CN1985750B - Pulse wave detecting method and device by means of cardiac symbol signal - Google Patents

Abstract

The invention discloses a method and device for detecting pulse wave by using a symbolic signal of heartbeat, detects the distance value of R wave and pulse wave in time, obtains a reference distance value, uses the reference distance value to locate and search the pulse wave amplitude, obtains Baseline pulse wave amplitude under different pressures, so as to further calculate mean pressure, systolic blood pressure and diastolic blood pressure by ratio method. Compared with the method of directly searching the pulse wave peak value in the pulse wave signal used in most current blood pressure measurements, the present invention improves the anti-interference ability, and can effectively improve the accuracy of blood pressure measurement in the presence of exercise and arrhythmia .

Description

A method and device for detecting pulse waves using heartbeat symbolic signals

【Technical field】

The invention relates to a pulse wave detection method, in particular to a pulse wave detection method and device which use electrocardiographic signals to guide pulse wave search and enhance anti-interference performance, and an electronic sphygmomanometer including the device.

【Background technique】

At present, the oscillation method is usually used for non-invasive blood pressure measurement. The measurement process is to inflate the cuff first. When the pressure reaches greater than the systolic blood pressure of the human body, it can be considered that the blood vessel has been completely blocked. At this time, there should be no pressure at the cuff. There is a pulsation of the pulse. Then start to deflate slowly or in steps. When the cuff pressure is lower than the systolic pressure, the blood vessel has been partially connected. At this time, the pulse will gradually increase with the decrease of the cuff pressure. Due to the influence of the pulse, the The pressure of the cuff fluctuates in a small range, that is, an oscillating signal is superimposed on the pressure signal, and the oscillating signal gradually increases as the cuff pressure decreases. But when the cuff pressure decreases to a certain extent, the amplitude of the oscillation signal will start to decrease instead. This is mainly because the pressure of the cuff decreases, which gradually increases the attenuation effect of the human subcutaneous tissue on the pulse. When the cuff pressure continues to decrease, the attenuation effect becomes more and more obvious, and the amplitude of the oscillation signal decreases more obviously. By searching the pulse wave amplitude under different pressures, the corresponding relationship curve between pulse pressure and pulse wave amplitude is obtained. Then find the pressure corresponding to the maximum pulse wave amplitude, which is considered to be the average pressure; use the pulse wave amplitude corresponding to the average pressure to multiply the systolic blood pressure amplitude coefficient to obtain the pulse wave amplitude corresponding to the systolic blood pressure, and then according to the corresponding relationship curve to cuff pressure high The direction of the corresponding cuff pressure is calculated, which is regarded as the systolic pressure; the pulse wave amplitude corresponding to the average pressure is multiplied by the coefficient of the diastolic pressure amplitude to obtain the pulse wave amplitude corresponding to the diastolic pressure, and then according to the corresponding relationship curve to the lower cuff pressure The pressure of the cuff is calculated according to the direction of the cuff, which is considered as the diastolic pressure. This method of calculating the mean pressure, systolic pressure and diastolic pressure is called the ratio method. In traditional measurement methods, the measurement results are easily affected by various interferences such as arm movements, resulting in no results or even large deviations.

Because the cuff needs to be tied to the patient's arm and inflated to a certain pressure during the measurement, the patient will inevitably feel oppression, tremors will occur unconsciously, or the patient's condition leads to muscle tremors, etc., or during surgery During the process or other situations, the patient's arm is touched by the outside world and shakes unexpectedly. In these cases, the baseline and amplitude of the pulse wave will be affected. The traditional method of finding the pulse wave amplitude is difficult to guarantee its accuracy. This results in an increased probability of identifying an incorrect pulse wave amplitude.

【Content of invention】

The main purpose of the present invention is to solve the problems of the prior art and provide a method for detecting pulse waves, which reduces interference and improves the accuracy of pulse wave detection by using the heartbeat symbolic signal reflecting the beating of the heart.

Another object of the present invention is to provide a pulse wave detection device to solve the problems of the prior art, which reduces interference and improves the accuracy of pulse wave detection by using the symbolic heartbeat signal reflecting the beating of the heart.

