DE8624683U1 - Disc-shaped sensor element for electrocardiograms - Google Patents

Description

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description

Disc-shaped sensor element for electrocardiograms

The invention relates to a disk-shaped sensor element for Taking electrocardiograms.

Such sensor elements are in the form of the usual electrodes known, of which then when an electrocardiogram should be included, each several at different Places of the chest and possibly also on the Extremities are attached. The need for multiple electrodes is troublesome for various reasons. First off multiple electrodes must be attached, which takes more time. Second, you have a larger number of wires, which must also be properly connected so that the electrocardiogram can be recorded correctly.

However, the multiple sensor elements are particularly annoying, if a patient is not examined for a relatively short period of time should be, but should be monitored over a longer period of time with the help of his electrocardiogram. In this case the multiple electrodes are very cumbersome.

The object of the invention is to provide a sensor element create that is more simply structured and for the examination, but especially the monitoring of patients is particularly suitable.

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The solution according to the invention consists in / that the sensor element has at least two on its one surface Has electrodes

The merit is to be attributed to the invention, recognized to have that it is not necessary to be different, spatially use separate electrodes. This prejudice that the electrocardiogram has existed since the existence of the Invention overcome.

The advantage is particularly evident in patient monitoring. Another very important one Simplification of patient monitoring occurs when if, according to the invention, the electrodes are not connected to the measuring device or monitoring device via wires or cables but wirelessly by adding on the disc-shaped Sensor element for this purpose a small transmitter is arranged. Its transmission power and thus the size of the to be accommodated in the sensor element battery can be kept relatively small if the antennas for Picking up the signals are arranged in the vicinity of the patient.

The sensor element is particularly useful when it is at least has three electrodes. A sensor element with exactly three electrodes has proven to be particularly suitable, which are arranged on the corners of an equilateral triangle are.

The sensor element of the invention is very compact, it can about 2 to 5 cm in diameter. A diameter of about 2 cm is used for premature births,

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a diameter of about 3 cm for children and one Provide a diameter of 5 cm for adults.

Despite these small dimensions and thus also the small spacing between the electrodes, it is surprisingly suitable for Made possible for the first time by the invention, yet reliable and complete with just one sensor element get proper electrocardiograms.

As mentioned, the sensor elements must have different sizes depending on the size of the patient. If you see it in front of it Sol Ibruch I inien, which extends through outer areas of the Elements and outer areas of the electrodes extend so only needs a size of sensor element in the hospital or to be kept by the doctor. Depending on the size of the patient can then outer areas of the sensor element and at the same time also the corresponding outer areas of the Electrodes are broken away so that the sensor element becomes smaller. Here the acceptance of the electrical Signals from the central area of the electrodes so that the electrical connections are not disturbed, if only the outer areas of the electrodes are broken away.

If it is provided according to the invention that a microphone is arranged on the surface with the electrodes, then not only can the electrocardiogram be examined or, in particular, monitored, but also the heart sound and also the breathing sounds. Finally, it can also be provided according to the invention that further sensors are arranged on the surface with the electrodes, namely, for example, a skin temperature sensor, a "sweat sensor", an O_ sensor and / or a CO _? -Sensor.

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Through the entirety of its characteristics, in particular through the microphone and possibly further sensors, the sensor element according to the invention enables a reliable and effective patient monitoring, details of which are provided in the should be described below. The invention is not limited to the sensor element per se. she is Rather, it is also aimed at the special examination methods and the equipment required for them, which are described below should be described.

The invention enables the heartbeat rate to be determined, what is still possible to control the heart's activity is when in addition to the typical ones obtained from cardiac activity Measurement pulses also have irregular interference signals are present that are significantly larger than the amplitudes of the useful signal. Furthermore, the invention enables Respiratory rate and an indicative extent of ventia ition of the lungs to eat. Furthermore, obstructions of the airways, which do not necessarily lead to a change in the respiratory rate and the Lung ventilation size are displayed.

The invention can be used in particular for assessing and monitoring the cardio-respiratory status of a person with cardio-pulmonary cells Risk-prone people are related.

Monitoring applications are found in people, especially children, e.g. with asthma, tracheotomy, threatening slow pulse rate (bradycardia), risk of respiratory failure (apnea) and children with so-called sudden infant death SIDS syndrome risk mainly during sleep. Furthermore, for patients who, as part of artificial respiration, use a tube in the windpipe via the same must be suctioned off.

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Representing all eligible Patient target groups should consider two areas of application more precisely to be discribed.

