CN1698535A - Method for measuring blood pressure change rate - Google Patents

Abstract

The invention discloses a method for measuring blood pressure parameters corresponding to one or more heart beats, which comprises the following steps: 1) acquiring a series of signals related to pulse wave generation and transmission characteristics from a human body; 2) acquiring a characteristic parameter sequence of the signal from the acquired signal; 3) and determining a blood pressure parameter according to the acquired signal characteristic parameter sequence. The invention can further determine the blood pressure parameter according to the acquired signal characteristic parameter sequence by combining the pulse transmission time sequence and other related parameters. The invention can realize the nondestructive continuous measurement of the blood pressure and the blood pressure change rate for a long time, is suitable for middle-aged and elderly people with cardiovascular diseases, brings great convenience for the measurement of the blood pressure change rate, and provides useful information for medical treatment and health care.

Description

How to measure the rate of change in blood pressure

technical field

The present invention relates to a method for measuring blood pressure, in particular to a method for measuring the change rate of blood pressure corresponding to each or multiple consecutive heart beats.

Background technique

Measuring blood pressure is a basic method for understanding health conditions and observing conditions, especially necessary for middle-aged and elderly people suffering from cardiovascular diseases. Blood pressure tends to fluctuate greatly in a day or even in a certain period of time, so it is difficult to provide accurate and reliable data and enough useful information with a single or a small amount of measurement, let alone calculate the blood pressure corresponding to the heartbeat. various rates of change. Specifically, each heartbeat will generate a corresponding blood pressure value, that is to say, the blood pressure value actually changes continuously like the heart rate and corresponds to one of them, so the continuously measured blood pressure value can be called the heart rate. The blood pressure value sequence corresponding to the beat, and the rate of change of the sequence can be calculated to obtain the rate of change of the blood pressure corresponding to each heart beat.

Continuous measurement of blood pressure for a long period of time and calculation of the continuous change rate of blood pressure corresponding to each heartbeat within a certain period of time is very necessary for monitoring some physiological state changes of the human body, such as illness, pathology, emotional state, etc. Especially for some people whose physiological status changes frequently, such as athletes and people who are busy with work.

Blood pressure measurement is mainly divided into two categories: invasive measurement and non-destructive measurement. Invasive measurement is a direct measurement method in which a catheter is inserted into the artery and the arterial pressure is measured through a transducer connected to a fluid column. This method needs to be operated by professional medical personnel, which is expensive and likely to cause medical risks such as bacterial infection and blood loss. It is not suitable for daily measurement and health care, and it is impossible to perform continuous blood pressure measurement and calculation of the continuous rate of change of blood pressure.

Nondestructive measurement is an indirect method of measurement using mainly three types of equipment: pulse sphygmomanometers, tone-determining sphygmomanometers, and pulse wave transit time-based sphygmomanometers.

There are two measurement methods of pulse sphygmomanometer: auscultation method and oscillation method. The principle of auscultation is to collect Korotkoff sounds, and the whole device includes a cuff that can be inflated and deflated, a mercury manometer (electronic pressure sensors are also used in recent years) and a stethoscope. When measuring upper extremity blood pressure, exhaust the air in the cuff first, then wrap the cuff around the upper arm flat and without folds, feel the pulse of the brachial artery, and place the chest piece of the stethoscope there. Turn on the mercury column switch, when the cuff is inflated by the balloon holding the live valve, the mercury column or the watch hands will move immediately, and when the mercury column rises to the default value, the inflation will stop. Then, slightly open the balloon valve to deflate slowly, and the mercury column will slowly descend (the hands rotate). At this time, the scale of the mercury column or the movement of the hands should be observed. It is systolic blood pressure, referred to as systolic blood pressure; when the mercury column drops to the point where the sound suddenly becomes weak or inaudible, the scale indicates diastolic blood pressure, referred to as diastolic blood pressure. However, this method can only determine systolic and diastolic blood pressure and is not suitable for some patients with weak or inaudible 5th Korotkoff sound.

The oscillation method can make up for the above-mentioned shortcomings of the auscultation method to a certain extent, and blood pressure can also be measured for patients with weak Korotkoff sounds. When in use, wrap the cuff around the upper arm flat and without pleats, and inflate and deflate the cuff. Blood pressure values are determined by measuring the amplitude of pressure oscillations in the inflated cuff, which are caused by the constriction and dilation of arterial vessels. Values for systolic, mean and diastolic pressure can be obtained from monitoring the pressure in the cuff as the cuff is slowly deflated. The mean pressure corresponds to the pressure in the attenuation means of the cuff at the moment of the peak of the envelope. Systolic blood pressure is usually estimated as the pressure in the attenuating means of the cuff corresponding to a moment before the peak of the envelope corresponding to a time when the magnitude of the envelope is equal to a certain proportion of the peak magnitude. Diastolic pressure is typically estimated as the pressure in the cuff's attenuating means at a time after the peak of the envelope that corresponds to a time when the magnitude of the envelope is equal to a certain proportion of the peak magnitude. Using different scale values will affect the accuracy of blood pressure measurement.

Most of the products currently on the market use auscultation or oscillation. However, since these two methods both need to inflate and deflate the cuff, it is difficult to achieve frequent measurement, let alone continuous measurement. Also, the frequency of measurements using a cuff is limited by the time required to inflate the cuff and deflate the cuff while taking a measurement. Usually, a complete blood pressure measurement takes about 1 minute. In addition, the size of the cuff will also affect the blood pressure measurement results. Combining the above factors, it is impossible to continuously measure multiple blood pressure values using the traditional auscultation or oscillation method, and it is impossible to measure the blood pressure value sequence corresponding to each heart beat, so it is also impossible to calculate the blood pressure value corresponding to each heart beat. The corresponding continuous rate of change of blood pressure within a certain period of time.

The basic principle of the tone measuring sphygmomanometer is: when the blood vessel is oppressed by external objects, the circumferential stress of the blood vessel wall is eliminated, and the internal pressure and external pressure of the blood vessel wall are equal at this time. By applying pressure to the artery, the artery is flattened. The pressure keeping the artery flattened is recorded. This pressure is measured by an array of pressure sensors placed on the surface arteries, from which the patient's blood pressure is calculated. However, the disadvantage of this method is that the cost of the sensor used is relatively high, and its measurement accuracy is easily affected by the measurement position, so it is not popular in the market. Obviously, it is impossible to continuously measure multiple blood pressure values by using this method, so it is also impossible to calculate the continuous change trend of blood pressure within a certain period of time.

Blood pressure monitors based on pulse wave transit time determine blood pressure based on the relationship between arterial blood pressure and pulse wave transit velocity. When the blood pressure rises, the blood vessels dilate and the pulse wave transmission speed increases. On the contrary, the pulse wave transmission speed slows down. For details, please refer to the following literature:

1) Messers.J.C.Bramwell and A.V.Hill, "The Velocity of the Pulse Wave in Man", Proceedings of the Royal Society, London, pp. 298- 306 pages, 1922;

2) B. Gribbin, A. Steptoe, and P. Sleight, "Pulse Wave Velocity as a Measure of Blood Pressure Change", "Psychophysiology", Vol. 13, No. 1 , pp. 86-90 (Psychophysiology, vol.13, no.1), 1976.