Another object of the present invention is to provide an electronic sphygmomanometer, which can improve the accuracy of the pulse wave curve, thereby improving the accuracy of blood pressure measurement using the oscillation method.

In order to achieve the above object, the present invention discloses a method for detecting a pulse wave using a heartbeat symbolic signal, comprising the following steps:

A1. Set the cuff on the specified part of the body;

B1. Control the inflation of the cuff to a certain pressure, so that the cuff compresses the artery, and then gradually deflate;

C1. During the deflation process, sample the pressure in the cuff;

D1. Detect the pulse wave under the pressure, sample the ECG signal, and record the moment when the symbolic signal of heartbeat generated by the beating of the heart appears;

E1, detecting the reference delay value of the pulse wave relative to the heartbeat symbolic signal;

F1. Search the pulse wave within the effective range after the heartbeat symbol signal delay reference delay value;

G1. Obtain the reference pulse wave under the pressure according to the searched pulse wave.

Wherein, the heartbeat symbolic signal is preferably an R wave or a blood oxygen pulse wave.

Wherein, the effective range is a range of 1/15 second around the point where the symbolic heartbeat signal is delayed by the reference delay value as the center.

Wherein, the preferred version of the step E1 includes the following steps:

E11, detecting the distance between the heartbeat symbolic signal and the detected pulse wave;

E12. Establish a spacing array, and the differences between the spacing values in the spacing array are all less than the set difference;

E13. Average the spacing values in the spacing array as the reference delay value.

The preferred solution of the above steps is: the minimum number of interval values in the array of interval values is 3, and the set difference is 1/15 second.

In order to continuously correct the reference delay value, the following steps are also included after step E13:

E14. Search for the next pulse wave within the effective range after the heartbeat symbolic signal delay reference delay value, and add the distance value between the pulse wave and the corresponding heartbeat symbolic signal to the distance array;

E15. Sorting the spacing values of the spacing array, looking for a collection of spacing values that differ from other spacing values in the array by less than the set difference value;

E16. Update the reference delay value by using the average value of the interval values in the set.

In order to achieve the above object, the present invention also discloses a pulse wave detection device, which includes: a cuff, which is arranged on a specified part of the body; an air pressure control module, which inflates the cuff to a certain pressure, so that the cuff compresses the artery, and It can gradually deflate; the pressure detection module detects the pressure in the cuff; the pulse wave detection module detects the pulse wave signal generated by the pressure of the cuff; The symbolic signal of the heartbeat, and record the moment of its appearance; The reference delay value detection module detects the reference delay value of the pulse wave relative to the symbolic signal of the heartbeat in time; The pulse wave search module is used for delaying the reference delay value in the symbolic signal of the heartbeat The pulse wave is searched in the effective range after the search; the reference pulse wave calculation module obtains the reference pulse wave under different pressures according to the searched pulse wave.

Wherein, the heartbeat symbolic signal is preferably an R wave or a blood oxygen pulse wave.

Wherein, the effective range is a range of 1/15 second around the point where the symbolic heartbeat signal is delayed by the reference delay value as the center.

The reference delay value detection module includes: a distance value detection unit, which detects the distance value between the heartbeat symbolic signal and the detected pulse wave; a distance array processing unit, which establishes a distance array, and the distance values in the distance array The difference between the intervals is all less than the set difference; the reference delay value calculation unit averages the interval values in the interval array as the reference delay value.

The minimum number of interval values in the array of interval values is preferably 3, and the set difference is preferably 1/15 second.

In order to constantly revise the reference delay value, the further improvement of the present invention is: it also includes a reference delay value update module, which is used to search for the next pulse wave and the corresponding heartbeat within the effective range after the heartbeat symbolic signal is delayed by the reference delay value. Add the spacing value of the symbolic signal to the spacing array, sort the spacing values of the spacing array, find the set of spacing values with the largest difference from other spacing values in the array that is less than the set difference, and update with the average value of the spacing values in the set The reference delay value in the reference delay value detection module.

