A blood pressure measurement device and method based on fiber optic ultrasound sensing

Abstract

The present invention discloses a blood pressure measurement device and method based on fiber optic ultrasound sensing, belonging to the field of human health parameter measurement. The device includes: a first integrated fiber optic ultrasound probe for transmitting an ultrasonic pulse signal to the radial artery; a second integrated fiber optic ultrasound probe for extracting ultrasonic echo signal intensity information and frequency information; a feature extraction module for establishing a blood flow velocity curve based on the ultrasonic echo signal frequency, establishing a pulse wave pressure curve based on the ultrasonic echo signal intensity, and extracting pulse wave pressure signal features. At the same time, the following features are extracted from the blood flow velocity signal: the time interval SW when the main peak rises and falls by half, the ratio Hc / Hb of the dicrotic notch amplitude to the main wave peak amplitude, and the ratio Hd / Hb of the secondary wave peak amplitude to the main wave peak amplitude; a blood pressure calculation module for calculating the systolic blood pressure SBP and diastolic blood pressure DBP through a neural network according to the feature values. The present invention can improve the accuracy of blood pressure measurement, and only a single-point measurement of the radial artery is required throughout the process, which is simple and easy to implement.

Description

Technical Field

[0001] The present invention belongs to the field of measuring human health parameters, and more specifically, relates to a blood pressure measuring device and method based on fiber optic ultrasonic sensing. Background Art

[0002] With the rapid development of social economy, people's lifestyles have changed. Coupled with the increasing and aging population, the awareness of health preservation has gradually been taken seriously by everyone. In addition, in recent years, the prevalence of cardiovascular diseases in our country has been on the rise, and the demand for cardiovascular monitoring technology in a healthy society has increased greatly. Therefore, blood pressure monitoring technology has gradually attracted people's attention.

[0003] Ultrasonic blood pressure monitoring technology is one of the current mainstream blood pressure detection technologies. In ultrasonic blood pressure monitoring, a piezoelectric ultrasonic transducer is often used as the ultrasonic transceiver device. However, most piezoelectric transducers are relatively large in size and have a small response angle, which is inconvenient in monitoring and cannot be worn. In addition, the current common methods for ultrasonic blood pressure measurement are mainly two types. One type uses ultrasonic Doppler to detect blood flow velocity and then detect blood pressure, and the other type uses echo intensity signals to sense changes in blood vessel wall thickness and then detect blood pressure. The ultrasonic Doppler scheme often requires the use of the PWTT (Pulse Wave Transit Time) measurement method later, and this measurement method requires either simultaneous measurement of two points on the pulse wave conduction tree or simultaneous measurement of the pulse wave signal and the electrocardiogram signal. Therefore, multi-point or multi-signal measurement has certain inconveniences and cannot achieve simple measurement. In the wall thickness detection scheme, the accuracy is often reduced due to the insufficient accuracy caused by many disturbances in the ultrasonic echo intensity signal.

[0004] Therefore, there is an urgent need to develop a lightweight and simple blood pressure monitoring device that can accurately obtain systolic and diastolic blood pressure information and provide an important basis for the early diagnosis and prevention of related diseases. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement requirements of the prior art, the present invention provides a blood pressure measuring device and method based on fiber optic ultrasonic sensing, aiming to solve the technical problems of inconvenient measurement and low accuracy of existing ultrasonic blood pressure monitoring devices.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided a blood pressure measuring device based on fiber optic ultrasonic sensing, including:

[0007] A first integrated fiber optic ultrasonic probe for transmitting ultrasonic pulse signals to the radial artery;

[0008] A second integrated fiber optic ultrasonic probe for extracting ultrasonic echo signal intensity information and frequency information;

[0009] A feature extraction module, which is used to establish a blood flow velocity curve according to the frequency of the ultrasonic echo signal, establish a pulse wave pressure curve according to the intensity of the ultrasonic echo signal, extract the characteristics of the pulse wave pressure signal, and at the same time extract the following characteristics from the blood flow velocity signal: the time interval SW when the main peak rises and falls by half, the ratio Hc / Hb of the amplitude of the dicrotic notch to the amplitude of the main wave peak, and the ratio Hd / Hb of the amplitude of the double wave peak to the amplitude of the main wave peak;

[0010] A blood pressure calculation module, which is used to calculate the systolic blood pressure SBP and diastolic blood pressure DBP through a neural network according to the characteristic values.

[0011] Furthermore, a BP neural network with two hidden layers is used to calculate the systolic blood pressure SBP and diastolic blood pressure DBP. Its network structure is that the first hidden layer has 64 neurons and uses the tanh activation function; the second hidden layer has 32 neurons and uses the relu activation function.

