TWI380798B - Method and device for measuring blood vessel hardness - Google Patents

Description

Blood vessel hardness measuring method and device

The invention relates to a measuring method and device, in particular to a blood vessel hardness measuring method and device.

In the paper 'Shing-Hong Liu, Jia-Jung Wang, and Kuo-Sheng Huang, "A new oscillometry-based method for estimating the brachial arterial compliance under loaded conditions," IEEE Trans. Biomedical Engineering, Vol. 55, No. 10 , pp. 2463-2470, October 2008.' proposes a method for deriving the stiffness (reciprocal reciprocity) of the brachial artery through the balloon and arterial dynamics model, but with the following disadvantages:

(1) The prior art must pass the hypothetical and complex mathematical model to estimate the compliance of the arterial vessels, and must use complicated calculation steps and calculation procedures.

(B) is a derived vascular compliance obtained when the blood vessel is subjected to a certain degree of external loading, and the derived vascular compliance is different from the actual normal load of the blood vessel.

(3) It is necessary to simultaneously derive the amount of change in blood vessel dynamic volume and measure the amount of blood pressure change in order to estimate the compliance of the measured arterial blood vessels.

(4) The vascular compliance that is derived is a volumetric compliance and is only an indicator of blood vessel hardness.

(5) The magnitude of the vascular compliance that is derived is only a relative value, not the absolute value of the hardness, and its accuracy and reliability still need to be further verified to reduce its practical application value.

Accordingly, it is an object of the present invention to provide a blood vessel hardness measuring method which avoids the above-described deficiency and increases efficiency.

The blood vessel hardness measuring method comprises the steps of: generating a sinusoidal vibration signal having a set frequency and a set maximum displacement amplitude to be transmitted to a tube wall of a superficial artery of a subject; sensing simultaneously reflects the string The wave vibration signal and the wall reaction force reflecting the superficial arterial blood vessel pulsation to obtain a high frequency wall reaction force reflecting the sinusoidal vibration signal and a low frequency wall reaction force reflecting the superficial artery vascular blood pressure pulsation a digital measurement signal; finding a maximum value of the high frequency wall reaction force at a set time as a maximum reaction force; and dividing the maximum reaction force by the set maximum displacement amplitude to obtain a corresponding set time The blood vessels are elastic.

Still another object of the present invention is to provide a blood vessel hardness measuring device which avoids the above-described deficiency and increases efficiency.

The blood vessel hardness measuring device comprises: a processor outputting a digital signal having a set frequency and a set maximum displacement amplitude; and a vibration generating circuit that touches a superficial artery of the subject and is electrically connected Receiving, by the processor, the digital signal having the set frequency and the set maximum displacement amplitude, and generating a sine wave vibration signal transmission having the set frequency and the set maximum displacement amplitude according to the set frequency and the set maximum displacement amplitude To the superficial artery; and a responsiveness sensing circuit electrically connected to the processor and touching the superficial artery to sense the wall reaction force from the superficial artery, and Generating a digital measurement signal having a sampling value of the wall reaction force at the sampling frequency; and further, the processor receives the digital measurement signal having the sample value of the wall reaction force, and finds a wall reaction at a set time The maximum value of the force sampling value is used as a maximum reaction force; and the processor further divides the maximum reaction force by the maximum displacement amplitude to obtain a corresponding time Pipes elastic force.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

A preferred embodiment of the blood vessel hardness measuring device of the present invention is adapted to conduct a sinusoidal vibration signal having a displacement amplitude to a wall of a superficial artery of a subject to measure the wall reaction force of the blood vessel. And estimating a vascular elastic resistance data based on the wall reaction force and the maximum displacement.

Wherein, as shown in FIG. 1, a mechanical model conforming to the superficial arterial vascular characteristics of the present invention is constructed, respectively, using an damper (Inertia) element M, a viscous (Viscosity) element η, and a time-varying anti-elastic force. (Elastance) element E(t) is constructed in parallel, wherein the resistance generated by the damping element M is acceleration In proportion, the resistance generated by the viscous element η is the speed In proportion, the resistance generated by the time-varying anti-elastic force element E(t) is proportional to the displacement (X). Therefore, if the mechanical model is subjected to a time-varying displacement X(t), the mechanical model is A reaction force F(t) is then generated as the sum of the above three resistances, as in equation (1).

