Blood pressure measuring system and method based on multi-airbag cooperative control and oscillatory wave analysis

Abstract

The invention provides a blood pressure measurement system and method based on multi-airbag cooperative control and oscillatory wave analysis, and relates to the technical field of medical instruments. Comprising an integrated cuff cover body, an inflator pump, an electromagnetic valve, a pressure balancing device and a microprocessor, a first air bag, a second air bag and a third air bag are arranged in the integrated cuff cover body, firstly, an inflation pump is started, the multiple air bags are synchronously inflated to preset initial pressure, then a first air bag electromagnetic valve and a third air bag electromagnetic valve are closed, a pressure balance device dynamically adjusts a miniature deflation valve, and the pressure in the first air bag and the pressure in the third air bag are kept constant; the inflator pump continues to inflate until the pressure in the second airbag is higher than the systolic pressure level; the measuring method specifically comprises a multi-air-bag pressure measuring mode and a double-air-bag pressure measuring mode. The multi-air-bag pressure measuring mode is that three air bags are used for measuring pressure at the same time, and the double-air-bag pressure measuring mode is that only the second air bag and the third air bag are pressurized, so that blood pressure measurement is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly to a blood pressure measurement system and method based on multi-airbag collaborative control and oscillometric wave analysis. Background Art

[0002] In the current field of electronic sphygmomanometers, most products use the single-airbag oscillometric method to measure blood pressure. These include the amplitude coefficient method, variable amplitude coefficient method, inflection point method, coefficient difference ratio method, etc. These methods deduce blood pressure values through empirical formulas, but there are obvious limitations. Therefore, in recent years, many new blood pressure measurement methods have begun to be widely used.

[0003] Chinese Utility Model Patent CN201977786U mainly emphasizes its double-airbag structure design. By means of the double-airbag structure, it attempts to amplify the changes in the oscillometric wave, but its focus is not on the filtering process and algorithm of the oscillometric wave. Only measured by visual inspection or simple methods, only some cases with large changes can increase the accuracy of blood pressure measurement, and it is difficult to further find the common characteristic changes and amplification effects of distal oscillometric waves. Secondly, whether it is the first airbag or the second airbag, through the study of the changes in invasive blood pressure during the cuff pressurization process, it is found that the cuff pressurization will affect the invasive blood pressure under the cuff, causing the invasive systolic blood pressure SBP to increase by up to 20 mmHg at most, and the invasive diastolic blood pressure DBP also changes significantly with the increase in cuff pressure. The invasive blood pressure changes more at the distal end of the cuff. Therefore, even though the first airbag can better highlight the change characteristics of the systolic blood pressure SBP, along with the blood pressure changes under the cuff and at the distal end of the cuff, its measurement effect and accuracy will inevitably be affected. In contrast, the cuff pressurization has less impact on the invasive blood pressure at the proximal end of the cuff. This patent does not conduct a comprehensive analysis of the changes in the double-airbag oscillometric wave, nor does it design an additional third airbag at the proximal end as a standard airbag for blood pressure measurement. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a blood pressure measurement system and method based on multi-airbag collaborative control and oscillometric wave analysis; A blood pressure measurement system based on multi-airbag collaborative control and oscillometric wave analysis includes: an integrated cuff cover, an air pump, a solenoid valve, a pressure balance device, and a microprocessor; The integrated cuff cover is internally provided with a first airbag, a second airbag, and a third airbag. Among them, the first airbag is arranged at the distal end, the third airbag is arranged at the proximal end, and the second airbag is arranged between the first airbag and the third airbag. The three airbags are arranged at intervals; The air pump simultaneously inflates the first airbag, the second airbag, and the third airbag with constant pressure through the main air pipe; The solenoid valves include a first airbag solenoid valve and a third airbag solenoid valve, which are respectively arranged at the joints of the main air pipe with the first airbag and the third airbag. The first airbag solenoid valve controls the on-off of the inflation of the first airbag, and the third airbag solenoid valve controls the on-off of the inflation of the third airbag; The pressure balance device includes a pressure sensor and a micro air release valve. The pressure sensor is respectively arranged in the first airbag and the third airbag, and is used to monitor the pressure in the first airbag and the third airbag in real time, and maintain the constant pressure of the first airbag and the third airbag by dynamically adjusting the opening and closing of the micro air release valve; The microprocessor is connected to the air pump, solenoid valve, pressure sensor and micro air release valve, and is used to execute the inflation control logic; The microprocessor integrates an oscillation wave analysis module, which is used to collect the pressure data from the first airbag to the third airbag in real time, identify the oscillation wave changes of the first airbag and the third airbag based on the elastic template matching method, and obtain the blood pressure measurement result; The first airbag, the second airbag and the third airbag are all rectangular in shape. Among them, the first airbag and the third airbag have the same size, and the size of the second airbag is larger than that of the first airbag and the third airbag. The size of the airbag is adjusted in a timely manner according to the actual situation; The inflation rate of the air pump is 3 - 10 mmHg per second.

