WO1999059466A1

WO1999059466A1 - Ecg monitoring apparatus controlling blood pressure measurement

Info

Publication number: WO1999059466A1
Application number: PCT/HU1998/000053
Authority: WO
Inventors: Miklós ILLYÉS; József VÖRÖS; Béla KÖVÉR; Péter KENDE; László MELEG
Original assignee: Illyes Miklos; Voeroes Jozsef; Koever Bela; Kende Peter; Meleg Laszlo
Priority date: 1998-05-19
Filing date: 1998-05-19
Publication date: 1999-11-25
Also published as: AU7543898A

Abstract

The field of the invention is a combined electrocardiograph (ECG) and blood-pressure measuring apparatus (10) which is provided with ECG sensitive elements (5) to be fixed onto body surface (skin) of a patient and a pressure measuring cuff (1) driven by a pump (5) and signal outputs are connected to inputs of signal receiving units (21) connected to inputs of a controlling and evaluating device (11), which in turn is connected to input of a signal storing device (22). Characteristic features of the invention are that outputs of controlling and evaluating device (11) processing signals of ECG sensitive elements have controlling connections with said pump (2), and valve (3) of cuff (1) and signal storing device (22) of the apparatus (10) includes on-volatile memory (14) and a known per se connecting bus (17) which enable bidirectional data transfer with a PC. Characteristic features of the procedure according to the invention are that samples are taken from each new ECG signal series, characteristic i.e. statistically significant values thereof are determined, then differences are made between determined characteristic values of ECG features and actual values of ECG; the obtained differences are compared with previously theoretically determined limit values and in the event of surpassing said limits an output controlling signal is induced which starts the blood pressure measuring device (20); finally values of blood pressure and ECG signals surrounding those which produced inducing difference signal are simultaneously stored into non-volatile memory (14).

Description

ECG MONITORING APPARATUS CONTROLLING BLOOD PRESSURE MEASUREMENT

Field of invention:

A combined electrocardiograph (ECG) and blood-pressure measurement apparatus (haemodynamometer) for studying the relationship of the myocardial ischaemical events and the arterial blood-pressure, provided with sensitive elements which should be placed onto body surface of the patient and a pump-driven pressure measuring cuff. The signal outputs of all these elements are connected to inputs of a signal receiver connected to the input of a control and evaluating device, which in turn is connected to input of a signal storage unit. This apparatus and a procedure based on said measurements are the subject-matter of this application.

Prior art

There are numerous solutions in the state of art with the aim to carry out a continuous medical observation of the patient like in a hospital, nevertheless he should not occupy a bed in hospital but could rest at home and could move freely according to his everyday life. This objective requires portable measuring instruments, which provide series of data equivalent to results of a 24 hours long continuous measurement rich of details, showing all anomalies for evaluation, and said apparatuses should be inexpensive, light and simple in usage. The portable blood-pressure measuring instrument according to US patent No. 4,830,018 advertises the patient according to a built-in timing program to perform the actual blood-pressure measurement and its results are stored in the apparatus.

The apparatus according to Hungarian patent No. HU 176 288 perceives pulse of the patient and performs a blood-pressure measurement on the base thereof. According to US patent No. 4,608 994 the blood-pressure measurement is combined with heart-rate and temperature ones.

All known procedures are either very expensive or complicated and in this reason they cannot turn into widely used tools according to medical expectations, or although they are inexpensive and simple but do not afford data series with all required details and related to required time period needed to a complete evaluation by a physician. A software system meeting all logically completely defined medical requirements can be successfully developed in general, but no hardware configuration is known yet in the present state of art, which could perform such software in accordance of above stated physical and economic requirements.

Disclosure The present invention has the target to develop an inexpensive, easily applicable and comfortable portable personal measuring apparatus, which provides with a series of data about the variation of blood-pressure relating to a time period adequate for a safe evaluation, rich on details as required in regard of a whole picture of blood-pressure for the physician. The invention is based on the recognition that moments for blood-pressure measurement can be very accurately defined as function of ECG measurement data provided that ECG data are evaluated continuously in several aspects with regard to individual nature of person being examined

The invention is based on the recognition that the price of apparatus can be substan- tially reduced by means of reduction of storage and storing only data of those events which would be evaluated effectively by a physician, even if he had the whole data series. The examination program being reduced to time intervals which are relevant in view of measurement technique and mathematical statistics enables to reduce operation of electric motors in the apparatus, that energy supply sources can also be considerably reduced in regard of their weight, dimensions and expenses equally.