In the Federal Republic z. Currently 2000 to 4000 children in the first year of life suffer from sudden infant death syndrome (SIDS), ie they are found dead without any previously recognizable symptoms. You stop breathing for no apparent reason, and a little later your heart rate drops and cardiac arrest occurs. The incidence of this syndrome is 0.2 per cent to 0.4 per cent of all live births. This statistical expectation applies to the entire western world. Even higher Incidenzen occur in so-called Ri zi kokindern on, for example, premature infants of less than 2,000 g birth weight. Continuously improved intensive medical care, even of very immature children, down to a birth weight of 750 g C600 g), increases their survival expectancy and with it the incidence rate of SIDS-endangered children.

This overall situation is increasingly in the public Media accounted for through educational work. Farther For children with SIDS risk, home monitors have been developed in the last few years, for whom we are already advocating Leasing market has formed.

The ones on the market for this patient group Home monitors and their measurement methods are briefly presented:

1. The abdominal wall swaying when the child breathes in the abdomen compresses a pressure capsule glued to the skin of the abdomen. The pressure fluctuations are v. "·" Is one thing incompressible hose forwarded to a monitor. If the child does not breathe / there will be no pressure fluctuations

registered. After a latency period, the device gives acoustic alarm.

2. The child lies on a parallely arranged Air hoses existing mattress. The through the Evoked breathing movement of the chest and abdomen Pressure fluctuations in the mattress are as described under 1. registered.

3. Wrap around the child's chest with the help of a belt Via electrodes and strain gauges, heart rate and Breathing registered.

What all devices have in common is that they have a connection (cable, hose) from the child to the monitor (unwieldy, Strangulation hazard, alarm device necessarily close to Child). In addition, a movement of the chest, e.g. at Obstruction of the airways (without lung ventilation) as breathing detected. This is exactly what happens when the child is rhythmically cramping as a result of decreased ventilation and not breathes.

Since devices that exclusively monitor breathing are still in use, the actual Sudden infant death syndrome presumably preceding indicative bradycardia not noticed. Can also be used with a strong heartbeat the same can be registered as breathing.

Furthermore, any escape of air from said air systems as well as the detachment of sensors from the skin of the Child's SI DS-adequate alarm, thus creating a high mental level Burden on parents occurs.

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As it is increasingly reported in the literature that in retrospect at. SIDS children increased in the time before the event Sweats and temperature increases occur (Adrenaline rush), would be special for this Additional temperature and sweat formation monitoring is desirable in the patient group.

In another group of patients, however, there is not just one more secure registration of heart and lung activity It would be necessary, but would be desirable for patients with the additional risk of airway obstruction Possibility of surveillance.

In the case of artificially ventilated premature babies and newborns, for example, it has recently become increasingly common to purge secretion and condensed water from the tube in the trachea of secretion and condensation by suction only when necessary and not as before routinely every two hours. The reasons are that the strain of suction leads to increased intracranial pressure, burst lungs (pneumothorax), pulmonary bleeding, insufficient ventilation or non-ventilation of lung sections (atelectasis) and of course a lack of oxygen. So far, the necessity of suction has been increased by listening to the breath sounds relatively closely with the stethoscope or by decreasing the oxygen tension / increasing the CO _? -Tension detected in the skin (main probe) or as part of a blood gas analysis. Monitoring in this direction, which already reveals the trend towards the obstruction of the airways, is now created by the invention.

In summary, monitoring is therefore possible, which ever according to patient group, make partial quantities from the following list:

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1. There is not necessarily a physical (cable, Hose) connection to the patient, this allows a greater distance between the patient and the alarm device.

2. The sensor on the patient shows only a small spatial Expansion to.

3. There are few false positives, and between true ones A distinction can be made between cardiopulmonary alarm and sensor detachment noise will.

4. The heart and breathing activity are monitored.

5. Detection of temperature increase and increased perspiration is possible.

6. Obstruction of the airway despite regular breathing can be recognized.

7. In the case of an already existing narrowing or relocation of the In the respiratory tract, an increase or change in this disorder triggers the alarm.

8. Shallow but regular, low frequency breathing is also used as a sign of a lack of lung ventilation recognized.

The ideas underlying the invention are as follows:

Those arising in the course of heart and lung activity Sound phenomena are recorded with the help of a microphone, which is on placed on the chest.

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With the help of filters, those for the respective organ atypical frequency bands are suppressed and freed from interfering noise / then an interpretation of the remaining Make signals regarding pathological relevance. For the The procedure is called: Phonocardiography (PKg) for the heart Lung phonopneumography (PPg). The PKg shows an I and II Heart sound, the PPg has an inhalation and an exhalation sound.

