CN101484068A - Wearable blood pressure monitoring system - Google Patents

Abstract

A system for measuring/monitoring the vital signs of a patient especially blood pressure, comprising a plurality of electrodes arranged at least in the waistband of an undergarment, and means for deriving measurements from the electrodes using pulse- transit times.

Description

Wearable blood pressure monitoring system

The present invention relates to the monitoring system that is suitable for continuously or at least termly person under inspection's vital sign monitored, and be particularly related to a kind of system that is used to measure blood pressure.

In all developed countries, the influence to mortality rate and sickness rate increases day by day as myocardium infarction, congestive heart failure or hypertensive cardiovascular disease.Thereupon, for providing the demand that patient's vital sign is carried out long-term continuous monitoring of chance, the performance of estimating cardiovascular system progressively increases.In the past, usually use various blood pressure measuring system, need pressurize band or similarly in the time will measuring, must be attached at patient's equipment specially of these blood pressure measuring systems, and this blood pressure measuring system also needs suitable and skilled clinician to come they are operated.Therefore, such equipment only limits to use in doctor's place or in hospital usually, and for example, they are unsuitable for continuous or periodic monitoring purpose.

Therefore, the present invention aims to provide a kind of blood pressure measuring system.This system is used for deriving from detected signal (as electrocardiogram) the pulse conduction time method of measured value, and this system also is used to monitor other vital sign.It is particularly suitable for realizing in the underwear of the sustainable wearing that is integrated with measuring transducer or electrode, so that directly contact person under inspection's skin.Preferably, this clothes comprises at least 4 electrodes, so that measure not allowing to carry out PTT under the situation of the extra connection of patient body.

Preferably, this pick off is that a kind of specific applicator system, gel or paste of not needing produces the suitable pick off that electrically contacts, for example, they can be the dried electrodes of being made by conductive rubber of exploitation recently, and this dried electrode only relies on the excretory sweat of nature just can constitute a conducting bridge between skin and electrode.Preferably, this underwear comprises the underwear that has built-in electrode at least in waist area.

Preferably, arrangement of electrodes is transmission and the ECG of measurement pulse by central artery and left and right sides femoral artery.This system also can be arranged as monitoring person under inspection's body temperature, posture and active level.

Preferably, pulse detection is to utilize bioimpedance method to inject small AC current by utilizing first electrode pair, and utilizes second electrode pair to detect the change in voltage that is caused by this injection current, realizes thereby produce the impedance plethysmogram.The preferred arrangements of this electrode is to make it can measure the plethysmogram of central aorta and left and right sides femoral artery.Simultaneously, it also is possible utilizing dried electrode in the belt to measure ECG.

In conjunction with the accompanying drawings, some embodiments of the present invention will be described below by way of example, wherein:

Fig. 1 is the sketch that shows main tremulous pulse in the human body;

Fig. 2 shows the typical electrode that is used for impedance plethysmogram and arranges;

Fig. 3 shows the dried electrode of conductive rubber;

Fig. 4 shows the underwear that is integrated with dried electrode;

Fig. 5 shows the ECG signal of measuring at waist;

Fig. 6 diagram shows the relative position and the measurement of correlation zone of integrated dried electrode in underwear;

Fig. 7 is the sketch map of signal processing unit;

Fig. 8 shows ECG, IPG1 and the IPG2 signal with systematic survey of the present invention; And

Fig. 9 is the feature of the signal among Fig. 8.

This invention is intended to the pulse wave velocity method as the means of measuring life parameters.

Pulse wave velocity (PWV) method is a kind of proper method that is used for the monitoring force mathematic(al) parameter, but it needs one group (at least two) to be distributed in health pick off on every side.For example, nearest research is verified has good dependency between blood pressure BP and the pulse wave velocity (PWV).For example, after the calibration via the blood pressure baseline measurements of utilizing band to obtain, this technology allows the determining of heart beating one by one of BP.Typically, blood pressure in the tremulous pulse and the relation of PWV concern by Moens-Korteweg to be expressed, and it can be derived from Hydrodynamics Theory:

$c=\sqrt{\frac{{\mathrm{<figure-callout\; id="2"\; label="hE\; t"\; filenames="A200780025297E00111.png,A200780025297E00151.png"\; state="\{\{state\}\}">hE</figure-callout>}}_t}{2\mathrm{\&rho;R}}}$

Equation 1:Moens-Korteweg equation is through being usually used in describing the relation between pulse wave velocity and the blood pressure

Wherein: c=pulse wave velocity, E _t=tangent modulus of elasticity, ρ=density

R=tremulous pulse radius, h=arterial wall thickness.

Pass through experimental verification is:

E＝E ₀e ^αp，α≈0.017mmHg ^-1

Above-mentioned relation provides the contact between pulse wave velocity and blood pressure (P) variation.This calibration steps is necessary to weigh the conversion of PWV to BP, other parameter (α, E ₀, h r) obviously depends on person under inspection and very difficult directly measurement.