It is known, that it has been recently ascertained that diminution of ST level in ECG can be an expression of abnormally insufficient blood supply of heart musculature and as such can be a highly probable prediction of event of myocardial ischaemic events. According to our recognition underlying to invention the simultaneous registration and evaluation of images of ECG and blood-pressure enables the device to show local deficiencies of oxygen in the tissues as complement for attending physician and to reveal silent ischaemic events.

It is our further recognition underlying to invention, that software defining indirectly but with full reliability timing of necessary and at the same time indispensable examinations can be executed by means of a relatively simple, inexpensive but very effective and reliable hardware.

On the basis of our aforementioned recognitions the inventive solution is a combined apparatus, consisting of an electrocardiograph and a blood-pressure measuring device, said apparatus disposes over sensitive elements which should be placed onto body surface that is onto skin of the examined person, and it is furthermore provided with a motor-driven pump operating the pressure measuring cuff, and signal outputs of sensitive elements of electrocardiograph and those of pressure measuring cuff are connected to signal receivers, the outputs of latter devices are connected to a controlling and evaluating device and to a control- ling and signal storing one. The apparatus can be characterized by facts, that the controlling and evaluating device which processes data entering from sensitive elements of electrocardiograph has controlling connection with the pump driving said cuff on one hand and with valve reducing pressure in the cuff, the signal storage device contains a non-forgetting memory and the apparatus is provided with a known per se bus enabling both-way data transfer with an external PC .

The apparatus made according to invention can be advantageously characterized by the fact, that said controlling and evaluating device contains an unit which evaluates R- amplitude, where R-amplitude means the height of R-peak of a characteristic curve of ele- crocardiogram. The apparatus made according to invention can be also advantageously characterized by the fact, that said controlling and evaluating device contains a R to R rhythm evaluating unit where the distance between two adjacent R-peaks i. e. their periodicity and frequency should be understood under R to R rhythm.

The apparatus made according to invention can be furthermore advantageously char- acterized by the fact, that said controlling and evaluating device contains a ST level evaluating unit, where ST level means ordinate of ST sections in two adjacent P, Q, R, S and T segments of a characteristic ECG image, which gives information about ST depression in relation to regular level of ST.

The apparatus made according to invention can be furthermore advantageously char- acterized by the fact, that said controlling and evaluating device contains more than one of the aforementioned evaluating devices or all of them, and the controlling and evaluating unit and said evaluating ones are carried out as united into a common microprocessor

An advantageous accomplishment of the apparatus according to invention can be characterized by the fact, that said connecting bus is a standard RS-232 C connection appli- cable for serial data transfer.

A further advantageous accomplishment form of the apparatus according to invention can be characterized by the fact, that the connection between the apparatus and PC s matched by an optical connection, that is the immediate electric connection is broken by means of an optical one, which ensures shock-proof connection, this way enabling the phy- sician to control proper placement of sensitive elements of electrocardiograph by means of PC of the hospital without any danger of electric shocks for the examined person. The optical connecting device is included between the controlling and evaluating device and an interface unit which unit is organic part of said apparatus in view of signal handling, but physically is a part of said PC so it does not burden the apparatus. The signal receivers of the apparatus according to invention contain an operational amplifier selecting change of the signal to be evaluated from the basic one, a noise filter and an A/D transformer in a further advantageous implementation form.

A characteristic feature of said apparatus according to invention is that in event of output signal denoting anomaly delivered by any of said evaluating units the output signal of controlling and evaluating unit starts and performs the blood-pressure measurement according to programmed timing procedure receiving simultaneously data of blood-pressure measurement.

