CN100512750C - Process of calibrating no-cuff arterial blood gauge - Google Patents

Abstract

The process of calibrating no-cuff arterial blood pressure gauge includes the following steps: 1. measuring reference arterial blood pressure value BP0 and recording related pulse wave signal; 2. extracting at least one pulse wave characteristic quantity from the related pulse wave signal; 3. changing the height of the limb or trunk part for measuring related pulse wave signal, recording related pulse wave signal and extracting at least one pulse wave characteristic quantity from the related pulse wave signal; and 4. determining the relationship between the pulse wave characteristic quantity and the reference arterial blood pressure value. The present invention can obtain relatively precise calibration relationship in the condition of unchanging the individual physiological state.

Description

Sleeveless belt arterial blood pressure measuring device is carried out Calibration Method

Technical field

The present invention relates generally to calibrate the method for sleeveless belt arterial blood pressure measuring device.

Background technology

Sleeveless belt arterial blood pressure measuring device adopts pulse wave characteristic quantity to estimate the arteriotony value usually.A kind of method wherein commonly used utilizes the pulse wave transmission time (speed) to predict arteriotony exactly.Studies show that in a large number, present the relation of approximately linear between pulse wave transmission time and the blood pressure, and this relation is the object dependence.This that is to say, utilizes the pulse wave transmission time to estimate at first will calibrate at each user before the arteriotony, promptly sets up the relation between pulse wave transmission time and the user arteriotony.

The step of calibration generally includes utilizes standard-sphygmomanometer to measure arteriotony and corresponding pulse wave transmission time, then the measured value of correspondence is input to the control unit of sleeveless belt type apparatus so that set up arteriotony and pulse wave concerned between the transmission time.For example, United States Patent (USP) 6,603,329 disclose a kind of multifunctional blood pressure meter, and it provides a kind of blood pressure measuring method based on pulse wave transmission time theory.This device comprises an input block, is used for importing the required pressure value of calibration.Japan Patent 2002-172094 discloses a kind of blood pressure measuring system, comprises a device of directly measuring blood pressure (normally based on cuff formula method) and the electronics wrist formula wrist-watch sphygomanometer based on the pulse transmission theory.The principal character of this invention is, by the measurement device of direct measurement blood pressure to blood pressure values can be transferred to electronics wrist formula wrist-watch sphygomanometer automatically and be used for its calibration, so user need not manually be imported calibration data.In case calibration is finished, electronics wrist formula wrist-watch sphygomanometer can utilize by detected electrocardiosignal and detected pulse wave signal and calculate the pulse wave transmission time, comes estimated service life person's pressure value.

Calibration obviously can improve the accuracy that blood pressure is estimated if can carry out in certain blood pressure dynamic change scope.For example, the blood pressure wrist-watch of the individual blood pressure of the measurement that Casio company releases changes blood pressure range by exercise test, to obtain the relation between pulse wave transmission time and the blood pressure.European patent 0875200 also proposes to measure pulse wave transmission times different with when moving when static and blood pressure to obtain a dynamic range of the relationship of the two.Different pressure values when United States Patent (USP) 5649543 proposes to measure flat crouching when sitting up are calibrated the blood pressure measurement equation.In order to handle owing to the change reduction of the certainty of measurement that the change that concerns between the pulse wave transmission time that causes and the blood pressure causes of the physiological situation of object own, United States Patent (USP) 5755669, propositions such as 6022320,6083171 judge that with the pressure value of estimating the many groups pulse wave transmission time that whether needs to recalibrate and utilize under the different physiological situations and the data of arteriotony calibrate.And Chinese patent CN1127939C propose to utilize the different pulse wave transmission times and the pressure value that place palm on the heart level face and measure when leaving the heart level face to determine to calibrate equation.But in the method, the pressure value behind the change height adopts average method to be similar to and obtains, and does not consider that the pulse wave transmission speed all is different at the every bit of arterial tree.The new method that proposes among the present invention is made above-mentioned deficiency just.