It has been shown that the intensities and spectral distributions of the frequencies of heart sounds and Breath noises are significantly different. Of the The predominant frequency component of the heart tones, which is decisive with regard to its intensity, is below 100 Hz, the Breathing sound frequencies, however, are above 'ιύΟ Hz.

By an applied to the chest above the heart The heart and lung sounds are recorded simultaneously with the microphone to save space. To corresponding preprocessing with regard to noise removal, Smoothing, frequency cutting, amplification, filtering and A / D conversion are used to split the frequencies into and below performed over 100 Hz.

Both partial signals are adequate to the problem in real time working spectrum analysis algorithm. In the for the two periodically recurring double signals originating from the heart and lungs are each a separate one Characteristic space with the help of the four variable frequency services I. (db), spectral frequencies, roughness of the signal and time spanned.

In the two feature spaces, you can then use Pattern recognition algorithms determine the frequencies of the in- and

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Expiration caused by breathing, as well as the frequency of the I and II heart tones are determined.

Does the system also have the separately derived electrical EKG-Si gna Ie, then causes the given Redundancy high functional safety and reduces the frequency of false alarms in the heart monitor ring.

With the help of the parallel EKG signals is continued Decisive in which sampling intervals during the long as a heart-sounding phase of inhalation and exhalation, frequencies from heart-tones cannot be included. If you save a at a defined (starting) point in time small number of sampling intervals of pure breathing, see above you can use their pattern as a reference pattern for comparison with later trend changes, caused by a "change in the sound of breath (Laying e.g. through slime).

The entire monitoring device consists of two sub-units, the patient-side sensor and the actual evaluation and monitoring device. The signals are transmitted from the sensor to the monitoring device either by wire or by Wireless.

The sensor combines the EKG electrodes, the microphone and other sensors in a flat body (diameter max. 5 cm), e.g. for the skin temperature, the C0_ and O ^ voltage in of the skin. The sensor also contains the electronics required for the sensors for recording and preprocessing and transmission of the signals to the transmitter. When the signals are forwarded wirelessly, the energy source is a battery intended.

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Regarding the minimum distance between the EKG electrodes, it has been shown / that the electrodes are quite directly on the derri The heart may still be arranged in a triangle shape Useful signal amplitudes are far greater than those of the interfering signals (Photos) .

In this new form of derivation, the three electrodes form for example the corner points of an equilateral triangle (also two electrodes on the longitudinal axis of the heart are conceivable) in the center of which there is a microphone. To attach the Sensor (e.g. above Erb's point) a bds. adhesive round foil applied to the skin. A surface area (part) that is also adhesive and facing away from the patient has the shape of the sensor. Furthermore, the film has recesses (holes), which in shape, size and arrangement with correspond to the electrodes and the microphone of the sensor. In the recesses provided for the electrodes Electrode paste applied to the skin. Then the sensor can be pressed onto the adhesive surface, whereby Microphone and electrodes as well as partial sensors maintain close skin contact.

The transmission of the recorded signals takes place e.g. multiplexed wirelessly to the receiver, which carries out the further processing.

The sensor part can have the following variations: It can have, for example, a skin temperature sensor and / or a "sweat sensor" and / or an O ^ sensor and / or a C0 _? - have sensors.

Furthermore, a fitting, hemispherical rubber dome made of elastic material can be folded into the edge of the sensor the following can be achieved:

If the elastic "dome" is pressed in so that air escapes via the neck connection, it comes through perpendicular to the Skin air channels drilled through the sensor plate for vacuum-related suction of the sensor on the skin, since the elastic rubber dome tries to expand in order to regain its original shape. This will make that Risk of detachment from the skin reduced, one continues to occur Shielding against background noise.

Due to the structure described, the shearing leads to a EKG electrode from the skin to a dissociation of electrical and acoustic heart signal, "detachment alarm" can be "detected". Furthermore, this "release information" be designed redundantly if a sensor, which the under the rubber dome registers decreasing negative pressure, available is.

The actual monitoring device enables a appropriate distance at any time to hear the heart and breath sounds separately acoustically. Regarding automatic Monitoring of the heart and breathing can set upper and lower alarm limits for the frequencies in a conventional manner can be set.

The detachment of the sensor from the skin is signaled by an extra acoustic signal.

That part of the invention that applies to the sensor element itself is directed, is intended in the following on the basis of advantageous embodiments with reference to the attached Drawings are described. Show it:

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Figure 1 shows an embodiment of the sensor element in Top view; and

Figure 2 shows another embodiment of the sensor element.