[0005] The inflation control logic, that is, the blood pressure measurement method based on multi-airbag collaborative control and oscillation wave analysis, is specifically as follows: Step S1: Initial inflation stage: The air pump is started, and the multi-airbags are inflated synchronously to a preset initial pressure; Step S2: Airbag constant pressure stage: The first airbag solenoid valve and the third airbag solenoid valve are closed; Step S3: The pressure balance device dynamically adjusts the micro air release valve to maintain the constant pressure in the first airbag and the third airbag; Step S4: Second airbag pressure boost stage: The air pump continues to inflate until the pressure in the second airbag is higher than the systolic blood pressure level; The blood pressure measurement method for multi-airbag collaborative control and oscillometric wave analysis includes a multi-airbag pressure measurement mode and a dual-airbag pressure measurement mode; the multi-airbag pressure measurement mode is to measure the pressure simultaneously using 3 airbags. Specifically, the first airbag amplifies the change characteristics of the systolic blood pressure (SBP) to identify the SBP, the second airbag measures the mean arterial pressure (MAP), and the third airbag, as a standard airbag, amplifies the change characteristics of the SBP and diastolic blood pressure (DBP) to identify the SBP and DBP. Then, the blood pressure value is obtained by mutual calibration of the three airbags; the dual-airbag pressure measurement mode is to only pressurize the second airbag and the third airbag, that is, the first airbag is not pressurized. The second airbag and the third airbag are pressurized according to the descriptions in steps S4 and S1 respectively. Finally, the MAP is measured by the second airbag, and the SBP and DBP are identified by the third airbag amplifying the change characteristics of the SBP and DBP. The blood pressure value is obtained by calibrating the third airbag with the second airbag; The oscillometric wave analysis module specifically includes: a signal preprocessing unit, a signal quality evaluation unit, and a feature point identification unit; The signal preprocessing unit: First, use Fourier transform to determine the distribution characteristics of noise and effective signals; then remove the high-frequency noise in the original oscillometric wave signal through a low-pass filter, and remove the influence of baseline drift on the oscillometric wave through a high-pass filter; perform secondary analysis using Fourier transform to provide a basis for frequency band division for empirical wavelet transform; then eliminate artifacts through the empirical wavelet transform method; finally, use the methods of normalization processing and non-normalization processing respectively. Normalization processing is used to adjust the amplitude differences between different waveforms and identify the changes in waveform characteristics; the non-normalization processing method is used to identify the amplitude differences of the oscillometric waves.

[0006] The signal quality evaluation unit: includes the data quality evaluation of the oscillometric wave and the data quality evaluation related to blood pressure measurement during inflation and deflation under high pressure; the data quality evaluation under a constant pressure is to extract each oscillometric wave under the preset constant pressure to construct a quality evaluation template, match the template signal with each waveform of this section of the oscillometric wave and calculate the distance of DTW, and judge whether the data is available according to the average value of all DTW distances; The data quality evaluation of the oscillometric wave is to extract each waveform of the waveforms under all pressure ranges to construct a quality evaluation template; match the template signal with each single-cycle waveform and calculate the distance of DTW, and judge whether the data is available according to the average value of all DTW distances; For the data quality evaluation related to blood pressure measurement during inflation and deflation under high pressure, first calculate the average pressure position of the oscillometric wave in the inflated state and the average pressure position in the deflated state, calculate the position deviation between the two and compare it with a preset threshold to judge whether the data is available. Select the previous single-cycle waveform as the template, and perform waveform template matching with the single-cycle waveform and its corresponding template based on the DTW algorithm to find the matching waveform and preliminarily estimate the blood pressure value; The feature point recognition unit: First, read the second airbag oscillation wave and locate it by the variable amplitude coefficient method, that is, use the variable amplitude coefficient to determine the position ranges of the systolic blood pressure SBP and the diastolic blood pressure DBP. Based on the DTW algorithm, estimate the blood pressure for the waveforms in the position ranges of the systolic blood pressure SBP and the diastolic blood pressure DBP of the first airbag and the third airbag oscillation waves. Among them, the third airbag is used as the standard airbag, the first airbag oscillation wave assists in calculating the systolic blood pressure SBP, the second airbag oscillation wave assists in calculating the mean arterial pressure MAP, and the latter single-cycle waveform uses the previous single-cycle waveform as a template. By identifying the morphological and amplitude changes of the oscillation wave and based on the waveform template matching method, estimate the blood pressure; Specifically: For the normalized waveform, identify the changes in the waveform morphological features, and mark the position with the maximum DTW value within the position ranges of the systolic blood pressure SBP and the diastolic blood pressure DBP as D norm .

[0007] For the non-normalized waveform, identify the amplitude changes of the waveform, and mark the position with the maximum DTW value within the position ranges of the systolic blood pressure SBP and the diastolic blood pressure DBP as D non-norm .

[0008] Finally, comprehensively calculate the DTW distances obtained from the normalized and non-normalized oscillation wave signals, set the weight parameters, and calculate the weighted value to obtain the final D final ; Take the second airbag pressure value at the same moment of the oscillation wave corresponding to D final as the systolic blood pressure SBP and the diastolic blood pressure DBP output to achieve blood pressure measurement.

