CN204813858U - Blood pressure appearance based on pulse back wave transmission time - Google Patents

Abstract

The utility model relates to a blood pressure appearance based on pulse back wave transmission time, including pulse sensor, pulse sensor has connected gradually linear current -voltage conversion circuit, unity gain buffer, low pass amplifier circuit, analog to digital conversion circuit and treater, the treater still is connected with the power. The utility model discloses the blood pressure appearance only uses 1 sensor measurements fingertip pulse, and is simple, convenient, swift, through the relevant basis theory of assay pulse back wave with human blood pressure, sets up the relevant model of RWTT and systolic pressure and diastolic pressure to calculate systolic pressure and diastolic pressure according to two blood pressure models, the utility model discloses the systolic pressure and the diastolic pressure that calculate are more accurate, and the error is littleer, and the scope that is suitable for is big.

Description

A kind of blood pressure instrument based on the pulse reflective wave transmission time

Technical field

This utility model relates to a kind of blood pressure instrument based on the pulse reflective wave transmission time, belongs to technical field of medical instruments.

Background technology

Traditional electronic sphygmomanometer must be pressurizeed by oversleeve and reduce pressure, and adopts auscultation or oscillographic method to carry out Measure blood pressure.Because oversleeve pressurizes the sense of discomfort caused, this kind of blood pressure instrument is called as intrusive mood (Invasive) blood pressure instrument.There is the blood pressure instrument of some non-intrusion types (Non-Invasive) in recent years, generally based on measurement pulse wave transmission time (PulseTransitTime, PTT) and PTT-BP blood pressure model calculate pulse wave velocity, and then estimation systolic pressure.

As Chinese patent Authorization Notice No. CN102223837B, name are called in the patent of " measuring the blood pressure information measurement apparatus of pulse wave velocity as blood pressure information " open: in determinator, utilize the cuff being worn on upper arm and lower limb (ankle) respectively to the blood pressure (S101) of the blood pressure and lower limb that measure upper arm.And, utilize these cufves synchronously to measure the pulse wave of upper arm and the pulse wave (S103) of lower limb.Then, the time of occurrence based on these two pulse waves is poor, calculates upper arm lower limb portion pulse wave velocity (baPWV) (S105, S107).And the time of occurrence penetrating blood ripple and echo based on upper arm pulse wave is poor, calculate upper arm pulse wave velocity (upper arm PWV) (S109, S111).This method needs 2 sensors, usual 1 is positioned near heart for receiving cardiechema signals (ECG), another 1 the position such as to be positioned over after human limb (wrist, finger, vola etc.) or ear for receiving the pulse wave signal (usually being obtained by plethysmography, i.e. PPG) propagating into this place.By comparing 2 signals, calculate the pulse wave transmission time.In the method, 2 each own corresponding circuit of sensor also by wire interconnection, therefore use and inconvenience, are usually fabricated in some wearable garment (decorations).Also there is method directly 2 sensors to be positioned over wrist and finger place in addition, measure the PTT from wrist to finger by the pulse wave signal comparing this 2 place.But the pulse wave velocity that the method calculates is local, and do not meet the definition in PTT-BP blood pressure model, therefore estimated systolic pressure value has larger deviation.

Utility model content

The technical problems to be solved in the utility model is: for overcoming the problems referred to above, there is provided a kind of completely newly based on pulse reflective wave transmission time (ReturnWaveTransmissionTime, RWTT) blood pressure instrument, only need 1 sensor, utilize the mode of finger touching sensor, calculated by the algorithm of complexity, diastolic pressure, systolic pressure and HR values can be calculated within the short several seconds.

This utility model solves the technical scheme that its technical problem adopts:

A kind of blood pressure instrument based on the pulse reflective wave transmission time, comprise pulse transducer, described pulse transducer is connected with linear current-voltage conversion circuit, unity gain buffer, low pass amplifying circuit, analog to digital conversion circuit and processor in turn, and described processor is also connected with power supply.

Preferably, described pulse transducer only arranges one.

Preferably, described processor is also connected with memorizer and/or display and typing module and/or low pressure difference linear voltage regulator.

Preferably, the corner frequency of described low pass amplifying circuit is 20-50Hz.

Preferably, the sample rate of analog-digital conversion circuit as described is set to 1kS/s.

Preferably, described processor carries out low-pass digital filter to the data after digitized, and corner frequency is 10Hz, removes noise further.