This PWV can propagate the used time of certain distance by different way by the gaging pressure ripple and determine (this time will be called as pulse conduction time PTT) in Arterial system, for example:

1, pulse passes through the time difference apart from two points of d.

2, the time difference between the transmission pulse in the tremulous pulse under R peak and a certain position in the ECG signal.

Typically be provided with in the document:

1, ECG and photoelectricity capacity of blood vessel figure PPG; PTT is provided by the time difference between the characteristic point among R peak and the PPG.PPG can record at the diverse location of health such as ear or finger.

2, the biological impedance of ECG and arm (impedance capacity trace IPG); PTT is provided by the time difference between the characteristic point among R peak and the IPG.

3, the biological impedance (IPG) of the impedance cardiography (ICG) of chest and arm; PTT is provided by characteristic point among the ICG and the time difference between the characteristic point among the IPG.

4, the biological impedance (IPG2) at second position place on the impedance plethysmogram (IPG1) at primary importance place and the arm on the arm; PTT is provided by characteristic point among the IPG1 and the time difference between the characteristic point among the IPG2.

If adopt clinical criteria pick off or method, all there are some shortcomings in all these methods, especially in individual healthcare applications.The pick off of state of the art as measuring the finger or the ear pick off of photoelectricity capacity of blood vessel figure or bioimpedance method, is quite inconvenient in the daily life of needs finger and ear PPG pick off or specific medical electrode, and it must stick on the skin.Therefore, the pick off of this state of the art is unsuitable for carrying out long-continued monitoring in individual health care is used.

Caption among Fig. 2 the General Principle of biological impedance, it shows the technology of the lower limb 2 that is applied to the patient, wherein, small AC current via first electrode pair 4 by lower limb 2.Exciting current is the constant high frequency rate alternating current with low-down amplitude (about 1 milliampere), and therefore, imperceptible this electric current of patient and this electric current are without any great physiological effect.

Then, another electrode pair 6 is used for detecting the change in voltage that is caused by this exciting current, and it is the tolerance of the impedance variation that causes of volumetric blood and velocity variations.This makes it possible to measure arterial volume pulsation via control/measuring circuit 8.

Should be noted that same principle also can be applicable to the measurement to other zone of health.Therefore, this invention is intended to measuring as lumbar region and the 12 and 14 indicated left and right sides femoral artery of 10 indicated persons under inspection in the sketch map of Fig. 1, this is because these location tables illustrate the main branch point of person under inspection's Arterial system.Simultaneously, also there is remarkable advantages the belt position, that is: owing to the normal position of this belt position corresponding to the clothes belt, so the person under inspection can accept to be installed in rightly this regional electrode more naturally.This position also significantly near patient's heart, is measured to be used for ECG, and, to compare with other possible monitoring points (as extremity), it still less produces hydrostatic effects and motion artifacts.

Fig. 3 shows the dried electrode of being made by conductive rubber, and this dried electrode has flexible main body, therefore is very suitable for being integrated in certain part of medicated clothing.In preferred arrangements of the present invention, kind electrode is integrated in the underwear, underwear 16 as shown in Figure 4, wherein, shown in position 18, many such electrodes are installed in the belt.Like this, only by the electric conductivity of the excretory sweat of nature, these electrodes are suitable for electrically contacting well with the skin of wearer, and need not any special paste or gel.As shown in the drawing equally, behind the slide fastener form pocket shown in 20, also can be integrated in the belt of clothes corresponding to the signal processing circuit 20 of circuit shown in Figure 28.

Fig. 5 shows the person under inspection's who is in quiescent condition typical ECG, this ECG utilizes the arrangement of electrodes of Fig. 4 to record, wherein, electrode position approaches patient's buttocks, thereby these electrodes can be relatively well spaced apart, and therefore, these electrodes surrounding the suitable big volume of person under inspection's health.As can be seen, all important areas, promptly P ripple, QRS complex wave and T ripple are clearly depicted in this signal.

Fig. 6 shows different zones with schematic form, and wherein suitable underwear can have Integrated electrode, thereby can measure in femoral artery position, the left and right sides and waist area as shown in Figure 4.In the figure as can be seen, first electrode pair 22 in the belt is arranged in the buttocks position, injection current I1 in first electrode pair, promptly usually corresponding to as shown in Figure 2 electrode 4, simultaneously, another electrode pair 24 in the belt is used for change in voltage V1 is measured accordingly, promptly usually corresponding to the electrode among Fig. 26.

Other electrode 26 and 28 is arranged in lower limb position, the left and right sides, and, by this way, for example, but between corresponding belt electrode 22 and right lower limb electrode 26 injection current I2 so that voltage V2 records at electrode 30 places with respect to the belt position.Similarly, by injection current I3 between left lower limb electrode 28 and corresponding belt electrode 22, voltage V3 is recorded at electrode 32 places with respect to belt.

Fig. 7 shows and is applicable to the signal processing circuit that is integrated into the clothes shown among Fig. 4 20, wherein combines multiple function in same unit.The front-end circuit 34 that is used for impedance is connected to CPU 38 with the front-end circuit 36 that is used for the ECG measurement, and, also can incorporate 3 axis accelerometers 40 and temperature sensing equipment 42 in order to allow that patient's motion and patient's posture and active detection are compensated.

