CN106580303A - Method for correcting systolic pressure-related pulse wave propagation time - Google Patents

Abstract

The invention belongs to the technical field of arterial blood pressure measurement and provides a method for correcting systolic pressure-related pulse wave propagation time, and the method can provide adaptive correction for the change in systolic pressure-related pulse wave propagation time due to the factors such as blood and liquid transfusion, vasoactive drugs, and surgical intervention under clinical conditions. The change in the systolic pressure-related pulse wave propagation time is corrected herein by: detecting in real time, auricular pulse wave and toe pulse wave in a same cardiac cycle, calculating the systolic pressure-related pulse wave propagation time, and extracting correcting variables according to morphological characteristics of the pulse waves to obtain a correcting matrix; the corrected propagation time is applicable to existing mathematical models to continuously measure the systolic pressure in each cardiac cycle under clinical conditions, and measuring accuracy is high.

Description

Correction method of pulse wave transit time related to systolic blood pressure

technical field

The invention relates to the technical field of arterial blood pressure measurement, in particular to a correction method for pulse wave transit time related to systolic blood pressure.

Background technique

Arterial blood pressure is one of the main indicators to reflect the state of the circulatory system and evaluate organ perfusion, and is an important vital sign parameter for perioperative monitoring. At present, the commonly used blood pressure monitoring methods in the perioperative period can be divided into invasive measurement and noninvasive measurement. Invasive measurement refers to the technology of placing special pipes into the body's circulatory system, converting mechanical potential energy into electronic signals through converters, and displaying blood pressure changes in real time on monitoring equipment. Invasive measurement methods can measure pulse blood pressure continuously and accurately, but the possible dangers and injuries cannot be ignored. The common method of non-invasive measurement is the cuff oscillometric method, which is simple to operate and has been clinically recognized for its accuracy, and is widely used in health checkups and perioperative monitoring. However, the cuff oscillometric method can only measure blood pressure intermittently every 3-5 minutes, and cannot track changes in arterial blood pressure in real time.

For this reason, the medical community has proposed continuous non-invasive pulse blood pressure measurement technology, among which the continuous non-invasive measurement of stroke-per-stroke blood pressure using pulse wave travel time/velocity (PTT/PWV) has gradually become a research hotspot. This measurement method obtains the volume pulse wave (PhotoPlethysmoGraphy PPG) and the electrocardiogram signal (ECG) synchronously through one or more photoelectric sensors and a group of electrocardiographic electrodes, and uses the time difference between PPG and ECG or the time difference between two PPGs to calculate Produce PTT/PWV; explore the functional relationship between PTT/PWV and blood pressure and establish a mathematical model, and use measurable PTT/PWV to estimate blood pressure. Many academic papers have reported the principle of using PTT/PWV for continuous non-invasive measurement of stroke-per-stroke blood pressure, such as Yan Chen, Changyun Wen, Guocai Tao, Min Bi, and Guoqi Li "A Novel Modeling Methodology of the Relationship Between Blood Pressure and Pulse Wave Velocity"; Yan Chen, Changyun Wen, Guocai Tao and Min Bi《Continuous and Noninvasive Measurement of Systolic and Diastolic Blood Pressure by One Mathematical Model with the SameModel Parameters and Two Separate Pulse Wave Velocities》; Younhee Choi, QiaoZhang, Seokbum Ko《Noninvasive cuffless blood pressure using pulsetransit time and Hilbert–Huang transform"; Zheng Y, Poon CC, Yan BP, Lau JY "Pulse Arrival Time Based Cuff-Less and 24-H Wearable Blood Pressure Monitoring and its Diagnostic Value in Hypertension"; Mukkamala R, Hahn JO, Inan OT, Mestha LK, Kim CS, H, Kyal S "Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Theory and Practice". Many patents disclose specific implementation methods or devices for continuous non-invasive measurement of stroke blood pressure using PTT/PWV, such as Chinese patents CN101229058A, CN102811659A, CN1127939C, US patents 5865755, 5857975, 5649543, 9364158 and European patent 0413267.

Existing methods and techniques for measuring blood pressure using PTT/PWV all need to use the traditional cuff oscillometric method to measure one or a set of blood pressure values for initial calibration. The reason for the calibration is that the correlation between PTT/PWV and blood pressure is subject-dependent Yes, that is, there is a definite relationship between each individual's PTT/PWV and blood pressure, and the purpose of calibration is to determine the parameters of the mathematical model that are suitable for the subject.

However, existing methods have certain limitations and can only be applied when the circulatory system is not disturbed by the outside world. Because only under the condition of no interference, the relationship between PTT and blood pressure has a strong regularity for the individual, and it is possible to describe it through a definite function and mathematical model. However, during the perioperative period, under the influence of confounding factors such as fluid therapy, drugs, surgical operations, and temperature, the patient’s circulatory system will experience a series of abnormal changes in PTT. Using the abnormal PTT and the inherent mathematical model to estimate blood pressure will produce large error. Since the relationship between the variable PTT and blood pressure no longer has a definite regularity, even if the mathematical model parameters are frequently calibrated to adapt to the PTT variation, the fundamental problem cannot be solved, and the accuracy and real-time requirements of clinical measurement cannot be met.

Contents of the invention

Aiming at the defects of the prior art, the present invention provides a correction method of pulse wave transit time PTT, which can correct the pulse wave transit time related to systolic blood pressure caused by blood transfusion, vasoactive drugs, surgical intervention and other reasons under clinical conditions. The mutation is adaptively corrected, and the accuracy is high.