The beneficial effects of the utility model are: (1) this utility model blood pressure instrument only uses 1 sensor measurement finger tip pulse, simply, convenient, fast, theoretical by the relevant rudimentary analyzing pulse echo and human blood-pressure, set up the correlation model of RWTT and systolic pressure and diastolic pressure, and calculate systolic pressure and diastolic pressure according to two blood pressure models, the systolic pressure that this method calculates and diastolic pressure are more accurate, and error is less, and the scope be suitable for is large.This utility model is by this technology and the perfect adaptation of photoelectricity volume pulse transducer simultaneously, utilizes finger contact pulse transducer obtain pulse wave and carry out a series of analysis and calculation for pulse wave, finally calculates blood pressure and obtain heart rate data simultaneously.

(2) the second diastolic pressure DIA formula in this utility model is owing to take into account the impact of standard slope, with the addition of the parameter of standard slope especially, therefore the personage for blood pressure relaxing period rate of decay exception is more applicable, and the diastolic pressure measured is more accurate.

(3) this utility model carries out individual's correction to the systolic pressure finally calculated and diastolic pressure, user needs first typing height and its measurement result data with standard mercury sphygomanometer when using electronic product of the present utility model, use individual height values and carry out individual blood pressure automatic calibration, measurement result more accurately can be obtained for different patients.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, this utility model is further illustrated.

Fig. 1 is the graph of a relation of pulse reflective wave transmission time RWTT and pulse wave transmission time PTT;

Fig. 2 is the flow chart of the blood pressure computational methods that blood pressure instrument described in the utility model adopts;

Fig. 3 is the structured flowchart of blood pressure instrument described in the utility model;

Fig. 4 is the pulse wave profile diagram of five kinds;

Fig. 5 is a concrete blood pressure waveform figure.

Labelling in figure: 1-pulse wave sensor, 2-linear current-voltage conversion circuit, 3-unity gain buffer, 4-low pass amplifying circuit, 5-analog to digital conversion circuit, 6-processor, 7-internal storage, 8-external memory storage, 9-display and typing module, 10-power supply, 11-low pressure difference linear voltage regulator.

Detailed description of the invention

By reference to the accompanying drawings this utility model is described in further detail now.These accompanying drawings are the schematic diagram of simplification, only basic structure of the present utility model are described in a schematic way, and therefore it only shows the formation relevant with this utility model.

Embodiment 1

A kind of blood pressure computational methods based on the pulse reflective wave transmission time that this utility model as shown in Figure 2 adopts, comprise the following steps:

S1: gather the pulse wave data of finger tip and store, in actual electronic measurement technique of the present utility model, the pulse waveform using finger place to record characterizes the blood pressure waveform at this place;

S2: process described pulse wave data, draw the parameter of heart rate and multiple pulse cycle, the basic key parameter reflective wave transmission time (ReturnWaveTransmissionTime that this utility model is implemented, RWTT) definition as shown in Figure 1, is the interval between the main ripple starting point of blood pressure waveform and its echo growth point.Therefore the time shaft coordinate of the main ripple starting point SPL1 of pulse wave and echo growth point SPL2 is detected in pulse cycle described in each, calculate corresponding pulse reflective wave transmission time RWTT:RWTT=SPL2-SPL1, also as shown in Figure 1, PTT is defined as the interval between the R peak value of cardiechema signals and the main ripple starting point of blood pressure (pulse) waveform in the difference that RWTT and pulse wave transmission time PTT defines;

S3: by the pulse reflective wave transmission time RWTT in each described pulse cycle in pulse wave data described in above-mentioned formulae discovery, forms RWTT array;

S4: according to described RWTT array and heart rate, set up the computing formula of RWTT array and systolic pressure and diastolic pressure respectively, calculate systolic pressure and diastolic pressure.

This utility model blood pressure instrument only uses 1 sensor measurement finger tip pulse, simply, convenient, fast, theoretical by the relevant rudimentary analyzing pulse echo and human blood-pressure, set up the correlation model of RWTT and systolic pressure and diastolic pressure, and calculate systolic pressure and diastolic pressure according to two blood pressure models, the systolic pressure that this utility model calculates and diastolic pressure are more accurate, and error is less, and the scope be suitable for is large.This utility model is by this technology and the perfect adaptation of photoelectricity volume pulse transducer simultaneously, utilizes finger contact pulse transducer obtain pulse wave and carry out a series of analysis and calculation for pulse wave, finally calculates blood pressure and obtain heart rate data simultaneously.

