CN101006919A - Detection method of cardiac output under the high differential pressure and device thereof - Google Patents

Abstract

A method for detecting cardiac output under large pressure difference and a device thereof belong to the field of human body parameter detection of biomedical engineering. The characteristic of the present invention is to use the heart rate HR and the characteristic quantity K of the pulse chart detected by the pressure pulse wave waveform, cooperate with the systolic blood pressure _Ps and the diastolic blood pressure _Pd measured by the sphygmomanometer, and the age Age to obtain the detection method of the cardiac output CO under a large pressure difference , and a detection device that can be embedded into a mobile phone using this method. This device includes the following three parts in turn: a pressure pulse wave sensor, a detection circuit and a mobile phone main control circuit. Compared with similar devices, this device has low cost. High accuracy, easy to carry and suitable for daily detection.

Description

A method and device for detecting cardiac output under large pressure difference

technical field

The invention belongs to the field of human body parameter detection of biomedical engineering. By detecting blood pressure (including systolic pressure P _s and diastolic blood pressure P _d ), heart rate HR, age, and pulse chart feature K of a living body, a detection method and device for cardiac output CO under large pressure difference are obtained.

Background technique

The use of pressure pulse waves to detect cardiac output has been studied since the 1960s. KH Wesseling proposed the elastic tube model in 1983, and designed a simple device for calculating cardiac output, but it could not reflect the influence of peripheral resistance, blood vessel elasticity and blood viscosity on physiological parameters. In 1988, Luo Zhichang et al. proposed A non-invasive, practical device suitable for all age groups, which takes into account the peripheral resistance, blood vessel elasticity and blood viscosity, and satisfies the practical application better. However, this device is only relatively accurate in detection under normal physiological conditions, and in many other cases, especially under large pressure differences, the detection distortion is relatively large.

At present, the detection of cardiac output under large pressure difference mainly relies on invasive catheter method or non-invasive echocardiography method, cardiac impedance method, spiral CT method, magnetic resonance method and cardiac nuclear medicine method. The catheter method is an invasive detection method, which is mainly used in operations and rescue of critically ill patients. The above-mentioned non-invasive methods are all used in hospitals. The cost of the instrument itself is high, and the detection cost is expensive, so it is not suitable for daily detection.

Contents of the invention

The purpose of the present invention is to: propose a method for detecting cardiac output by pressure pulse wave under large pressure difference, improve the existing deficiency of detecting cardiac output distortion by using pressure pulse wave under large pressure difference, and provide a civilian, low An inexpensive device that can be embedded into a mobile phone for routine testing.

The invention provides a method for detecting cardiac output under a large pressure difference, which is characterized in that it comprises the following steps:

(1) Record the age of the subject;

(2) Measure systolic pressure P _s and diastolic pressure P _d ;

(3) The pressure pulse wave waveform is obtained by using the pressure pulse wave sensor, and the pressure pulse wave waveform is obtained by the pressure pulse wave waveform

Obtain the heart rate HR and the pulse map feature quantity K, and the pulse map feature quantity K and the heart rate HR are obtained by the following formula:

$\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; =</span>\frac{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

t is time, P(t) is the pressure pulse wave waveform, the highest point is the systolic pressure P _s , the lowest point is the diastolic pressure P _d , and T is a cycle of the pressure pulse wave waveform;

$\mathrm{<span\; class="notranslate">\; HR</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

(4) Cardiac output CO can be obtained from the following formula according to Age, systolic blood pressure P _s , diastolic blood pressure P _d , heart rate HR and pulse chart feature K

$\mathrm{<span\; class="notranslate">\; CO</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 17</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; R</span>}}{{\mathrm{<span\; class="notranslate">\; K</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Among them, R is a dimensionless quantity, and its value is

R=-0.011*( _Ps - _Pd )+0.005*HR-0.002*Age+3.055*K.

A detection device for cardiac output under a large pressure difference, characterized in that the device includes the following three parts in sequence: a pressure pulse wave sensor, a detection circuit and a mobile phone main control circuit; the sensor adopts a pressure pulse wave sensor, and the detection circuit includes A differential amplifier circuit and a second-order low-pass amplifier circuit, the second-order low-pass amplifier circuit includes a second-order low-pass amplifier and a digital potentiometer, the second-order low-pass amplifier is externally connected to a digital potentiometer for a feedback circuit with adjustable gain, and the digital The potentiometer is used to receive the control signal transmitted by the controller of the main control circuit of the mobile phone, and the control signal is used to control the digital potentiometer to realize the adjustment of the analog signal amplitude; the main control circuit of the mobile phone includes an A/D converter, a controller, and a CPU chip.

The sensor is connected with the differential amplifier circuit, and the controller controls the digital potentiometer to realize the adjustment of the analog signal amplitude; the waveform analysis and the above-mentioned cardiac output parameter calculation are completed by the CPU chip of the main control circuit of the mobile phone.