Summary of the invention

The objective of the invention is to simplify calibration steps, improve calibration accuracy simultaneously overcoming above-mentioned the deficiencies in the prior art, the present invention proposes following sleeveless belt arterial blood pressure measuring device to be carried out Calibration Method, may further comprise the steps:

(1) witness mark arteriotony value BP ₀And record pulse wave coherent signal;

(2) extract at least one pulse wave characteristic quantity according to the pulse wave coherent signal;

(3) change to measure the height h at the limbs position of pulse wave coherent signal, record pulse wave coherent signal and according at least one pulse wave characteristic quantity of this signal extraction;

(4) determine pulse wave characteristic quantity and with reference to the relation between the arteriotony value.

Wherein, the pulse wave coherent signal can be selected from one or more in capacity trace signal, pressure wave signal, electrical impedance signal, piezoelectric signal and the electrocardiosignal.One or more pulse wave coherent signals according to record can calculate pulse wave characteristic quantity.Relation between pulse wave characteristic quantity and the arteriotony can be described by at least one coefficient and a constant by the distributed model integration is obtained.One or more pulse wave characteristic quantity that coefficient and constant can utilize the limbs position to write down when differing heights are determined.Pulse wave characteristic quantity can be by in one or more the pulse wave amplitudes determined in capacity trace signal, pressure wave signal, electrical impedance signal, piezoelectric signal and the electrocardiosignal, area, High Order Moment, characteristic time, the period region characteristic quantity one or more.Characteristic time wherein can be the pulse wave transmission time (PTT).Height h can calculate by the reading of accelerometer.With reference to arteriotony value BP ₀The fluid pressure that the height of correspondence produces in the time of can utilizing limbs position capacity trace signal waveforms amplitude when differing heights maximum is determined.BP ₀Also can utilize succusion or auscultation to measure.

Description of drawings

Below in conjunction with accompanying drawing specific embodiments of the present invention is elaborated.By these explanations, it is clearer that above-mentioned purpose of the present invention, advantage and feature will become.In following accompanying drawing:

Fig. 1 is a flow chart of realizing the inventive method calibration process;

The sketch map of each parameter when Fig. 2 is the explanation Level Change;

Fig. 3 is the sketch map that explanation capacity trace signal amplitude changes with percutaneous pressure;

Fig. 4 is that explanation utilizes the limbs height change to measure BP ₀Flow chart.

Specific embodiments

The relation between pulse wave characteristic quantity and the arteriotony is promptly found in calibration.Preferably, in this specific embodiment, pulse wave characteristic quantity is selected the pulse wave transmission time for use.

Embodiment 1

The calibration process that carries out blood pressure measurement in the present embodiment can be referring to the flow chart of Fig. 1.At first will be in step 101 witness mark pressure value BP ₀If adopt cuff formula method, succusion or auscultation, user needs cuff is wrapped in certain position of health, and as upper arm, this position and heart are in same level height.If adopt sleeveless to wear formula, then concrete steps are described further below.The recording step 103 of pulse wave coherent signal can carry out with the measurement synchronization of pressure value.The pulse wave coherent signal that writes down is the photoplethaysmography signal, also can write down electrocardiosignal.The record of cuff formula blood pressure measurement and pulse wave coherent signal preferably carries out on the arm of the same side synchronously.Because cuff pressure can influence the pulse wave coherent signal, so can utilize the cuff inflation starting stage in step 104, one section pulse wave coherent signal when promptly cuff pressure is lower than diastolic pressure calculates pulse wave transmission time PTT ₀Perhaps, the record of pulse wave coherent signal can carry out with the measuring sequence of reference pressure value.After measurement is finished, in step 102, obtain when time reference pressure value of measurement.In step 105, the pulse wave coherent signal is write down again with respect to the height h of heart in change record pulse wave coherent signal limbs position, calculates the pulse wave transmission time PTT that measures on new height then in step 106 ₁As required, this step can repeat repeatedly, a plurality of PTT that obtain at differing heights.Can in step 107, determine relational expression between pulse wave transmission time and the arteriotony according to above-mentioned information.The concrete steps of determining this relational expression will describe in detail below.At last, in step 108, it is stored in the memory element, and finishes calibration.