This solution according to our invention covers also a procedure of simultaneous handling of signals generated by work of heart muscles and electric ones of blood-pressure measurement, the analogous electric signals obtained from sensitive elements of electrocardiograph and those from pressure sensor of the blood-pressure measuring unit are lead into an evaluating unit after amplification, filtering of noise and digitalization according to said procedure. This procedure can be characterized by the fact, that an unknown series of electrocardiocardiograph signals is sampled, the characteristic features of said electrocar- diogram are defined and then differences between defined features and actual values thereof made of continuously arriving ECG signals are established and compared with previously defined limits, and when any of this differences surpasses said limit value, a control signal initiating the blood-pressure measurement is induced and finally the values resulting from blood-pressure measurement and the environment of ECG signal series giving the difference over limit value are stored for further processing.

The procedure can be also advantageously characterized by the fact, that R- amplitudes of ECG data series are treated as characteristic feature of ECG.

The procedure can be advantageously characterized furthermore that rhythm R to R of the ECG data series is treated as characteristic feature of ECG. The procedure can be advantageously characterized furthermore that ST level of the

ECG data series is treated as characteristic feature of ECG.

The procedure can be advantageously characterized furthermore that more than one of said features are simultaneously handled during establishment and modification of electric signals. Finally, the procedure can be advantageously characterized that an output containing the ECG image, blood pressure and oxygen supply of tissues relating to the same moment is made for the user.

The apparatus and procedure according to invention are shown using attached figures, without any limitation either to applicability or to extent of protection claimed. Drawings:

Figure 1. Block-scheme of the apparatus according to invention.

Figure 2. Schematic flowchart of operation of the apparatus

The central unit of the combined ECG and blood-pressure measuring apparatus 10 is a controlling and evaluating device 11 to which output signals of electrocardiograph (ECG) 6 are connected through a signal receiving unit 21 on one hand, and output signals of blood- pressure measuring device 20 similarly to the previous device through a signal receiving unit 21. Twice two sensitive elements 5 of those of electrocardiograph device 6 transmit measured signals from the body of the examined person to controlling and evaluating device 11 and a fifth, driven sensitive element 5 provides with control signal. The signal receiving unit 21 contains an amplifier 7, expediently a noise filter 8 and an analogous to digital signal transformer 9, the output of said electrocardiograph 6 is connected to its input points, and output of said signal receiving unit 21 is connected reasonably to input of controlling and evaluating device 11. Pneumatic part of blood-pressure measuring device 20 consists of a cuff 1 to be put onto arm of the examined person, a pneumatically connected motor-driven pump 2, (M), and a valve 3 (Sz). The pneumatic part is connected also pneumatically to pressure sensing unit 4 the output thereof is connected onto a signal receiving unit 21 as output of blood-pressure measuring unit 20. The structure and construction of this signal receiving unit 21 is identical with the signal receiving unit 21 used in the transmission line of ECG signals. Starting device of pump 2 and opening device of valve 3 are connected to one of outputs of controlling and evaluating device respectively on a way applicable to transmit control signals. The controlling and evaluating device contains a R-amplitude evaluating unit 24, a R to R rhythm evaluating unit 25, a ST level evaluating unit 26 in addition to a control unit and an internal ROM memory 12 as well. The controlling and evaluating device 11 is carried out advantageously united into one microcontroller (MC). The controlling and evaluating device 11 is connected with a signal storing unit 22 consisting of a memory eligible for writing (RAM) 13, and a non-forgetting memory (EPROM) 14 by means of one bus for each enabling both-way data transfer. The controlling and evaluating device 11 is provided with a connecting bus 17 enabling both-way data transfer of type RS-232 C. The con- necting bus 17 is connected to a PC through an appropriately configured and enabling the correct matching interface 16 The PC may be the hierarchically resident computer of the apparatus 10. The interface 16 is substantially part of the external PC and it is connected to apparatus 10 at the time when said apparatus 10 is connected to PC. In order to extend field of applicability of the apparatus 10 an optical connecting device 15 is inserted which re- places electric signals with light ones, this way it discontinues the immediate electric connection between external PC and apparatus 10.