Further, the sinusoidal vibration signal X(t) is applied to a superficial artery under the skin of a subject whose mechanical characteristics are equivalent to those achieved by the mechanical model shown in FIG. 1, wherein X(t) =A sin(2π f t), A is the maximum displacement amplitude f is the vibration frequency. Therefore, after deriving X(t) once and differentially, it is possible to obtain equations (2) and (3), respectively.

Substituting the formulas (2) and (3) into the formula (1) gives the formula (4).

F ( t )=- MA (2π f ) ² sin(2π ft )+η A (2π f )cos(2π ft )+ E ( t ) A sin(2π ft )...(4)

Equation (5) can be obtained by dividing each of the left and right sides of the equation (4) by A and merging the right side of the equal sign.

When X(t) has the maximum displacement amplitude, that is, X(t)=A, then sin(2πft) has a maximum value equal to 1, and cos(2πft) has a minimum value equal to 0, and again at X(t). When there is a maximum displacement amplitude, the blood vessel also produces the maximum reaction force (Fm), and the time-dependent elastic resistance force at that time is E, so the formula (5) can be simplified into the formula (6).

After the formula (6) is moved, it can be simplified.

Since the experimental results of the set vibration frequency are known, the value of the first term on the right side of the upper equal sign is much larger than the value of the second term, so the second term can be ignored, and the formula (7) can be reduced to the formula (8). .

It can be known from equation (8) that when X(t) has the maximum displacement amplitude A, the magnitude of the vascular elastic force E at that time approximates the ratio of the maximum reaction force Fm divided by the maximum displacement amplitude A (Fm/A). The vascular anti-elastic force may represent the hardness of the blood vessel. Therefore, the hardness of the blood vessel can be derived from the measured maximum reaction force Fm of the blood vessel and the maximum displacement amplitude A of the sine wave vibration signal.

As shown in FIG. 2, the blood vessel hardness measuring device comprises: a processor 5, a vibration generating circuit 6, a reaction force sensing circuit 7, and a screen 8.

The processor 5 is electrically connected between the vibration generating circuit 6, the reaction force sensing circuit 7, and the screen 8.

The vibration generating circuit 6 further touches the superficial artery blood vessel, and includes a probe 61, a micro vibrator 62, a pusher 63, a sine wave generator 64, and a digital analog converter 65.

The reaction force sensing circuit 7 also touches the superficial artery blood vessel, and includes a reaction force sensor 71, a frequency division amplification module 72, and an analog-to-digital converter 73.

The reaction force sensor 71 and the probe 61 are disposed above the wall of the superficial artery and are electrically connected to the frequency division amplification module 72, but are not shown together in FIG. 2 for convenience of explanation.

The analog digital converter 73 is electrically coupled between the frequency division amplification module 72 and the processor 5.

The frequency division amplifying module 72 has a low pass filter 74, a high pass filter 75, a first amplifier 76 and a second amplifier 77.

The blood vessel hardness measuring device performs a blood vessel hardness measuring method, and as shown in FIG. 3, the following steps are included: Step 1: The processor 5 controls the vibration generating circuit 6 to generate a setting according to a set frequency and a set maximum displacement amplitude. The frequency and the sinusoidal vibration signal of the set maximum displacement amplitude are regarded as high frequency compared with the blood vessel pulsation which is changed by the vascular cavity pressure and is low frequency. In the embodiment, the optimal range of the set frequency is 20~50Hz, and the optimal range of the maximum displacement amplitude is 0.5~4mm, and the following substeps are included as shown in FIG. 4: Step 11: The processor 5 outputs a digit having the set frequency and the set maximum displacement amplitude. signal.

Step 12: The vibration generating circuit 6 receives the digital signal from the set frequency and the set maximum displacement amplitude, and generates a sine wave having the set frequency and the set maximum displacement amplitude according to the set frequency and the set maximum displacement amplitude. The vibration signal is transmitted to the superficial artery.