A method for correcting pulse wave transit time related to systolic blood pressure, comprising the following steps:

S1) Real-time detection of the pulse wave at the ear under each cardiac cycle and analysis to obtain the following data of the ear pulse wave: the height h _sd of the aortic valve closing point on the ear pulse wave, the systolic time t _s of the ear pulse wave, in milliseconds , the diastolic time t _d of the ear pulse wave, in milliseconds, and the maximum height h _max of the ear pulse wave;

S2) Real-time detection of the pulse wave at the toe under each cardiac cycle and analysis to obtain the following data of the toe pulse wave: the systolic time t _s-toe of the toe pulse wave, in milliseconds, and the diastolic time t _d-toe of the toe pulse wave , the unit is milliseconds, the maximum height of the toe pulse wave h _max-toe , the time t _ch-toe from the start point of the toe pulse wave to the midpoint of the peak, the unit is milliseconds, the time t from the start point of the toe pulse wave to the highest point of the peak _max-toe , in milliseconds; the midpoint of the peak refers to the midpoint of the turning point of the rising edge and the turning point of the falling edge at the peak;

S3) Calculate the pulse wave propagation time T _s related to systolic blood pressure, said T _s refers to the time difference between the aortic valve closing point on the ear pulse wave and the aortic valve closing point on the toe pulse wave; h is the ear pulse wave Or the amplitude of the toe pulse wave in the direction of the vertical axis;

S4) Using the data obtained through steps S1 and S2 in the same cardiac cycle, to calculate and obtain the correction variable in the cardiac cycle;

S5) Calculate and obtain a correction matrix for the cardiac cycle according to the correction variable for the cardiac cycle obtained in step S4;

S6) Continuously obtain correction matrices under multiple cardiac cycles, and correct T _s obtained through step S3;

Preferably, the correction matrix in the step S5 a _i is the i-th correction variable among the correction variables.

Preferably, the step S6 is specifically: acquiring the correction matrix under 8 cardiac cycles continuously. The correction method is: T _sma =T _sm (1-A _m ); where, A _i is the correction matrix in the i-th cardiac cycle, and T _si is the T _s in the i-th cardiac cycle.

Preferably, the _first corrected variable a1 is calculated by the following formula:

If d ₁ ≤k _sd-m-0 ≤d _1-2 , then a ₁ =(d _1-2 -k _sd-m-0 )×0.50;

If k _sd-m-0 <d ₁ , then a ₁ =28×0.50;

If k _sd-m-0 >d _1-2 , then a ₁ =0;

in, d ₁ =76-84, d _1-2 =104-112.

Preferably, the _second correction variable a2 is calculated by the following formula:

If k _sd-m >(d ₂ +(age-14)/15/100), then a ₂ =k _sd-m -(d ₂ +(age-14)/15/100);

If k _sd-m ≤ (d ₂ +(age-14)/15/100), then a ₂ =0;

Among them, if |k _sd-m-0 -k _sd-m-ts |≥40 and (k _sd-m-0 +k _sd-m-ts )/2≥k _sd-m-2 , then k _{sd- m} = 2×k _sd-m-2 -(k _sd-m-0 +k _sd-m-ts )/2, otherwise k _sd-m =k _sd-m-2 ;

age is age, d ₂ =1.17-1.27.

Preferably, the _third correction variable a3 is calculated by the following formula:

If c ₄ <k _dma <c ₅ , then a ₃ =0;

If k _sd-m-0 <d ₆ or k _sd-m-2 >d ₇ , then a ₃ =0;

If k _sd-m-0 ≥d ₆ +0.10 and k _sd-m-2 ≤d ₈ and k _dma ≤c ₄ , then a ₃ =(c ₄ -k _dma )×67/100;

like or Then a ₃ =(c ₄ -k _dma )×50/100;

If k _sd-m-0 ≥d ₆ +0.10 and k _sd-m-2 ≤d ₈ and k _dma ≥c ₅ , then a ₃ =(c ₅ -k _dma )×62/100;

like or Then a ₃ =(c ₅ -k _dma )×45/100;

Among them, if |k _sd-m-0 -k _sd-m-ts |≥40 and (k _sd-m-0 +k _sd-m-ts )/2≥k _sd-m-2 and k _{sd-m -ts} ≥d _3-2 , then ,otherwise

If k _sd-m-ts ≤d _3-2 , then like but like but c ₄ =(d ₄ +(age-14)/8)/100, d ₄ =23-35, c ₅ =(d ₅ +(age-14)/8)/100, d ₅ =27-39, d ₆ =0.97-1.03, d ₇ =1.52-1.58, d ₈ =1.42-1.48, d _3-2 =1.21-1.31, d ₃ =0.02-0.14, age is age.