Embodiment 2

On the basis of the blood pressure computational methods based on the pulse reflective wave transmission time described in embodiment 1, also comprise step S5: individual is carried out to the systolic pressure finally calculated and diastolic pressure and corrects, user needs first typing height and its measurement result data with standard mercury sphygomanometer when using electronic product of the present utility model, use individual height values and carry out individual blood pressure automatic calibration, accurately measuring result to obtain.

Preferably also comprise step S21: described echo growth point SPL2 is corrected accordingly according to the contour feature of dissimilar pulse wave, in the present embodiment, the five type pulse wave profiles that the correction of described echo growth point SPL2 relates to as shown in Figure 4, divide four large classifications, wherein classification three has two types.Cheuch (notch) is presented between the echo of classification one and main ripple; There is no cheuch between the echo of classification two and main ripple, but present a bit of more smooth turn section; There is no cheuch between the echo of classification three and main ripple, but have the change of slope; Classification three point of two type, the first type main peak keeps original shape, and the second type main peak occurs broadening, is covered by the echo of appropriate section; The echo part of classification four further near and incorporate main ripple, slope variation is therebetween not obvious.In the second order waveform of classification one pulse wave, echo growth point SPL2 does not need to correct, and is the crest location that echo growth point is caused; Classification two and the first type of classification three need carry out suitable fine setting to echo growth point SPL2; The echo growth point SPL2 of classification three the second type need carry out larger adjustment, is more than adjusted to and carries out front or rear movement to transmitted wave growth point SPL2, is existing technological means.

Embodiment 3

On the basis based on the blood pressure computational methods of pulse reflective wave transmission time described in above embodiment 1 and embodiment 2, calculate systolic pressure step to be specially: according to described RWTT array, set up systolic pressure SYS formula, according to pulse wave transmission time PTT-blood pressure BP model, blood can be equivalent to by the process that tremulous pulse network propagates into finger tip the process that pulse wave propagates in a rigid conduit by ventricle, therefore pressure work equals the summation of kinetic energy and potential energy, if finger is placed on the position contour with heart when we are defined in measurement, then only can consider kinetic energy.According to relevant physical theory, can derive: wherein K _sbe 1.5, by its accuracy of lot of experiment validation; The unit of the systolic pressure SYS that this formula is released is kg/m3, and can be exchanged into millimetres of mercury by converting is unit.

Calculate diastolic pressure step to be specially: diastolic pressure is defined as the minimum point that arterial blood pressure waveform is decayed at relaxing period.The rate of decay of diastolic blood pressure depends on series of factors, is included in the Cumulate Sum Arterial system impedance (relevant to the hardness of Arterial system especially small artery blood vessel wall) etc. of systole aortic blood pressure; Same and the BP of diastolic pressure has very high degree of association, namely with PTT ²and RWTT ²all there is high degree of association; Therefore according to described RWTT array, the first diastolic pressure DIA formula is set up: wherein K _d1be 2.7, K _d2be 0.5; HR is heart rate, and the unit of the diastolic pressure DIA that this formula is released is millimetres of mercury, and in this utility model, the numerical value of parameter can convert according to environment for use; employ computing formula in this utility model, only parameter is carried out routine variations and fall into protection domain of the present utility model.

Embodiment 4

Described in above embodiment based on the blood pressure computational methods basis of pulse reflective wave transmission time, calculate diastolic pressure be specially: according to described RWTT array, set up the second diastolic pressure DIA formula: wherein K _d1be 2, K _d2be 15, K _d3be 66 (P _nor-DC), SL is standard slope, and the unit of the diastolic pressure DIA that this formula is released is millimetres of mercury.For specific individuality, the minimum level that arteriotony decays to is relevant with the die-away time that it allows, also relevant with the slope on its decay slope; Wherein be directly proportional to the cycle of this blood pressure waveform die-away time, be inversely proportional to instantaneous heart rate; And the slope on slope of decaying is relevant with the power (amplitude) of this waveshape signal in pulse (blood pressure) waveform measuring gained, therefore need to carry out standardization (normalization) process.