The schematic block structure of apparatus 10 is represented in Figure 1. The apparatus itself is small and light, the box containing it can be held in a big pocket or in a bag on the belt with exception of the cuff 1 and sensitive elements of ECG 5 which are lead out from said container box. We describe the application and operation of the apparatus 10 according to logical flowchart in the Figure 2. The apparatus 10 is programmed for long-time observation and the sensitive elements of ECG 5 are placed onto body by a specialized physician. The physician verifies the appropriateness of placing by means of the hospital's PC, and the optical connecting device 15 disconnects apparatus 10 from voltage of PC this way protects the patient against electric shocks. The apparatus 10 being in operation takes a representative sample from ECG image entering through ECG sensitive elements 5 into controlling and evaluating device 11 makes up ECG characteristics individually characterizing the examined person and stores them into memory. The individual ECG characterictics and procedure to make them are determined on the basis of medical and biological aspects and their essential features are as follows: the known ECG curve goes after a relatively small height P on a relatively constant level into point Q, then begins a higher rise to peak R, after trailing edge of said peak R a relatively constant or slightly oscillating section begins from point S up to rise T of medium height. The features characterizing an individual person are the height of R (R-amplitude), the heart rhythm, that is the distance between two adjacent peaks R (rhythm R to R) and finally the level of section S to T (ST level). The deviation of value of any said feature of ECG image from the normal one characterizing the person indicates an anomaly, that is an unfavorable event, or at least a remarkable one. Having established and stored the individual ECG features the apparatus 10 continuously detects, processes and evaluates data coming from measurement comparing them to individual ECG features. During this procedure the controlling and evaluating device distributes signals to R- amplitude evaluating device 24, to R to R rhythm evaluating one 25, and to ST level evaluating one 26. The same procedure is performed after establishment of individual ECG features during continuous ECG measurement and processing of measured data. Simultaneous operation of said separate devices enables a real-time answer in event of occurrence of an abnormal condition. If any one of devices 24, 25 or 26 or simultaneously more than one thereof indicate an anomaly to the controlling device 11, it initiates the measurement of blood-pressure through its controlling output, that is the motor driving pump 2 starts operation, valve 3 is closed and cuff 1 is blown up and the measurement of blood-pressure is performed according to built-in program. It should be remarked here that basic program of measurement of blood-pressure measurement can be specified in regard to some parameters e. g. ascending of pressure, its highest value and its reduction, according to examined person by attending physician. The program of blood-pressure measurement is stored in the internal memory 12. If any anomaly is recognized in the ECG image relating to one or simultaneously to more features, said ECG image surrounding anomaly is stored together with results of blood-pressure measurement into non-forgetting memory 14 by apparatus 10. So it is procured that data recorded according to Holter's program (measurement during 24 hours) are stored in a semiconductor memory. All significant ECG values and those of blood-pressure measurements are recorded and available for attending physician despite of the ECG record of whole period is not made. Data collected by said procedure are repre- sented in an output containing reasonably in analogous form the simultaneous proceedings of ECG image, blood-pressure and supply with oxygen of tissues of heart muscles as well as possible deficiency of oxygen thereof in time. The silent ischaemic events, and their predecessor situations can be read well from output record. Signals arriving from cuff 1 are transformed into analogous electric signals by pressure sensor 4 then transformed into digi- tal ones by A/D transformer 9 for controlling and evaluating device 11. As resolution of A/D transfer is limited, the amplification of changes and exclusion of background noise are ensured by an amplifier 7 and a noise filter 8 installed before said A/D transformer. A compensating series of sensed noise signals with inverse phase is transferred through driven ECG sensitive element 5 during ECG measurement in order to reduce noise level. The des- tination and function of signal receiving unit 21 is the same as said above.

The combined ECG and blood-pressure measuring device according to invention resolves the first time Holter's examination of cardio-vascular diseases and control of effects of medicaments at a level meeting physician's requirements and those of comfort, safety, technique and economics as well. The completely new solution of this measuring instrument offers modem hardware possibilities to carry out a modem medical program. The simultaneous measurement of ECG and blood pressure means not only combination of two measuring instruments or resolves combined performance of two measurements by means of one measuring instrument but it carries out a new type of measurement. It controls blood- pressure measurement on the basis of a new type of evaluation of ECG data and chooses ECG values to be stored. Using this, a really comfortable, small, light and relatively inexpensive measuring instrument stores all significant results of a Holter's examination. The blood-pressure measuring cuff can be any commercial product which can be joined an oscillometric blood-pressure measuring instrument, pump, valve, and pressure sensing unit can be any known products in an advantageous realization of the apparatus according to invention. In the prototype products of OMRON were used'. We used as ampli- fier an operational amplifier of type TLC 214, as A/D transformer of type MAX 186 converter, as MC e. g. a μPD78014 for internal ROM, as RAM an unit of 62256, as non- forgetting memory (EPROM) a 28F008 FlashROM. The units constituting evaluating devices of controlling and evaluating unit are as follows: AD, Serial Interface O,Timer O,RAM for R-amplitude evaluating unit, the parts of ST level sensing device are similar to those of R-amplitude sensing one. The standard serial data transfer is carried out by means of Serial Interface 1, Timer 1.