Preferably, the fourth correction variable a ₄ is calculated by the following formula: if k _st-toe >0.8, then a ₄ =k _st-toe -0.8;

If k _st-toe ≤0.8, then a ₄ =0;

Among them, if t _max-toe ≥ t _ch-toe , then otherwise

Preferably, the _fifth correction variable a5 is calculated by the following formula:

If k _sm-toe <d ₉ , then a ₅ =0;

If k _sm- toe ≥ d ₉ and k _st-toe ≥ 0.8 then a ₅ =k _sm-toe -d ₉ ;

If k _sm-toe ≥ d ₉ and k _st-toe <0.8, then a ₅ =(k _sm-toe -d ₉ )/2;

Among them, d ₉ =0.67～0.73,

Preferably, the _sixth correction variable a6 is calculated by the following formula:

If k _sm-toe-ear <1.0, then a ₆ =0;

When k _sm-toe-ear >1.08, then c ₆ =1.08, at this time, if t _s >220 and k _sd-m-0 >0.88, then a ₆ =c ₆ -1.0, if t _s <160 or k _sd-m-0 <0.80, then a ₆ =(c ₆ -1.0)×0.34, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₆ =(c ₆ -1.0) ×0.67;

When 1.0≤k _sm-toe-ear ≤1.08, then c ₆ =k _sm-toe-ear -1.0, if t _s >220 and k _sd-m-0 >0.88, then a ₆ =c ₆ , if t _s ≤160 or k _sd-m-0 ≤0.80, then a ₆ =c ₆ ×0.34, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₆ =c ₆ ×0.67 ;

in,

Preferably, the seventh correction variable _a7 is calculated by the following formula:

If k _ts-toe-ear <1.0, then a ₇ =0;

When k _ts-toe-ear >1.08, then c ₇ =1.08, at this time, if t _s >220 and k _sd-m-0 >0.88, then a ₇ =c ₇ -1.0, if t _s <160 or k _sd-m-0 <0.80, then a ₇ =(c ₇ -1.0)×0.34, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₇ =(c ₇ -1.0) ×0.67;

When 1.0≤k _ts-toe-ear ≤1.08, then c ₇ =k _ts-toe-ear -1.0, at this time, if t _s >220 and k _sd-m-0 >0.88, then a ₇ =c ₇ , If t _s ≤160 or k _sd-m-0 ≤0.80, then a ₇ =c ₇ ×0.34, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₇ =c ₇ × 0.67;

in,

It can be seen from the above technical solution that the method for correcting the pulse wave transit time related to systolic blood pressure provided by the present invention calculates the pulse wave transit time related to systolic blood pressure by detecting the ear pulse wave and toe pulse wave in the same cardiac cycle in real time , and according to the morphological characteristics of the pulse wave, the correction variable is extracted and the correction matrix is obtained, and the above-mentioned variation of the pulse wave propagation time is adaptively corrected. The corrected propagation time can be used in the existing mathematical model, and continuous, Accurately measures systolic blood pressure every cardiac cycle.

detailed description

Embodiments of the technical solution of the present invention will be described in detail below. The following examples are only used to illustrate the technical solution of the present invention more clearly, so they are only examples, and should not be used to limit the protection scope of the present invention.

Perioperative changes in PTT can be divided into two categories. Type I changes: PTT changes caused by blood pressure changes; Type II changes: PTT and blood pressure asynchronous changes (the direction or amount of change of the two does not conform to the regular function law). For example, PTT will increase when there is mild hypovolemia, but due to the body's own regulation of peripheral resistance, blood pressure may not change much; the use of retractors in thoracoabdominal surgery may seriously affect PTT, but the impact on blood pressure is small; noradrenaline The hormone makes the arterioles strongly contract, and the blood pressure increases obviously, but it has little effect on the average PTT of the whole body.

When a type of change occurs in PTT, its relationship with blood pressure can still be expressed by a definite function, and the change of blood pressure can be estimated by a mathematical model. However, when PTT changes in the second category, using a mathematical model based on the conventional circulatory system to estimate blood pressure will produce large errors. This kind of error is the principle error of using PTT to measure blood pressure, which cannot be solved by initial calibration and regular calibration of mathematical model parameters. The difference of PTT between different individuals and the variation of PTT in the same individual are two different types of problems, which need to be solved by different methods. For this reason, the present invention extracts multiple variables according to the morphological changes of the pulse wave to indirectly identify and self-adaptively correct the various second-type changes of PTT, and overcome the above-mentioned principle errors; The method of continuous non-invasive blood pressure measurement does not need to rely on conventional methods such as cuff oscillometric method for repeated calibration.

The human body position for detecting pulse wave is preferably ears and toes. The pulse wave of these two parts can obtain the physiological and pathological information of the aorta and peripheral arteries, and is representative in the transmission route. The sensor for detecting the pulse signal is preferably an infrared photoplethysmography (PPG). The morphological changes of the ear and toe pulse waves themselves and the relative morphological changes between the two pulse waves provide a wealth of information for identifying the second type of changes in PTT and the changes in the difference in blood pressure between different parts of the body. The present invention collects invasive arterial blood pressure, pulse waveforms of ears and toes, and PTT of a large number of surgical cases for several years for analysis, and extracts multiple variables according to the two pulse waves themselves and relative morphological changes, and studies different variables that are different from PTT. The relationship between the two types of changes, and to define the scope of application of various variables.

In clinical application, in the process of continuously measuring blood pressure using PPT, real-time analysis of pulse waveform and extraction of variables, according to whether the variables fall into the applicable range to determine whether PTT has a second-type change, and according to the nature of the applicable variable to determine the nature and nature of the PTT second-type change If a variable exceeds the applicable range, indicating that there is no corresponding second-type change in PTT, the variable is not applicable; the applicable variables are fused, and the correction amount is calculated to correct the PTT. The corrected PTT/PWV is applicable Accurately calculate blood pressure based on existing mathematical models.

The invention utilizes limited variables to express the most important and basic changing law of the pulse wave shape, and studies the relationship between these laws and PTT. The ordinate of the pulse wave described below is the amplitude h on the plane coordinate, the abscissa is the time t, and the starting point of the pulse wave is the coordinate origin.