In order to achieve the above object, the present invention also discloses an electronic sphygmomanometer, comprising: a cuff, which is arranged on a prescribed part of the body; Deflate gradually; Pressure detection module detects the pressure in the cuff; Pulse wave detection module detects the pulse wave signal generated by the pressure of the cuff; The symbolic heartbeat signal, and record the moment when it appears; the reference delay value detection module detects the reference delay value of the pulse wave relative to the symbolic heartbeat signal in time; the pulse wave search module is used to delay the reference delay value after the symbolic heartbeat signal The pulse wave is searched within the effective range; the reference pulse wave calculation module obtains the reference pulse wave under different pressures according to the searched pulse wave; the blood pressure calculation module uses the ratio method to calculate the average pressure, systolic and diastolic pressure.

In order to achieve the above object, the present invention also discloses an electronic sphygmomanometer, comprising: a cuff, which is arranged on a prescribed part of the body; Deflate gradually; Pressure detection module detects the pressure in the cuff; Pulse wave detection module detects the pulse wave signal generated by the pressure of the cuff; The symbolic heartbeat signal, and record the moment when it appears; the processing module is used to detect the reference delay value of the pulse wave relative to the symbolic heartbeat signal, and search for the pulse wave in the effective range after the symbolic heartbeat signal is delayed by the reference delay value, according to the searched out The pulse wave obtains the reference pulse wave under different pressures, and calculates the mean pressure, the systolic blood pressure and the diastolic blood pressure by using the ratio method according to the obtained pressure series and the reference pulse wave series.

Effects of the present invention: 1) Utilize the principle that the pressure of the blood ejected after the heart beats to the blood vessels of the arm is transmitted to the arm blood vessel arm to the principle that the same person basically remains unchanged, after the R wave or blood oxygen pulse wave occurs, the fixed time Searching for pulse waves in the area can effectively eliminate interference and improve the accuracy of pulse wave detection. 2) Reasonably detect the reference delay value between R wave or blood oxygen pulse wave and pulse wave, which is conducive to the location search of pulse wave, and further reduces the probability of using interference signal as pulse wave. 3) According to the R wave or blood oxygen pulse wave and pulse wave detected later, the reference delay value is continuously corrected, so that the reference delay value used to guide the pulse wave positioning search is closer to the actual distance, and the anti-interference performance of pulse wave detection is further improved and accuracy.

The features and advantages of the present invention will be described in detail with reference to the accompanying drawings.

【Description of drawings】

Fig. 1 is a connection block diagram of an embodiment of the present invention;

Fig. 2 is a flow chart of an embodiment of the present invention;

Fig. 3 is the flowchart of obtaining reference delay value in Fig. 2;

Fig. 4 is the flowchart of updating reference delay value;

Fig. 5 is a flow chart of using the R wave to guide the pulse wave location search in Fig. 2 .