Accompanying drawing 5 is shown in by the derivation schematic diagram of standard slope SL, according to diagram, and T _dfor the die-away time of each wave period, P _norrepresent crest, V _norrepresent trough; Each waveform basis reference crest P _norcarry out standardization, the trough V therefore after standardization _norfor:

$V_{nor}=DC-\frac{(DC-V)(P_{nor}-DC)}{P-DC}$

The wherein DC reference level of pulse voltage waveform after amplifying that collect for sensor of DC, above T _d, V _nor, P _norwith the parameter that DC is pulse cycle, it is all parameter conventional in prior art.The slope S L that then can release the decay slope after standardization is:

$SL=\frac{P_{nor}-V_{nor}}{T_d}$

In the present embodiment, the second diastolic pressure DIA formula is more applicable for the personage of blood pressure relaxing period rate of decay exception, and the diastolic pressure measured is more accurate.

Embodiment 5

On the basis of the blood pressure computational methods based on the pulse reflective wave transmission time described in above embodiment, described step S5 is specially: by the systolic pressure calculated and diastolic pressure and in advance standard results compare, for comparison is convenient, the intermediate value of calculated systolic pressure and diastolic pressure can be used to compare, in comparison process, diastolic pressure is difference, namely deducts result of calculation by standard results and obtains difference; Systolic pressure is the relation removed, and namely standard results is divided by result of calculation, obtains systolic pressure correction parameter K respectively _scwith diastolic pressure correction parameter K _dc, by described systolic pressure correction parameter K _scsubstitute into described systolic pressure SYS formula and form systolic pressure SYS updating formula, by described diastolic pressure correction parameter K _dcsubstitute into described first diastolic pressure DIA formula and the second diastolic pressure DIA formula, form the first diastolic pressure DIA updating formula and the second diastolic pressure DIA updating formula respectively.

When user uses electronic product of the present utility model first time, can first carry out measuring with the mercurial sphygmomanometer of standard and measurement result input is inputted in advance; Then measured with electronic product of the present utility model in 5 minutes, carry out in computational process at product, can systolic pressure SYS formula and first (or second) diastolic pressure DIA formula be first used to calculate, and the standard results that its result and user input is compared, draw correction parameter K _scwith K _dcvalue and permanent storage.When using next time electronic product of the present utility model to measure, product can use systolic pressure SYS updating formula and first (or second) diastolic pressure DIA updating formula to calculate automatically.After user performs above-mentioned trimming process each time, the correction parameter K that product stores _scwith K _dcvalue can corresponding renewal.

Described systolic pressure SYS updating formula is specially: wherein K _sbe 1.5.

First diastolic pressure DIA updating formula is specially: wherein K _d1be 2.7, K _d2be 0.5, HR be heart rate.

Second diastolic pressure DIA updating formula is specially: wherein K _d1be 2, K _d2be 15, K _d3be 66 (P _nor-DC), SL is standard slope.

Described RWTT array above in all formula all can be replaced the intermediate value RTM of the RWTT array that all pulse cycles that the 10s time gathers calculate, thus the intermediate value of the systolic pressure calculated in the 10s time and diastolic pressure.

Calculate by RWTT array, then what calculate is one group of data, can be understood as real-time blood pressure data, may have deviation between these group data, or the good not mistake in computation causing certain data of certain waveform owing to gathering.Replace with intermediate value RTM, then can obtain the intermediate value of systolic pressure and diastolic pressure in 10s, guarantee correctly stable measurement result.Described heart rate HR above in all formula and standard slope SL can be replaced intermediate value or the meansigma methods of heart rate HR that all pulse cycles that the 10s time gathers calculate and standard slope SL.

Below for the patient that a height is 1.7m, there is provided this method concrete use procedure: before using electronic product of the present utility model first, this patient first records its blood pressure data with the mercurial sphygmomanometer of standard: systolic pressure 120mmHg, diastolic pressure 78mmHg.This group normal data is inputted electronic product of the present utility model by patient, and measures with electronic product of the present utility model in 5 minutes.Suppose that the intermediate value of the RWTT array that product records within the 10s time is 0.27s, and heart rate meansigma methods is 65, T in measuring first _dto be 0.56s, SL meansigma methods be meansigma methods 1.61 (supposes P _nor=2.6V, DC=2V, K _d3=40); These measurement data are substituted into systolic pressure SYS updating formula and first (or second) diastolic pressure DIA updating formula, and obtain after unified use millimetres of mercury unit:

Systolic pressure SYS=118K _scwith

First diastolic pressure DIA=69.5+K _dcor

Second diastolic pressure DIA=79+K _dc

By can K be obtained with the contrast of standard blood data _sc=120/118=1.017, K _dc=78-69.5=8.5, or K _dc=78-79=-1; Correction parameter K _scwith K _dcvalue permanent storage, next time, this patient was when using electronic product of the present utility model to measure, and product can use systolic pressure SYS updating formula and first (or second) diastolic pressure DIA updating formula calculate automatically.After this patient performs above-mentioned trimming process each time, the correction parameter K that product stores _scwith K _dcvalue can corresponding renewal.

Such as this patient is when second time uses electronic product of the present utility model to measure, and the intermediate value of the RWTT array that product records within the 10s time is 0.26s, and heart rate meansigma methods is 70, Td meansigma methods be 0.6s, SL meansigma methods is 1.33 (P _nor, DC, K _d3remain unchanged, because be identical product); By these measurement data, and the correction parameter K stored _scwith K _dcvalue substitute into systolic pressure SYS updating formula and first (or second) diastolic pressure DIA updating formula and can calculate:

Systolic pressure $SYS=1.5\×266\×\frac{{1.7}^2}{{0.26}^2}\×1.017=17348kg/m^3=130mmHg$ With

First diastolic pressure $DIA=\frac{2.7}{{0.26}^2}+0.5\×70+8.5=83.5mmHg$ Or

Second diastolic pressure $DIA=\frac{2}{{0.26}^2}+\frac{15}{0.6}+\frac{40}{1.33}-1=84mmHg.$

Embodiment 5

A kind of blood pressure instrument based on the pulse reflective wave transmission time, as shown in Figure 3, comprise pulse transducer, described pulse transducer can use the pulse transducer based on photoplethymograph, the type pulse transducer is highly sensitive, is more suitable for finger contact formula sensing equipment.

Described pulse transducer is connected with linear current-voltage conversion circuit, unity gain buffer, low pass amplifying circuit, analog to digital conversion circuit and processor in turn, described processor is also connected with power supply, and described power supply can adopt 3.7V (or 3.8V) chargeable lithium cell or Ni-MH battery to power to circuit; Also USB (5V) can be adopted to power;

Above circuit can adopt complementary metal oxide semiconductors (CMOS) CMOS (ComplementaryMetalOxideSemiconductors) Technology design and integrated.CMOS technology is cheap, and design and fabrication technology is ripe, stable performance, and development rapidly, is therefore large scale integrated chip standardization, microminiaturized preferred;

Preferred as other, above circuit also can use discrete elements to realize, and is integrated in a printed circuit board by these discrete elements; Processor can by field programmable gate array (FieldProgrammableGateArray, FPGA) or the realization such as digital signal processor (DigitalSignalProcessing, DSP) or single-chip microcomputer.

Described processor is also connected with memorizer and/or display and typing module and/or low pressure difference linear voltage regulator, and typing module is before the height of user's typing oneself or individual correct pressure value, and system can select the height values given tacit consent to and computing formula calculating blood pressure; Correct after pressure value in the height of user's typing oneself or individual, the height of user and the individual correction parameter that calculates will by persistences, until next time new typing occur just meeting replace by new numerical value; Described memorizer can be internal storage and/or external memory storage, specifically selectes according to demand, does not specifically limit.

If partial circuit needs to use 3.3V normal voltage, then low pressure difference linear voltage regulator (lowdropoutregulator, LDO) can be used to produce, and corresponding signal level can use level shifter adjustment.

The corner frequency of described low pass amplifying circuit is 20-50Hz, should not arrange too low to avoid making original pulse wave produce deformation; Follow-uply in the analysis to original pulse wave, do further digital filtering to reject low-frequency noise by processor.

The sample rate of analog-digital conversion circuit as described is set to 1kS/s, and analog to digital conversion circuit should have the precision of more than 10 to keep accuracy of sampling, and namely 10s can obtain about 10000 samples.

Described processor carries out low-pass digital filter to the data after digitized, and corner frequency is 10Hz, removes noise further.