Power supply 44 is used for being this unit power supply that it preferentially adopts long-life or rechargeable battery, and RF transceiver 46 makes this equipment carry out data communication with external system (as user interface).Also can incorporate storage device 48 into, to allow storage or data cached where necessary.Like this, this equipment also can be used as " Holter monitor " (ambulatory electrocardiogram equipment), so that write down cardiomotility in the time period of a prolongation.

Fig. 8 shows the example of the signal measurement that is undertaken by this system, and wherein Fig. 8 (a) shows the ECG measurement of obtaining at the belt place.Equally, Fig. 8 (b) shows the IPG1 (impedance plethysmogram) that measures at the belt place, and Fig. 8 (c) shows the corresponding plethysmogram IPG2 that obtains in right femoral artery.

Fig. 9 is the amplification close up view of signal among Fig. 8, and it has shown how to extract feature from signal.By comparison diagram 9 (a) and Fig. 9 (b), promptly from ECG to IPG1, can derive pulse conduction time 1, and, by comparison diagram 9 (a) and Fig. 9 (c), promptly from ECG to IPG2, can also derive pulse conduction time PTT2.

Thereby, should be noted that system of the present invention allows to adopt following different measurement:

The signal of measuring:

● person under inspection's ECG, cardiac electrical activity (not having standard lead)

● enter the volumetric blood pulse (the impedance plethysmogram (IPG) by left and right sides lower limb records) of left and right sides lower limb between heart beat period, this has shown the mechanical property of cardiomotility.

● 3 axle accelerations (static state and dynamic)

● temperature

● the time

Therefore, this system can provide the information of a large amount of cardio-vascular parameters of deriving from the signal of measuring, as:

● heart rate

● arrhythmia detection

● 4 several pulse conduction times (ECG-〉IPG1, ECG-〉IPG2, ECG-〉IPG3, IPG1-〉IPG2)

● arterial stiffness/enhancing index

● relative blood pressure

● absolute blood pressure

● to the hemoperfusion of left and right sides lower limb

● stroke volume

● movable tolerance (tranquillization, posture, motion)

● stem from the background information (time, temperature, acceleration) of these signals

Therefore, various useful application is possible, as:

-continuous blood pressure monitoring

-sleep quality detects

The management of-hypertension

-blood pressure Holter monitoring

-old people nursing

-continuous monitoring is as the continuous monitoring during cardiac rehabilitation.

Claims (14)

1, a kind of vital sign that is used to measure/monitor patient system of blood pressure especially comprises:

At least be arranged in a plurality of electrodes in the belt of underwear, and

Be used to utilize the pulse conduction time to derive the device of measured value from described electrode.

2, system according to claim 1, wherein, described electrode comprises the dried electrode of conductive rubber.

3, system according to claim 1 and 2, wherein, four electrodes are arranged in described belt, and described four electrodes comprise first electrode pair that is used for injection current and are used to measure second electrode pair of the change in voltage that causes, thereby can utilize the bio-impedance technology to measure.

4, according to the described measuring system of aforementioned arbitrary claim, wherein, described arrangement of electrodes is for measuring the pulse that transmits in described patient's central aorta.

5, according to the described measuring system of aforementioned arbitrary claim, wherein, described underwear comprises underwear.

6, measuring system according to claim 5 wherein, is provided with extra electrode at the shank of described underwear, so that measure the pulse that transmits in the muscular artery of the left and right sides.

7, according to the described measuring system of aforementioned arbitrary claim, wherein, the pulse conduction time between the pick off of opening by assay intervals carries out pulse wave velocity and measures.

8, according to each described measuring system in the claim 1 to 6, wherein, the time difference between the pulse that transmits in the tremulous pulse by given sensing station place on R peak and the health among the detection ECG is carried out pulse wave velocity and is measured.

9, according to the described measuring system of aforementioned arbitrary claim, also comprise the 3-axis accelerometer, can detect described patient's posture or active level, and can compensate by the pseudo-shadow of kinetic signal by the described system of described accelerometer.

10, according to the described measuring system of aforementioned arbitrary claim, comprise signal processing unit, described signal processing unit has the front-end circuit that is used for sensor-lodging, be used to store the device of data, and be used for handling and/or radio-frequency receiving-transmitting apparatus that control device communicates with external data.

11, measuring system according to claim 10, wherein, described unit also is suitable for receiving described patient's manual input and sends the information relevant with described system and described patient's situation to described external device (ED).

12, according to claim 10 or 11 described measuring systems, also comprise the alarm that is used to warn the critical situation of described patient.

13,, also comprise the device that is used for sending warning to the professional auxiliary source in outside according to each measuring system among the claim 10-12.

14, according to each measuring system among the claim 10-13, wherein, with described system layout for being used as the Holter monitor or Holter ECG equipment is operated, so that on a time period that prolongs, write down cardiomotility.

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