The detailed method of step 12 is: the digital analog converter 65 is electrically connected to the processor 5 to receive the digital signal having the set frequency and the set maximum displacement amplitude, and respectively generated according to the set frequency and the set maximum displacement amplitude. A first voltage indicating the set frequency value and a second voltage indicating the set maximum displacement amplitude value.

The sine wave generator 64 is electrically connected to the digital analog converter 65 to receive the first voltage and the second voltage to generate a sine wave voltage whose frequency is relative to the set frequency and the voltage magnitude is relative to the set maximum displacement amplitude signal.

The pusher 63 is electrically connected to the sine wave generator 64 to receive the sine wave voltage signal, and converts the sine wave voltage signal into a sine wave current signal whose current magnitude is linearly proportional to the magnitude of the voltage of the sine wave voltage signal. .

The micro vibrator 62 is electrically connected to the pusher 63 to receive the sine wave current signal to generate a mechanical force.

The probe 61 is electrically connected to the micro-vibrator 62, and is vertically displaced by the mechanical force to generate a sine wave vibration signal having the set frequency and the set maximum displacement amplitude transmitted to the superficial artery.

Step 2: The reaction force sensing circuit 7 senses the wall reaction force of the superficial artery from the superficial artery and reflects the sinusoidal vibration signal and reflects the superficial artery blood vessel pulsation, so as to obtain a reflection of the sine wave vibration signal The high frequency wall reaction force and a digital measurement signal reflecting the low frequency wall reaction force of the arterial blood pressure pulsation, and include the following sub-steps, as shown in FIG. 5: Step 21: Responsive sensor 71 sensing The superficial arterial blood vessel wall reaction force is used to generate a measurement signal.

Step 22: The frequency division amplification module 72 receives the measurement signal, and performs frequency division to output a high frequency analog signal reflecting the wall reaction force of the sine wave vibration signal and a reflection of the superficial artery blood vessel pulsation The low frequency analog signal of the wall reaction force is amplified separately.

The detailed operation of step 22 is: the low pass filter 74 and the high pass filter 75 respectively filter the received measurement signals by the high frequency component and the low frequency component to obtain signals of two different frequencies, and then the two different frequencies are The signal amplifies the magnitude of the amplitude via the first and second amplifiers 76, 77, respectively, to obtain the low frequency analog signal and the high frequency analog signal.

Step 23: The analog-to-digital converter 65 receives and temporarily stores the high-frequency analog signal and the low-frequency analog signal, and further samples the two signals according to a sampling frequency to obtain the sample value of the high-frequency wall reaction force. And a digital measurement signal of the low frequency wall reaction sample value.

Step 3: The processor 5 receives the digital measurement signal having the sampling value of the high frequency wall reaction force for a set time, and finds the maximum value of the wall reaction force sampling value at the set time as a maximum response. The force Fm, wherein the set time refers to a time when the displacement amplitude of the sine wave vibration signal reaches a maximum.

Step 4: The processor 5 divides the maximum reaction force Fm by the maximum displacement amplitude A to obtain a blood vessel anti-elastic force E corresponding to the set time and displays it on the screen 8.

In addition, the measurement process may be repeated, and after obtaining a plurality of blood vessel anti-elastic forces at the set time point, the processor 5 may display a blood vessel anti-elastic waveform on the screen 8 as a function of time.

In summary, the present invention has the following advantages:

(1) The vascular anti-elastic force can be calculated by using the preset maximum displacement amplitude and vibration frequency, and the maximum reaction force measured, which can reduce the complexity of the calculation.

(2) Simultaneously displaying a blood vessel anti-elastic waveform on the screen 8 to let the user know the magnitude of the blood vessel anti-elastic force at which point in time.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

1. . . Vibration step

11. . . Provided steps

12. . . Steps generated

2. . . Measuring step

twenty one. . . Sensing step

twenty two. . . Frequency dividing step

twenty three. . . Sampling step

3. . . Reaction step

4. . . Calculation step

5. . . processor

6. . . Vibration generating circuit

61. . . Probe

62. . . Micro vibrator

63. . . Pusher

64. . . Sine wave generator

65. . . Digital analog converter

7. . . Responsive sensing circuit

71. . . Responsive sensor

72. . . Frequency division amplification module

73. . . Analog digital converter

74. . . Low pass filter

75. . . High pass filter

76. . . First amplifier

77. . . Second amplifier

8. . . Screen

Figure 1 is a mechanical model diagram of the characteristics of superficial arterial vessels constructed in accordance with the present invention;

Figure 2 is a functional block diagram of a preferred embodiment of the present invention;

Figure 3 is a flow chart of the preferred embodiment;

Figure 4 is a flow chart of the first step; and

Figure 5 is a flow chart of the second step.