The sensor element (1) shown in FIG. 1 is disk-shaped and has three electrodes (2) on its end faces, which are arranged on the rear side of the sensor element Cable connections or via one in the sensor element arranged transmitter with a monitoring and evaluation device get connected. The electrodes will be separated as much as possible, i.e. normally even more further than shown in the figure. Instead of three electrodes, two electrodes or more than three can also be used Electrodes are used. The embodiment of FIG. 1 furthermore has a microphone (3) and a further sensor (4), e.g. for the skin temperature.

In the embodiment of Figure 2, the sensor element (1) also disc-shaped. However, the sensor element has several circular, concentric so-called breaking points in the form of Perforations (5) or the like. Through this it becomes Sensor element (1) in a central disk-shaped area (6), an outer annular area (8) and a intermediate annular area (7) divided. The outer ring-shaped area (8) or one after the other or both annular areas (7 and 8) are separated or broken off at the same time.

On the side of the sensor element (1) facing the patient three radially outwardly directed elongated electrodes (2) are arranged, which extend over the "'"' • forations (5) and in the area of these perforations (5) also with corresponding perforations can be provided. In any

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In the event, the arrangement is such that when the outer ring (8) is cut off, the corresponding part of the electrodes (2) is also included is separated. The same applies to the severing of the inner ring (7).

There is a pre-made one on the electrodes. Conductive, sticky "Jelly" is applied, or a special electrode button must be used when using the sensor element be applied.

The part of the sensor element not covered by electrodes (1) is made with non-conductive adhesive or gel, as well has a KLebewi rkung, so that the Lemerst sensor (1) can be attached to the patient.

On the surfaces of the washer (6) and the rings (7 and 8) are 'Insulating paper rings are applied, which are peeled off individually, peeling off with the help of a small flap or the same can be facilitated. This has the advantage that With this universally applicable sensor, optimum sensitivity is achieved even with different body sizes will.

SoLL the sensor element (1) of Figure 2 in an adult are used, the inner areas (6 and 7) remain covered with the insulating paper layers or the like, so that only the areas arranged on the ring (8) Electrodes (2) effectively detect cardiac tension; these sensitive areas then have a particularly large one Distance, so that particularly good signals are obtained. If a measurement is to be carried out on a child, one will sever the outer annular region (8), e.g. B. break off and remove the paper layer from the annular area (7) subtract so that the relatively close

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juxtaposed ends of the electrodes (2) on the Disc (6) do not contribute to the measurement, as the electrode spacing is again as large as possible. Only when taking measurements Small children, if the ring (7) is also broken off, will you then remove the insulating layer from the disc (6).

For the measurement, the electrodes <2) are of course on the Provide the rear in the area of the disc (6) with appropriate lines so that a connection can be made with the help of wires or wirelessly to the monitoring device.

Oie sensor elements (1) can essentially with the means are attached, which are essentially known. As far as these processes require special foils, one will SelbstV'tjrständli ch for the sensor element according to the invention a Use a shape for the foil that matches the shape of the sensor element or their electrodes (2), the microphone (3) and possibly other sensors (4) is adapted.

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Claims (8)

S 1 t 1 3 3 1 3 · I * ■ Dr. H (H ler-Wickop, Hamburg Disc-shaped sensor element for electrocardiograms ρ 12055/86 N / Bi protection claims 1. Disc-shaped SensoreLersent for picking up Electrocardiograms, characterized in that it is on its one surface has at least two electrodes (2). 2. Sensor element according to claim 1, characterized in that there are at least three electrodes on one surface (2). 3. Sensor element according to claim 2, characterized in that it has exactly three electrodes (2). I I ti I I I II III • << I Il I I I I fill f> 111 * 11 I. I ■! -J ι iii 111 * 1 11 11 4. Sensor element according to one of claims 1 to 3, characterized characterized as having an outside diameter of approximately 2 to 5 cm. 5. Sensor element according to one of claims 1 to 4, characterized characterized as having an outside diameter of approximately 3 to 5 cm. 6. Sensor element according to one of claims 1 to 5, characterized characterized that -? s So L Lbruch Li ni en has, which extending through outer regions of the element (1) and outer regions of the electrodes (2). 7. Sensor element according to one of claims 1 to 6, characterized in that it is on the surface with the Electrodes (2) has a microphone (3). 8. Sensor element according to one of claims 1 to 7, characterized marked that it has further sensors (4) on the surface with the electrodes (2). • I III