CN102018507A - Data analysis processing method for measuring blood pressure by oscillography - Google Patents

Abstract

The invention discloses a data analysis processing method for measuring the blood pressure by the oscillography, aiming to solve the anti-jamming problem in the process of measuring blood pressure by oscillography. Polynomial fitting is carried out on a pulse wave envelope and then a blood pressure value is obtained from the envelope obtained by fitting. The method comprises the following steps of: (1) obtaining a pressure signal in the blood pressure measuring process by utilizing a blood pressure cuff and an air pressure sensor; (2) carrying out filtering processing on the pressure signal obtained in the step (1) to obtain the pulse wave envelope yi and the corresponding pressure value xi; (3) carrying out the polynomial fitting on an envelope signal obtained in the step (2) to obtain a new pulse wave envelope Oi, wherein the used degree of polynomial is not less than 2, and the least square principle is utilized to carry out the fitting; and (4) obtaining average pressure, systolic pressure and diastolic pressure with a fixed ratio calculation method by the envelope Oi obtained in the step (3) in figure 1.

Description

A kind of data analysis processing method of measuring blood pressure based on oscillographic method

One, technical field:

The invention belongs to the medical electronic apparatus field, particularly utilize oscillographic method to measure the data analysis processing method of limbs blood pressure.

Two, background technology:

At present the noinvasive electric sphygmomanometer substantially all uses oscillometric method, realizes blood pressure measurement based on the blood vessel unloading principles.The quick-reading flow sheets of measuring blood pressure is exactly by a cuff limbs to be forced into a pressure that surpasses the human body systolic pressure.Then cuff is tried one's best and exit at a slow speed equably, make blood vessel from being closed into opening.Oscillographic method is exactly the variation of observing along with the cuff internal pressure, blood vessel is from being closed into when open, and the variation of pulse wave amplitude realizes blood pressure measurement.The fluctuation of noting cuff internal pressure in this process with pressure transducer changes.This signal is changed by a static pressure that descends gradually and an oscillating component that produces because of arteriopalmus is formed by stacking.Through after the specific Filtering Processing, just can obtain the wave of oscillation by the arteriopalmus generation, again its vibration envelope extraction is come out.Utilize the ratio Calculation Method then, determine pressure value: be about to oscillation amplitude maximum point O _mCuff internal pressure P _mAs mean pressure; In addition, seek corresponding systolic pressure Ps and diastolic pressure P respectively at envelope rising edge and envelope trailing edge _dOscillation amplitude O _sAnd O _dO _sAnd O _dBig I determine according to following formula:

$\frac{O_s}{O_m}=0.55$

$\frac{O_d}{O_m}=0.82$

The value of this two number can change to some extent under the practical situation.Detailed process as shown in Figure 1.

But in actual applications, because a variety of causes, as disease, collision and limbs are moving etc., and envelope is not strictly to rise earlier to descend again, as shown in Figure 2.This can have influence on the accuracy of measurement to a great extent.And the envelope that extracts from the wave of oscillation simply is discontinuous, the O that calculates _sAnd O _dThere is a strong possibility is between twice vibration, can only a bit obtain pressure value from leaning on closerly with result of calculation, and this also can influence the precision of measurement.

Three, summary of the invention:

The present invention is directed to the shortcoming of above-mentioned existing oscillographic method, after obtaining envelope, use a kind of approximating method, make envelope become level and smooth and enough close, remove the vibration that increases suddenly or reduce, guarantee the precision of oscillographic method measurement blood pressure, also can obtain pressure value accurately when making envelope be subjected to influencing of singular signal.

Technical characterictic of the present invention is earlier the pulse wave envelope to be carried out fitting of a polynomial, obtains pressure value again from the envelope that match obtains, and may further comprise the steps:

1) utilize blood pressure cuff and baroceptor to obtain pressure signal in the blood pressure measurement process;

2) gained pressure signal in the step 1) is carried out Filtering Processing, obtain pulse wave envelope yi and corresponding force value xi;

3) to step 2) in the envelope signal yi of gained carry out fitting of a polynomial, obtain new pulse wave envelope Oi, the use therein degree of polynomial is more than or equal to 2, and uses the least square principle to carry out match:

If the function of the match of wanting is P (x)=a ₀+ a ₁X+...+a _nx ⁿ, a wherein ₀, a ₁..., a _nBe the coefficient that needs are asked, these coefficients are calculated by following formula in n＞=2