5. . . processor

6. . . Vibration generating circuit

61. . . Probe

62. . . Micro vibrator

63. . . Pusher

64. . . Sine wave generator

65. . . Digital analog converter

7. . . Responsive sensing circuit

71. . . Responsive sensor

72. . . Frequency division amplification module

73. . . Analog digital converter

74. . . Low pass filter

75. . . High pass filter

76. . . First amplifier

77. . . Second amplifier

8. . . Screen

Claims (17)

A blood vessel hardness measuring method comprising the steps of: generating a sinusoidal vibration signal having a set frequency and a set maximum displacement amplitude to be transmitted to a wall of a superficial artery of a subject; sensing simultaneously reflects the string The wave vibration signal and the wall reaction force reflecting the superficial arterial blood vessel pulsation to obtain a high frequency wall reaction force reflecting the sinusoidal vibration signal and a low frequency wall reaction force reflecting the superficial artery vascular blood pressure pulsation a digital measurement signal; finding a maximum value of the high frequency wall reaction force at a set time as a maximum reaction force; and dividing the maximum reaction force by the set maximum displacement amplitude to obtain a corresponding set time The blood vessels are elastic. The blood vessel hardness measuring method according to claim 1, wherein the step of generating the sine wave vibration signal comprises: outputting a digital signal having the set frequency and the set maximum displacement amplitude; receiving the digital signal, and Generating, according to the set frequency and the set maximum displacement amplitude, a first voltage indicating the set frequency and a second voltage indicating the set maximum displacement amplitude; receiving the first voltage and the second voltage to generate a frequency is relative At the set frequency and a voltage magnitude is a sine wave voltage signal relative to the set maximum displacement amplitude; converting the sine wave voltage signal into a sine wave current having a magnitude proportional to a magnitude of the voltage of the sine wave voltage signal Receiving the sine wave current signal to generate a mechanical force; and controlling the probe to perform up and down displacement by the mechanical force to generate a sine wave vibration signal having the set frequency and the set maximum displacement amplitude. The blood vessel hardness measuring method according to claim 1, wherein the step of obtaining the digital measuring signal comprises: sensing a wall reaction force of the superficial artery; and dividing the wall reaction force and then respectively Amplifying to generate an analog signal representative of a high frequency component of the wall reaction force reflecting the sinusoidal vibration signal, and an analog signal representing a low frequency component of the wall reaction force reflecting the superficial arterial blood vessel pulsation; and The frequency samples the two kinds of ratio signals respectively to obtain the digital measurement signal having the high frequency tube wall reaction sample value and the low frequency tube wall reaction sample value. The blood vessel hardness measuring method according to claim 1, wherein the optimal range of the set frequency is 20 to 50 Hz. The blood vessel hardness measuring method according to claim 1, wherein the optimum range of the maximum displacement amplitude is 0.5 to 4 mm. The blood vessel hardness measuring method according to claim 1, wherein the set time is a time when the displacement amplitude of the sine wave vibration signal reaches a maximum. According to the blood vessel hardness measuring method according to the first aspect of the patent application, the blood vessel anti-elasticity corresponding to each of the set times is further repeatedly performed, and then a blood vessel anti-elastic waveform which changes with time is obtained. A blood vessel hardness measuring device comprises: a processor for outputting a digital signal having a set frequency and a set maximum displacement amplitude; a vibration generating circuit that touches a superficial artery of a subject and is electrically connected Receiving, by the processor, the digital signal having the set frequency and the set maximum displacement amplitude, and generating a sine wave vibration signal transmission having the set frequency and the set maximum displacement amplitude according to the set frequency and the set maximum displacement amplitude To the superficial artery; and a responsiveness sensing circuit electrically connected to the processor and touching the superficial artery to sense the wall reaction force from the superficial artery, and Generating a digital measurement signal having a sampling value of the wall reaction force at the sampling frequency; and further, the processor receives the digital measurement signal having the sample value of the wall reaction force, and finds a wall reaction at a set time The maximum value of the force sampling value is used as a maximum reaction force; and the processor further divides the maximum reaction force by the maximum displacement