Example:

A method for correcting pulse wave transit time related to systolic blood pressure, comprising the following steps:

S1) Real-time detection of the pulse wave at the ear under each cardiac cycle and analysis to obtain the following data of the ear pulse wave: the height h _sd of the aortic valve closing point on the ear pulse wave, that is, the systolic and diastolic phases presented on the ear pulse wave The height of the junction, the systolic time t _s of the ear pulse wave, in milliseconds, the diastolic time t _d of the ear pulse wave, in milliseconds, the maximum height h _max of the ear pulse wave;

S2) Real-time detection of the pulse wave at the toe under each cardiac cycle and analysis to obtain the following data of the toe pulse wave: the systolic time t _s-toe of the toe pulse wave, in milliseconds, and the diastolic time t _d-toe of the toe pulse wave , the unit is milliseconds, the maximum height h _max-toe of the toe pulse wave, the time t _ch-toe from the starting point of the toe pulse wave to the midpoint of the peak, the unit is milliseconds, the time t from the starting point of the toe pulse wave to the highest point of the peak _max-toe , the unit is milliseconds; the midpoint of the peak refers to the midpoint of the turning point of the rising edge and the turning point of the falling edge at the peak; the definition of the midpoint of the peak can refer to the literature YAN CHEN, CHANGYUN WEN, GUOCAI TAO, and MIN BI《 Continuous and Noninvasive Measurement of Systolic and Diastolic Blood Pressure by One Mathematical Model with the SameModel Parameters and Two Separate Pulse Wave Velocities" understanding.

S3) Calculate the pulse wave propagation time T _s related to the systolic blood pressure, its definition can refer to the literature YAN CHEN, CHANGYUN WEN, GUOCAI TAO, and MIN BI "Continuous and Noninvasive Measurement of Systolic and Diastolic Blood Pressure by One Mathematical Model with the SameModel Parameters and Two Separate Pulse Wave Velocities"understanding; h is the amplitude of the ear pulse wave or toe pulse wave in the direction of the longitudinal axis;

S4) Using the data obtained through steps S1 and S2 in the same cardiac cycle, to calculate and obtain the correction variable in the cardiac cycle;

S5) Calculate and obtain a correction matrix for the cardiac cycle according to the correction variable for the cardiac cycle obtained in step S4;

S6) Continuously obtain correction matrices under multiple cardiac cycles, and correct T _s obtained through step S3.

This method can detect the ear pulse wave and toe pulse wave in the same cardiac cycle in real time, calculate the pulse wave propagation time related to the systolic pressure, and extract the correction variables and obtain the correction matrix according to the pulse wave morphological characteristics, and the above pulse wave propagation Time variation is corrected, and the corrected propagation time can be used in existing mathematical models to continuously measure systolic blood pressure every cardiac cycle under clinical conditions.

First correction variable a ₁ :

The correction variables obtained in the step S4 include the first correction variable a ₁ , a ₁ is used to correct the second-type change of the propagation time T _s related to the systolic blood pressure in a hypotensive state, and the applicable range of a ₁ is a ₁ >0, The larger a ₁ is, the lower the blood pressure is indicated.

k _sd-m-0 represents the ratio of h _sd to the average systolic height of the ear pulse wave. In some cases, when the blood pressure is low, the peak of the pulse wave presents a forward-leaning triangle. The h _sd decreased a lot, and the k _sd-m-0 became smaller, indicating that the waveform of the end-systolic period of the aorta decreased a lot, the continuous power to propel the pulse wave propagation was insufficient, and the propagation time was prolonged. Diastolic information in this state is unstable and should not be used. d ₁ =76-84, preferably 80; d _1-2 =104-112, preferably 108.

When the continuous power to propel the pulse wave propagation is insufficient, the propagation time T _s is prolonged, requiring a ₁ correction. That is, if d ₁ ≤k _sd-m-0 ≤d _1-2 , then a ₁ =(d _1-2 -k _sd-m-0 )×0.50;

When the continuous power to propel the pulse wave propagation is seriously insufficient, the propagation time T _s is prolonged a lot, and a ₁ is corrected by taking the upper limit value. That is, if k _sd-m-0 <d ₁ , then a ₁ =28×0.50;

When the continuous power to propel the pulse wave propagation is sufficient, no correction of T _s is required, a ₁ is not applicable. That is, if k _sd-m-0 >d _1-2 , then a ₁ =0.

Second correction variable a ₂ :

The correction variable obtained in the step S4 also includes a second correction variable a ₂ , a ₂ is used for the hypertensive state and the change process from the normal blood pressure state to the hypertensive state, and corrects the pulse wave propagation time T _s related to the systolic blood pressure The applicable range of a ₂ is a ₂ >0, and the larger the a ₂ is, the higher the systolic blood pressure is.

k _sd-m-ts represents the ratio of h _sd to the average height of ear pulse wave diastolic period t _s -2t _s segment, which is used to judge the variation of pulse wave diastolic period. For example, in thoracoabdominal surgery, the upper retractor leads to changes in the force on the aorta, which reduces the diastolic waveform of the ear pulse wave and increases the k _sd-m-ts .

k _sd-m-2 represents the ratio of h _sd to the average height of the 0-2t _s segment of the ear pulse wave, which contains the waveform information of the systolic and partial diastolic phases, and is mainly used for hypertensive states and from normal blood pressure states to hypertensive states Changes in the process, such as endotracheal intubation leading to increased heart rate and blood pressure. During the change from normotensive state to hypertensive state, the peak of the ear pulse wave gradually presents an equilateral triangle or a retroverted triangle, h _sd gradually increases, and k _sd-m-2 gradually increases; in the state of hypertension, The pulse wave of the whole ear presents an equilateral triangle or a retroverted triangle, h _sd rises a lot, and k _sd-m-2 becomes very large; the duration of the triangular top (namely the highest blood pressure) of the above two waveforms is very short, which is consistent with Corresponding to the continuous lack of motivation of the highest blood pressure, the transmission time T _s is relatively prolonged.