【Detailed ways】

As shown in FIG. 1 , the cuff is used to be worn on a prescribed part of the body to be measured when measuring blood pressure, usually on the arm, and can also be worn on the wrist. The air pressure control module is connected with the cuff, and the air pressure control module includes a motor, an inflation unit, a valve and a logic control unit, and the motor, the inflation unit, the cuff, and the valve form an inflation passage, which is controlled by the logic control unit. First close the valve, power on the motor, inflate the cuff to the specified pressure, then stop inflation, open the valve, and control the deflation valve to gradually deflate the cuff, such as step deflation. The pressure detection module includes a pressure sensor, an amplifier and an A/D converter. The pressure sensor is placed in the cuff close to the artery. During the deflation process, the pressure sensor detects the pressure in the cuff and converts the pressure into an electrical signal output. The amplifier amplifies the electrical signal, and then divides it into two paths, of which the first path is directly output to the A/D converter, and the current pressure is obtained after calculation. The second output is to the pulse wave detection module. The pulse wave detection module includes a high-pass filter to filter out the DC pressure signal, and then amplifies the output to the A/D converter to obtain the AC pulse wave signal. The electrocardiographic signal detection module detects the R wave by existing means, and records the moment when it appears. The reference delay value detection module receives the R wave output by the ECG signal detection module and the moment when it appears, and also receives the pulse wave output by the pulse wave detection module, compares the pulse wave with the R wave, and detects that the pulse wave is relative to the R wave The reference delay value in time. The pulse wave search module guides the positioning search of the pulse wave according to the reference delay value, that is, the time when the R wave appears is delayed to search for the pulse wave within the effective range after the reference delay value, and the effective range is preferably the point after the delay reference delay value as the center. In the range of 1/15 second, if the sampling frequency is 75Hz, the effective range is the 5 sampling points before and after the point after the delay reference delay value as the center, and the pulse wave not searched within this range is considered not blood pressure Pulse wave amplitude is interference. The reference delay value update module receives the next pulse wave searched by the pulse wave search module within the effective range after the R wave delay reference delay value, and adds the interval value between the pulse wave and the corresponding heartbeat symbolic signal to the interval array, and the interval array Sort the spacing values of the array, find the set of points whose pairwise difference with other spacing values in the array is less than the set difference, and update the reference delay value in the reference delay value detection module with the average value of the spacing values in the set. The reference pulse wave calculation module uses the similar wave clustering method to find similar pulse wave amplitudes based on several pulse wave peak values found under the same pressure, and averages them as the reference pulse wave amplitude under the current pressure. The above-mentioned modules form a pulse wave detection device, and then the pressure sequence after A/D conversion and the reference pulse wave sequence corresponding to the pressure can be stored in the storage module first, and the optimization processing module reads the pressure sequence and the reference pulse wave sequence in the storage module Pulse wave sequence, normalize, interpolate, and weighted average the pressure sequence and the reference pulse wave sequence, and then output to the blood pressure calculation module, which uses the ratio method to calculate the average pressure, systolic blood pressure and diastolic blood pressure, because it improves The accuracy of the pulse wave curve is improved, so as to realize the anti-interference of blood pressure measurement and improve the accuracy of blood pressure measurement by oscillation method. It is also possible to further calculate the pulse rate.

The above-mentioned reference delay value detection module, reference delay value update module, pulse wave search module, reference pulse wave calculation module, storage module, optimization processing module and blood pressure calculation module can also be integrated in the processing module and completed by software, such as integrating in the microcontroller.

Since the R wave, the blood oxygen pulse wave period and the pulse wave period all reflect the heartbeat frequency, the distance between the corresponding R wave or the blood oxygen pulse wave and the pulse wave is certain. The time to transmit the pulse to the arm is constant for the same person, and there is no change. According to this feature, the pulse wave can be searched only within a certain distance after the R wave or the blood oxygen pulse wave, which can effectively remove the interference. The specific process of this embodiment is shown in Figure 2, including the following steps:

In step 1, inflate and deflate the cuff to a pressure step;

In step 2, under the current pressure step, during the timing interruption, the oscillation signal, that is, the pulse wave signal, is sampled, and the sampled data is preprocessed; the R wave pulse is sampled, and the moment when the R wave pulse appears is recorded, Then perform step 3;

In step 3, judge whether it is the first pressure step, if yes, execute step 4, if not, execute step 5;

In step 4, obtain the reference distance value between the R wave and the corresponding pulse wave, and then perform step 6;

In step 5, update the reference spacing value, and then perform step 6;

In step 6, locate the search range of the pulse wave according to the reference interval value, and search out the pulse wave within this range. The optimal solution for the search range is to delay the R wave to the point after the reference delay value as the center and the range of 1/15 seconds before and after pulse wave within. Then perform step 7;

In step 7, the pulse waves under the same pressure are processed by similar clustering method to find similar pulse wave amplitudes, and average them as the reference pulse wave amplitude under the current pressure, and then perform step 10;

In step 8, during the timing interruption, sample the cuff pressure value, and then perform step 9;

In step 9, the pressure sampling signal is processed, and the sampling value is converted into a pressure unit mmHg value to obtain the current pressure value, and then step 10 is performed;

In step 10, it is judged whether to continue to deflate, if it is necessary to continue to deflate, then turn to step 1, if it is not necessary to continue to deflate, then perform step 11;

In step 11, a pressure sequence and a reference pulse wave sequence are obtained.