amplitude to obtain a corresponding set time Anti-vascular elastic force. According to the blood vessel hardness measuring device of claim 8, wherein the reaction force sensing circuit senses the wall reaction force from the sine wave vibration signal and the superficial artery blood vessel pulsation to output a digital measurement signal reflecting the high frequency wall reaction force of the sinusoidal vibration signal and a digital measurement signal reflecting the low frequency wall reaction force of the superficial artery blood vessel pulsation; and the processor receives the high frequency tube The digital measurement signal of the wall reaction force and the digital measurement signal of the low frequency wall reaction force. The blood vessel hardness measuring device according to claim 8, wherein the reaction force sensing circuit comprises: a reaction force sensor disposed on the superficial artery blood vessel to sense the superficial artery blood vessel a wall reaction force to output a measurement signal; a frequency division amplification module electrically connected to the reaction force sensor to receive the measurement signal, and frequency-divided and then separately amplified to output a representation of the tube wall a high frequency analog signal of the reaction force and a low frequency analog signal representing the reaction force of the tube wall; and an analog digital converter electrically connected to the frequency division amplification module to receive and temporarily store the high frequency analog signal and the low frequency analogy The signal, and then the two kinds of ratio signals are respectively sampled according to a sampling frequency to obtain a digital measurement signal of the wall reaction force sampling value. The blood vessel hardness measuring device according to claim 10, wherein the frequency dividing amplifying module has a low pass filter electrically connected to the reactive force sensor and a high pass filter, and an electrical connection a first amplifier between the low pass filter and the analog to digital converter, and a second amplifier electrically coupled between the high pass filter and the analog to digital converter, the low pass filter and the high pass filter The measured signal is filtered to remove the high frequency component and the low frequency component respectively to obtain signals of two different frequencies, and the signals of the two different frequencies are respectively subjected to amplitudes of the first and second amplifiers. Amplifying to obtain the low frequency analog signal and the high frequency analog signal. The blood vessel hardness measuring device according to claim 8, further comprising a screen electrically connected to the processor, wherein the screen is used to display the blood vessel anti-elastic force. The blood vessel hardness measuring device according to claim 8, wherein the vibration generating circuit comprises: a digital analog converter electrically connected to the processor to receive the digital bit having the set frequency and the set maximum displacement amplitude And generating, according to the set frequency and the set maximum displacement amplitude, a first voltage indicating the set frequency and a second voltage indicating the set maximum displacement amplitude; a sine wave generator electrically connected to the digital analog conversion Receiving the first voltage and the second voltage, thereby generating a sine wave voltage signal with respect to the set frequency and a voltage magnitude relative to the set maximum displacement amplitude; a pusher electrically connected to the string The wave generator receives the sine wave voltage signal, and converts the sine wave voltage signal into a sine wave current signal whose current magnitude is linearly proportional to the voltage magnitude of the sine wave voltage signal; a micro vibrator electrically connected The pusher generates a mechanical force to receive the sine wave current signal; and a probe is disposed on the superficial artery and connected to the The micro vibrator is vertically displaced by the mechanical force to generate a sinusoidal vibration signal having the set frequency and the set maximum displacement amplitude transmitted to the wall of the superficial artery. The blood vessel hardness measuring device according to claim 8, wherein the optimum range of the set frequency is 20 to 50 Hz. The blood vessel hardness measuring device according to claim 8, wherein the optimum range of the set maximum displacement amplitude is 0.5 to 4 mm. The blood vessel hardness measuring device according to claim 8, wherein the set time is a time when the displacement amplitude of the sine wave vibration signal reaches a maximum. According to the blood vessel hardness measuring device described in claim 8 of the patent application, the wall reaction force of the superficial artery blood vessel is more repeatedly measured, so that the processor obtains a plurality of blood vessel anti-elasticity corresponding to the set time respectively. After the force, a vascular anti-elastic waveform that changes with time is displayed on the screen.