This detection device is developed based on the mobile phone, and a detection device for cardiac output under large pressure difference is embedded in the mobile phone. Its main feature is that a surface-mounted detection circuit for cardiac output under large pressure difference is added to the original mobile phone circuit. And this device has civilian, lower cost, is convenient to the characteristics of daily detection; Because the palmtop computer circuit also has A/D converter, controller, CPU chip, in the palmtop computer, embeds the detection device of cardiac output under big pressure difference, also can Break away from the protection scope of the present invention.

Description of drawings

Figure 1 is a typical pulse wave diagram

Figure 2 is a block diagram of the detection device

Fig. 3 is the comparative result of the cardiac output CO detected by ultrasound and the cardiac output CO detected by the method and device thereof of the present invention

Fig. 4 is the scatter diagram of the cardiac output CO detected by ultrasound and the cardiac output CO detected by the method and device thereof of the present invention

Detailed ways

The sensor adopts a pressure sensor, such as a strain-type piezoelectric sensor or a polyvinylidene fluoride (PVDF) film sensor; the detection circuit includes a differential amplifier circuit and a second-order low-pass amplifier circuit, and the second-order low-pass amplifier circuit includes a second-order low-pass amplifier And digital potentiometers, second-order low-pass amplifiers use high-precision, single-supply, rail-to-rail surface-mount operational amplifier devices, such as a MCP6234 in SOIC14 package containing four operational amplifiers to complete the differential amplifier circuit and two The design of the second-order low-pass amplifier, the feedback circuit connected to the second-order low-pass amplifier to realize the adjustable gain adopts a digital potentiometer, and the digital potentiometer also adopts a surface-mounted device, such as X9313 in SOIC8 package, which is used to receive The control signal transmitted by the controller of the control circuit; the main control circuit of the mobile phone provides the necessary A/D converter and controller for detection, and adopts the mobile phone containing the main control circuit of the mobile phone (such as Samsung 2410) with integrated A/D converter. The sensor is connected to the differential amplifier of the detection circuit in the mobile phone. The connection line is composed of power line, data line (+), data line (-) and ground line. The power line and ground line are respectively connected to the power line and ground line of the differential amplifier circuit. The data line (+) and the data line (-) are respectively connected to the two input terminals of the differential amplifier circuit. The control signals are generated by the controller in the main control circuit of the mobile phone, which are CS, INC and U/D respectively, and are used to control the digital potentiometer to realize the adjustment of the analog signal amplitude. Waveform analysis and the above-mentioned cardiac output parameter calculation are completed by the CPU chip of the main control circuit of the mobile phone. as shown in picture 2.

The cardiac output of 30 cases of large pressure difference experimenters was detected by using the method and the device thereof, and compared with the detection results of the color Doppler echocardiography detector. The test results are shown in Table 1. The results of the two tests are basically the same. After calculation, the average relative error of heart rhythm HR is 5.36%. The heart rate HR is a time-varying parameter, which may change with the emotional and mental state of the experimenter. It is normal to fluctuate during the experiment. For cardiac output CO, Fig. 3 has listed the scatter diagram of the cardiac output CO detected by ultrasonic detection of different pressure differences under the large pressure difference and the cardiac output CO detected by the device of the present invention, in which the abscissa is the pressure Difference (mmHg), the ordinate is the cardiac output CO (L/min), "×" represents the cardiac output CO detected by ultrasound, and "●" represents the cardiac output CO detected by the device corresponding to the ultrasonic detection. , which shows that the CO value of the cardiac output detected by the method and the device of the present invention has a higher accuracy. For the detection accuracy of cardiac output CO, that is, for the individual differences of a single measurement, the average error between the CO detected by ultrasound and the CO detected by the device of the present invention is 0.006 ± 0.435 (Mean ± SD), as shown in Fig. 4. Listed the scatter diagram of the cardiac output CO detected by ultrasound and the cardiac output CO detected by the device of the present invention, the abscissa in the figure is the cardiac output CO detected by the device of the present invention , the ordinate is the cardiac output CO detected by ultrasound, as can be seen from the figure, the data point "●" is better close to the reference line, indicating that for a single measurement of an individual, the cardiac output detected by the device of the present invention The CO is consistent with the cardiac output CO detected by ultrasound.

The method and device for detecting cardiac output under large pressure difference proposed by the present invention can collect pressure pulse wave signals in real time, automatically and accurately analyze pressure pulse wave signals and calculate cardiac output CO. The detection device is embedded in a mobile phone or a handheld computer, can be carried around, has low cost, and is convenient for daily detection.

