulse waves, and the heart stroke quantity is calculated by matching the waveform and characteristic point parameters of each pulse wave with the systolic pressure and diastolic pressure of the blood pressure of the person to be measured; the invention can change the pressure of the measuring platform by selecting the pressure of the measuring platform in a proper interval of 55-70 mm Hg in cooperation with the diastolic pressure and the physiological condition of different testees and the signal quality of the electronic sphygmomanometer, so that each tester can obtain a typical pulse waveform by proper measuring platform, the accuracy of the measuring result is improved, and the proportion of people who cannot be measured is reduced.

Description

Hemodynamic platform measurement method

Technical Field

The present invention relates to a measurement method, and in particular to a hemodynamic platform measurement method.

Background Art

Hemodynamic monitoring is a very important treatment activity for cardiovascular diseases. Its parameters, such as cardiac output (CO), refer to the total amount of blood ejected by a single ventricle per minute. It is the product of heart rate (HR) and stroke volume (SV), and is an important indicator of cardiac function. Through hemodynamic monitoring, clinical medical staff can identify the cause of the disease at an early stage, provide patients with appropriate medical treatment in a timely manner, and reduce the mortality rate of heart patients.

Currently, cardiac output monitoring technologies include invasive and non-invasive technologies. Invasive cardiac output detection technologies, such as cardiopulmonary volume monitoring (PiCCO), use the transpulmonary temperature dilution method and pulse curve analysis method to place a central venous catheter and an arterial catheter in the human body, inject a certain amount of ice water from the central venous end, and measure the temperature and time change line at the arterial end to measure the cardiac output.

Non-invasive cardiac output detection technologies such as impedance cardiovascular flow graph (ICG) are to set electrodes at both ends of the tissue chest cavity to measure the impedance cardiovascular flow graph, and substitute the parameters in the graph into the Kubicek stroke volume formula to calculate the cardiac output (CO); non-invasive cardiac output detection also has a pulse wave-based method, which is based on the elastic organ model (Windkessel Model). After obtaining the pulse wave using a pressure pulse device, the cardiac output (CO) is calculated using the pulse wave signal, waveform, and characteristic points of the waveform. Compared with invasive methods, the above non-invasive measurement methods have the advantages of being non-invasive, safe, and simple. However, in the method of calculating cardiac output using pulse waves, whether the waveform of the pulse wave typically shows each characteristic point is related to the pressure of the compression cuff. Therefore, choosing an appropriate platform pressure to measure the pulse wave is very important for the measurement result. Too high or too low will reduce the accuracy and reduce the number of people who can use this method for measurement.

Summary of the invention

Since the accuracy of the existing method of calculating cardiac output using pulse waves is related to the pressure of the selected measuring platform, the present invention sets a measuring platform in a preferred pressure range, and measures the pulse wave of the subject at a fixed pressure on the measuring platform, thereby improving the accuracy of the measurement results and reducing the proportion of people who cannot be measured.

In order to achieve the above-mentioned object of the invention, the present invention provides a hemodynamic platform measurement method, the steps of which include:

Measuring pulse waves on a measuring platform: inflate a pressure cuff of an electronic sphygmomanometer to a measuring platform with a pressure between 55 and 70 mmHg, and maintain the pressure on the measuring platform for a set time, measure the pulse wave of the subject, and extract at least one pulse wave from the measured multiple pulse waves, wherein the waveform of each pulse wave has characteristic points such as the highest point, the maximum slope point, the turning point, and the lowest point in time sequence;

Blood pressure measurement: measuring the systolic and diastolic blood pressure of the subject; and

Apply the measured parameters to calculate the cardiac output: The cardiac output is calculated based on the waveform of each pulse wave and the parameters of each characteristic point of the waveform in combination with the data of systolic pressure and diastolic pressure.

Furthermore, after the step of measuring the pulse wave on the measuring platform of the present invention, the electronic sphygmomanometer maintains the pressure of the cuff and continues to inflate the cuff to perform the step of measuring the blood pressure of the subject.

Furthermore, in the present invention, the step of measuring blood pressure precedes the step of measuring pulse wave by the measuring platform, and after the step of measuring blood pressure is completed, the step of measuring pulse wave by the measuring platform is then performed.

Furthermore, the present invention further includes a step of measuring heartbeat, measuring the heart rate of the subject to be tested, and in the step of calculating the cardiac output using the measured parameters, the cardiac output of the subject to be tested is obtained by multiplying the cardiac output by the heart rate.

Furthermore, the calculation of the stroke volume (SV) conforms to the following formula:

Among them, the highest point T _sys (P _sys , t _sys ), the maximum slope point _Tinst (P _inst , t _inst ), the turning point T _dic (P _dic , t _dic ), and the lowest point T _dia (P _dia , t _dia ).

Compared with the prior art, the present invention has the following beneficial effects:

The measuring platform for measuring the pulse wave of the present invention is an appropriate range of 55 to 70 mmHg. During measurement, the pressure of the measuring platform can be changed according to the diastolic pressure, physiological conditions and signal quality of the electronic sphygmomanometer of different subjects, so that each subject can obtain a typical pulse waveform at an appropriate measuring platform, thereby improving the accuracy of the measurement results and reducing the proportion of people who cannot be measured.