If |k _sd-m-0 -k _sd-m-ts |≥40 and (k _sd-m-0 +k _sd-m-ts )/2≥k _sd-m-2 ,

Then k _sd-m =2×k _sd-m-2 -(k _sd-m-0 +k _sd-m-ts )/2,

Otherwise k _sd-m = k _sd-m-2 ;

If the waveform of the ear pulse wave in the diastolic period varies, for example, the force change of the aorta caused by the pulling hook in the thoracic and abdominal surgery, and the shape of the pulse wave in the diastolic period changes significantly, then correct k sd- _m , otherwise k _sd-m = k _sd-m-2 . d ₂ =1.17˜1.27, preferably 1.22.

If k _sd-m >(d ₂ +(age-14)/15/100), where age is age, and age≥14 years old, it indicates that the pulse wave of the whole ear or its peak becomes a regular triangle or a backward triangle, which is consistent with The sustained lack of power corresponding to the highest blood pressure and the relatively prolonged propagation time T _s require a ₂ to correct, then a ₂ =k _sd-m -(d ₂ +(age-14)/15/100).

If k _sd-m ≤(d ₂ +(age-14)/15/100), the peak of the pulse wave is gentle, and the continuous power corresponding to the highest blood pressure is sufficient, and a ₂ is not needed for correction, then let a ₂ =0 .

The third correction variable a ₃ :

The correction variable obtained in the step S4 further includes a third correction variable a ₃ , a ₃ is used to correct T _s when the blood volume changes or the body temperature of the sensor placement site changes.

It is the ratio of the average diastolic height of the ear pulse wave to the maximum height h _max . When the patient fasts and drinks less water before the operation, the blood volume decreases, Decrease, pulse wave propagation time prolongs, when blood transfusion during operation leads to increased blood volume, increases, the propagation time shortens.

If k _sd-m-ts ≤d _3-2 , it indicates that the wave form of the ear pulse wave in the early diastole is elevated and exceeds the normal range, and it needs to be checked Correction is carried out, and the correction result is recorded as

like It can be judged that the ear pulse wave is disturbed, then d ₃ =0.02-0.14, preferably 0.08; d _3-2 =1.21-1.31, preferably 1.26.

is the ratio of the average diastolic height of the toe pulse wave to the maximum height h _max-toe , t _s-toe represents the systolic time recognized on the toe pulse wave, and t _d-toe represents the diastolic time recognized on the toe pulse wave. like but and same function and nature.

The two variables with the same properties of the ear and toe pulse wave are combined, and the average value is taken as the variable for calibrating T _s ; if the waveform of the pulse wave in the diastolic period varies, the k _dma is corrected.

If |k _sd-m-0 -k _sd-m-ts |≥40 and (k _sd-m-0 +k _sd-m-ts )/2≥k _sd-m-2 and k _sd-m-ts ≥d _3-2 ,

but

In the state of normal blood volume and normal body temperature at the place where the sensor is placed, a ₃ is not applicable. That is, if c ₄ <k _dma <c ₅ , then set a ₃ =0. c ₄ =(d ₄ +(age-14)/8)/100, d ₄ =23-35, preferably 29; c ₅ =(d ₅ +(age-14)/8)/100, d ₅ = 27-39, preferably 33.

In states of very low or very high blood pressure, the diastolic information is not stable, a ₃ is not applicable. That is, if k _sd-m-0 <d ₆ or k _sd-m-2 >d ₇ , then set a ₃ =0. d ₆ =0.97-1.03, preferably 1.00; d ₇ =1.52-1.58, preferably 1.55.

In normotensive state, when the blood volume decreases or the body temperature of the place where the sensor is placed decreases, a ₃ takes 67% of the positive value. That is, if k _sd-m-0 ≥d ₆ +0.10 and k _sd-m-2 ≤d ₈ and k _dma ≤c ₄ , then a ₃ =(c ₄ −k _dma )×67/100. d ₈ =1.42˜1.48, preferably 1.45.

In the state of low or high blood pressure, when the blood volume decreases or the body temperature of the place where the sensor is placed drops, a ₃ takes 50% of the value in the state of normal blood pressure. That is if or Then a ₃ =(c ₄ -k _dma )×50/100;

In normotensive state, when the blood volume increases or the body temperature of the place where the sensor is placed rises, a ₃ takes 62% of the negative value. That is, if k _sd-m-0 ≥d ₆ +0.10 and k _sd-m-2 ≤d ₈ and k _dma ≥c ₅ , then a ₃ =(c ₅ -k _dma )×62/100;

In the state of low or high blood pressure, when the blood volume increases or the body temperature of the place where the sensor is placed rises, a ₃ takes 45% of the negative value of the normal blood pressure state. That is if or Then a ₃ =(c ₅ −k _dma )×45/100.

Fourth correction variable a ₄ :

The correction variable obtained in the step S4 also includes a fourth correction variable a ₄ , a ₄ corrects T _s when the peripheral blood vessel dilation leads to lower extremity blood pressure (relative to the radial artery blood pressure), and the applicable range of a ₄ For a ₄ >0, the larger a ₄ indicates that the blood pressure of the lower extremities is lowered more than the blood pressure of the radial artery.

