WO2019170285A1

WO2019170285A1 - Apparatus and method for assisting a user during a cardiopulmonary resuscitation and manufacturing method

Info

Publication number: WO2019170285A1
Application number: PCT/EP2019/000069
Authority: WO
Inventors: Dominic Oliver DUSSAULT
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-03-09
Filing date: 2019-03-08
Publication date: 2019-09-12
Anticipated expiration: 2020-09-09
Also published as: DE112019001221T5

Abstract

An apparatus (1, 31) for assisting a user during cardiopulmonary resuscitation of a patient comprises a force transmission unit (10) with a lower plate (14), an upper plate (15) and a force sensor (11) arranged between the lower plate (14) and the upper plate (15) for detecting a force exerted on the patient's chest by means of the upper plate (15) and the lower plate (14), a flexible mat (2) in which the force transmission unit (10) is partially or completely embedded, a signaling device (8, 23) for generating at least one signal perceivable by the user, and an electronic control device for controlling the signaling device (8, 23) based on the force detected by te force sensor (11), wherein the force sensor (11) is arranged in a floating manner between the lower plate (14) and the upper plate (15). The invention also relates to a method for assisting a user during cardiopulmonary resuscitation, as well as a method for manufacturing a corresponding apparatus (1, 31).

Description

Apparatus and Method for Assisting a User During A Cardiopulmonary Resuscita- tion and Manufacturing Method

The present invention concerns an apparatus and a method for assisting a user during cardiopulmonary resuscitation, as well as a method for manufacturing such an appa- ratus. When a person suffers cardiac arrest, cardiopulmonary resuscitation must be initiated immediately whenever possible. In this process, cardiac massage, in which a com- pressive force is exerted on the center of the patient's chest at a rate of approximately 100 to 120 times a minute, is of primary importance. This force presses the sternum down so that blood is forced out of the heart into the circulation. In the relaxation phases between compressions, the heart again fills with blood. Whenever possible, cardiac massage should be supplemented with ventilation.

In particular, in accidents and other emergency situations, there are often no medical- ly trained personnel present. The performance of Cardiopulmonary resuscitation, par- ticularly cardiac massage, by a lay person is then decisive for the survival of the pa- tient. Because of a lack of training and/or practice, however, lay persons are often incapable of correctly performing cardiopulmonary resuscitation. In particular, there is often uncertainty, for example regarding the point at which the compressive force must be exerted, the amount of compressive force to be exerted, how long the relaxation period between two compressions should be, and/or the frequency of the com- pressions. This uncertainty may be increased by the situation in which cardiac arrest occurs, for example in a traffic accident. Devices for assisting a user, specifically a medical lay person, during cardiopulmonary resuscitation have therefore been devel- oped.

US 5,496,257 discloses a portable apparatus for assisting a rescuer in administering cardiopulmonary resuscitation on a patient having a housing that rests on the patient's chest so that compressive forces can be applied to the patient's chest by means of the apparatus. In US 4,355,634, WO 2004/056303 Al, US 2011/0201979 Al, WO 2014/071915 A2, and DE 202007009575 Ul various devices are described for use in connection with cardiopulmonary resuscitation.

In WO 2016/188629 Al, which is incorporated herein by reference, an apparatus for assisting a user during cardiopulmonary resuscitation of a patient is disclosed. The apparatus comprises a force transmission unit with a lower plate that can be placed on the patient's chest, an upper plate located at a distance from the lower plate, and a force sensor arranged between the lower plate and the upper plate for detecting a force that can be exerted on the patient's chest by means of the upper plate and the lower plate. The apparatus further comprises an indicator device for generating at least one signal that can be perceived by the user, and an electronic control device for controlling the indicator device based on the force detected by the force sensor. The force transmission unit is embedded in a flexible mat.

In practice, it has turned out that many of the known devices do not correctly meas- ure or indicate the force applied by the user for compressing the patient’s chest. It has been found that this is due, at least in part, to the force not being applied perpen- dicularly upon the patient’s chest. Such direction-dependence is undesirable, as in the situation in which cardiopulmonary resuscitation is required it is often hard for the user to make sure that the force is always exerted in the perpendicular direction. A direction-dependent signal may be misleading to the user resulting in insufficient resuscitation.

It is an object of the present invention to provide an improved apparatus for assisting a user during cardiopulmonary resuscitation, in particular an apparatus which is im- proved with respect to force direction dependence, simplicity and safety of use, and/or storage and transport capability. Further objects of the invention are to pro- vide an improved method for assisting a user during cardiopulmonary resuscitation and a method for manufacturing a corresponding apparatus.