If it is necessary to use the pulse wave to calculate the blood pressure, step 12 can be further performed;

In step 12, optimize the pressure sequence and the reference pulse wave sequence, such as normalization, interpolation and weighted average processing, and then perform step 13;

In step 13, find out the pulse wave with the largest amplitude, the pressure value corresponding to the pulse wave amplitude is the mean pressure, and then perform step 14;

In step 14, the systolic and diastolic blood pressures are calculated using the ratio method based on the amplitude coefficients obtained empirically.

For a series of reference pulse wave signals obtained under different pressures, the change trend can also be judged, and the pulse wave amplitude that does not meet the change trend of the pulse wave amplitude under pressure during the deflation process is deleted to ensure that the reference pulse wave sequence conforms to the ratio method Some properties that need to be met.

In the above steps, the process of obtaining the reference delay value for the first time is shown in Figure 3, including the following steps:

In step 401, receive the R wave and the pulse wave corresponding to the R wave, detect the distance value between the R wave and the pulse wave, and then perform step 402;

In step 402, set up the spacing array, put the spacing value into the spacing array, and then perform step 403;

In step 403, it is judged whether the quantity of distance values in the distance array is greater than 2, if so, then step 404 is performed, if not, then step 401 is performed, and the distance value between the R wave and the next pulse wave is continued to be detected;

In step 404, calculate the difference between two interval values in the interval array, if the difference between the interval value and other interval values is all less than 1/15 second, then keep the interval value in the interval array, and then perform the steps 405. If the difference between the interval value and other interval values is not all less than 1/15 second, delete the interval value; in this step, the setting difference is preferably 1/15 second, because the setting difference If it is too small, it is easy to miss the blood pressure pulse wave. If the setting difference is too large, the anti-interference performance will be reduced. If the sampling frequency is 75Hz, the setting difference is preferably 5 sampling points;

In step 405, it is judged whether the quantity of the interval value in the interval array reaches 3, if yes then execute step 406, if not then execute step 401;

In step 406, average the spacing values in the spacing array as a reference delay value.

In the above steps, the process of updating the reference delay value is shown in Figure 4, including the following steps:

In step 501, search for the next pulse wave within the effective range after the R wave delay reference delay value, and then perform step 502;

In step 502, the trough and the pulse wave reference point have been found in the pulse wave search, and then step 503 is performed;

In step 503, calculate the interval value between the pulse wave and the previous R wave, and add the interval value to the interval array, and then perform step 504;

In step 504, judge whether the quantity of the interval value of interval array is greater than 2, if yes then execute step 505, if not then turn to step 501, continue to search next pulse wave;

In step 505, the distance values of the distance array are sorted, and then step 506 is performed;

In step 506, look for the distance value with the most difference of less than 5 from other distance values in the array to form a set, if there is only one distance value that meets the condition, then form a set together with the distance value and its nearby distance values, and then Execute step 507;

In step 507, the distance values in the set are averaged, and then step 508 is performed;

In step 508, the reference delay value is updated with the average value of the distance values in the set.

Wherein, the process of using R wave to guide the pulse wave location search is shown in Figure 5, including the following steps:

In step 601, search for the next pulse wave within the effective range after the R wave delay reference delay value, and then perform step 602;

In step 602, it is judged whether the distance between the pulse wave and the corresponding R wave is within the range of plus or minus 5 of the reference delay value, that is, it is judged whether the pulse wave is centered on the point after the R wave is delayed by the reference delay value Within the range of 5 points, if yes then execute step 603, if not then discard the pulse wave, then execute step 601;

In step 603, save the current pulse wave amplitude, and enter the pulse wave sequence judgment.

Laboratory tests have proved that when using the BIO-TECK simulator to output various types of interference, the algorithm of introducing ECG R wave to locate the pulse wave search can measure more accurate blood pressure results. The comparison results are shown in Table 1 .