This type of sphygmomanometer collects photoplethysmographic signals and electrocardiographic signals from photoelectric sensors arranged at fingertips or other peripheral tissue positions during use. This method can provide a simple and easy-to-use blood pressure measuring device, and compared with the traditional cuff-type blood pressure monitor, it has the advantages of low development cost (the cost can be reduced by more than half), small size (about a hundred times reduction), and energy consumption. It has the advantages of less electricity (it can be reduced by about hundreds of times), and it can realize long-term continuous measurement of arterial blood pressure. Before the sphygmomanometer using this method measures blood pressure, it must be calibrated with a standard sphygmomanometer, that is, to find the relationship between upper arm blood pressure and pulse wave transit time. Then multiple blood pressure values can be continuously measured according to the determined relationship between the blood pressure and the pulse wave transit time. Therefore, the blood pressure measurement method based on pulse wave transit time can realize continuous blood pressure measurement within a certain period of time. However, due to the method of utilizing electrocardiographic signals, the signals need to be collected simultaneously on two fingers (or other parts). This still brings some inconvenience to the measurement, and it is also difficult to realize long-term continuous measurement in the real sense.

The method of measuring blood pressure based on the characteristic parameters of the photoplethysmography signal only needs to collect the signal from one finger (or other parts), so it can provide great convenience for the measurement, so as to truly realize long-term non-destructive continuous measurement. But so far, there is no technology that uses this measurement method to specifically determine the blood pressure corresponding to one or several heart beats or the continuous rate of change of blood pressure. It should be noted that the blood pressure corresponding to several heart beats referred to in this specification refers to the average value of several blood pressures corresponding to several heart beats. Therefore, the continuous measurement of blood pressure and its rate of change corresponding to each or several heart beats is still a blank.

Contents of the invention

The purpose of the present invention is to provide a method for obtaining the continuous rate of change (including absolute rate of change and relative rate of change) of blood pressure corresponding to each or every several heart beats in any period of time by continuous blood pressure measurement, thereby providing Medical and healthcare provides new and useful information.

To achieve the above object, the present invention provides a method for measuring blood pressure parameters corresponding to one or more heart beats, comprising the following steps: a) collecting signals related to pulse waves from the human body; b) collecting signals from the collected signals Obtaining the characteristic parameters in the process to obtain the corresponding characteristic parameter sequence; c) determining the blood pressure parameter corresponding to each or multiple heart beats according to the determined characteristic parameter sequence of the signal.

In the above method, the blood pressure parameters may include: blood pressure value, continuous rate of change of blood pressure, rate of change of instantaneous blood pressure, and rate of change of multiple blood pressure values corresponding to each (or several) heart beats.

Wherein, the continuous change rate of blood pressure refers to the change rate of the measured continuous blood pressure value. The continuous blood pressure value refers to the sequence of blood pressure values corresponding to each or several heart beats obtained by continuous measurement within a certain period of time. The sequence obtained by measuring a blood pressure value at intervals is called a discontinuously measured blood pressure value. What is mainly solved in the present invention is the determination of the continuous rate of change of blood pressure.

The algorithm of the continuous rate of change of blood pressure may include the absolute rate of change of blood pressure and/or the relative rate of change of blood pressure. The calculation method of the absolute rate of change of blood pressure may include time-domain and frequency-domain methods.

When using the time-domain approach, one of the following methods can be used to determine the rate of change of blood pressure:

Assume that T={t ₁ , t ₂ , t ₃ ,...t _n } ^T represents the sequence of blood pressure values, t represents the average value of sequence T, T ₁ ={t ₁ ′, t ₂ ′, t ₃ ′,... t _n-1 ′} ^T = {t ₂ −t ₁ , t ₃ −t ₂ , t ₄ −t ₃ , ... t _n −t _n-1 }, t′ represents the average value of sequence T ₁ . )

(序列T的标准方差)

(standard deviation of sequence T)

(序列T₁的标准方差)

(standard deviation of sequence T ₁ )

The frequency domain method is to perform Fourier transform (or other transformation from time domain to frequency domain) on the sequence T to obtain the frequency spectrum of the sequence T.

The calculation method of the relative rate of change of blood pressure can be expressed as: (±absolute rate of change of blood pressure÷average value of blood pressure)×100%.

The instantaneous blood pressure rate of change is the slope of any point on the continuous waveform reflecting the change of blood pressure with time, that is, dP/dt, where P represents the instantaneous blood pressure value. The continuous waveform of blood pressure over time can be obtained by extracting and estimating characteristic parameters from signals related to pulse wave generation and transmission characteristics. The algorithm of the instantaneous blood pressure change rate may include the instantaneous blood pressure relative change rate (dP/dt/P) and the instantaneous blood pressure absolute change rate (|dP/dt|).

The rate of change of the blood pressure value corresponding to each (or several) heart beats refers to the variation between two consecutive blood pressure values corresponding to each (or several) heart beats. It can be a relative rate of change in blood pressure or an absolute rate of change in blood pressure, depending on the calculation method used. For example, if the method of dividing the difference between the two blood pressure values by the average value of the two blood pressure values and multiplying by 100%, the instantaneous rate of change is the relative rate of change; If the absolute difference is divided by the time interval between two blood pressure values, then the instantaneous rate of change is the absolute rate of change.

Therefore, in the present invention, the continuous change rate of blood pressure, the instantaneous change rate of blood pressure and the change rate of blood pressure corresponding to each (or several) heart beats are three parallel concepts. The relative change rate of blood pressure and the absolute change rate of blood pressure refer to specific calculation methods of the change rate.

In addition, the pulse wave is a fluctuating signal generated by the contraction and expansion of the heart, or a signal related to blood flow caused by the beating of the heart.

In a preferred embodiment of the present invention, the measurement of the pulse wave adopts photoplethysmography, that is, photoplethysmography signals and electrocardiographic signals are collected from the peripheral tissues of the human body by photoelectric sensors. According to the collected photoplethysmography signal, determine the start point and corresponding vertex of each waveform, and intercept a certain section between the start point and the vertex as one of the characteristic parameters of the photoplethysmography signal, which can be called the FY interval. The FY distance section can take the entire period from the starting point to the apex, or take a part of it. For example, the period from the start point to 90% of the apex, the period from the start point to 80% of the apex, etc., and so on.

In the above scheme, the relationship between FY distance and blood pressure can be determined as follows: blood pressure=m·FY ⁿ +c, n≠0, where FY represents the FY distance, and m and c represent the different measured subjects. The calibration coefficient obtained by calibrating the standard sphygmomanometer indicates the relationship coefficient between the upper arm blood pressure and the FY distance. When calibrating, change the contact pressure between the sensor and the measured position of the body appropriately, and choose to complete the calibration under different contact pressure values.

In addition, when the accuracy of blood pressure measurement needs to be further improved, the blood pressure value can be calculated according to the determined FY interval sequence, combined with the pulse wave transit time, and another characteristic parameter YG interval of the photoplethysmography signal. The calculation formula is: blood pressure=m·FY ⁿ +a/PTT ² +b·YG+d, n≠0, where a∈[0,m/2], b∈[0,m/5].

Said step a) may include: determining the corresponding waveform feature point positions of a series of signals related to pulse wave generation and transmission time collected; The transit time of one or several pulse waves corresponding to a heart beat.