The contraction and expansion of peripheral blood vessels will cause the peak of the toe pulse wave to move back and forth on the time axis. If t _max-toe ≥t _ch-toe , then otherwise k _st-toe is the ratio of the time from the starting point of the toe pulse wave to the peak to the time of systole, and 200 is the adjustment coefficient. When the highest point of the peak moves back beyond the midpoint, that is, when t _max-toe ≥ t _ch-toe , k _st-toe is corrected; when the value of k _st-toe is larger, it indicates that the blood vessels of the toes are dilated and the blood pressure of the lower extremities is lowered. That is, if k _st-toe >0.8, then a ₄ =k _st-toe −0.8. If k _st-toe ≤0.8 and a ₄ is not applicable, set a ₄ =0.

fifth correction variable a ₅ ;

The correction variable obtained in step S4 also includes a _fifth correction variable _a5 , the function and nature of _a5 are the same as those of a4, and it corrects T _s when the blood pressure of the lower extremities decreases relative to the blood pressure of the radial artery.

k _sm-toe is the ratio of the average systolic height of the toe pulse wave to the maximum height h _max-toe ; when k _sm-toe is large, it means that the peak of the toe pulse wave is broad and gentle, indicating that the blood vessels of the toe are dilated. Compared with the radial artery, the lower extremity _The blood pressure is lowering, and the function and properties of _a5 are the same as that of a4.

When the blood vessels in the toes are not dilated, a ₅ is not applicable. That is, if k _sm-toe <d ₉ , set a ₅ =0. d ₉ =0.67˜0.73, preferably 0.7.

When the blood vessels in the toes are dilated and the highest point of the pulse wave crest moves back beyond the midpoint, a ₅ takes a positive value. That is, if k _sm-toe ≥d ₉ and k _st-toe ≥0.8, then a ₅ =k _sm-toe −d ₉ .

When the blood vessels of the toes are dilated but the highest point of the pulse wave peak does not exceed the midpoint, a ₅ takes a positive value and halves it. That is, if k _sm-toe ≥ d ₉ and k _st-toe <0.8, then a ₅ =(k _sm-toe −d ₉ )/2.

The sixth correction variable a ₆ ;

The correction variable obtained in the step S4 also includes a sixth correction variable a ₆ , a ₆ represents the relative change of the two pulse wave areas, and is used to correct T _s when the blood vessels of the toes are dilated and the blood pressure of the lower extremities decreases relative to the blood pressure of the radial artery . The applicable range of a ₆ is a ₆ >0.

k _sm-toe-ear is the ratio of the systolic area of the toe pulse wave to the area of the ear pulse wave systolic period, and 100 is the adjustment coefficient; the functions and properties of k _sm-toe-ear and k _ts-toe-ear are the same.

When the toe wave area is smaller than the ear wave area, the blood vessels in the toe are not relatively expanded, and a ₆ is not applicable. That is, if k _sm-toe-ear <1.0, set a ₆ =0.

Under the first prerequisite, the area of the toes is much larger than the area of the ears, and the blood vessels of the toes expand more. The constant 1.08 of c ₆ is used as the maximum value for backup. That is, if k _sm-toe-ear >1.08, set c ₆ =1.08.

If the shape of the ear pulse wave is normal, a ₆ takes the maximum correction value. That is, if t _s >220 and k _sd-m-0 >0.88, then a ₆ =c ₆ -1.0.

If the ear pulse wave shows a very sharp forward-leaning triangle or the waveform is very narrow, it means that the shape of the ear pulse wave is seriously abnormal. At this time, the relative change between the two pulse waves is amplified, and the calibration value needs to be reduced for use. a ₆ Take 1/3 of the maximum calibration value. That is, if t _s <160 or k _sd-m-0 <0.80, then a ₆ =(c ₆ −1.0)×0.34.

When the ear pulse wave morphological changes are not too serious, a ₆ takes 2/3 of the maximum correction value. That is, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₆ =(c ₆ −1.0)×0.67.

Under the second prerequisite, the area of the toes is larger than the area of the ears, and the relative expansion of blood vessels in the toes is not too serious, and c ₆ takes a positive variable for use. That is, if 1.0≤k _sm-toe- ear≤1.08, then c ₆ =k _sm-toe-ear- 1.0.

If the shape of the ear pulse wave is normal, a ₆ takes a positive variable as the correction value. That is, if t _s >220 and k _sd-m-0 >0.88, then a ₆ =c ₆ .

If the shape of the ear pulse wave changes seriously, the relative change between the pulse waves will be amplified, and the calibration value needs to be reduced for use, and a ₆ takes 1/3 of the positive variable. That is, if t _s ≤160 or k _sd-m-0 ≤0.80, then a ₆ =c ₆ ×0.34.

If the ear pulse wave is not too serious, a ₆ takes 2/3 of the positive variable, that is, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₆ =c ₆ ×0.67 .

the seventh correction variable a ₇ ;

The correction variable obtained in step S4 also includes a seventh correction variable a ₇ , the function and properties of a ₇ are the same as those of a ₆ , and a ₇ represents the relative change of the systolic width (systolic time) of the two pulse waves.

k _ts-toe-ear is the ratio of the systolic time identified on the toe pulse wave to the systolic time identified on the ear pulse wave, and 825 is the adjustment coefficient; the increase of k _ts-toe-ear indicates that the blood vessels in the toe are dilated, Blood pressure in the lower extremities is decreasing relative to radial blood pressure.