[0012] Furthermore, the characteristics extracted from the pulse pressure signal are the time TmAC from the wave trough to the dicrotic notch, the time interval TmBB between two adjacent cycle main wave points, and the ratio RSD of TmAC to the time TmCA from the dicrotic notch to the next wave trough.

[0013] Furthermore, the first integrated fiber optic ultrasonic probe forms an angle of 30° with the surface of the skin to be measured.

[0014] Furthermore, the device further includes a denoising unit, which is used to perform denoising processing on the pulse pressure signal and the blood flow velocity signal.

[0015] Furthermore, the frequency of the ultrasonic pulse signal excited by the first integrated fiber optic ultrasonic probe is 2 kHz.

[0016] Furthermore, the device further includes a wearing module; the wearing module includes a magic tape and a flexible wristband; both ends of the flexible wristband are attached with magic tapes to form a wearing device with adjustable length; the flexible wristband body is made of a highly elastic skin-friendly material.

[0017] The present invention also provides a blood pressure measurement method based on fiber optic ultrasonic sensing, including:

[0018] S1. Transmit an ultrasonic pulse signal to the radial artery;

[0019] S2. Extract the intensity information and frequency information of the ultrasonic echo signal;

[0020] S3. Establish a blood flow velocity curve based on the frequency of the ultrasonic echo signal, establish a pulse wave pressure curve based on the intensity of the ultrasonic echo signal, extract the characteristics of the pulse wave pressure signal, and simultaneously extract the following characteristics from the blood flow velocity signal: the time interval SW when the main peak rises and falls by half, the ratio Hc / Hb of the amplitude of the dicrotic notch to the amplitude of the main wave peak, and the ratio Hd / Hb of the amplitude of the secondary wave peak to the amplitude of the main wave peak;

[0021] S4. Calculate the systolic blood pressure SBP and diastolic blood pressure DBP through a neural network based on the eigenvalues.

[0022] Generally speaking, compared with the prior art by the above technical solution conceived by the present invention, the following beneficial effects can be achieved.

[0023] (1) Compared with the traditional measurement method that only uses vascular pressure signals, the present invention simultaneously captures blood flow velocity and vascular pressure signals, extracts eigenvalue integrations from the two types of signals respectively and performs neural network operations. Since the frequency component accuracy characteristics of the ultrasonic echo signal are high and the ultrasonic echo intensity signal is easily interfered with and has low accuracy characteristics, the high-precision characteristics of the blood flow velocity signal are used to compensate for the instability of the single vascular pressure signal characteristics, which can improve the blood pressure measurement accuracy, and the whole process only requires a single-point measurement of the radial artery, which is simple and easy to operate.

[0024] (2) The present invention uses an integrated fiber optic ultrasonic probe to capture blood pressure physiological activity signals, which is more portable compared with the traditional piezoelectric ultrasonic transducer device. And combined with a wearable module, blood pressure can be conveniently monitored at any time in daily life.

[0025] (3) The materials required for the device of the present invention are easy to obtain, the whole device is easy to implement, has a low cost, and operates reliably. Description of the Drawings

[0026] Figure 1 is the structural diagram of the wearable blood pressure measurement device based on fiber optic ultrasonic sensing provided by the present invention;

[0027] Figure 2 is the definition of the eigenvalue in the pulse wave signal used in the present invention;

[0028] Figure 3 is the definition of the eigenvalue in the blood flow velocity signal used in the present invention;

[0029] Figure 4 is the neural network blood pressure calculation model provided by the present invention; Detailed Embodiments

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The blood flow velocity signal needs to be obtained by detecting the frequency change of the ultrasonic echo signal. Under the disturbance of noise and the like, the frequency characteristics of the signal can still be clearly extracted with little influence. Therefore, the blood flow velocity signal has high-precision characteristics. The pulse wave pressure signal is extracted based on the peak value of the echo signal intensity and belongs to the extraction of time-domain information. This peak value is easily offset or misjudged due to the ultrasonic multiple reflection echo signal or noise interference, resulting in the drift of the pulse wave pressure signal curve and making the feature extraction vulnerable to disturbance.