In the above method, for the photoplethysmography signal, the waveform feature point is the peak and/or bottom point of the waveform; for the ECG signal, the waveform feature point is the R wave peak and/or the R wave rise Onset and/or end of R wave, and any characteristic point on Q, S, and T waves. In this case, the pulse wave transmission time series can be obtained by using the time difference between the peak time of the ECG signal or the bottom point of the photoplethysmography signal or the time difference between the peak time of the ECG signal or the peak point of the photoplethysmography signal.

The present invention may further include obtaining the continuous change rate of the blood pressure according to the blood pressure value sequence corresponding to each or several heart beats, and by a certain method reflecting the change trend of the numerical sequence. The specific method may be one of the time-domain or frequency-domain methods for determining the rate of change described above.

In another preferred solution of the present invention, the step of determining the relative continuous rate of change of blood pressure may be by using the relationship between FY distance, YG distance, blood volume and blood pressure, which corresponds to one or several heart beats. The relative change trend of the FY interval sequence and the relative change trend of the YG interval reflect the relative change trend of the blood pressure value sequence corresponding to one or several heart beats. That is, the relative percentages of fluctuations in one or several FY intervals and the relative percentages of changes in YG intervals and blood volume within a certain period of time can be used to reflect the relative percentages of the corresponding fluctuations in blood pressure values to reflect the fluctuations in blood pressure within a certain period of time. relative trends.

The blood volume can be obtained by using the area of the waveform of the photoplethysmography signal (including the area of the rising edge of the waveform, the area of the falling edge of the waveform and the area of the entire waveform).

The relationship between the FY interval, YG interval, blood volume and blood pressure is: blood pressure=m·FY ⁿ +a·YG+b·SV+c, n≠0, wherein m and c represent the The calibration coefficient obtained by calibrating it with a standard sphygmomanometer means the relationship coefficient between upper arm blood pressure and FY distance, YG distance and blood volume. FY represents FY distance, YG represents YG distance, and SV represents blood volume. , a, b, m are constants and a∈[0, m/2], b∈[0, m/5].

When the rate of change of the heart rate within a specified period is less than a certain threshold, the calculation of the blood pressure can also ignore the influence of the heart rate. At this time, a=0 can be set.

According to yet another embodiment of the present invention, the method for directly determining the continuous rate of change of blood pressure may include: determining the rate of change of FY interval, the rate of change of YG interval, and the rate of change of blood volume; according to the determined rate of change of FY interval, the change rate of YG interval rate and the rate of change of blood volume, and based on the relationship between blood pressure and these parameters, determine the continuous rate of change of blood pressure corresponding to one or more heart beats.

Using the time domain method or the frequency domain method to determine the FY interval change rate FYV, the pulse wave transit time change rate PTTV, the YG interval change rate YGV, or the blood volume change rate VR, where

The time domain method is to determine FYV using any of the following equations:

Let T={t ₁ , t ₂ , t ₃ ,...t _n } ^T represents FY interval sequence, pulse wave transmission time sequence, YG interval sequence, or blood volume sequence, t represents the average value of sequence T, T ₁ = {t ₁ ′, t ₂ ′, t ₃ ′, ... t _n-1 ′} ^T = {t ₂ -t ₁ , t ₃ -t ₂ , t ₄ -t ₃ , ... t _n -t _{n- 1} }, t′ represents the average value of the sequence T ₁ .

1) FYV, PTTV, YGV or $\mathrm{VR}=\sqrt{\frac{1}{\mathrm{no}-1}\underset{i=1}{\overset{\mathrm{no}}{\∑}}{(t_i-\stackrel{\‾}{t})}^2},$

2) FYV, PTTV, YGV or $\mathrm{VR}=\sqrt{\frac{1}{\mathrm{no}-2}\underset{i=1}{\overset{\mathrm{no}-2}{\∑}}{(t_{i+1}^{\′}-t_i^{\′})}^2}$

3) FYV, PTTV, YGV or $\mathrm{VR}=\sqrt{\frac{1}{\mathrm{no}-2}\underset{i=1}{\overset{\mathrm{no}-1}{\∑}}{(t_i^{\′}-\stackrel{\‾}{t^{\′}})}^2}$

The frequency domain method is: performing Fourier transform or other time domain to frequency domain transformation on the sequence T to obtain the frequency spectrum of the sequence T.

In the above method of the present invention, the frequency domain method may further include: finding extremely low-frequency changes in the continuously changing frequency spectrum of the obtained sequence T (for example, blood pressure value sequence, and its corresponding frequency spectrum is called blood pressure spectrum). rate, low frequency rate of change, and high frequency rate of change, and determine physiological conditions corresponding to the extremely low frequency rate of change, low frequency rate of change, and high frequency rate of change of the blood pressure spectrum, respectively.

Among them, the extremely low-frequency change rate, low-frequency change rate and high-frequency change rate of the blood pressure spectrum are defined using the area method, that is, the area of each frequency component is compared to the total area of the spectrum to determine the change of each frequency component, thereby reflecting the relevant physiological state The change.

In addition, the method of defining the ultra-low frequency change rate, extremely low-frequency change rate, low-frequency change rate and high-frequency change rate of the blood pressure spectrum is as follows:

Ultra-low frequency change rate: area of blood pressure spectrum within the range of 0-0.003Hz/total area of blood pressure spectrum;

Very low frequency change rate: within the range of 0.003 ~ 0.04Hz blood pressure spectrum area / total area of blood pressure spectrum;

Low frequency change rate: area of blood pressure spectrum in the range of 0.04～0.15Hz/total area of blood pressure spectrum;

High-frequency change rate: area of blood pressure spectrum within the range of 0.15 to 0.4 Hz/total area of blood pressure spectrum.

In addition, in all the related methods mentioned above, the pulse wave transit time (PTT) can be used instead of the FY interval to estimate the blood pressure or the rate of change of blood pressure.

The present invention can be used to carry out long-term continuous blood pressure measurement for middle-aged and elderly people suffering from cardiovascular diseases, and some people whose physiological status changes frequently, such as athletes and busy people, and then obtain the blood pressure of each blood pressure within the time period. The continuous change rate of blood pressure corresponding to the heartbeat reflects the changes in the physiological state or emotional state of the human body, and even reveals some state changes that are difficult to detect, thus providing sufficient useful information for medical and health care.

Brief description of the drawings

The following describes the specific embodiments of the present invention in conjunction with the accompanying drawings. Through these descriptions, the above-mentioned objectives, advantages and features of the present invention will become more clear. The attached drawings include:

Fig. 1 is used to illustrate the flow chart of the measuring method of continuous rate of change of blood pressure;

Figure 2 is a flow chart for illustrating the determination of the rate of change of blood pressure;

Figure 3 is used to illustrate how to use the electrocardiographic signal and the photoplethysmography signal to define the FY interval, the pulse wave transit time, and each feature point on the photoplethysmography signal;

Figure 4 is used to illustrate the fluctuation of the pulse wave transit time in a relatively short period of time;

Figure 5 is used to illustrate the fluctuation of blood pressure in a day;

Figure 6 is used to illustrate the fluctuation of the blood pressure value corresponding to each heart beat in a short period of time;

Figure 7 is used to illustrate the fluctuation of the blood pressure value corresponding to every five heart beats in a short period of time;

FIG. 8 is a frequency spectrum for illustrating a blood pressure value corresponding to each heartbeat in a short period of time;

Figure 9(a) is used to illustrate the fluctuation of the FY interval corresponding to each heart beat in the photoplethysmography signal in a short period of time, and Figure 9(b) is the corresponding frequency spectrum;

Fig. 10 shows the specific definition of each feature pitch and amplitude on the photoplethysmography signal;

Fig. 11 is a graph for illustrating the comparison of the blood pressure value estimated with the FY interval and the true value (n=2).