[0009] The beneficial effects of adopting the above technical solutions are as follows: The present invention provides a blood pressure measurement system and method based on multi-airbag collaborative control and oscillation wave analysis. By using multi-airbags to amplify the oscillation wave feature changes of the systolic blood pressure SBP and the diastolic blood pressure DBP, and through the oscillation wave analysis module, based on the elastic template matching method, identify the oscillation wave amplitude differences, and then accurately identify the systolic blood pressure and the diastolic blood pressure. This device through multi-airbag collaborative control and signal analysis, by optimizing the airbag inflation and deflation control and signal processing algorithms, effectively reduces the measurement error caused by uneven airbag deformation, ensures the stability of blood pressure data, significantly improves the blood pressure measurement accuracy, and is applicable to multi-site measurements such as the arm and wrist; adopts a flexible and breathable material to reduce the pressure on the skin during the measurement process and avoid discomfort caused by long-term measurement; the intelligent adaptive algorithm can automatically adjust the measurement parameters according to the physiological characteristics of different users and is applicable to people of different ages and health conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a diagram of a blood pressure measurement device based on multi-airbag collaborative control and oscillation wave analysis provided by an embodiment of the present invention; Among them, 1 - the first airbag, 2 - the second airbag, 3 - the third airbag, 4 - the main air pipe, 5 - the solenoid valve, 6 - the pressure balance device, 7 - the pressure sensor, 8 - the micro air release valve, 9 - the microprocessor, 10 - the oscillation wave analysis module, 11 - the air inflation pump; Figure 2 Schematic diagram of the device measurement method provided by the embodiment of the present invention; Figure 3 Block diagram of the hardware system provided by the embodiment of the present invention; Figure 4 Implementation block diagram of the signal preprocessing unit provided by the embodiment of the present invention; Figure 5 Implementation block diagram of the signal quality evaluation unit provided by the embodiment of the present invention; Figure 6 Schematic diagram of the single - cycle waveform template matching method provided by the embodiment of the present invention; Figure 7 Comparison diagram of the oscillation waveform of the first airbag and the normal oscillation waveform provided by the embodiment of the present invention; Among them, (a) - the oscillation waveform of the first airbag, (b) - the normal oscillation waveform; Figure 8 Oscillation waveform diagram of the second airbag provided by the embodiment of the present invention; Figure 9 Comparison diagram of the diastolic pressure part of the oscillation waveform of the third airbag and the normal oscillation waveform provided by the embodiment of the present invention; Among them, (a) - the diastolic pressure part of the oscillation waveform of the third airbag, (b) - the normal oscillation waveform; Figure 10 Comparison diagram of the systolic pressure part of the oscillation waveform of the third airbag and the normal oscillation waveform provided by the embodiment of the present invention; Among them, (a) - the systolic pressure part of the oscillation waveform of the third airbag, (b) - the normal oscillation waveform. Detailed implementation manners

[0011] The following combines the drawings and embodiments to further describe in detail the specific implementation manners of the present invention. The following embodiments are used to illustrate the present invention, but not to limit the scope of the present invention.

[0012] The present invention takes the third airbag as the standard. It is found through research that due to the change of invasive pressure, the oscillation waves of the first and second airbags are not the oscillation waves of the true blood pressure and are not completely accurate. However, the invasive blood pressure under the third airbag changes little. Therefore, the third airbag is used as the standard airbag for measurement. The third airbag can amplify the change characteristics of the systolic blood pressure (SBP) and diastolic blood pressure (DBP) of the second airbag, especially the change characteristics of the diastolic blood pressure (DBP) are more obvious. In the algorithm, based on the change of the oscillation wave of the third airbag, the oscillation wave characteristics of the three airbags are analyzed in both the time domain and the frequency domain, and the characteristic changes of the vast majority of cases can be identified. Taking the change characteristics of the oscillation wave of the second airbag as a rough coordinate to assist the third airbag oscillation wave to determine the characteristic changes. Even if its position is distorted, since it is not the standard airbag, it will not affect the overall result accuracy. The research on invasive blood pressure also finds that the characteristics of the oscillation wave of the first airbag often change over time, affecting the blood pressure value; while the characteristics of the third airbag are constant. Through the comparative analysis of 42 cases of invasive blood pressure data and hundreds of cases of auscultatory blood pressure data, the blood pressure value measured by the third airbag designed based on the hemodynamic principle has the highest accuracy. Finally, through the collaborative analysis of the oscillation waves of the three airbags, accurate blood pressure identification is performed on the oscillation wave of the third airbag.

[0013] Traditional sphygmomanometers on the market usually adopt a single airbag design, which is made of a biocompatible fabric wrapping a single airbag. The airbag extends to the outside through a trachea for inflation and deflation operations. The multi-airbag cuff provided by the present invention is a measuring band sewn by three independent airbags with a certain distance, as Figure 1 shown, each has a trachea led out and connected to the same inflator pump for simultaneous inflation and deflation. Among them, the first airbag and the third airbag have the same size, and the second airbag is larger. Its usage method is the same as that of other ordinary cuffs. According to different usage sizes, it can be put on the upper arm, wrist, leg, etc., and even on parts such as the ankle and finger for blood pressure measurement.

[0014] A blood pressure measurement system based on multi-airbag collaborative control and oscillation wave analysis. The hardware system is as Figure 3 shown, including: an integrated cuff cover, an inflator pump 11, a solenoid valve 5, a pressure balancing device 6, and a microprocessor 9; The integrated cuff cover is internally provided with a first airbag 1, a second airbag 2, and a third airbag 3. Among them, the first airbag 1 is arranged at the distal end, the third airbag 3 is arranged at the proximal end, and the second airbag 2 is arranged in the middle of the first airbag 1 and the third airbag 3. The three airbags are arranged at intervals; The inflator pump 11 simultaneously inflates the first airbag 1, the second airbag 2, and the third airbag 3 at a constant pressure through the main trachea 4; The solenoid valve 5 includes a first airbag solenoid valve and a third airbag solenoid valve, which are respectively arranged at the joints of the main air pipe and the first airbag 1 and the third airbag 3. The first airbag solenoid valve controls the inflation and cut-off of the first airbag 1, and the third airbag solenoid valve controls the inflation and cut-off of the third airbag 3; The pressure balancing device 6 includes a pressure sensor 7 and a micro air release valve 8. The pressure sensor 7 is respectively arranged in the first airbag 1 and the third airbag 3, and is used to monitor the pressure in the first airbag 1 and the third airbag 3 in real time, and maintain the constant pressure of the first airbag 1 and the third airbag 3 by dynamically adjusting the opening and closing of the micro air release valve 8; The microprocessor 9 is connected to the air pump 11, the solenoid valve 5, the pressure sensor 7 and the micro air release valve 8, and is used to execute the inflation control logic; The microprocessor 9 integrates an oscillation wave analysis module 10, which is used to collect the pressure data from the first airbag to the third airbag in real time, identify the oscillation wave changes of the first airbag and the third airbag based on the elastic template matching method, and obtain the blood pressure measurement result; The first airbag, the second airbag and the third airbag are all rectangular in shape. Among them, the first airbag and the third airbag have the same size, which is 300 mm in length and 30 mm in width. The size of the second airbag is larger than that of the first airbag and the third airbag, which is 300 mm in length and 50 mm in width. The airbag size is adjusted in a timely manner according to the actual situation, for example, different sizes are set according to different body parts or different limb lengths and thicknesses of different people in the same body part; The inflation rate of the air pump is 3 - 10 mmHg per second.