Table 1 Comparison of cardiac output test results

serial number Systolic blood pressure P _s (mmHg) Diastolic pressure _Pd (mmHg) Pressure difference (P _s -P _d )(mmHg) Age use the system Heart rate HR   Pulse map feature quantity K Cardiac output CO(L/min) 1 156 88 68 52 Ultrasound M 8780 -0.383 5.185.66 2 126 60 66 72 Ultrasound M 7776 -0.418 4.545.05 3 134 60 74 60 Ultrasound M 7267 -0.428 4.324.87 4 140 74 66 70 Ultrasound M 7273 -0.324 5.765.22 5 146 80 66 53 Ultrasound M 5355 -0.375 4.774.70 6 164 82 82 68 Ultrasound M 5558 -0.340 3.583.51 7 138 78 60 51 Ultrasound M 8477 -0.394 5.635.43 8 136 64 72 62 Ultrasound M 5149 -0.346 3.353.95 9 200 108 92 64 Ultrasound M 7775 -0.383 4.664.32 10 140 70 70 81 Ultrasound M 8380 -0.375 5.525.19 11 140 76 64 62 Ultrasound M 9087 -0.387 6.125.73 12 124 60 64 75 Ultrasound M 7070 -0.309 4.885.01 13 170 90 80 65 Ultrasound M 8483 -0.361 4.925.30 14 140 80 60 64 Ultrasound M 6266 -0.375 5.624.99

serial number Systolic blood pressure P _s (mmHg) Diastolic pressure _Pd (mmHg) Pressure difference (P _s -P _d )(mmHg) Age use the system Heart rate HR   Pulse map feature quantity K Cardiac output CO(L/min) 15 120 60 60 31 Ultrasound M 6866 -0.363 5.175.55 16 140 70 70 67 Ultrasound M 6771 -0.329 4.495.01 17 136 70 66 63 Ultrasound M 5456 -0.324 4.594.47 18 180 86 94 71 Ultrasound M 6469 -0.377 3.843.61 19 170 90 80 66 Ultrasound M 6462 -0.383 4.594.34 20 148 80 68 62 Ultrasound M 7273 -0.342 4.905.32 twenty one 154 72 82 81 Ultrasound M 5866 -0.406 3.714.28 twenty two 140 80 60 77 Ultrasound M 5549 -0.319 3.414.06 twenty three 142 72 70 57 Ultrasound M 6657 -0.266 3.763.59 twenty four 144 78 66 59 Ultrasound M 5251 -0.336 4.734.35 25 164 90 74 56 Ultrasound M 8579 -0.397 5.705.44 26 150 78 72 72 Ultrasound M 6366 -0.383 5.294.71 27 164 80 84 64 Ultrasound M 7566 -0.395 4.654.44 28 120 60 60 47 Ultrasound M 4844 -0.297 4.974.32 29 120 60 60 56 Ultrasound M 7979 -0.340 5.245.84 30 160 96 64 29 Ultrasound M 8377 -0.332 6.566.29

Note: "ultrasound" in the table represents the detection result of the color Doppler echocardiography detector, "M" represents the detection result of the method and its device according to the present invention, and "-" represents the detection result of the color Doppler echocardiography The instrument does not have the pulse map feature quantity K as the detection item.

Claims (2)

1. a cardiac output detecting methods that is used under the big pressure reduction is characterized in that, may further comprise the steps:

1) record subject age Age;

2) measure systolic pressure P _sWith diastolic pressure P _d

3) utilize the pressure pulse wave sensor to obtain the pressure pulse wave waveform, and obtain heart rate HR and sphygmogram characteristic amount K by the pressure pulse wave waveform, sphygmogram characteristic amount K and heart rate HR are obtained by following formula:

$K=\frac{\frac{1}{T}\&Integral;P\left(t\right)\mathrm{dt}-P_d}{P_s-P_d}---\left(1\right)$

T is the time, and P (t) is the pressure pulse wave waveform, and its peak is systolic pressure P _s, minimum point is diastolic pressure P _d, T is the cycle of a pressure pulse wave waveform;

$\mathrm{HR}=\frac{1}{T}---\left(2\right)$

4) cardiac output CO is according to age Age, systolic pressure P _s, diastolic pressure P _d, heart rate HR and sphygmogram characteristic amount K obtain by following formula

$\mathrm{CO}=\frac{17\&times;R}{K^2}(P_s-P_d)---\left(3\right)$

Wherein, R is a characteristic, and its numerical value is

R＝-0.011×(P _s-P _d)+0.005×HR-0.002×Age+3.055×K。

2. a cardiac output checkout gear that is used under the big pressure reduction is characterized in that, this device comprises following three parts successively: pressure pulse wave sensor, testing circuit and mobile phone governor circuit; Pick off adopts the pressure pulse wave sensor, testing circuit comprises differential amplifier circuit and step low-pass amplifying circuit, the step low-pass amplifying circuit comprises step low-pass amplifier and digital regulation resistance, and the mobile phone governor circuit comprises A/D converter, controller, cpu chip;

Pick off links to each other with differential amplifier circuit, and controller control figure potentiometer is realized the adjusting of analogue signal amplitude; Waveform analysis and above-mentioned cardiac output calculation of parameter are finished by the cpu chip of mobile phone governor circuit.

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