Detailed ways

Fig. 1 is a flowchart of a method for measuring the continuous rate of change of blood pressure according to an embodiment of the present invention. As shown in Figure 1, in this embodiment of the present invention, it mainly includes the step 101 of collecting signals from the human body, the step 102 of signal preprocessing, the step 103 of determining the corresponding waveform feature points in the signal, determining the FY distance, pulse wave transmission Time and YG interval sequence step 104, step 105 of determining FY interval change rate (FYV), pulse wave transit time change rate (PTTV), heart rate change rate (HRV), and blood volume change rate (VR), based on the determined Parameters such as FYV, PTTV, HRV and VR directly calculate the step 106 of the blood pressure change rate (BPV), the step 107 of calculating the relative change rate of blood pressure, the step 108 of calculating the blood pressure with the FY interval (or in combination with other parameters), and from the sequence of blood pressure values Step 109 of calculating the rate of change of blood pressure.

Each step is described in detail below.

●Step 101: Signal acquisition

This step 101 includes using certain sensors to collect signals related to pulse waves, such as electrocardiographic signals or photoelectric The plethysmographic signal, thereby determining characteristic parameters related to the pulse wave, such as the pulse wave transit time. The time for signal acquisition can be determined according to needs. The technical content of this signal acquisition method can be found in:

1) "Variability of photoplethysmography peripheral pulse measurements at the ears, thumbs and toes" by Allen, J. and Murray, A., published in IEEE Proceedings of Science, Measurement and Technology (IEEE Science, Measurement and Technology Transactions), Vol. 147, Pages 403-407, 2000;

2) "Comparison of regional variability inmulti-site photoplethysmographic pulse wave characteristics" by Allen, J. and Murray, A., published in First International Conference on Advances in Medical Signal and Information Processing (The First International Conference on Advances in Medical Signal and Information Processing, pp. 26-31, 2000;

3) "Noninvasive and cuffless measurements of blood pressure for telemedicine" by Chan, K.W., Hung, K., Zhang, Y.T., published in Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society), Volume 4, Pages 3592-3593, 2001. etc.

●Step 102: Signal preprocessing

This step 102 includes performing preprocessing such as noise removal and smoothing on the series of signals collected in step 101 related to the pulse wave transit time. Of course, whether to perform preprocessing depends on the quality of the collected signal and the function of related hardware. Among them, the noise removal mainly adopts methods such as filtering the signal, and the smoothing process can adopt, for example, subdividing the signal into several small segments, and replacing the value of each point in each small segment with the average value of the segment. These signal preprocessing methods can all use existing technologies, which will not be repeated here.

●Step 103: Determine the corresponding waveform feature points in the signal

This step 103 is used to determine the FY interval interception method of the photoplethysmography signal, and the corresponding waveform feature point positions among a series of signals related to the pulse wave transit time. Specifically, the physiological significance corresponding to certain points of the signal can be used to decide whether to use this point to calculate the pulse wave transit time, as shown in FIG. 3 . Parameters such as the corresponding FY interval, YG interval and pulse wave transmission time can be defined. For example, the interception method of the FY interval segment includes: the entire period from the start point to the apex, the period from the start point to 90% of the apex, the period from the start point to 80% of the apex, etc. and so on. Calculation method of pulse wave transit time: For the photoplethysmography signal, the waveform feature points may include the apex, bottom point and any point between these two points. For ECG signals, the waveform feature points can include R wave top, R wave start point, R wave end point, and any other feature points on R wave, as well as any feature points on Q wave, S wave, and T wave .

●Step 104: Determine FY spacing, pulse wave transit time and YG spacing sequence

In this step 104, each FY interval, YG interval and pulse wave transit time are calculated according to the respective waveform characteristic points of the signal determined in step 103 by a predetermined method.

Figure 3 illustrates how to determine the characteristic points F, Y, G, etc. of the photoplethysmographic signal in the signal and the corresponding pulse wave waveform characteristic points, and use the determined waveform characteristic points to calculate the FY interval, YG interval and pulse wave transit time . It utilizes electrocardiographic signals and photoplethysmographic signals to define the pulse wave transit time. As shown in Figure 3(a), time 301 represents the position of the R-wave apex on the ECG signal on the time axis, and time 302 and time 303 respectively represent a bottom point and a vertex on the photoplethysmography signal on the time axis s position. These time values can be used to determine the pulse wave transit time in different ways. One method of determination is to calculate the time difference between time 301 and time 302 to obtain the pulse wave transmission time Ts 304. Another determination method is to calculate the time difference between the time 301 and the time 303 to obtain the pulse wave transit time Td 305.

Since Td 304 or Td 305 is calculated through the characteristic points of different photoplethysmographic signals, the information they convey is different physiologically and numerically. Each characteristic point of the photoplethysmography signal is defined as follows: 1) F309: the starting point of the rapid rise of the waveform amplitude (or the turning point of the waveform amplitude from falling to rapidly rising); 2) Y310: the highest point of the waveform amplitude; 3 ) W311: the first turning point of the falling edge of the waveform (for signals without this turning point, point W is defined as the point on the falling edge of the waveform reaching 50% of the highest amplitude of the waveform); 4) G312: the first turning point on the falling edge of the waveform A minimum amplitude point, as shown in G313 in Figure 3(b); or a point on the falling edge of the waveform that reaches 1% of the highest waveform amplitude, as shown in G312 in Figure 3(b); or and F The point where the points overlap is shown as G(F) 314 in Fig. 3(b) (different definitions depend on different signals). The FY interval is defined by the photoplethysmography signal, as shown in Figure 3 (a), the interception method of the FY interval section includes: the entire period of time FY307 from the starting point to the apex, and can also include 50% from the starting point to the apex This period of time FY308 and so on, and so on.

The pulse wave transmission time series described by Td 305 or Td 306 can be obtained through multiple calculations, as well as the FY interval and YG interval determined by F309, Y310 and G312.

At this time, if the calculation of the relative rate of change of blood pressure is not performed, proceed to step 105 to determine FYV, PTTV, HRV and VR, and then determine BPV; otherwise, calculate the relative rate of change of blood pressure (step 107).

● Step 105: Determine FYV, PTTV, YGV and VR

This step 105 is used to calculate the rate of change of FY interval (FYV), the rate of change (PTTV) of pulse wave transit time, the rate of change of YG interval (YGV) and the relationship between the rate of change of YG interval (YGV) and blood volume using certain time-domain and frequency-domain rate-of-change analysis methods. Relative Rate of Change (VR). For example, the specific method could be:

When the frequency domain method is used, let T={t ₁ , t ₂ , t ₃ ,...t _n } ^T represents the FY interval sequence, or the pulse wave transmission time, or the YG interval, and t represents the average value of the sequence T, then The corresponding rate of change FYV, PTTV or YGV can be calculated using any of the following equations.