[0015] The inflation control logic is a blood pressure measurement method based on multi-airbag collaborative control and oscillation wave analysis. Specifically: Step S1: Initial inflation stage: The air pump is started, and the multi-airbags are inflated synchronously to a preset initial pressure. In this embodiment, the preset initial pressure is 50 mmHg - 70 mmHg; Step S2: Airbag constant pressure stage: The first airbag solenoid valve and the third airbag solenoid valve are closed; Step S3: The pressure balancing device dynamically adjusts the micro air release valve to maintain the constant pressure in the first airbag and the third airbag; the pressure balancing device dynamically releases air to offset the pressure increase caused by soft tissue extrusion; Step S4: Second airbag pressure increase stage: The air pump continues to inflate until the pressure in the second airbag is higher than the systolic blood pressure level; The blood pressure measurement method for multi-airbag collaborative control and oscillometric wave analysis includes a multi-airbag pressure measurement mode and a dual-airbag pressure measurement mode; the multi-airbag pressure measurement mode is to measure pressure simultaneously using 3 airbags, that is, to identify the systolic blood pressure SBP by amplifying the change characteristics of the systolic blood pressure SBP through the first airbag, measure the mean arterial pressure MAP with the second airbag, and use the third airbag as a standard airbag to amplify the change characteristics of the systolic blood pressure SBP and diastolic blood pressure DBP to identify the systolic blood pressure SBP and diastolic blood pressure DBP, and then obtain the blood pressure value by mutual calibration of the three airbags; the dual-airbag pressure measurement mode is to only pressurize the second airbag and the third airbag, that is, the first airbag is not pressurized, and the second airbag and the third airbag are pressurized according to the steps described in S4 and S1 above. Finally, the mean arterial pressure MAP is measured with the second airbag, and the third airbag amplifies the change characteristics of the systolic blood pressure SBP and diastolic blood pressure DBP to identify the systolic blood pressure SBP and diastolic blood pressure DBP. At the same time, the third airbag can also be calibrated by the second airbag to obtain an accurate blood pressure value; The oscillometric wave analysis module specifically includes: a signal preprocessing unit, a signal quality assessment unit, and a feature point recognition unit; The signal preprocessing unit: The signal preprocessing implementation process is as Figure 4 shown. First, use Fourier transform to determine the distribution characteristics of noise and effective signals; then remove high-frequency noise such as high-frequency interference in the original oscillometric wave signal through a low-pass filter, and remove the influence of baseline drift on the oscillometric wave through a high-pass filter; perform secondary analysis using Fourier transform to provide a basis for frequency band division for empirical wavelet transform; then eliminate artifacts caused by various factors through the empirical wavelet transform method; finally, use the methods of normalization processing and non-normalization processing respectively. Normalization processing is used to adjust the amplitude differences between different waveforms to facilitate subsequent template matching and identify waveform feature changes; the non-normalization processing method is used to identify the amplitude differences of oscillometric waves.

[0016] The signal quality assessment unit: As Figure 5 shown, it includes the data quality assessment of oscillometric waves and the data quality assessment related to blood pressure measurement during inflation and deflation under high pressure; the data quality assessment under a constant pressure is to construct a quality assessment template by extracting each oscillometric wave under the preset constant pressure, match the template signal with each waveform of this section of oscillometric wave and calculate the DTW distance, and judge whether the data is available according to the average value of all DTW distances; The data quality assessment of the oscillometric wave is to construct a quality assessment template by extracting each waveform of the waveforms under all pressure ranges; match the template signal with each single-cycle waveform and calculate the DTW distance, and judge whether the data is available according to the average value of all DTW distances; For the data quality assessment related to inflation and deflation blood pressure measurement under high pressure, first calculate the mean pressure position of the oscillation wave in the inflation state and the mean pressure position in the deflation state, calculate the position deviation between the two and compare it with a preset threshold to determine whether the data is available. Select the previous single-cycle waveform as the template, and perform waveform template matching between the single-cycle waveform and its corresponding template based on the DTW algorithm to find the matching waveform and preliminarily estimate the blood pressure value; In this embodiment, the data quality assessment module of the oscillation wave constructs a quality assessment template by extracting waveforms in all pressure ranges. First, extract the single-cycle waveform Xpressure(i) after normalization in each pressure range, and take the waveform of the first single-cycle oscillation wave as the assessment template Ypressure. Match the assessment template Ypressure with the single-cycle oscillation waves Xpressure(i) in each pressure range, and calculate the DTW distance Dpressure between each single-cycle waveform Xpressure(i) and the assessment template Ypressure. And so on, take the waveforms of each single-cycle oscillation wave at other pressures as the assessment template Ypressure, and calculate the DTW distance Dpressure between the single-cycle waveforms Xpressure(i) in each pressure range and the assessment template Ypressure. Take the average value of all DTW distances and compare it with a preset threshold. When it is less than the preset threshold, the data is available; otherwise, the signal is unavailable.