The blood pressure measuring step of the present invention can be immediately followed by the step of measuring the pulse wave on the measuring platform, or the two steps can be performed separately at different times or in reverse order. A further effect of the present invention is that if the blood pressure measuring step is performed by inflating the cuff immediately after the step of measuring the pulse wave on the measuring platform, the pulse wave waveform parameters, heart rate and blood pressure required for calculation can be measured in one cycle of inflation and deflation of the cuff, thereby accelerating the efficiency of measuring the cardiac output.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of the steps of a preferred embodiment of the present invention.

FIG. 2 is a pressure-time coordinate diagram of a measurement platform and blood pressure measurement according to a preferred embodiment of the present invention.

FIG. 3 is a pressure-time coordinate diagram of a pulse wave waveform according to a preferred embodiment of the present invention.

Explanation of symbols:

A Main wave B Dicrotic wave

T _sys highest point T _inst maximum slope point

T _dic turning point T _dia lowest point

τ time constant X measurement platform

Steps S01-S04

DETAILED DESCRIPTION

In order to understand the technical features and practical effects of the present invention in detail and to implement it according to the contents of the specification, a preferred embodiment as shown in the drawings is further described in detail as follows.

As shown in the flowchart of FIG1 , a preferred embodiment of the present invention provides a hemodynamic platform measurement method, the steps of which include:

(S01) Pulse wave measurement on the measuring platform: As shown in FIG. 2 , a pressure cuff of an electronic sphygmomanometer is inflated to a measuring platform X with a pressure between 55 and 70 mmHg. In the preferred embodiment, 65 mmHg is selected as the measuring platform X. The platform pressure of 65 mmHg is maintained on the measuring platform X for a set time, such as 8 seconds. During the set time, the pulse wave of the subject is measured. At least one pulse wave is captured from the measured continuous multiple pulse waves. In the preferred embodiment, one pulse wave with a typical waveform is captured. The waveform of the pulse wave is plotted with the horizontal axis as the unit time and the vertical axis as the pressure as shown in FIG. 3 . The front and rear waveforms of the pulse wave are divided into a main wave A and a dicrotic wave B corresponding to the systolic period and the diastolic period of the heart, and have, in chronological order, a highest point T _sys at the top of the main wave A, a maximum slope point T _inst with the largest slope in the waveform, and a turning point T _dic between the main wave A and the dicrotic wave B. , as well as characteristic points such as T _dia, the lowest point at the end of the B wave of the dicrotic wave.

The typical pulse wave refers to a pulse wave with an obvious turning point at the turning point T _dic between the main wave A and the dicrotic wave B. When the inflation pressure selected by the compression cuff of the electronic blood pressure machine is close to 70 mmHg or even exceeds 70 mmHg, the turning point T _dic of the pulse wave measured by the electronic blood pressure machine will gradually become flat and close to the curve. This deformed pulse wave is not suitable for calculating cardiac output (CO). When the inflation pressure of the compression cuff is lower than 55 mmHg, the characteristic points of the relevant pulse wave may disappear or be unclear, increasing the error after calculation.

(S02) Measuring blood pressure: In the preferred embodiment, as shown in FIGS. 2 and 3 , after the step of measuring the pulse wave on the measuring platform X, the electronic sphygmomanometer maintains the pressure of the cuff, that is, maintains the pressure of 65 mmHg and continues to inflate the cuff, and performs the step of measuring the blood pressure of the subject to measure the systolic and diastolic pressures of the subject. For example, the systolic and diastolic pressures measured in the preferred embodiment are 106 mmHg and 68 mmHg, respectively. In other preferred embodiments, the step of measuring blood pressure can be performed first and then the measuring platform can measure the pulse wave. In this case, the step of measuring blood pressure can be performed successively with the step of measuring pulse wave by the measuring platform or separately with a certain period of time interval. Relatively speaking, the advantage of the preferred embodiment of successively performing the step of measuring pulse wave by the measuring platform and the step of measuring blood pressure is that the cardiac output (CO) can be measured in the same cycle of inflation and deflation of the cuff, and the cuff pressure for measuring blood pressure can be avoided to the greatest extent to affect the elasticity of blood vessels and cause distortion of the subsequently measured pulse wave. However, the step of measuring blood pressure and the step of measuring pulse wave by the measuring platform performed successively can also have an accuracy of more than 80%.

(S03) Measuring heart rate: In the preferred embodiment, the heart rate (HR) of the subject is measured during the step of measuring blood pressure, and the measured value is 71 beats/minute. In other preferred embodiments, the heart rate can be measured during the step of measuring the pulse wave on the measuring platform, or at other times.

(S04) Calculating the stroke volume using the measured parameters: Calculating the stroke volume (CO) using the pulse wave waveform, the highest point T _sys , the maximum slope point T _inst , the turning point T _dic , and the lowest point T _dia , along with the systolic and diastolic pressure data, into the stroke volume calculation formula.