Table 1

patient mode emulator settings Old algorithm measurement results New Algorithm Test Results Mild Exercise moderate exercise 140/106/90120BPM 149/110/96119BPM 147/110/97119BPM Geriatric Subject Aging Model 150/123/11095BPM 163/126/11595BPM 156/126/11596BPM Patients with Artial Fib and PVC premature beats 139/94/7291BPM 127/95/80 81BPM 138/97/82 83BPM High Way Level 8 Sports Level 8 120/93/80 135/91/82 120/93/80

It can be seen from the table that in the four modes, adding the R wave anti-interference algorithm, the measurement accuracy is significantly improved, especially in the sports level 8 mode, the introduction of the R wave anti-interference algorithm can accurately calculate the blood pressure value.

Similarly, replacing the ECG R wave in the above embodiment with feature points on the blood oxygen pulse wave, such as peak points or valley points, can also be used to guide and locate the search for the blood pressure pulse wave.

In summary, the present invention uses the ECG R-wave signal to search for the pulse wave amplitude, compared with the method of directly searching the pulse wave peak value in the pulse wave signal used in most current blood pressure measurements, it improves the anti-interference ability , in the presence of exercise and arrhythmia, it can effectively improve the accuracy of blood pressure measurement.

Claims (16)

1. A method utilizing heartbeat symbolic signal to detect pulse wave is characterized in that comprising the following steps: A1. Set the cuff on the specified part of the body; B1. Control the inflation of the cuff to a certain pressure, so that the cuff compresses the artery, and then gradually deflate; C1. During the deflation process, sample the pressure in the cuff; D1. Detect the pulse wave under the pressure, sample the ECG signal, and record the moment when the symbolic signal of heartbeat generated by the beating of the heart appears; E1, detecting the reference delay value of the pulse wave relative to the heartbeat symbolic signal; F1. Search the pulse wave within the effective range after the heartbeat symbol signal delay reference delay value; G1. Obtain the reference pulse wave under the pressure according to the searched pulse wave. 2. The method according to claim 1, wherein the symbolic heartbeat signal is an R wave or a blood oxygen pulse wave. 3 . The method according to claim 2 , wherein the effective range is a range of 1/15 seconds around a point after the heartbeat symbolic signal is delayed by a reference delay value as a center. 4 . 4. The method according to any one of claims 1 to 3, characterized in that: said step E1 comprises the following steps: E11, detecting the distance between the heartbeat symbolic signal and the detected pulse wave; E12. Establish a spacing array, and the differences between the spacing values in the spacing array are all less than the set difference; E13. Average the spacing values in the spacing array as the reference delay value. 5. The method according to claim 4, characterized in that: the minimum number of interval values in the interval array is 3, and the set difference is 1/15 second. 6. The method according to claim 4, further comprising the following steps after step E13: E14. Search for the next pulse wave within the effective range after the heartbeat symbolic signal delay reference delay value, and add the distance value between the pulse wave and the corresponding heartbeat symbolic signal to the distance array; E15. Sorting the spacing values of the spacing array, looking for a collection of spacing values that differ from other spacing values in the array by less than the set difference value; E16. Update the reference delay value by using the average value of the interval values in the set. 7. The method according to claim 5, further comprising the following steps after step E13: E14. Search for the next pulse wave within the effective range after the heartbeat symbolic signal delay reference delay value, and add the distance value between the pulse wave and the corresponding heartbeat symbolic signal to the distance array; E15. Sorting the spacing values of the spacing array, looking for a collection of spacing values that differ from other spacing values in the array by less than the set difference value; E16. Update the reference delay value by using the average value of the interval values in the set. 8. A pulse wave detection device, comprising: The cuff is set on a prescribed part of the body; The air pressure control module inflates the cuff to a certain pressure, so that the cuff compresses the artery and can gradually deflate; a pressure detection module, detecting the pressure in the cuff; The pulse wave detection module detects the pulse wave signal produced by the pressure of the cuff; it is characterized in that it also includes: The ECG signal detection module detects the symbolic heartbeat signal generated by the beating heart, and records the moment when it appears; The reference delay value detection module detects the reference delay value of the pulse wave relative to the heartbeat symbolic signal; The pulse wave search module is used to search for the pulse wave within the effective range after the heartbeat symbolic signal delays the reference delay value; The reference pulse wave calculation module obtains reference pulse waves under different pressures according to the searched pulse waves. 