When the blood vessels of the toes are not relatively dilated, a ₇ does not apply. That is, if k _ts-toe-ear <1.0, set a ₇ =0.

Under the first prerequisite, when the blood vessels in the toe are relatively dilated, c ₇ takes a constant of 1.08 as the maximum value for backup. That is, if k _ts-toe-ear >1.08, set c ₇ =1.08.

If the shape of the ear pulse wave is normal, a ₇ takes the maximum correction value. That is, if t _s >220 and k _sd-m-0 >0.88, then a ₇ =c ₇ -1.0.

If the shape of the ear pulse wave changes seriously, the relative change between the pulse waves will be amplified, and the calibration value needs to be reduced for use, and a ₇ takes 1/3 of the maximum correction value. That is, if t _s <160 or k _sd-m-0 <0.80, then a ₇ =(c ₇ −1.0)×0.34.

If the ear pulse wave shape variation is not too serious, a ₇ takes 2/3 of the maximum correction value. That is, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₇ =(c ₇ −1.0)×0.67.

Under the second prerequisite, when the width of the toe is greater than the width of the ear, the relative expansion of the blood vessels of the toe is not too serious, and c ₇ takes a positive variable for use. That is, if 1.0≤k _ts-toe- ear≤1.08, then c ₇ =k _ts-toe-ear- 1.0.

If the shape of the ear pulse wave is normal, a ₇ takes a positive variable as the correction value. That is, if t _s >220 and k _sd-m-0 >0.88, then a ₇ =c ₇ .

If the shape of the ear pulse wave varies seriously, a ₇ takes 1/3 of the positive variable. That is, if t _s ≤160 or k _sd-m-0 ≤0.80, then a ₇ =c ₇ ×0.34.

If the variation of the ear pulse wave shape is not too serious, a ₇ takes 2/3 of the positive variable. That is, if 160<t _s ≤220 or 0.80<k _sd-m-0 ≤0.88, then a ₇ =c ₇ ×0.67.

Correction matrix in the step S5 Wherein, if a _i =0, it means that a _i is not applicable. The step S6 is specifically: continuously obtain the correction matrix under 8 cardiac cycles, use the average value of the variables of the 8 cardiac cycles to overcome the interference of respiratory fluctuations, select the 8 variables in a recursive manner, and calculate a newest variable every time Just eliminate the oldest variable. The correction method is: T _sma =T _sm (1-A _m ); where, A _i is the correction matrix in the i-th cardiac cycle, and T _si is the T _s in the i-th cardiac cycle.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. All of them should be covered by the scope of the claims and description of the present invention.

Claims (10)

1. A method for correcting the pulse wave propagation time related to the systolic pressure, characterized by comprising the steps of:

s1) detecting the pulse wave at the ear in real time in each cardiac cycle and analyzing to obtain the following data of the ear pulse wave: height h of aortic valve closing point on ear pulse wave_sdTime t of contraction of ear pulse wave_sIn milliseconds, the diastolic time t of the ear pulse wave_dIn milliseconds, the maximum height h of the ear pulse wave_max；

S2) detecting each heart in real timePulse waves at toes under the action cycle are analyzed to obtain the following data of the toe pulse waves: systolic time t of toe pulse wave_s-toeIn milliseconds, the diastolic time t of the toe pulse wave_d-toeIn milliseconds, the maximum height h of the pulse wave of the toes_max-toeTime t from the starting point of the toe pulse wave to the midpoint of the peak_ch-toeUnit is millisecond, and time t from starting point of toe pulse wave to peak of peak_max-toeIn milliseconds; the middle point of the wave crest refers to the middle point of the turning point of the rising edge and the turning point of the falling edge at the wave crest;

s3) calculating a pulse wave propagation time T associated with the systolic pressure_sSaid T is_sThe time difference from the closing point of the aortic valve on the ear pulse wave to the closing point of the aortic valve on the toe pulse wave is defined; h is the amplitude of the ear pulse wave or the toe pulse wave in the direction of the longitudinal axis;

s4) calculating correction variables in the cardiac cycle by using the data obtained in the steps S1 and S2 in the same cardiac cycle;

s5) according to the correction variable under the cardiac cycle obtained in the step S4, calculating to obtain a correction matrix under the cardiac cycle;

s6) obtaining correction matrices for a plurality of cardiac cycles in succession, for the T obtained through step S3_sCarrying out correction; .

2. The method for correcting systolic pressure-related pulse wave propagation time according to claim 1, characterized in that the correction matrix in step S5a_iIs the ith of the correcting variables.

3. The method for correcting systolic pressure-related pulse wave propagation time according to claim 1, characterized in that said step S6 specifically includes: continuously acquiring correction matrixes under 8 cardiac cycles; the correction method comprises the following steps: t is_sma＝T_sm(1-A_m) (ii) a Wherein,A_ifor the correction matrix at the i-th cardiac cycle, T_siIs T at the ith cardiac cycle_s。