Studies show that to have the relation of approximately linear between pulse wave transmission speed and the blood pressure in a large number.This relation can be expressed as:

PWV＝a×P _t+b?(1)

Wherein, a and b are undetermined parameter.

P _t＝P _in+P _h-P _e (2)

P _tBe percutaneous pressure, P _InBe intravascular pressure, the arteriotony of the heart level position of often saying just, P _hBe owing to the caused fluid pressure of Level Change, and P _eBe the pressure of external influence.Owing to ambient pressure is generally zero, so the pulse wave transmission speed is just only relevant with the fluid pressure that the height h variation of leaving heart causes with intravascular pressure.

P _t＝P _in+ρgh＝P _in+ghlsinθ (3)

When the limbs position was positioned at the heart top, h was a negative value; Otherwise, then be on the occasion of.L is meant limbs height change section distance between 2 on the tremulous pulse, but is measuring amount, and θ is that limbs are raised or when reducing and the angle between the heart level face, as shown in Figure 2.Further,

PWV＝a×(P _in+ρgh)+b (4)

Wherein ρ is a density of blood, and pressure value can descend when the limbs position was higher than the heart level position, and pressure value can rise when being lower than the heart level position.Following formula can further be rewritten as,

PWV＝(a*P _in+b)+aρgh＝v ₀+aρgh (5)

V wherein ₀=a*P _In+ b is limbs position and the pulse wave transmission speed of heart when same horizontal level.At intravascular pressure P _InUnder the immovable situation, the pulse wave transmission speed is relevant with the height h that limbs leave the heart level position.

The pulse wave transmission speed can be by directly but measuring amount---the pulse wave transmission time reflects.Strictly, the pulse wave transmission time is meant that pulse wave is in the transmission time between 2 on the tremulous pulse.Because the every bit of pulse wave transmission speed on arterial tree be all inequality, therefore, the pulse wave transmission time can be by obtaining along the arterial tree integration the pulse wave transmission speed,

$\mathrm{PTT}={\∫}_0^l\frac{\mathrm{dx}}{{\mathrm{PWV}}_x}={\∫}_0^l\frac{\mathrm{dx}}{v_0+\mathrm{a\ρ}\mathrm{gx}\sin \mathrm{\θ}}---\left(6\right)$

Wherein, starting point limbs position and heart are positioned at same horizontal plane.Following formula is carried out integration and carry out Taylor expansion being similar to, obtain

$\mathrm{PTT}=\frac{l}{v_0}+\frac{1}{2}\frac{\mathrm{a\ρg}}{v_0^2}{l}^2\sin \mathrm{\θ}=\frac{l}{v_0}+\frac{1}{2}\frac{\mathrm{a\ρg}}{v_0^2}\mathrm{lh}---\left(7\right)$

In following formula, PTT, but l is a measuring amount, h can calculate by the reading of accelerometer, so can determine wherein unknown quantity v by following formula ₀And a.When h=0, promptly on the tremulous pulse 2 when all being in the heart level position, $v_0=\frac{l}{{\mathrm{PTT}}_0}.$ When the terminal point position on the tremulous pulse 2 is higher or lower than the heart level position, can determine $a=\frac{2l}{\mathrm{\ρgh}}\left(\frac{{\mathrm{PTT}}_1-{\mathrm{PTT}}_0}{{\mathrm{PTT}}_0^2}\right).$ With v ₀In the numerical value substitution formula (5) of a, can determine b, thereby obtain the relation between pulse wave transmission time and the arteriotony (it is comparatively suitable that arteriotony value is herein brought into mean pressure):