[0032] Based on this, the present invention proposes a blood pressure measurement device based on fiber optic ultrasonic sensing, including a main control module and a wearable module. Figure 1This is the structural diagram of the blood pressure measurement device based on fiber optic ultrasound sensing provided by the present invention. As shown in the figure, the main control module 1 is embedded in the middle of the wearable module 2. Among them, the main control module 1 uses an integrated fiber optic probe to emit ultrasonic waves to the radial artery area and obtains the frequency and intensity information of the echo signal. Based on the obtained echo signal information, a blood flow velocity curve and a pulse wave curve are respectively established, feature values are extracted from them, and the blood pressure value is calculated through a neural network based on the feature values and displayed in real time; the wearable module 2 is used to fix the blood pressure monitoring device at the test point, and the wristband can be adjusted in length to adapt to different monitoring objects. The main control module 1 includes a fiber optic ultrasound blood pressure sensing module 3, a calculation module 4, and a data display module 5; among them, the output end of the fiber optic ultrasound blood pressure sensing module 3 is connected to the input end of the calculation module 4, and the output end of the calculation module 4 is connected to the input end of the data display module 5; the fiber optic ultrasound blood pressure sensing module 3 is based on the ultrasonic Doppler effect, emits ultrasonic waves to the radial artery through an integrated fiber optic ultrasound sensor, and collects the frequency change of the ultrasonic echo caused by blood flow; at the same time, this module is based on the strong reflection of the ultrasonic echo signal at the blood vessel wall, emits ultrasonic waves to the radial artery through an integrated fiber optic sensor, and collects the intensity information of the ultrasonic echo signal. This module mainly includes an ultrasonic emission unit 31 and an ultrasonic reception unit 32; the ultrasonic emission unit 31 includes an optical transmission unit and a first integrated fiber optic ultrasound probe; the output end of the optical transmission unit is connected to the first integrated fiber optic ultrasound probe; the optical transmission unit is used to send a 532 nm laser signal to the integrated fiber optic probe to excite ultrasonic waves; the first integrated fiber optic probe is excited by the laser to emit ultrasonic waves; the ultrasonic reception unit 32 includes an optical transmission unit, a second integrated fiber optic ultrasound probe, an optical reception unit, and a three-port unit; the three-port unit includes an input port, a middle port, and an output port; the output end of the optical transmission unit is connected to the input port of the three-port unit, one of the second integrated fiber optic ultrasound probes is connected to the middle port of the three-port unit, and the input end of the optical reception unit is connected to the output port of the three-port unit; the optical transmission unit is used to send a narrow linewidth laser in the C band to the integrated fiber optic probe; the end face of the second integrated fiber optic ultrasound probe interacts with the echo ultrasonic signal to modulate the phase of the narrow linewidth laser in the C band; the optical reception unit converts the optical signal into an electrical signal to extract the intensity information and frequency information of the ultrasonic echo signal. The calculation module 4 is used to process the captured ultrasonic echo signal, including a feature extraction module and a blood pressure calculation module; the feature extraction module is used to establish a blood flow velocity curve according to the ultrasonic echo signal frequency, establish a pulse wave pressure curve according to the ultrasonic echo signal intensity, and extract the features in the pulse wave pressure signal and the blood flow velocity signal respectively; the blood pressure calculation module is used to calculate the systolic blood pressure SBP and diastolic blood pressure DBP through a neural network based on the feature values. The data display module 5 is used to display the measurement result of the blood pressure in real time and play a role in real-time monitoring.The wearable module includes a flexible wristband 6 and a magic tape 7; the main body of the flexible wristband 6 is made of a highly elastic skin-friendly material, and the magic tape 7 includes a pair of buckles that can adjust the length while being tightly joined.

[0033] Further, on the one hand, the calculation module 4 extracts the peak intensity interval time from the ultrasonic echo signal intensity information, calculates the change in blood vessel wall thickness based on the interval time and the speed of sound, and converts the wall thickness into a pulse wave pressure waveform using an empirical model formula:

[0034]

[0035] where A(t) is the cross-sectional area of the blood vessel wall and p(t) is the relative blood pressure, thereby obtaining a pulse wave signal as shown in Figure 2 Extract three characteristic constants, TmAC, TmBB, and RSD, from the pulse wave signal shown. These three characteristic constants are defined as follows: TmAC: the time from the wave trough to the dicrotic notch; TmBB: the time interval between the main wave points of two adjacent cycles; RSD is defined as TmAC / TmCA, where TmCA is the time from the dicrotic notch to the next wave trough.