Please refer to the pulse wave waveform diagram of FIG3 , in which the abscissa represents unit time, the pressure of the ordinate is normalized with the data of systolic pressure 106 mmHg and diastolic pressure 68 mmHg, the origin of the abscissa 0 seconds is the starting point of the pulse wave, and the coordinates of the characteristic points of the processed waveform are: the highest point T _sys (P _sys , t _sys ) is (0.144, 106), the maximum slope point T _inst (P _inst , t _inst ) is (0.272, 96), the turning point T _dic (P _dic , t _dic ) is (0.344, 89), and the lowest point T _dia (P _dia , t _dia ) is (0.800, 68). The above parameters and data are substituted into the stroke volume calculation formula and the calculation process is described as follows:

As shown in Formula 1, the stroke volume (SV) is equal to the area A under the systolic waveform divided by the inverse Z of the instantaneous acceleration of the blood vessel cross section. In the preferred embodiment, A is 10.1256. As shown in Formula 4, the time constant τ is the constant of the pulse wave in the diastolic period. The value is obtained by the curve approximation method based on the waveform of the pulse wave in the diastolic period. In the preferred embodiment, τ is 0.20671. C is arterial compliance, which is the volume change caused by each unit pressure change. It reflects the buffering capacity of the arterial blood vessels and can be obtained by control measurement method or model estimation method. Since the C value of healthy people is similar when the electronic blood pressure meter with the same pressure cuff is used with the same pressure measurement platform X, this value is set as a constant. For example, the C value of the preferred embodiment is 0.20671. The pulse waveform of each person is different, so the value of τ is different. R is the total peripheral vascular resistance. Substituting the above τ and C into Formula 4, the R of the preferred embodiment is 6.36157*10 ^-4 .

Substituting the coordinate parameters of the above feature points into formula 3, the dP is calculated to be 277.25, and the calculation formula is:

将心搏量(SV)乘以心跳速率(HR)即得出待测者的心输出量(CO)为为4.08公升(L)，计算式为57.41*71/1000。Substituting the data of A, R and dP into formula 2, the stroke volume SV (ml) is 57.41, calculated as:

Multiplying the stroke volume (SV) by the heart rate (HR) gives the subject's cardiac output (CO), which is 4.08 liters (L), calculated using the formula 57.41*71/1000.

In addition to the above-mentioned preferred embodiment, the present invention calculates the stroke volume (SV) and cardiac output (CO) based on the waveform parameters of one pulse wave, and can also calculate the values of the stroke volume (SV) and cardiac output (CO) using the waveform parameters of two or more pulse waves, and then take the arithmetic average to improve the accuracy of the calculated stroke volume (SV) and cardiac output (CO).

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (7)

1. A method for measuring a hemodynamic platform, the method comprising:

the measuring platform measures pulse waves: inflating a pulse pressing belt of an electronic sphygmomanometer to a measuring platform with the pressure of 55-70 mm Hg, keeping the pressure on the measuring platform for a set time by fixing the pressure, measuring pulse waves of a person to be measured, and capturing at least one pulse wave from a plurality of measured pulse waves, wherein the waveform of each pulse wave has characteristic points such as a highest point, a maximum slope point, a turning point, a lowest point and the like according to a time sequence;

measuring blood pressure: measuring the systolic pressure and diastolic pressure of the blood pressure of the person to be measured; and

calculating stroke volume using the measurement parameters: the heart stroke volume is calculated by matching the waveform of each pulse wave and the parameters of each characteristic point of the waveform with the data of systolic pressure and diastolic pressure.

2. The method of claim 1, wherein after the step of measuring the pulse wave by the measuring platform, the electronic sphygmomanometer keeps the pressure of the tourniquet to continue to inflate the tourniquet, so as to perform the step of measuring the blood pressure of the subject.

3. The method of claim 1 or 2, further comprising a step of measuring the heart rate of the subject, and multiplying the heart rate by the heart stroke volume in the step of calculating the heart stroke volume using the measurement parameter to obtain the cardiac output of the subject.

4. The method of claim 3, wherein the Stroke Volume (SV) is calculated according to the following formula:

wherein the highest point T _sys (P _sys ,t _sys ) Maximum slope point T _inst (P _inst ,t _inst ) Turning point T _dic (P _dic ,t _dic ) Lowest point T _dia (P _dia ,t _dia )。

5. The method of claim 1, wherein the step of measuring the blood pressure is performed before the step of measuring the pulse wave by the measuring platform, and the step of measuring the pulse wave by the measuring platform is performed after the step of measuring the blood pressure is completed.

6. The method of claim 5, further comprising a step of measuring the heart rate of the subject, and in the step of calculating the heart rate using the measurement parameters, the step of multiplying the heart rate by the heart rate to obtain the cardiac output of the subject.

7. The method of claim 6, wherein the Stroke Volume (SV) is calculated according to the following formula:

wherein the highest point T _sys (P _sys ,t _sys ) Maximum slope point T _inst (P _inst ,t _inst ) Turning point T _dic (P _dic ,t _dic ) Lowest point T _dia (P _dia ,t _dia )。

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