9. The pulse wave detection device according to claim 8, wherein the symbolic heartbeat signal is an R wave or a blood oxygen pulse wave. 10 . The pulse wave detection device according to claim 9 , wherein the effective range is a range of 1/15 second around a point where the symbolic heartbeat signal is delayed by a reference delay value as a center. 11 . 11. The pulse wave detection device according to any one of claims 8 to 10, wherein the reference delay value detection module comprises: A distance value detection unit detects the distance between the symbolic heartbeat signal and the detected pulse wave; The distance array processing unit: establish a distance array, and the differences between the distance values in the distance array are all less than the set difference; The reference delay value calculation unit averages the spacing values in the spacing array as the reference delay value. 12. The pulse wave detection device according to claim 11, characterized in that: the minimum number of interval values in the interval array is 3, and the set difference is 1/15 second. 13. The pulse wave detection device according to claim 11, further comprising: The reference delay value update module is used to add the spacing value of the next pulse wave and the corresponding heartbeat symbolic signal to the spacing array searched within the effective range after the heartbeat symbolic signal delays the reference delay value, and sort the spacing values of the spacing array, Find the set of spacing values whose pairwise difference with other spacing values in the array is smaller than the set difference, and use the average value of the spacing values in the set to update the reference delay value in the reference delay value detection module. 14. The pulse wave detection device according to claim 12, further comprising: The reference delay value update module is used to add the spacing value of the next pulse wave and the corresponding heartbeat symbolic signal to the spacing array searched within the effective range after the heartbeat symbolic signal delays the reference delay value, and sort the spacing values of the spacing array, Find the set of spacing values whose pairwise difference with other spacing values in the array is smaller than the set difference, and use the average value of the spacing values in the set to update the reference delay value in the reference delay value detection module. 15. An electronic sphygmomanometer comprising: The cuff is set on a prescribed part of the body; The air pressure control module inflates the cuff to a certain pressure, so that the cuff compresses the artery and can gradually deflate; a pressure detection module, detecting the pressure in the cuff; The pulse wave detection module detects the pulse wave signal produced by the pressure of the cuff; it is characterized in that it also includes: The ECG signal detection module detects the symbolic heartbeat signal generated by the beating heart, and records the moment when it appears; The reference delay value detection module detects the reference delay value of the pulse wave relative to the heartbeat symbolic signal; The pulse wave search module is used to search for the pulse wave within the effective range after the heartbeat symbolic signal delays the reference delay value; The reference pulse wave calculation module obtains the reference pulse waves under different pressures according to the searched pulse waves; The blood pressure calculation module calculates mean blood pressure, systolic blood pressure and diastolic blood pressure by ratio method according to the obtained pressure series and reference pulse wave series. 16. An electronic sphygmomanometer comprising: The cuff is set on a prescribed part of the body; The air pressure control module inflates the cuff to a certain pressure, so that the cuff compresses the artery and can gradually deflate; a pressure detection module, detecting the pressure in the cuff; The pulse wave detection module detects the pulse wave signal generated by the pulse due to the compression of the cuff; It is characterized in that it also includes: The ECG signal detection module detects the symbolic heartbeat signal generated by the beating heart, and records the moment when it appears; The processing module is used to detect the reference delay value of the pulse wave relative to the heartbeat symbolic signal, search the pulse wave within the effective range after the heartbeat symbolic signal is delayed by the reference delay value, and obtain the reference pulse wave under the pressure according to the searched pulse wave, According to the obtained pressure series and the reference pulse wave series, mean pressure, systolic blood pressure and diastolic blood pressure are calculated by ratio method.

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