$P_{\mathrm{in}}=\frac{l}{a*\mathrm{PTT}}-(\mathrm{\ρgh}+\frac{b}{a})---\left(8\right)$

For measuring conveniently, the starting point of measuring the pulse wave transmission time is elected the summit of the R type ripple of electrocardiosignal usually as.If consider this kind situation, the actual pulse wave transmission time that measures is the whole propagation time from the heart to the measuring position, and whole transmission path can be divided into canned paragraph and active segment.Canned paragraph is meant the limbs section (raising/reduce section stretch footpath before from the heart to limbs) that does not highly have variation when measuring, and PWV of this section and height change are irrelevant, only with intravascular pressure P _InRelevant; And active segment is meant that limbs raise/reduce the stretch footpath of the starting point of section to the limbs position of measuring the pulse wave coherent signal.Therefore above-mentioned formula (7) can be rewritten into:

${\mathrm{PTT}}_{\mathrm{total}}=\frac{l_0}{v_0}+\frac{l}{v_0}+\frac{1}{2}\frac{\mathrm{a\ρg}}{v_0^2}\mathrm{lh}=\frac{l_0+l}{v_0}+\frac{1}{2}\frac{\mathrm{a\ρg}}{v_0^2}\mathrm{lh}---\left(9\right)$

Wherein, I ₀Be the equivalent length of canned paragraph, it equals the pulse wave transmission time (can survey) of from heart to the canned paragraph end (active segment initiating terminal) and the product (can calculate) of canned paragraph pulse wave transmission speed.The pulse wave transmission speed of canned paragraph equals the pulse wave transmission speed of active segment when the same horizontal level of heart approx, and it can be determined in the transmission time of active segment divided by pulse wave by the length of active segment.Therefore, can obtain relation between pulse wave transmission speed and the arteriotony:

$P_{\mathrm{in}}=\frac{l+l_0}{a*{\mathrm{PTT}}_{\mathrm{total}}}-(\mathrm{\ρgh}+\frac{b}{a})---\left(10\right)$

Wherein, PTT _TotalBut be measuring amount.

Embodiment 2

Relation between pulse wave transmission time and the blood pressure also can obtain by the relation (11) between pulse wave transmission speed and the percutaneous pressure and percutaneous pressure and the volumetrical relation of blood (12).

$\mathrm{PWV}=\sqrt{\frac{V}{\mathrm{\ρ}}\frac{{\mathrm{dP}}_t}{\mathrm{dV}}}---\left(11\right)$

$V=\frac{a}{1+\exp (-{\mathrm{bP}}_t)}---\left(12\right)$

Wherein, V is the blood volume, and a and b are undetermined parameter.Further combined with formula (3), bring formula (12) and its integrated form into formula (11) and can obtain active segment length l integration,

$\mathrm{PTT}=\left\{\begin{array}{cc}\frac{l\sqrt{\mathrm{\ρb}}}{\sqrt{1+\exp \left({\mathrm{bP}}_{\mathrm{in}}\right)}}& ;h=0\\ \frac{2l}{\sqrt{\mathrm{\ρb}}\mathrm{gh}}\ln \left|\frac{\sqrt{\exp \left[b(P_{\mathrm{in}}-\mathrm{\ρgh})\right]+\exp (-\mathrm{b\ρgh})}-\sqrt{\exp (-\mathrm{b\ρgh})}}{\sqrt{\exp \left[b(P_{\mathrm{in}}-\mathrm{\ρgh})\right]+1}-1}\right|& ;h\≠0\end{array}\right.---\left(13\right)$

Wherein but PTT and l are measuring amount.

So the relation in the blood pressure of heart level position and pulse wave transmission time can be expressed as:

$P_{\mathrm{in}}=\frac{1}{b}\ln (\frac{l^2\mathrm{\ρb}}{{\mathrm{PTT}}^2}-1)---\left(14\right)$

For avoiding the error of the calculating b that single measurement may cause, can determine b by method of least square then by a plurality of b values that the many groups of PTT that record at differing heights obtain.