[0036] At the same time, the calculation module 4 also extracts the blood flow velocity signal from the ultrasonic echo signal frequency information:

[0037]

[0038] where c is the speed of sound, f is the frequency of the transmitted sound wave, f d is the frequency of the received sound wave, and θ is the angle between the sound beam and the blood flow direction. Preferably, θ is taken as 30°. Thereby obtaining a blood flow velocity signal as shown in Figure 3 Extract three characteristic parameters, SW, Hc / Hb, and Hd / Hb, from the blood flow velocity signal shown. Among them, SW is defined as the time interval when the main peak rises and falls by half, Hc / Hb is defined as the ratio of the amplitude of the dicrotic notch to the amplitude of the main wave peak, and Hd / Hb is defined as the ratio of the amplitude of the re-wave peak to the amplitude of the main wave peak.

[0039] As shown in Figure 4 is the neural network blood pressure calculation model used. Specifically, it is a BP neural network with two hidden layers. The network structure is 64 neurons in the first hidden layer, using the tanh activation function; 32 neurons in the second hidden layer, using the relu activation function. The input parameters of the neural network are the six parameter values of TmAC, TmBB, RSD, SW, Hc / Hb, and Hd / Hb. The systolic blood pressure SBP and diastolic blood pressure DBP are output at the output end.

[0040] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A blood pressure measuring device based on fiber optic ultrasonic sensing, characterized in that, Comprising: A first integrated fiber optic ultrasonic probe for transmitting ultrasonic pulse signals to the radial artery; A second integrated fiber optic ultrasonic probe for extracting ultrasonic echo signal intensity information and frequency information; A feature extraction module for establishing a blood flow velocity curve based on the ultrasonic echo signal frequency, establishing a pulse wave pressure curve based on the ultrasonic echo signal intensity, and extracting pulse wave pressure signal features. At the same time, the following features are extracted from the blood flow velocity signal: the time interval SW when the main peak rises and falls by half, the ratio Hc / Hb of the dicrotic notch amplitude to the main wave peak amplitude, and the ratio Hd / Hb of the secondary wave peak amplitude to the main wave peak amplitude; A blood pressure calculation module for calculating the systolic blood pressure SBP and diastolic blood pressure DBP through a neural network based on the pulse wave pressure signal features and the features extracted from the blood flow velocity signal.

2. The blood pressure measuring device based on fiber optic ultrasonic sensing according to claim 1, characterized in that, The systolic blood pressure SBP and diastolic blood pressure DBP are calculated using a BP neural network with two hidden layers. Its network structure is 64 neurons in the first hidden layer, using the tanh activation function; 32 neurons in the second hidden layer, using the relu activation function.

3. The blood pressure measuring device based on fiber optic ultrasonic sensing according to claim 2, characterized in that, According to the blood pressure measurement device based on fiber optic ultrasonic sensing described in claim 1, wherein the features extracted from the pulse pressure signal are the time TmAC from the wave trough to the dicrotic notch, the time interval TmBB between adjacent cycle main wave points, and the ratio RSD of TmAC to the time TmCA from the dicrotic notch to the next wave trough.

4. The blood pressure measuring device based on fiber optic ultrasonic sensing according to claim 3, characterized in that, The first integrated fiber optic ultrasonic probe forms an angle of 30° with the surface of the skin to be measured.

5. A blood pressure measuring device based on fiber optic ultrasound sensing according to any one of claims 1-4, characterized in that, The device further includes a denoising unit for denoising the pulse pressure signal and the blood flow velocity signal.

6. The blood pressure measurement device based on fiber optic ultrasonic sensing according to claim 3, wherein The ultrasonic pulse signal excitation frequency of the first integrated fiber optic ultrasonic probe is 2 kHz.

7. A blood pressure measurement device based on fiber optic ultrasonic sensing according to any one of claims 1-6, characterized in that, The device further includes a wearing module; the wearing module includes a magic tape and a flexible wristband; both ends of the flexible wristband are attached with magic tapes to form a wearable device with adjustable length; the flexible wristband body is made of a highly elastic skin-friendly material.

8. A blood pressure measurement method based on fiber optic ultrasonic sensing, characterized in that, Comprising: S1. Transmitting ultrasonic pulse signals to the radial artery; S2. Extracting ultrasonic echo signal intensity information and frequency information; S3. Establishing a blood flow velocity curve based on the ultrasonic echo signal frequency, establishing a pulse wave pressure curve based on the ultrasonic echo signal intensity, and extracting pulse wave pressure signal features. At the same time, the following features are extracted from the blood flow velocity signal: the time interval SW when the main peak rises and falls by half, the ratio Hc / Hb of the dicrotic notch amplitude to the main wave peak amplitude, and the ratio Hd / Hb of the secondary wave peak amplitude to the main wave peak amplitude; S4. Calculating the systolic blood pressure SBP and diastolic blood pressure DBP through a neural network based on the pulse wave pressure signal features and the features extracted from the blood flow velocity signal.

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