These objects are achieved by an apparatus according to claim 1, by a method ac- cording to claim 10, and by a manufacturing method according to claim 11. Advantageous embodiments of the invention are given in the dependent claims. An apparatus according to the invention is configured for assisting a user during car- diopulmonary resuscitation of a patient. The term "user" is understood here to refer to a person who administers cardiopulmonary resuscitation, without this implying any limitation on the persons in question. In particular, the user can be a medical lay person, but can also be a medically trained person, for example a trained first re- sponder. Several persons may also perform the cardiopulmonary resuscitation, for example with multiple persons alternately or simultaneously carrying out cardiac massage and/or one or more other persons carrying out ventilation; in this case, the multiple persons carrying out the resuscitation will also be referred to as "the user". The term "patient" used in the following refers to the person on whom eardiopulmo- nary resuscitation is performed, regardless of the cause and circumstances of the re- suscitation. Use of the apparatus according to the invention will be described in the following with respect to a person, but it is understood that the apparatus can also be used on a manikin for training purposes. The apparatus according to the invention comprises a force transmission unit, which is configured for transmission and detection of a force that can be exerted by a user during cardiac massage on the patient's chest. This force, which should be exerted in a direction essentially perpendicular to the surface of the chest and which is transmit- ted via the force transmission unit to the chest, is also referred to in the following as "compressive force". The apparatus is preferably configured only for exerting a com- pressive force on the chest and not for exerting a pulling force.

The force transmission unit comprises a lower plate that is sized and shaped for be- ing placed on the patient's chest; in particular, the lower plate may be a flat, circular disk having a diameter of approximately 5 cm. This size approximately corresponds to the size of that surface region of the chest to which pressure is to be applied during cardiac massage. For example, the lower plate can be configured as a thin disk hav- ing a thickness of approximately 1 mm.

The force transmission unit also comprises an upper plate that is arranged parallel to the lower plate and largely congruent therewith, so that the upper and the lower plate essentially overlap each other or are congruent to each other. The upper plate is pref- erably configured identically to the lower plate, i.e. in particular as a thin, flat, circu- lar disk with a diameter of approximately 5 cm and a thickness of approximately 1 mm, for example. The force transmission unit further comprises a force sensor configured for detecting a force applied by means of the upper plate to the lower plate, the force sensor being arranged between the lower and the upper plate, thus forming a sandwich-like struc- ture. The force sensor thus supports the upper plate on the lower plate and is config- ured to transmit forces from the upper to the lower plate while simultaneously detect- ing said forces. If a compressive force is exerted on the upper plate, said force, when the lower plate rests directly or indirectly on the surface of the chest, is transmitted from the upper to the lower plate and further to the chest, and is detected by the force sensor. In particular, the force sensor can emit a sensor signal that represents the force detected by the force sensor and thus allows a conclusion to be drawn regard- ing the compressive force exerted by the user on the upper plate and transmitted by the force transmission unit to the patient's chest. At least the lower plate, preferably the lower and the upper plate, may be composed of a hard plastic having some degree of flexibility, for example similar to an ordinary credit card. Thus, at least the lower plate may be deformable for adaptation to the surface of the patient's chest. Preferably the lower plate, the force sensor and the up- per plate are deformable in this manner, such that the force transmission unit as a whole, on application of the force required for the cardiac massage, conforms to the shape of the surface of the chest. Most preferably, the force transmission unit as a whole is substantially elastically deformable. For example, the stiffness of the force transmission unit can be specified such that when it is lying on a substrate with two edges opposite to each other, it yields in the middle relative to the edges by approxi- mately one centimeter on exertion of a target force for the cardiac massage. In this way the exerted force can be distributed over a suitable area of compression of the chest, for example over a circular surface essentially arranged symmetrically to the sternum with a diameter of approximately 5 cm on the front side of the sternum.

The force transmission unit is partially or completely embedded in a mat. The mat is configured to be flexible, i.e. bendable in at least one direction, and it is preferably slack. In particular, the flexible mat is configured in sheetlike form. The at least two layers may be composed e.g. of rubber or a suitable foam. The mat has a larger sur- face than the force transmission unit and extends beyond the force transmission unit preferably on all sides of the force transmission unit. The mat may be rectangular, rectangular with rounded comers, or configured in another form. The flexible mat preferably comprises at least two flat layers between which the force transmission unit is embedded, the at least two layers both being flexible, and being connected to one another in a planar manner. In particular, the mat may comprise a lower and an upper layer, both of which may be formed substantially of a natural rubber material. The mat may comprise further layers. The upper and the lower layer may have the same shape and dimensions and overlap each other in total and may be glued directly to each other. The force transmission unit preferably is embedded completely in the flexible mat. The flexible mat can thus be used to protect the force transmission unit from soiling or moisture and may even be water-tight. The flexible mat can serve as a mechanical carrier in order to improve handling of the force transmission unit. The flexible mat may further serve to distribute more evenly the compressive force exert- ed by the force transmission unit over the patient's chest and for preventing any edg- es of the force transmission unit from injuring the patient. The mat may be config- ured to be slip-resistant at least on its underside, i.e. on its side facing the patient, and/or may be printable or printed on its upper side, i.e. on its side facing the user. The shape of the mat may be adapted to physical characteristics and may have mark- ings for alignment with physical features of the patient, so that correct placement of the force transmission unit is facilitated. For example, instructions for performing cardiopulmonary resuscitation or cardiac massage may be printed on the upper side of the mat.