$\left[\begin{array}{c}{a}_0\\ a_1\\ M\\ a_n\end{array}\right]={\left(\left[\begin{array}{cccc}1& 1& L& 1\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ M& M& O& M\\ {x_1}^n& {x_2}^n& L& {x_N}^n\end{array}\right]\left[\begin{array}{cccc}1& {x_1}^2& L& {x_1}^n\\ 1& {x_2}^2& L& {x_2}^n\\ M& M& O& M\\ 1& {x_N}^2& L& {x_N}^n\end{array}\right]\right)}^{-1}\left[\begin{array}{cccc}1& 1& L& 1\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ M& M& O& M\\ {x_1}^n& {x_2}^n& L& {x_N}^n\end{array}\right]\left[\begin{array}{c}{y}_1\\ y_2\\ M\\ y_N\end{array}\right]$

In the formula, y ₁, y ₂..., y _NBe exactly the range value of oscillography envelope, x ₁, x ₂..., x _NIt is the corresponding force value of this envelope point;

4) use the fixed ratio computing method to obtain mean pressure, systolic pressure, diastolic pressure by gained envelope 0i in the step 3).

Just can obtain fitting result by simple matrix operations, can realize on computers at an easy rate, can remove a lot simultaneously because interference artificial or that external factor causes improves stability and the accuracy of measuring pressure value.

Four, description of drawings:

Fig. 1 is the sketch map that oscillographic method is measured blood pressure

Fig. 2 is irregular envelope sketch map

Fig. 3 is a flow chart of the present invention

Fig. 4 is actual effect figure of the present invention

Five, the specific embodiment:

The present invention comes the oscillography envelope is carried out match with a function y=f (x) who meets the data rule by mathematical method, makes the oscillography envelope become continuous and level and smooth, can remove the interfering signal in the envelope simultaneously, makes final calculation result more accurate.And the realization of this algorithm only needs to increase simple several times matrix operations, has easy realization and implements characteristics of high efficiency.

Below of the present invention using made a detailed description, idiographic flow mainly contains following steps as shown in Figure 3:

(1) pressure signal in the cuff the deflation course when pressure transducer obtains measuring blood pressure carries out Filtering Processing to the pressure signal that collects then, and the passband of wave filter is 0.3～15Hz, extracts pulse wave envelope y _i

(2) with polynomial function to oscillography envelope y _iCarry out match, the degree of polynomial of use is got 4 order polynomials here and is carried out match more than or equal to 2.

Suppose that the multinomial that we need determine is P (x)=a ₀+ a ₁X+a ₂x ²+ a ₃x ³+ a ₄x ⁴, a wherein ₀, a ₁, a ₂, a ₃, a ₄Be the coefficient that requires, x is every envelope y _iCorresponding pressure value P _i。

The quadratic sum of the value behind the fitting of a polynomial and the residual error of original envelope is Wherein N is the number of original pulse wave envelope.

Here

Be actually a ₀, a ₁, a ₂, a ₃, a ₄The function of many variables, promptly

According to the least square principle, will make the quadratic sum minimum of residual error, make

Reach minimum, with the method for asking extreme value, order

Derivative equal 0, promptly

k＝0，1，2，3，4

Can obtain a system of linear equations of being made up of n n unit linear function like this, when N 〉=4, owing to this multinomial must uniquely exist, so there is unique solution in this equation group.

This equation group can be write as

$\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k(x_i^0{a}_0+x_i^1{a}_1+x_i^2{a}_2+x_i^3{a}_3+x_i^4{a}_4)=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k{y}_i,k=\mathrm{0,1,2,3,4}$

$\⇒$

$\left[\begin{array}{ccccc}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k{x}_i^0,& \underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k{x}_i^1,& \underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k{x}_i^2,& \underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k{x}_i^3,& \underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k{x}_i^4\end{array}\right]\left[\begin{array}{c}{a}_0\\ a_1\\ a_2\\ a_3\\ a_4\end{array}\right]=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{x}_i^k{y}_i,k=\mathrm{0,1,2,3,4}\⇒$