As it is shown, the procedure according to invention is not a diagnostic one, because it does not establish either any disease or deterioration of health state or any one disease out of possible damages or a height or extent of a defined deterioration of health state. The pro- cedure according to invention relates to handling, control and selection of circulation of electric signals, as well as recording and storing of chosen groups of signals only, for purposes of a later evaluation by physician or biologist.

Claims

C laim s

1. A combined electrocardiograph (ECG) and blood-pressure measuring apparatus for studying the relationship of the myocardial ischaemical events and the arterial blood- pressure, provided with ECG sensitive elements fixed on the patient's body surface (skin) and a pump-driven cuff the signal outputs thereof are connected to signal receiving input points of a controlling and evaluating device which in turn is connected to a signal storing device, characterized by that, the outputs of said controlling and evaluating device (11) processing output signals of ECG sensitive elements (5) are in controlling connection with pump (2) and valve(3) of cuff (1), furthermore said signal storing device (22) of this apparatus (10) includes a non-forgetting memory (14) and a known as such connecting bus (17) enabling a both-way data transfer with a PC.

2. The apparatus according to Claim 1, characterized by that, the said controlling and evaluating device (11) contains an R-amplitude evaluating unit (24).

3. The apparatus according to Claim 1, characterized by that, the said controlling and evaluating device (11) contains an R to R rhythm evaluating unit (25).

4. The apparatus according to Claim 1, characterized by that, the said controlling and evaluating device (11) contains a ST level evaluating device (26).

5. The apparatus according to any of Claims 1 to 4, characterized by that, the said controlling and evaluating device (11) several evaluating devices which are combined in a common microprocessor (MC).

6. The apparatus according to any of Claims 1 to 5 characterized by that, the connecting bus (17) is a type of RS-232 enabling standard serial signal transfer.

7. The apparatus according to any of Claims 1 to 6 characterized by that, the interface unit (16) of connecting bus (17) is matched to controlling and evaluating device (11) by means of an optical connection unit (15).

8. The apparatus according to any of Claims 1 to 7 characterized by that, the signal receiving unit (25) includes an amplifier (21) enhancing changes, advantageously a noise filter (8) and an A/D transformer (9).

9. A procedure for simultaneous handling of electric signals generated by activity of muscles of the hart and those generated by blood-pressure measurements to study the relationship of the myocardial ischaemical events and the arterial blood-pressure by method that analogous electric signals obtained from sensitive elements of ECG and those obtained from Blood-pressure measurement are transferred advantageously after amplification, filtering of noise and conversion into digital signals into an evaluating device, characterized by that, the samples are taken from a new series of ECG signals, characteristic, i. e. statistically significant values thereof are determined, thereafter differences are defined between actual values of characteristic features of entering ECG data series and determined characteristic ones the obtained differential signals are compared with previously determined limit values in event of surpassing said limits an output controlling signal is induced which starts operation of blood-pressure measuring device (20) and the ECG signal series surrounding those having produced said inducing difference signal and simultaneously the values of blood-pressure are stored into non-forgetting memory.

10. The procedure according to Claim 9 characterized by that, the R-amplitude of ECG data series is treated as characteristic feature of ECG.

11. The procedure according to Claim 9 characterized by that, the R to R rhythm of ECG data series is treated as characteristic feature of ECG.

12. The procedure according to Claim 9 characterized by that, the ST level of the ECG data series is treated as characteristic feature of ECG.

13. The procedure according to any of Claims 9 to 12 characterized by that, the several ECG features of said ones are simultaneously utilized in the procedure and any of them can induce said controlling output signal.

14. The procedure according to any of Claims 9 to 13 characterized by that, an output containing the ECG image, blood pressure and oxygen supply of tissues relating to the same moment is made for the user.