1) FYV, PTTV or $\mathrm{YGV}=\sqrt{\frac{1}{\mathrm{no}-1}\underset{i=1}{\overset{\mathrm{no}}{\∑}}{(t_i-\stackrel{\‾}{t})}^2}$ (standard deviation of sequence T)

In addition, it is assumed that T ₁ ={t ₁ ′, t ₂ ′, t ₃ ′, ... t _n-1 ′} ^T = {t ₂ -t ₁ , t ₃ -t ₂ , t ₄ -t ₃ , ... t _n -t _n-1 }, t' represents the average value of sequence T ₁ . Then the above rate of change can also be obtained by the following formula:

2) FYV, PTTV or $\mathrm{YGV}=\sqrt{\frac{1}{\mathrm{no}-2}\underset{i=1}{\overset{\mathrm{no}-2}{\∑}}{(t_{i+1}^{\′}-t_i^{\′})}^2}$

3) FYV, PTTV or $\mathrm{YGV}=\sqrt{\frac{1}{\mathrm{no}-2}\underset{i=1}{\overset{\mathrm{no}-1}{\∑}}{(t_i^{\′}-\stackrel{\‾}{t^{\′}})}^2}$ (standard deviation of sequence T ₁ )

In addition, a frequency-domain algorithm may also be used to perform Fourier transform (or other time-domain-to-frequency-domain transform) on the sequence T or _T1 above to obtain the frequency spectrum of the sequence T.

Among them, the frequency domain analysis mainly involves several frequency components: extremely low frequency components (including ultra-low frequency components), approximately between 0 and 0.04Hz; low frequency components, approximately between 0.04 and 0.15Hz; and high frequency components, approximately between Between 0.15 and 0.4Hz. The amplitude, area, etc. on the frequency spectrum can be calculated to obtain the corresponding rate of change.

FIG. 4 exemplarily illustrates the situation of the pulse wave transit time change rate PTTV corresponding to the pulse wave transit time sequence corresponding to one or more heart beats. As shown in Figure 4, the length of continuous signal recording is about 5 minutes, so that the pulse wave transmission time series corresponding to each heart beat and the pulse wave transmission time series corresponding to every five heart beats can be obtained.

Although the present invention has no strict limit on the number of heartbeats, if the number is too large, some rapid blood pressure changes cannot be reflected, that is, the high-frequency components of the blood pressure change rate will not be reflected, so the smaller the number of times, the better. good. The length of time for continuous signal recording depends on the time the subject needs to monitor, so that it can reflect changes in the condition of the patient during this period. The length of time for continuous recording is unlimited.

The rate of change 401 and the rate of change 402 in FIG. 4 are respectively the standard deviation of the corresponding pulse wave transmission time series. Figure 4(a) shows the pulse wave transit time corresponding to each heart beat, and Figure 4(b) shows the pulse wave transit time corresponding to every five heart beats, i.e. each value of the sequence is the average of every five values shown in Fig. 4(a). As shown, the pulse wave transmission time series of the examples shown in FIGS. 4(a) and 4(b) have large fluctuations between 0.3 seconds and 0.34 seconds. Let T={t ₁ , t ₂ , t ₃ ,...t _n } ^T represents the pulse wave transmission time series, t represents the average value of the sequence T, the rate of change PTTV 401 and the rate of change PTTV 402 can be calculated by the above formula Either one of 1)-3) is obtained, or the frequency domain analysis method is used to calculate PTTV, that is, Fourier transform (or other time domain to frequency domain transformation) is performed on the sequence T to obtain the frequency spectrum of the sequence T. By analyzing the frequency components, find out the corresponding physiological parameters and the represented physiological conditions.

Among them, the analysis of frequency components mainly includes: observing which frequency bands the signal has significant components through the spectrum, and then calculating the area of the corresponding frequency band or the ratio of the area of the corresponding frequency band to the total area of the spectrum, so as to reflect the The corresponding physiological parameters and the physiological conditions represented. For example, by calculating the area or area ratio of the 0.04-0.15Hz frequency band in the heart rate spectrum, it can reflect the activity of the sympathetic and parasympathetic nerves; and the frequency component of 0.15-0.4Hz can reflect the breathing and parasympathetic activity. Activity.

Similarly, the YG interval change rate YGV (refer to the above method) and the blood volume change rate (VR) can be calculated by reflecting the change trend of the numerical sequence. Its calculation method can still adopt the above-mentioned 1)-3) equation, or adopt the frequency domain analysis method to realize.

In addition, in the present invention, the heart rate signal can be obtained from the electrocardiographic signal or the photoplethysmography signal; and the blood volume sequence can be extracted from the waveform area of the photoplethysmography signal, including the area of the rising edge of the waveform, the area of the falling edge of the waveform and The area of the entire waveform. After the heart rate sequence and the blood volume sequence are obtained, the calculation method for the rate of change may also use the above-mentioned calculation methods in the time domain and frequency domain.

In addition, the calculation of the blood volume change rate (VR) can also be obtained by deriving the waveform area sequence of the photoplethysmography signal.

For example, in the case of calculating the entire area sequence, since the photoplethysmography signal has a relatively regular waveform, each individual waveform can obtain an area value, that is, integrate from the starting point of one waveform to the next waveform The area value of the waveform can be obtained at the starting point of the waveform, so that the sequence of the waveform area can be obtained, the rate of change can be calculated by the above method, and the rate of change of blood volume can be obtained by differentially deriving the area sequence.

● Step 106: Determine the blood pressure rate of change BPV. BPV generally refers to the continuous rate of change of blood pressure, which may include the relative rate of change of blood pressure and the absolute rate of change of blood pressure.

This step 106 uses the FY interval change rate (FYV), YG interval change rate (YGV) obtained in step 105, and the relationship between the blood volume change rate (VR) and BPV to directly calculate the blood pressure absolute change rate BPV . FIG. 2 is a flow chart for explaining the above-mentioned calculation of the rate of change of blood pressure. In step 201 , the rate of change of FY interval (FYV), the rate of change of YG interval (YGV) and the rate of change of blood volume (VR) are calculated according to the method described in step 105 .

The relational formula for calculating BPV can be expressed as BPV=f(FYV, YGV, VR, c) or BPV=f(PTTV, YGV, VR, c), the specific form of f( ) depends on the specific method for determining the rate of change, Based on the relationship between BP and FY or PTT, HR and SV: BP = m FY ⁿ + a YG + b SV + c or BP = m/PTT ² + a YG + b SV + c, n ≠0. Among them, m and c represent the calibration coefficients obtained by calibrating different subjects with standard sphygmomanometers, that is, the relationship coefficients between upper arm blood pressure and FY distance, YG distance and blood volume, FY table formula FY distance , PTT means pulse wave transit time, YG means YG interval, SV means blood volume, a, b, m are constants and a∈[0, m/2], b∈[0, m/5]. And it can be derived according to the specific change rate method. These constants can be determined by calibration, that is, by taking one or several measurements with a traditional standard instrument as a standard.