$\left[\begin{array}{cccc}1& 1& L& 1\\ x_1& x_2& L& x_N\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ {x_1}^3& {x_2}^3& L& {x_N}^3\\ {x_1}^4& {x_2}^4& L& {x_N}^4\end{array}\right]\left[\begin{array}{ccccc}1& x_1& {x_1}^2& {x_1}^3& {x_1}^4\\ 1& x_2& {x_2}^2& {x_2}^3& {x_2}^4\\ M& M& M& M& M\\ 1& x_N& {x_N}^2& {x_N}^3& {x_N}^4\end{array}\right]\left[\begin{array}{c}{a}_0\\ a_1\\ a_2\\ a_3\\ a_4\end{array}\right]=\left[\begin{array}{cccc}1& 1& L& 1\\ x_1& x_2& L& x_N\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ {x_1}^3& {x_2}^3& L& {x_N}^3\\ {x_1}^4& {x_2}^4& L& {x_N}^4\end{array}\right]\left[\begin{array}{c}{y}_1\\ y_2\\ M\\ y_N\end{array}\right]\⇒$

${\begin{array}{c}\left[\begin{array}{c}{a}_0\\ a_1\\ a_2\\ a_3\\ a_4\end{array}\right]\end{array}=\left(\left[\begin{array}{cccc}1& 1& L& 1\\ x_1& x_2& L& x_N\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ {x_1}^3& {x_2}^3& L& {x_N}^3\\ {x_1}^4& {x_2}^4& L& {x_N}^4\end{array}\right]\left[\begin{array}{ccccc}1& x_1& {x_1}^2& {x_1}^3& {x_1}^4\\ 1& x_2& {x_2}^2& {x_2}^3& {x_2}^4\\ M& M& M& M& M\\ 1& x_N& {x_N}^2& {x_N}^3& {x_N}^4\end{array}\right]\right)}^{-1}\left[\begin{array}{cccc}1& 1& L& 1\\ x_1& x_2& L& x_N\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ {x_1}^3& {x_2}^3& L& {x_N}^3\\ {x_1}^4& {x_2}^4& L& {x_N}^4\end{array}\right]\left[\begin{array}{c}{y}_1\\ y_2\\ M\\ y_N\end{array}\right]$

So just can obtain polynomial coefficient a by matrix operations ₀, a ₁, a ₂, a ₃, a ₄, obtain the pulse wave envelope after the match.The oscillography envelope O of match gained _iJust become a level and smooth and successive curve, as shown in Figure 4 from original a series of discrete points.

(3) the envelope maximum position is taken as mean pressure, and utilizes formula

$\frac{O_s}{O_m}=0.55$ With $\frac{O_d}{O_m}=0.82$

Obtain the envelope position of diastolic pressure and systolic pressure.Just can obtain diastolic pressure by static pressure and time relation curve then, the value of mean pressure and systolic pressure, specific implementation is seen Fig. 4.

Claims (1)

1. the data analysis processing method based on oscillographic method measurement blood pressure is characterized in that earlier the pulse wave envelope being carried out fitting of a polynomial, obtains pressure value again from the envelope that match obtains, and may further comprise the steps:

1) utilize blood pressure cuff and baroceptor to obtain pressure signal in the blood pressure measurement process;

2) gained pressure signal in the step 1) is carried out Filtering Processing, obtain pulse wave envelope Yi and corresponding force value xi;

3) to step 2) in the envelope signal Yi of gained carry out fitting of a polynomial, obtain new pulse wave envelope Oi, the use therein degree of polynomial is more than or equal to 2, and uses the least square principle to carry out match:

If the function of the match of wanting is P (x)=a ₀+ a ₁X+...+a _nx ⁿ, a wherein ₀, a ₁..., a _nBe the coefficient that needs are asked, these coefficients are calculated by following formula in n＞=2

$\left[\begin{array}{c}{a}_0\\ a_1\\ M\\ a_n\end{array}\right]={\left(\left[\begin{array}{cccc}1& 1& L& 1\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ M& M& O& M\\ {x_1}^n& {x_2}^n& L& {x_N}^n\end{array}\right]\left[\begin{array}{cccc}1& {x_1}^2& L& {x_1}^n\\ 1& {x_2}^2& L& {x_2}^n\\ M& M& O& M\\ 1& {x_N}^2& L& {x_N}^n\end{array}\right]\right)}^{-1}\left[\begin{array}{cccc}1& 1& L& 1\\ {x_1}^2& {x_2}^2& L& {x_N}^2\\ M& M& O& M\\ {x_1}^n& {x_2}^n& L& {x_N}^n\end{array}\right]\left[\begin{array}{c}{y}_1\\ y_2\\ M\\ y_N\end{array}\right]$

In the formula, yi is exactly the range value of oscillography envelope, and xi is the corresponding force value of this envelope point;

4) use the fixed ratio computing method to obtain mean pressure, systolic pressure, diastolic pressure by gained envelope Oi in the step 3).

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