[0017] For the data quality assessment related to inflation and deflation blood pressure measurement, first calculate the mean pressure position Loc1 of the oscillation wave envelope in the inflation state, then calculate the mean pressure position Loc2 of the oscillation wave envelope in the deflation state, calculate the position deviation Loc = |Loc1 - Loc2|. When Loc is less than the preset threshold, the data is available; otherwise, the signal is unavailable.

[0018] The feature point recognition unit is as Figure 6 shown. First, read the oscillation wave of the second airbag, and locate it by the variable amplitude coefficient method, that is, use the variable amplitude coefficient to determine the position ranges of the systolic blood pressure SBP and diastolic blood pressure DBP. Based on the DTW algorithm, estimate the blood pressure for the waveforms in the position ranges where the systolic blood pressure SBP and diastolic blood pressure DBP appear in the oscillation waves of the first airbag and the third airbag. Among them, the third airbag is used as the standard airbag, which can amplify the change characteristics of the systolic blood pressure SBP and diastolic blood pressure DBP. The oscillation wave of the first airbag assists in calculating the systolic blood pressure SBP, and the oscillation wave of the second airbag assists in calculating the mean arterial pressure MAP. The next single-cycle waveform uses the previous single-cycle waveform as the template, and estimates the blood pressure by identifying the oscillation wave form and amplitude changes and based on the waveform template matching method; Specifically: For the normalized waveform, identify the changes in waveform morphological features, and mark the position with the maximum DTW value within the range of the systolic blood pressure SBP and diastolic blood pressure DBP as D norm .

[0019] For the non-normalized waveform, identify the amplitude changes of the waveform, and mark the position with the maximum DTW value within the range of the systolic blood pressure SBP and diastolic blood pressure DBP as D non-norm .

[0020] Finally, comprehensively consider the DTW distances calculated from the normalized and non-normalized oscillatory wave signals, set the weight parameters, and calculate the weighted value to obtain the final D final ; Take the D final corresponding second cuff pressure value at the same moment of the oscillatory wave as the systolic blood pressure SBP and diastolic blood pressure DBP outputs to achieve blood pressure measurement.

[0021] In this embodiment, based on the DTW algorithm, the single-cycle waveform is matched with the previous waveform template. Specifically:[[]] First, read the second cuff oscillatory wave and locate it by the variable amplitude coefficient method, that is, roughly determine the position ranges of SBP and DBP using the variable amplitude coefficient. Specifically:[[]] Step A1: First, take the maximum value of the oscillatory wave envelope as MAP, and divide the 3 ranges of the variable amplitude coefficient according to the size of the cuff pressure corresponding to the maximum value of the oscillatory wave envelope. That is, for the three ranges where the maximum value of the oscillatory wave envelope > 100 mmHg, 100 mmHg ≥ the maximum value of the oscillatory wave envelope ≥ 80 mmHg, and the maximum value of the oscillatory wave envelope < 80 mmHg, calculate the empirical value ranges of the systolic pressure coefficient and diastolic pressure coefficient according to formulas (1) and (2) respectively:[[]] , ; where,[[]] K s is the systolic pressure coefficient; K d is the diastolic pressure coefficient; A SBP is the envelope amplitude corresponding to the position of the systolic blood pressure SBP; A DBP is the envelope amplitude corresponding to the position of the diastolic blood pressure DBP; A MAP is the envelope amplitude corresponding to the position of the mean pressure MAP; Step A2: Use the empirical value ranges of the systolic pressure and diastolic pressure coefficients to calculate the envelope amplitudes A(SBP) and A(DBP) corresponding to the positions of the systolic pressure and diastolic pressure according to the deformations of formulas (1) and (2)[[]] Next, based on the waveform template matching method, the waveforms of the positions where the first and third airbag oscillation waves SBP and DBP appear are identified, thereby realizing accurate calculation of blood pressure. Taking SBP as an example, the first single-cycle waveform in the located SBP range is selected as the standard waveform, and other single-cycle waveforms in the range are used to perform waveform template matching with the standard waveform based on the DTW method. Specifically: Step B1: For a standard single-cycle waveform p with a time series length of n and a single-cycle waveform t with a length of m to be matched, establish an n The matrix of m is Figure 6 As shown. Calculate the distance d between the sampling point of s and the sampling point of t corresponding to each unit matrix respectively ( i , j ) = ( p i - t j ) 2 , i=1,2…n, j=1,2…m. Each matrix element (i,j) represents a point p i and t j alignment.

[0022] Step B2: Find a path W that passes through several grid points in the matrix. The grid points that the path passes through are the points where p and t are aligned. The cumulative distance D of all grid points passing through the path is the total distance of matching p and t. The ultimate goal of matching is to find a path with the smallest cumulative distance. Define the path W=w1,w2,…w k ,…w K , max(n,m)≤K<m+n-1. In order to satisfy the order of point alignment and the continuity and monotonicity of the path, there are only three cases for the next grid point at the current position (i,j): (i+1,j), (i,j+1) or (i+1,j+1). Under this condition, the minimum cumulative path is defined according to formula (3): ; Step B3: Calculate the cumulative distance, which is the sum of the distance d(i, j) of the current grid point and the minimum cumulative distance that can reach the point, defined by formula (4) as follows: ; Step B4, and so on, perform template matching on other single-cycle waveforms and the previous single-cycle waveform. The matching result of each single-cycle waveform can obtain a D, and the maxD with the largest SBP position range is found. The second airbag pressure corresponding to the waveform is the systolic pressure.