4. Method for correcting the pulse wave propagation time related to systolic pressure according to claim 1, characterised in that the first correcting variable a₁Calculated by the following formula:

if d is₁≤k_sd-m-0≤d_1-2Then a is₁＝(d_1-2-k_sd-m-0)×0.50；

If k is_sd-m-0<d₁Then a is₁＝28×0.50；

If k is_sd-m-0>d_1-2Then a is₁＝0；

Wherein,d₁＝76～84，d_1-2＝104～112。

5. method for correcting the pulse wave propagation time related to systolic pressure according to claim 1, characterised in that the second correcting variable a₂Calculated by the following formula:

if k is_sd-m>(d₂+ (age-14)/15/100), then a₂＝k_sd-m-(d₂+(age-14)/15/100)；

If k is_sd-m≤(d₂+ (age-14)/15/100), then a₂＝0；

Wherein if k_sd-m-0-k_sd-m-ts| ≧ 40 and (k)_sd-m-0+k_sd-m-ts)/2≥k_sd-m-2Then k is_sd-m＝2×k_sd-m-2-(k_sd-m-0+k_sd-m-ts) /2, otherwise k_sd-m＝k_sd-m-2；

age is age, d₂＝1.17～1.27。

6. Method for correcting the pulse wave propagation time related to systolic pressure according to claim 1, characterised in that the third correcting variable a₃Calculated by the following formula:

if c is₄<k_d-m-a<c₅Then a is₃＝0；

If k is_sd-m-0<d₆Or k_sd-m-2>d₇Then a is₃＝0；

If k is_sd-m-0≥d₆+0.10 and k_sd-m-2≤d₈And k is_d-m-a≤c₄Then a is₃＝(c₄-k_d-m-a)×67/100；

If it isOrThen a₃＝(c₄-k_d-m-a)×50/100；

If k is_sd-m-0≥d₆+0.10 and k_sd-m-2≤d₈And k is_d-m-a≥c₅Then a is₃＝(c₅-k_d-m-a)×62/100；

If it isOrThen a₃＝(c₅-k_d-m-a)×45/100；

Wherein if k_sd-m-0-k_sd-m-ts| ≧ 40 and (k)_sd-m-0+k_sd-m-ts)/2≥k_sd-m-2And k is_sd-m-ts≥d_3-2Then, thenOtherwise

If k is_sd-m-ts≤d_3-2Then, thenIf it isThenIf it isThen c₄＝(d₄+(age-14)/8)/100，d₄＝23～35，c₅＝(d₅+(age-14)/8)/100，d₅＝27～39，d₆＝0.97～1.03，d₇＝1.52～1.58，d₈＝1.42～1.48，d_3-2＝1.21～1.31，d₃Age is 0.02-0.14, age is age.

7. Method for correcting the pulse wave propagation time related to systolic pressure according to claim 1, characterised in that the fourth correcting variable a₄Calculated by the following formula: if k is_s-t-toe>0.8, then a₄＝k_s-t-toe-0.8；

If k is_s-t-toe≤0.8, then a₄＝0；

Wherein if t_max-toe≥t_ch-toeThen, thenOtherwise

8. Method for correcting the pulse wave propagation time in relation to systolic pressure according to claim 1, characterised in that the fifth correcting variable a₅Calculated by the following formula:

if k is_s-m-toe<d₉Then a is₅＝0；

If k is_s-m-toe≥d₉And k is_s-t-toeA is more than or equal to 0.8₅＝k_s-m-toe-d₉；

If k is_s-m-toe≥d₉And k is_s-t-toe<0.8, then a₅＝(k_s-m-toe-d₉)/2；

Wherein d is₉＝0.67～0.73，

9. Method for correcting the pulse wave propagation time in relation to systolic pressure according to claim 1, characterised in that the sixth correcting variable a₆Calculated by the following formula:

if k is_s-m-toe-ear<1.0, then a₆＝0；

When k is_s-m-toe-ear>1.08, then c₆When t is equal to 1.08, the product is_s>220 and k is_sd-m-0>0.88, then a₆＝c₆1.0, if t_s<160 or k_sd-m-0<0.80, then a₆＝(c₆-1.0) × 0.34.34, if 160<t_sLess than or equal to 220 or 0.80<k_sd-m-0A is less than or equal to 0.88, then a₆＝(c₆-1.0)×0.67；

When k is more than or equal to 1.0_s-m-toe-earC is less than or equal to 1.08, then₆＝k_s-m-toe-ear-1.0, when t is_s>220 and k is_sd-m-0>0.88, then a₆＝c₆If t is_s160 or k or less_sd-m-0A is less than or equal to 0.80, then a₆＝c₆× 0.34.34, 160, if<t_sLess than or equal to 220 or 0.80<k_sd-m-0A is less than or equal to 0.88, then a₆＝c₆×0.67；

Wherein,

10. method for correcting the pulse wave propagation time in relation to systolic pressure according to claim 1, characterised in that the seventh correcting variable a₇Calculated by the following formula:

if k is_ts-toe-ear<1.0, then a₇＝0；

When k is_ts-toe-ear>1.08, then c₇When t is equal to 1.08, the product is_s>220 and k is_sd-m-0>0.88, then a₇＝c₇1.0, if t_s<160 or k_sd-m-0<0.80, then a₇＝(c₇-1.0) × 0.34.34, if 160<t_sLess than or equal to 220 or 0.80<k_sd-m-0A is less than or equal to 0.88, then a₇＝(c₇-1.0)×0.67；

When k is more than or equal to 1.0_ts-toe-earC is less than or equal to 1.08, then₇＝k_ts-toe-ear-1.0, in this case, if t_s>220 and k_sd-m-0>0.88, then a₇＝c₇If t is_s160 or k or less_sd-m-0A is less than or equal to 0.80, then a₇＝c₇× 0.34.34, 160, if<t_sLess than or equal to 220 or 0.80<k_sd-m-0A is less than or equal to 0.88, then a₇＝c₇×0.67；

Wherein,