For example, if BP=m·FY ² +c (where m and c represent the calibration coefficients obtained by calibrating the standard sphygmomanometer for each different subject), then it can be obtained by simple mathematical derivation $\mathrm{BPV}=\sqrt{\frac{m}{\mathrm{no}-1}\underset{i=1}{\overset{\mathrm{no}}{\&Sum;}}{({f{Y}_i}^2-\stackrel{\&OverBar;}{{\mathrm{<figure-callout\; id="2"\; label="FY"\; filenames="A20041004241000301.png,A20041004241000311.png"\; state="\{\{state\}\}">FY</figure-callout>}}^2})}^2}=\sqrt{m}\&CenterDot;f{Y}^{2}V.$ By analogy, when the blood pressure calculation formula includes multiple parameters: FY, YG and SV, the corresponding BPV=f(FYV, YGV, VR, c) can also be obtained.

Further, it may be judged whether the heart rate rate of change HRV (standard deviation) within a specified period of time is greater than a certain threshold Th. The threshold can be determined by calculating the ratio of the standard deviation of the heart rate change to the average heart rate within a specified time period. If the ratio is less than 3%, the influence of the heart rate change rate HRV can be ignored. If yes, then use the above formula to calculate BPV (step 203); otherwise, the calculation of blood pressure rate of change can ignore the impact of heart rate rate of change HRV, this time with formula BPV=f (PTTV, VR, c) to calculate BPV (step 204) .

The relative percentage of the corresponding blood pressure value fluctuation can be reflected by the relative percentage of one or several FY interval fluctuations and the relative change percentage of parameters such as YG interval and blood volume within a certain period of time, so it can be reflected in a certain period of time The relative change trend of blood pressure, rather than reflecting the absolute rate of change of blood pressure values. This is because, since the fluctuation trend of blood pressure values is the linear superposition of the fluctuation trends of parameters such as FY interval, YG interval and blood volume, knowing the fluctuation trend of pulse wave transit time and heart rate can roughly determine the fluctuation trend of blood pressure.

●Step 107: Calculate the relative change rate of blood pressure

This step 107 includes utilizing the relationship between pulse wave transit time and blood pressure (systolic pressure and diastolic pressure) to calculate the relative change rate of blood pressure, and its relational expression can be expressed as:

Blood pressure=m·FY ⁿ +a·YG+b·SV+c or blood pressure=m/PTT ² +a·YG+b·SV+c,

Where n≠0, m and c represent the calibration coefficients obtained by calibrating the standard sphygmomanometers for different subjects, that is, the relationship coefficients between upper arm blood pressure and FY distance, YG distance and blood volume, FY Table formula FY spacing, YG means YG spacing, SV means blood volume, a, b, m are constants and a∈[0, m/2], b∈[0, m/5].

Based on this relational expression, the relative change rate of the blood pressure value sequence corresponding to each (or several) cardiac beats can be reflected by the relative change rate of parameters such as FY interval, YG interval, and blood volume without calibration. That is, the relative percentages of fluctuations in blood pressure values corresponding to them are reflected by the relative percentages of fluctuations in each (or several) FY intervals and the relative percentages of changes in parameters such as YG intervals and blood volume within a certain period of time.

Figure 6 and Figure 7 are used to illustrate the relative fluctuation of blood pressure values. Fig. 6(a) shows the variation of the series of systolic blood pressure values corresponding to each heart beat within five minutes. It can be seen from Fig. 6(a) that even within a short period of 5 minutes, the systolic blood pressure corresponding to each heartbeat fluctuates greatly between 110mmHg and 118mmHg.

It should be noted that what is shown in Figure 6 and Figure 7 is only the fluctuation of blood pressure, that is, the numerical sequence obtained after subtracting the average value from the original sequence. The rate of change 601 is the standard deviation of the series of systolic blood pressure values. Fig. 6(b) shows the variation of the series of diastolic pressure values corresponding to each heart beat within five minutes. It can be seen from Fig. 6(b) that within 5 minutes, the diastolic pressure corresponding to each heart beat fluctuates greatly between 68mmHg and 73mmHg, and the rate of change 602 is the standard deviation of the diastolic pressure value sequence . Assuming BP={P ₁ , P ₂ , P ₃ ,...P _n } ^T represents the sequence of blood pressure values corresponding to each heart beat, P represents the average value of the sequence BP, and both the rate of change 601 and the rate of change 602 can be determined by The following calculation formula is obtained:

Formula 4:

Figure 7 illustrates how the blood pressure value corresponding to every fifth heart beat fluctuates over a short period of time.

Fig. 7(a) shows the variation of the series of systolic blood pressure values corresponding to every five heart beats within five minutes. It can be seen from Fig. 7(a) that the systolic blood pressure corresponding to each heartbeat fluctuates greatly between 110mmHg and 117mmHg, and the change rate 701 is the standard deviation of the systolic blood pressure value sequence. Fig. 7(b) shows the change of the series of diastolic pressure values corresponding to every five heart beats within five minutes. It can be seen from Fig. 7(b) that within 5 minutes, the diastolic pressure corresponding to each heartbeat also fluctuates greatly between 68mmHg and 73mmHg, and the change rate 702 is the standard of the diastolic pressure value sequence variance. The method for calculating the rate of change 701 and the rate of change 702 is as described in Equation 4 above.

- Step 108: Calculate blood pressure using FY interval (or in combination with other parameters)

Blood pressure=m·FY ⁿ +c, n≠0, where m and c represent the calibration coefficients obtained by calibrating different subjects with standard blood pressure monitors, that is, the relationship between upper arm blood pressure and FY distance Coefficient, FY means FY spacing. When calibrating, change the contact pressure between the sensor and the measured position of the body appropriately, and choose to complete the calibration under different contact pressure values.

In addition, when it is necessary to further improve the accuracy of blood pressure measurement, according to the determined FY interval sequence, combined with the pulse wave transit time, and another characteristic parameter YG interval of the photoplethysmography signal (its definition is shown in Figure 10), use It is determined as follows: blood pressure=m·FY ⁿ +a/PTT ² +b·YG+d, where a∈[0,m/2], b∈[0,m/5].

● Step 109: Calculate the rate of change of blood pressure from the sequence of blood pressure values

By using the FY interval (or in combination with other parameters) to measure the blood pressure value sequence corresponding to each (or several) cardiac beats, and the blood pressure value sequence is calculated and calculated by a change rate analysis method in a certain time domain and frequency domain analyze. The method described above can be used to obtain the change trend of the blood pressure within a certain period of time, so as to reflect the change of the corresponding physiological state.

Figure 5 is used to illustrate the absolute change of blood pressure in a day (from about 8:00 am to about 4:00 pm). As shown in Figure 5, the systolic and diastolic blood pressures have significant changes at different times of the day or in different states. The blood pressure 501 when driving to work corresponds to around 9:00 in the morning, at which time and state both systolic and diastolic blood pressures are at relatively low values for the day. The blood pressure 502 during lesson preparation corresponds to around 11 o'clock in the morning. In this time period and in this state, both the systolic blood pressure and the diastolic blood pressure are at relatively high values during the day. The blood pressure 503 when eating out corresponds to around 12:00 noon. In this time period and in this state, the sum of the systolic blood pressure drops to a relatively low value during the day; although the diastolic blood pressure also drops, but the magnitude of the fall is not as high as that of the systolic blood pressure big. The blood pressure 504 during busy work in the office corresponds to around 2:00 p.m. In this time period and in this state, the systolic blood pressure rises to a relatively high value during the day; while the diastolic blood pressure is relatively stable without significant changes. The blood pressure of 505 during class corresponds to around 3:00 p.m. In this time period and in this state, although the systolic blood pressure has dropped compared with the systolic blood pressure when the office is busy working, it is still at a relatively high value in a day; while the diastolic blood pressure is relatively high. Diastolic blood pressure rose during busy work in the office and was also at a relatively high value throughout the day.