[0023] For the normalized waveform, the main feature of the waveform is to identify the change in waveform morphology, and the point with the maximum DTW value within the range of SBP and DBP is marked as maxD.norm 。

[0024] For non-normalized waveforms, mainly identify the amplitude changes of the waveforms, and mark the position with the maximum DTW value within the SBP and DBP positions as maxD non-norm 。

[0025] Finally, based on D(w) calculated by comprehensively considering the normalized and non-normalized oscillatory wave signals, set the weight parameters. The weight of the preset normalized result w norm and the weight of the non-normalized result w non−norm are used to calculate the final blood pressure value, satisfying w norm +w non−norm = 1. maxD final is obtained through weighted calculation, and the calculation formula is as follows: ; Blood pressure calculation: Use the second airbag pressure value at the same moment of the oscillatory wave corresponding to maxD final as the SBP and DBP outputs.

[0026] According to a specific embodiment of the present invention, the method for measuring blood pressure using the multi-airbag measuring belt of the present invention is as Figure 2 shown. Put the multi-airbag measuring belt on the upper arm of the person to be measured. The air tubes of the three airbags of the measuring belt are connected to the same inflator. There is an electromagnetic valve between the first airbag and the third airbag and the inflator. There is a pressure sensor and a deflation valve inside each of the two airbags. The air pump and air valve are controlled by a driving circuit connected to the microprocessor MCU for inflation and deflation. The air pressure of the airbag is converted into a voltage signal through the pressure sensor and the amplification circuit and input to the MCU with an analog-to-digital conversion module. The MCU then performs accurate operation control and data analysis and displays the analysis results.

[0027] When used for arm measurement, the second airbag serves two purposes. Firstly, during the pressurization process, it applies an external force to the brachial artery. Since the proximal part of the brachial artery under the cuff is unevenly compressed, when the pressure at the proximal end of the cuff is greater than the systolic pressure, there is a surge of blood flow. At the same time, there is also a blood flow surge from the heart to the upper arm, which can be detected by the third airbag. Secondly, it is used to cut off the brachial artery to avoid the interference of the blood flow surge from the heart to the upper arm on the oscillation wave of the first airbag. The function of the first airbag is to detect and pick up the vibration of the brachial artery below the second airbag and send it to the MCU for analysis. The function of the third airbag is to detect and pick up the vibration of the brachial artery above the second airbag and send it to the MCU for analysis. When starting the measurement, driven by the air pump, the first airbag, the second airbag, and the third airbag are inflated together. When the first airbag and the third airbag are inflated to a level lower than the diastolic pressure (50 - 70 mmHg), the solenoid valves between the two airbags and the air pump are closed, so that the air pump can only continue to inflate the second airbag. While the second airbag continues to inflate, due to soft tissue compression, etc., the air pressure in the first airbag and the third airbag increases. After being sensed by the pressure sensors built in the two airbags, it is uploaded to the MCU, and at the same time, the MCU controls the deflation valve inside it to deflate, maintaining the constant pressure in the first airbag and the third airbag. The second airbag continues to inflate at a certain fixed speed to a level higher than the systolic pressure (usually ensuring a linear rise in the airbag pressurization curve). At this time, there is no oscillation wave signal in the first airbag. When the second airbag is pressurized to the diastolic pressure level, the blood flow in the brachial artery begins to be restricted, and the blood surge at its proximal end increases. The oscillation wave amplitude of the third airbag begins to increase, and the pressure in the corresponding second airbag is equal to the diastolic pressure. As the pressure in the second airbag continues to increase, the oscillation wave amplitude below the first airbag becomes smaller and smaller. When the amplitude disappears, it indicates that the blood flow in the brachial artery is completely cut off, and the pressure in the corresponding second airbag is equal to the systolic pressure. After converting and calculating the relevant pressure values through the MCU, the required readings can be obtained. After obtaining the results, multiple airbags deflate simultaneously to end a blood pressure measurement.

[0028] Of course, the measuring belt of the present invention can also be used for blood pressure measurement of other parts of the human body, such as the wrist, leg, arm, finger, ankle, and other human body parts that need blood pressure measurement. Its working principle is the same as or similar to that of upper arm measurement.

[0029] During the process of measuring blood pressure with a traditional single-airbag cuff, due to the existence of proximal blood flow surges, even after pressurizing to a level higher than the systolic pressure, the pulsation in the proximal blood vessels can still be felt, thus generating oscillation waves. Therefore, in order to shield this interference as much as possible, the multiple airbags designed in the present invention must be isolated from each other and not affect each other, but the distance should also be close enough to ensure that the volume of the cuff does not exceed the preset range, so as to measure more accurately.

[0030] The experimental results prove that the blood pressure values measured by this method are basically consistent with those measured by auscultatory Korotkoff sounds, confirming that under relatively stable human conditions, this measurement method is basically not affected by the upstream blood flow surge, can find the characteristic points of blood pressure more easily than other non-invasive indirect blood pressure measurement methods, and can measure blood pressure more accurately.

[0031] From the above theoretical derivation and experimental results, it can be determined that in this single-cuff multi-airbag blood pressure measurement device, the air pressure of the second airbag corresponding to the start of the rise in the oscillation wave amplitude detected by the third airbag is equal to the diastolic blood pressure, and the air pressure of the second airbag corresponding to the disappearance of the oscillation wave detected by the first airbag is equal to the systolic blood pressure. And from the working principle, it can be seen that this method is also applicable to human body parts such as wrists, legs, arms, fingers, ankles and other parts where blood pressure needs to be measured.