In actual measurement, be starting point if the pulse wave transmission time is summit with the R type ripple of electrocardiosignal, above-mentioned equation also needs to revise.

In above-mentioned two embodiment, the measurement of height can be finished by accelerometer.Accelerometer can be placed on the remote point of two measurement points on the tremulous pulse.If the reading of accelerometer is a _l, then height can calculate according to following formula:

$h=\frac{l}{g}{a}_l---\left(15\right)$

With reference to pressure value BP ₀Except that can also calculating acquisition by can measuring by succusion or auscultation by limbs height and fixed pressure pick off.Its cardinal principle be when percutaneous pressure be zero (P _t=P _In+ P _h-P _e=0, just intravascular pressure and external pressure equate) time, the pulse wave coherent signal will reach maximum as the amplitude of capacity trace signal, as shown in Figure 4.Concrete grammar is, in the step 401, applies certain cuff pressure acral, and it (is the external pressure P of blood vessel that the pressure transducer of cuff below will be read cuff pressure _e), then, in step 402, slowly changing the height (acral height changes thereupon) of limbs, record places the waveform of the capacity trace signal of cuff below simultaneously.In step 403, the limbs height h of correspondence when finding the wave-shape amplitude of noting to reach maximum _m(can record automatically) by accelerometer.At last, in step 404, obtain with reference to pressure value BP by following Equation for Calculating ₀=P _In=P _e-ρ gh _m

It is apparent to those skilled in the art that pulse wave characteristic quantity choose and calculating and regression equation in coefficient and constant fix on really under the situation that does not depart from spirit of the present invention, different implementation methods can be arranged.Protection scope of the present invention is to be defined by appended claim rather than specific embodiments.

Claims (10)

1. one kind is carried out Calibration Method to sleeveless belt arterial blood pressure measuring device, may further comprise the steps:

(1) witness mark arteriotony value BP0 and write down the pulse wave coherent signal;

(2) extract at least one pulse wave characteristic quantity according to the pulse wave coherent signal;

(3) change to measure the height h at the limbs position of pulse wave coherent signal, record pulse wave coherent signal and according at least one pulse wave characteristic quantity of this signal extraction;

(4) determine pulse wave characteristic quantity and with reference to the relation between the arteriotony value, this pulse wave characteristic quantity and with reference to the relation between the arteriotony value by the distributed model integration is obtained.

2. the method for claim 1 is characterized in that, the pulse wave coherent signal is to be selected from capacity trace signal, pressure wave signal, electrical impedance signal, piezoelectric signal and the electrocardiosignal one or more.

3. the method for claim 1 is characterized in that, pulse wave characteristic quantity is calculated from one or more pulse wave coherent signals.

4. the method for claim 1 is characterized in that, pulse wave characteristic quantity and definite by at least one coefficient and a constant with reference to the relation between the arteriotony value.

5. method as claimed in claim 4 is characterized in that, describes pulse wave characteristic quantity and determines with reference to one or more pulse wave characteristic quantity that the coefficient that concerns between the arteriotony value and constant utilize the limbs position to write down when the differing heights.

6. method as claimed in claim 5, it is characterized in that pulse wave characteristic quantity is for by in one or more the pulse wave amplitudes determined in capacity trace signal, pressure wave signal, electrical impedance signal, piezoelectric signal and the electrocardiosignal, area, High Order Moment, characteristic time, the period region characteristic quantity one or more.

7. method as claimed in claim 6 is characterized in that, the characteristic time is pulse wave transmission time (PTT).

8. the method for claim 1 is characterized in that, height h calculates by the reading of accelerometer.

10. the method for claim 1 is characterized in that, BP ₀Utilize the limbs position to determine at the capacity trace signal waveforms amplitude at the differing heights place fluid pressure that the height of correspondence produces during for maximum.

11. the method for claim 1 is characterized in that, BP ₀Utilize succusion or auscultation to measure.

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