Further, the present invention can observe ultra-low frequency, extremely low frequency, low frequency and high frequency components from the spectrum of blood pressure, so the rate of change of each frequency component can be defined, so that it can better reflect the change of the physiological state related to it . The definition method of the frequency change rate mainly includes the area method, etc., that is, the area of each frequency component is compared to the total area of the frequency spectrum to determine the change of each frequency component.

Fig. 8 is used to illustrate the frequency spectrum of the blood pressure value corresponding to each cardiac beat measured in a short period of time according to the method of the present invention. Figure 8(a) shows the spectrum of the systolic blood pressure corresponding to each heart beat, in which there are three more significant frequency components 801, 802 and 803. 801 is an extremely low frequency component (including the ultralow frequency component), about Between 0 and 0.04Hz; 802 is the low frequency component, approximately between 0.04 and 0.15Hz; 803 is the high frequency component, approximately between 0.15 and 0.4Hz. Fig. 8(b) shows the frequency spectrum of the diastolic pressure corresponding to each heart beat, in which there are also three frequency components 804, 805 and 806 that are consistent with the frequency components in (a). These frequency components have important physiological significance and can be associated with sympathetic, parasympathetic, and respiratory movements, respectively.

FIG. 9 is used to illustrate the fluctuation of the FY interval of the photoplethysmography signal in a short period of time, and its corresponding frequency spectrum. Figure 9(a) shows the fluctuation of the FY interval within 1 minute, and the fluctuation range is about ±0.03 seconds. Fig. 9(b) is a spectrum corresponding to the FY spacing sequence shown in Fig. 9(a). From Figure 9(b), two frequency components can be clearly seen: about 0.05Hz and 0.3Hz. These two frequency components can be associated with sympathetic and parasympathetic activity and respiratory motion, respectively. Therefore, the FY interval also contains frequency components similar to heart rate and blood pressure, which can reflect important physiological significance.

Fig. 10 is a specific definition for explaining each feature pitch and amplitude on the photoplethysmography signal, including FY pitch 1001, YW pitch 1002, WG pitch 1003, GF pitch 1004, FG pitch 1007, FY magnitude 1005 and YW magnitude 1006. The definitions of F, Y, W and G are as described in Figure 3. The representation method of the FY interval may also include any segment in the FY interval 1001 .

Fig. 11 is a comparison (n=2) of blood pressure values estimated with FY intervals and real values for illustrating the present invention. The estimation formula can be used: blood pressure=m·FY ² +c, where m and c represent the calibration coefficients obtained by calibrating the standard sphygmomanometer for each different subject, that is, the relationship coefficient between the upper arm blood pressure and the FY distance , FY represents the FY spacing. When calibrating, properly change the pressure between the sensor and the contact end of the body, and choose to calibrate under different pressure values. Figure 11(a) shows the comparison between the estimated systolic blood pressure and the real value. The abscissa indicates 7 measurements under 7 different pressure values, and the ordinate indicates the value of the systolic blood pressure; the average error of the measurement is only -1.8mmHg, while the standard deviation is 2.4mmHg. Figure 11(b) shows the comparison between the estimated diastolic pressure and the real value of the same subject, and the seven different pressure values represented by the abscissa correspond to the respective pressure values in Figure 11(a); The average error of the measurement is only -2.2mmHg, while the standard deviation is 3.3mmHg.

Above, the preferred embodiment of the present invention has been described in detail for the purpose of illustration, but those skilled in the art should realize that under the scope and spirit of the present invention, various improvements, additions and substitutions are all possible, And all within the scope of protection defined by the claims of the present invention.

Claims (21)

1. the method for measurement and the corresponding blood pressure parameter of one or many heartbeat may further comprise the steps:

A. from the human body collection signal relevant with pulse wave;

B. from the signal of being gathered, obtain characteristic parameter, obtain corresponding characteristic parameter sequence;

C. according to the characteristic parameter sequence of determined signal, determine and the corresponding blood pressure parameter of heartbeat at every turn or repeatedly.

2. method according to claim 1 is characterized in that, described blood pressure parameter comprises: pressure value, the continuous rate of change of blood pressure relative change rate and/or blood pressure, instantaneous blood pressure rate, and with the corresponding blood pressure rate of each heartbeat.

3. method according to claim 2, it is characterized in that, the described signal relevant with pulse wave be and the generation of pulse wave and the relevant signal of transmission characteristic, the fluctuation signal that the contraction that comprises heart and expansion are produced, or by the caused signal relevant with blood flow of heartbeat.

4. method according to claim 3 is characterized in that described pulse wave is measured by optical sensor, pressure transducer, sonic transducer, photoelectric sensor, acceleration transducer, displacement transducer or electrode.

5. method according to claim 1 is characterized in that, described step a adopts the photoelectricity volumetric method to gather the photoelectricity plethysmographic signal relevant with the transmission time of pulse wave, and described step b further comprises:

According to the photoelectricity plethysmographic signal that is collected, to determine the wherein starting point and the respective vertices of each waveform, and intercept between described starting point and the summit one section as the FY spacing, this FY spacing is as one of characteristic parameter of described photoelectricity plethysmographic signal,

Wherein said FY spacing comprises: begin to the limit whole period from described starting point, or segment section time wherein.

6. method according to claim 5 is characterized in that, described step c further comprises: according to determined FY spacing, and the relation between described FY spacing and the blood pressure: blood pressure=mFY ⁿ+ c obtains the pressure value sequence, n ≠ 0 wherein, and FY represents the FY spacing, m represents to adopt standard-sphygmomanometer to calibrate resulting calibration factor to each different measured with c.

7. method according to claim 6 is characterized in that described step c further comprises calibration steps, wherein when calibration, changes the contact pressure between pick off and the health measured position, and calibrates under different contact pressure values.

8. method according to claim 5, it is characterized in that described step c further comprises: according to determined FY pitch sequence, the described pulse wave transmission time, and another feature parameter YG spacing of photoelectricity plethysmographic signal, adopt following calculating formula to come the calculating blood pressure value:

Blood pressure=mFY ⁿ+ a/PTT ²+ bYG+d, n ≠ 0 wherein, a ∈ [0, m/2], b ∈ [0, m/5]

Wherein said YG spacing is Y point on the photoelectricity plethysmographic signal waveform and the spacing between the G point, and wherein, the Y point is the summit of photoelectricity plethysmographic signal waveform; The G point is first lowest amplitude point on the waveform trailing edge; Or reach waveform 1% point of high amplitude on the waveform trailing edge; Or and the point that coincides of next starting point.