[0032] Different from the existing single-airbag cuff, double-airbag double-cuff and double-airbag single-cuff for blood pressure measurement, the present invention provides a new type of cuff for blood pressure measurement device, which comprises three mutually independent airbags. Compared with the prior art, the beneficial effects of the present invention are as follows: First, the measurement belt of the present invention overcomes the interference of proximal blood flow surge in the traditional single-airbag blood pressure measurement process through three mutually independent airbags with appropriate distances, and also overcomes the defect of measurement error caused by the distance between airbags in multi-airbag multi-measurement belts, and can accurately measure the systolic and diastolic blood pressures of the human body; Second, according to the invasive blood pressure changes found during the cuff pressurization process, the invasive blood pressure under the third airbag designed by the present invention fluctuates minimally during the pressurization of the second airbag. By using the third airbag as a standard airbag, the accuracy of the blood pressure measurement result is increased; Finally, the first airbag and the third airbag of the present invention only need to be pressurized to a pressure lower than the diastolic blood pressure, and compared with other multi-cuff or multi-airbag devices, the measurement comfort is significantly improved.

[0033] Example: Blood pressure measurement on the arm: Wrap the cuff around the upper arm, with the first airbag located at the distal end of the elbow; the microprocessor starts the air pump, and the multi-airbag is inflated to 60 mmHg; close the solenoid valves of the first airbag and the third airbag, and the pressure balancing device maintains the constant pressure of the first airbag and the third airbag; The second airbag continues to be inflated to 180 mmHg. During the process: when the pressure of the second airbag reaches 80 mmHg (diastolic blood pressure), the oscillation wave amplitude of the third airbag rises by 30%; when the pressure of the second airbag reaches 120 mmHg (systolic blood pressure), the oscillation wave of the first airbag disappears; the microprocessor outputs a systolic blood pressure of 120 mmHg and a diastolic blood pressure of 80 mmHg. The experimental results are visualized as Figures 7 - 10 shown. The oscillation wave of the second airbag in the figure is the normal oscillation wave.

[0034] As Figure 7As shown in (a) and (b), when the second airbag is pressurized to the systolic blood pressure level, the oscillation wave of the first airbag disappears, and the systolic blood pressure characteristic changes significantly compared with the normal oscillation wave; as Figure 8 It can be seen that the systolic and diastolic blood pressures measured by the current amplitude coefficient method are mostly empirical based on the range of pressure value changes. Only the mean arterial pressure corresponds to the maximum amplitude, and the measurement result is relatively accurate; as Figure 9 (a), (b) and Figure 10 As shown in (a) and (b), when the second airbag is pressurized to the diastolic blood pressure level, the amplitude of the oscillation wave of the third airbag begins to increase, and the diastolic blood pressure characteristic changes significantly compared with the normal oscillation wave. When the second airbag is pressurized to the systolic blood pressure level, the shapes of the first and second peaks of the oscillation wave of the third airbag change, and the systolic blood pressure characteristic changes significantly compared with the normal oscillation wave. Experimental data: For 50 subjects measured, the error between this device and the auscultation method is < ±3 mmHg, and the consistency reaches 98%.

[0035] The above description is only the preferred embodiment of the present disclosure and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the embodiments of the present disclosure.