There is provided the concrete occupation mode of blood pressure instrument described in the utility model below: pulse wave sensor 1 detects the pulse change at finger place, and exporting (usually) corresponding small area analysis signal, small area analysis signal is converted into small voltage signal by linear current-voltage conversion circuit 2.Unity gain buffer 3 has the effect that high input impedance can play signal isolation, and drives next stage low pass amplifying circuit 4 as buffer.The small voltage signal of pulse is amplified to suitable level by low pass amplifying circuit 4, and does first time low-pass filtering, and corner frequency, at about 50Hz, largely can be removed high-frequency noise and original pulse wave can not be made to produce deformation.Analog quantity voltage signal is converted to digital signal through over-sampling and exports to processor 6 by analog to digital conversion circuit 5.Analog to digital conversion circuit 5 should have sufficiently high sample rate to obtain enough original pulse waveform information, stops gathering after the data point gathering full specified quantity (such as 10000).The data of these original waveform are stored in internal storage 7 by processor 6, also can be stored in external memory storage 8.The above-described blood pressure computational methods based on the pulse reflective wave transmission time are stored in described processor.Then the data of original waveform are done advanced treating and analysis by processor 6, the algorithm provided according to this utility model finds the main ripple starting point of pulse wave and by echo growth point in each pulse cycle, and calculates the RWTT of interval therebetween as this cycle.Processor 6 calculates the rhythmic RWTT of institute accordingly and gets intermediate value RTM, and calculates heart rate, systolic pressure and diastolic pressure respectively according to algorithm of the present utility model.

Those skilled in the art should understand, embodiment of the present utility model can be provided as method, system or computer program.Therefore, this utility model can adopt the form of complete hardware embodiment, completely software implementation or the embodiment in conjunction with software and hardware aspect.And this utility model can adopt in one or more form wherein including the upper computer program implemented of computer-usable storage medium (including but not limited to disk memory, CD-ROM, optical memory etc.) of computer usable program code.

This utility model describes with reference to according to the flow chart of the method for this utility model embodiment, equipment (system) and computer program and/or block diagram.Should understand can by the combination of the flow process in each flow process in computer program instructions realization flow figure and/or block diagram and/or square frame and flow chart and/or block diagram and/or square frame.These computer program instructions can being provided to the processor of general purpose computer, special-purpose computer, Embedded Processor or other programmable data processing device to produce a machine, making the instruction performed by the processor of computer or other programmable data processing device produce device for realizing the function of specifying in flow chart flow process or multiple flow process and/or block diagram square frame or multiple square frame.

These computer program instructions also can be stored in can in the computer-readable memory that works in a specific way of vectoring computer or other programmable data processing device, the instruction making to be stored in this computer-readable memory produces the manufacture comprising command device, and this command device realizes the function of specifying in flow chart flow process or multiple flow process and/or block diagram square frame or multiple square frame.

These computer program instructions also can be loaded in computer or other programmable data processing device, make on computer or other programmable devices, to perform sequence of operations step to produce computer implemented process, thus the instruction performed on computer or other programmable devices is provided for the step realizing the function of specifying in flow chart flow process or multiple flow process and/or block diagram square frame or multiple square frame.

Although described preferred embodiment of the present utility model, those skilled in the art once obtain the basic creative concept of cicada, then can make other change and amendment to these embodiments.So claims are intended to be interpreted as comprising preferred embodiment and falling into all changes and the amendment of this utility model scope.

Claims (6)

1. the blood pressure instrument based on the pulse reflective wave transmission time, comprise pulse transducer, it is characterized in that, described pulse transducer is connected with linear current-voltage conversion circuit, unity gain buffer, low pass amplifying circuit, analog to digital conversion circuit and processor in turn, and described processor is also connected with power supply.

2. blood pressure instrument as claimed in claim 1, it is characterized in that, described pulse transducer only arranges one.

3. blood pressure instrument as claimed in claim 2, is characterized in that, described processor is also connected with memorizer and/or display and typing module and/or low pressure difference linear voltage regulator.

4. the blood pressure instrument as described in any one of claim 1-3, is characterized in that, the corner frequency of described low pass amplifying circuit is 20-50Hz.

5. the blood pressure instrument as described in any one of claim 1-3, is characterized in that, the sample rate of analog-digital conversion circuit as described is set to 1kS/s.

6. the blood pressure instrument as described in any one of claim 1-3, is characterized in that, described processor carries out low-pass digital filter to the data after digitized, and corner frequency is 10Hz, removes noise further.