9. method according to claim 3 is characterized in that, according to determined and the corresponding pressure value sequence of heartbeat each time or several times, determines the continuous rate of change BPV of blood pressure by time domain or frequency domain method, wherein

Described time domain approach is:

If T={t ₁, t ₂, t ₃... t _n} ^TExpression pressure value sequence, t represents the meansigma methods of sequence T, T ₁={ t ₁', t ₂', t ₃' ... t _N-1' T={t ₂-t ₁, t ₃-t ₂, t ₄-t ₃... t _n-t _N-1, t ' expression sequence T ₁Meansigma methods

Method one: $\mathrm{BPV}=\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(t_i-\stackrel{\&OverBar;}{t})}^2}$

Method two: $\mathrm{BPV}=\sqrt{\frac{1}{n-2}\underset{i=1}{\overset{n-2}{\mathrm{\&Sigma;}}}{(t_{i+1}^{\&prime;}-t_i^{\&prime;})}^2}$

Method three: $\mathrm{BPV}=\sqrt{{\frac{1}{n-2}\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}(t_i^{\&prime;}-\stackrel{\&OverBar;}{t^{\&prime;}})}^2}$

Described frequency domain method obtains the frequency spectrum of sequence T for sequence T being carried out the conversion to frequency domain of Fourier transform or other time domain.

10. method according to claim 8, it is characterized in that, further comprise: from the waveform area of described photoelectricity plethysmographic signal, extract relevant information, described relevant information comprises the area of waveform rising edge, the area of waveform trailing edge and the area of whole waveform, determines the blood cubical content.

11. method according to claim 10, it is characterized in that, utilize FY spacing or pulse wave transmission time, relation between YG spacing, blood volume and the blood pressure, according to the relative change rate of the corresponding FY pitch sequence of one or many heartbeat, and YG spacing and the volumetrical relative change rate of blood, determine and the relative change rate of the corresponding pressure value sequence of heartbeat once or several times.

12. method according to claim 11, it is characterized in that, further comprise: utilize the relative percentage of one or more FY spacing fluctuations in certain period, and described YG spacing and the volumetrical relative change rate of blood, determine the relative percentage that corresponding pressure value fluctuates.

13. method according to claim 10 is characterized in that, determines the relation between described FY spacing, YG spacing and the blood pressure: blood pressure=mFY in the following manner ⁿ+ aYG+bSV+c, n ≠ 0, wherein m represents to adopt standard-sphygmomanometer to calibrate resulting calibration factor to each different measured with c, the relation between expression upper arm blood pressure and FY spacing, YG spacing and the blood volume, and FY represents the FY spacing, YG represents the YG spacing, SV represents the blood cubical content, and a, b are constant and a ∈ [0, m/2], b ∈ [0, m/5].

14. method according to claim 13 is characterized in that, when the heart rate rate of change is less than a certain threshold value in set period, ignores the influence of heart rate when determining blood pressure, at this moment a=0.

15. method according to claim 8 is characterized in that, further comprises: utilize time domain approach or frequency domain method to determine FY spacing rate of change FYV, pulse wave transmission time rate of change PTTV, YG spacing rate of change YGV, or blood rate of volumetric change VR, wherein

Described time domain approach is determined FYV for adopting in the following equation each:

If T={t ₁, t ₂, t ₃... t _n} ^TExpression FY pitch sequence, pulse wave transmission time sequence, YG pitch sequence or blood volume sequence, t represents the meansigma methods of sequence T, T ₁={ t ₁', t ₂', t ₃' ... t _N-1' ^T={ t ₂-t ₁, t ₃-t ₂, t ₄-t ₃... t _n-t _N-1, t ' expression sequence T ₁Meansigma methods.

1) FYV, PTTV, YGV or $\mathrm{VR}=\sqrt{\frac{1}{n-1}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(t_i-\stackrel{\&OverBar;}{t})}^2},$

2) FYV, PTTV, YGV or $\mathrm{VR}=\sqrt{\frac{1}{n-2}{\underset{i=1}{\overset{n-2}{\mathrm{\&Sigma;}}}(t_{i+1}^{\&prime;}-t_i^{\&prime;})}^2}$

3) FYV, PTTV, YGV or $\mathrm{VR}=\sqrt{\frac{1}{n-2}\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}{(t_i^{\&prime;}-\stackrel{\&OverBar;}{t^{\&prime;}})}^2}$

Described frequency domain method is: described sequence T is carried out the conversion to frequency domain of Fourier transform or other time domain, obtain the frequency spectrum of sequence T.

16. method according to claim 15, it is characterized in that, further comprise and utilize following relational expression BPV=f (FYV, YGV, VR c) directly determines blood pressure rate BPV, wherein the concrete form of f () depends on described each parameter rate of change FYV, YGV, the concrete account form of VR, c represents to adopt standard-sphygmomanometer that it is calibrated resulting calibration factor to each different measured.

17. method according to claim 9, it is characterized in that, further comprise the extremely low frequency rate of change, low frequency variations rate and the high frequency rate of change that adopt area-method to determine the blood pressure frequency spectrum, wherein said area-method is the area of each frequency content to be determined the variation of each frequency content with respect to the gross area of described blood pressure frequency spectrum.

18. method according to claim 17, the frequency component of wherein said blood pressure frequency spectrum comprises: the intrasonic component, and its frequency range is between 0～0.003Hz; The extremely low frequency component, its frequency range is between 0.003～0.04Hz; Low-frequency component, its frequency range is between 0.04～0.15Hz; And radio-frequency component, its frequency range is between 0.15～0.4Hz, and the method for the intrasonic rate of change of described definite blood pressure frequency spectrum, extremely low frequency rate of change, low frequency variations rate and high frequency rate of change is:

Intrasonic rate of change: the gross area of the area/blood pressure frequency spectrum of blood pressure frequency spectrum in 0～0.003Hz scope;

Extremely low frequency rate of change: the gross area of blood pressure frequency spectrum area in 0.003～0.04Hz scope/blood pressure frequency spectrum;

Low frequency variations rate: the gross area of the area/blood pressure frequency spectrum of blood pressure frequency spectrum in 0.04～0.15Hz scope;

High frequency rate of change: the gross area of the area/blood pressure frequency spectrum of blood pressure frequency spectrum in 0.15～0.4Hz scope.

19. according to claim 5, each described method in 6,8,13,14 is characterized in that, further comprises: in the estimation of carrying out blood pressure or blood pressure rate, substitute described FY spacing with the pulse wave transmission time.

20. method according to claim 19, it is characterized in that, further comprise: definite corresponding wave character point position that produces the signal relevant with pulse wave that collected with the transmission time, with utilize determined wave character point position calculation and one or many heartbeat corresponding pulse wave transmission time sequence

Wherein, for the photoelectricity plethysmographic signal, described wave character point is the summit and/or the end point of waveform;

For electrocardiosignal, described wave character point is R wave crest point and/or R ripple starting point and/or R ripple end of a period point, and the arbitrary characteristics point on Q ripple, S ripple and the T ripple.

21. method according to claim 20, it is characterized in that, utilize the time difference between the point at the bottom of electrocardiosignal summit time or the photoelectricity plethysmographic signal, or the time difference between electrocardiosignal summit time or the photoelectricity plethysmographic signal summit, determine described pulse wave transmission time sequence.

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