Claims

1. A blood pressure measurement system based on multi-airbag collaborative control and oscillometric wave analysis, characterized in that Comprising: An integrated cuff cover, an air pump, a solenoid valve, a pressure balancing device, a microprocessor; The integrated cuff cover is internally provided with a first airbag, a second airbag and a third airbag, wherein the first airbag is arranged at the distal end, the third airbag is arranged at the proximal end, and the second airbag is arranged between the first airbag and the third airbag, and the three airbags are arranged at intervals; The air pump simultaneously inflates the first airbag, the second airbag and the third airbag at a constant pressure through a main air pipe; The solenoid valve includes a first airbag solenoid valve and a third airbag solenoid valve, which are respectively arranged at the connection parts of the main air pipe with the first airbag and the third airbag. The first airbag solenoid valve controls the on-off of the inflation of the first airbag, and the third airbag solenoid valve controls the on-off of the inflation of the third airbag; The pressure balancing device includes a pressure sensor and a micro air release valve. The pressure sensors are respectively arranged in the first airbag and the third airbag, and are used for real-time monitoring of the pressures in the first airbag and the third airbag, and maintaining the constant pressures of the first airbag and the third airbag by dynamically adjusting the opening and closing of the micro air release valve; The microprocessor is connected to the air pump, the solenoid valve, the pressure sensor and the micro air release valve, and is used for executing an inflation control logic; The microprocessor integrates an oscillatory wave analysis module, which is used for real-time collecting the pressure data from the first airbag to the third airbag, identifying the oscillatory wave changes of the first airbag and the third airbag based on the elastic template matching method and obtaining a blood pressure measurement result; The oscillatory wave analysis module specifically includes: a signal preprocessing unit, a signal quality evaluation unit, a feature point identification unit, and a blood pressure calculation unit; The signal preprocessing unit: First, use Fourier transform to determine the distribution characteristics of noise and effective signals; then remove the high-frequency noise in the original oscillatory wave signal through a low-pass filter, and remove the influence of baseline drift on the oscillatory wave through a high-pass filter; perform a secondary analysis using Fourier transform to provide a frequency band division basis for empirical wavelet transform; then eliminate artifacts through the empirical wavelet transform method; finally, respectively adopt the methods of normalization processing and non-normalization processing. The normalization processing is used to adjust the amplitude differences between different waveforms and identify the waveform feature changes; the non-normalization processing method is used to identify the oscillatory wave amplitude differences; The signal quality evaluation unit: includes the data quality evaluation of the oscillatory wave and the data quality evaluation related to the blood pressure measurement during inflation and deflation under high pressure; the data quality evaluation under a constant pressure is carried out by extracting each oscillatory wave under the preset constant pressure to construct a quality evaluation template, matching the template signal with each waveform of this section of the oscillatory wave and calculating the DTW distance, and judging whether the data is available according to the average value of all DTW distances; The feature point recognition unit: First, read the second airbag oscillation wave and locate it by the variable amplitude coefficient method, that is, use the variable amplitude coefficient to determine the position ranges of the systolic blood pressure SBP and diastolic blood pressure DBP. Based on the DTW algorithm, estimate the blood pressure for the waveforms in the position ranges where the systolic blood pressure SBP and diastolic blood pressure DBP appear in the oscillation waves of the first airbag and the third airbag. Among them, the third airbag is used as the standard airbag, the oscillation wave of the first airbag assists in calculating the systolic blood pressure SBP, and the oscillation wave of the second airbag assists in calculating the mean arterial pressure MAP. The waveform of the latter single cycle uses the waveform of the previous single cycle as a template, estimates the blood pressure by identifying the changes in the oscillation wave form and amplitude, and based on the waveform template matching method; The feature point recognition unit is specifically: For the normalized waveform, identify the changes in the waveform morphological features, and mark the position with the maximum DTW value within the ranges of the systolic blood pressure SBP and the diastolic blood pressure DBP as D norm ; For the non-normalized waveform, identify the amplitude change of the waveform, and mark the position with the maximum DTW value within the range of the systolic blood pressure SBP and diastolic blood pressure DBP as D non-norm ; Finally, the DTW distance calculated from the comprehensive normalized and non-normalized oscillatory wave signals is used to set the weight parameter, and the final D is calculated by weighted calculation. final ; Take D final Output the second airbag pressure value of the corresponding oscillatory wave at the same moment as the systolic blood pressure SBP and diastolic blood pressure DBP to achieve blood pressure measurement; The blood pressure calculation unit uses the second airbag pressure value of the corresponding oscillation wave at the same moment as the systolic blood pressure and diastolic blood pressure output. final ​ 2. The blood pressure measurement system based on multi-airbag collaborative control and oscillometric wave analysis according to claim 1, characterized in that, The shapes of the first airbag, the second airbag, and the third airbag are all rectangular. Among them, the sizes of the first airbag and the third airbag are the same, and the size of the second airbag is larger than the sizes of the first airbag and the third airbag. The sizes of the airbags are adjusted in a timely manner according to the actual situation.

3. A blood pressure measurement system based on multi-airbag collaborative control and oscillometric wave analysis according to claim 1, wherein, The inflation rate of the inflator is 3 - 10 mmHg per second.

4. A blood pressure measurement system based on multi-airbag collaborative control and oscillometric wave analysis according to claim 1, wherein The data quality assessment of the oscillation wave is constructed by extracting each waveform of the waveforms in all pressure ranges to build a quality assessment template; match the template signal with each single cycle waveform and calculate the DTW distance, and judge whether the data is available according to the average value of all DTW distances; For the data quality assessment related to blood pressure measurement during inflation and deflation under high pressure, first calculate the average pressure position of the oscillation wave in the inflation state and the average pressure position in the deflation state, calculate the position deviation between the two and compare it with a preset threshold to judge whether the data is available; select the waveform of the previous single cycle as the template, and based on the DTW algorithm, perform waveform template matching between the single cycle waveform and its corresponding template to find the matching waveform and preliminarily estimate the blood pressure value.

5. The blood pressure measurement system based on multi-airbag collaborative control and oscillometric wave analysis according to claim 1, wherein The inflation control logic, that is, the blood pressure measurement method based on multi-airbag collaborative control and oscillation wave analysis, specifically includes: Step S1: Initial inflation stage: The inflator is started, and the multi-airbags are inflated synchronously to a preset initial pressure; Step S2: Airbag constant pressure stage: Close the solenoid valves of the first airbag and the third airbag; Step S3: The pressure balance device dynamically adjusts the micro deflation valve to maintain the constant pressure in the first airbag and the third airbag; Step S4: Second airbag pressure increase stage: The inflator continues to inflate until the pressure in the second airbag is higher than the systolic blood pressure level.

6. The blood pressure measurement system based on multi-airbag collaborative control and oscillometric wave analysis according to claim 1, characterized in that, The blood pressure measurement method based on multi-airbag collaborative control and oscillation wave analysis includes a multi-airbag pressure measurement mode and a dual-airbag pressure measurement mode; The multi-airbag pressure measurement mode is to measure blood pressure simultaneously using 3 airbags. Taking the third airbag as the standard airbag, amplify the change characteristics of the systolic blood pressure SBP and diastolic blood pressure DBP to obtain the standard blood pressure. At the same time, the oscillation wave of the first airbag amplifies the change characteristics of the systolic blood pressure SBP to correct the systolic blood pressure SBP, and the oscillation wave of the second airbag is used to identify the mean arterial pressure MAP. Then, the blood pressure value is obtained through mutual correction of the three airbags; The double-balloon pressure measurement mode is to pressurize only the second balloon and the third balloon, that is, the first balloon is not pressurized. The second balloon and the third balloon are pressurized according to the descriptions in steps S4 and S1 respectively. Finally, the mean arterial pressure MAP is measured through the second balloon, and the systolic blood pressure SBP and the diastolic blood pressure DBP are identified by amplifying the change characteristics of the systolic blood pressure SBP and the diastolic blood pressure DBP through the third balloon. The blood pressure value is obtained by calibrating the third balloon through the second balloon.

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