The apparatus according to the invention further comprises a signaling device con- figured for generating at least one signal that can be perceived by the user. In particular, the signal can be an acoustic, optical and/or haptic signal. Specifically, the type and intensity of the signal are such that it can be perceived under a wide variety of environmental conditions. Most preferably, an optical signal is bright enough and/or an acoustic signal is loud enough to be reliably perceivable by a user at an accident site with widely differing bright illumination and loud traffic noises, in particular the signals are clearly perceivable at a distance of about 75 cm from the apparatus. The signaling device is preferably configured to generate signals that can be perceived via different sensory channels, for example to generate synchronously an acoustic and an optical signal.

The apparatus further comprises an electronic control device that is configured for controlling the signaling device based on the force detected by the force sensor or the sensor signal emitted by the force sensor. For this purpose, the electronic control device is connected to the signaling device and to the force sensor, in particular via corresponding electrical wires. The electronic control device comprises a microcon- troller or a microprocessor, and may be configured for evaluation of the sensor signal received from the force sensor, for example by comparison with predetermined target values. In particular, the electronic control device is configured for controlling the signaling device such that the generated perceivable signal in some way is indicative of the force detected by the force sensor. The control device and the signaling device may be completely or partially embedded in the flexible mat.

According to a first aspect of the present invention, the force sensor is arranged in a floating manner between the lower plate and the upper plate. The force sensor is ar- ranged between the lower and the upper plate and may be able to float or to move between both plates over a small distance. In particular, if a force is exerted on the upper plate that is not perpendicular to the surface of the plates, the force sensor may be able to glide along the upper surface of the lower plate and/or the lower surface of the upper plate, most preferably with respect to both plates. If a shear force acts be- tween the lower and the upper plate, the shear force may be not or less transmitted to the force sensor, at least not in a way substantially biasing the sensor signal, even if the upper plate is slightly displaced with respect to the lower plate. In this respect a range of floating movement of the force sensor with respect to one of the plates of less than 0.1 mm may be sufficient to achieve a considerable reduction of the sensi- tivity to shear forces. In order to provide the floating arrangement of the force sensor, an upper surface of the lower plate and/or a lower surface of the upper plate may be configured smooth and plane and/or covered with a friction-reducing material, and the force sensor is not glued or bonded to the lower or to the upper plate.

Due to the floating arrangement of the force sensor between the lower and the upper plate, the sensor signal may be less susceptible to force components directed parallel to the lower and the upper plate. The sensor signal therefore more reliably represents that component of the exerted force that is perpendicular to the surface of the chest. If the force transmission unit is placed correctly on the patient’s chest, the sensor signal thus indicates more accurately the actual force compressing the patient’s chest.

It has been found that in practice, oblique pressing represents a major problem when cardiopulmonary resuscitation is administered by a lay person. Such oblique pressing frequently occurs, e.g. due non-optimal positioning of the user, and usually remains unnoticed by an unexperienced user. Any component of the applied force that is di- rected along the surface of the chest does not substantially contribute to compressing the chest and thus should be discarded, such that it does not bias a signal generated to guide the user during the cardiopulmonary resuscitation. If exclusively or almost exclusively that component of the applied force that is perpendicular to the surface of chest contributes to the force sensor signal, the generated perceivable signal can indi- cate to the user in an improved manner whether the applied compressive force is suf ficient or not. As described above, the floating arrangement of the force sensor helps to reduce or even eliminate any dependency of the sensor signal on such force com- ponents which are ineffective for compressing the chest. In particular, when the pa- tient is lying horizontally on a plane surface and the force transmission unit is cor- rectly placed, the force sensor signal is only or almost only dependent on the vertical force exerted onto the central portion of the sternum. In this way, the user is assisted by the inventive apparatus in a more reliable way in applying cardiopulmonary resuscitation.

Preferably, the force sensor is a sensor array or sensor film or foil that, in particular, extends over substantially a complete interface between the lower plate and the upper plate. Most preferably, the lower plate and the upper plate both are approximately circular, having approximately the same diameter and being arranged in a congruent manner, and the force sensor array or film covers substantially the complete upper surface of the lower plate and the complete lower surface of the upper plate. In par- ticular, the force sensor array or film may also have an approximately circular shape, having approximately the same diameter as the lower and the upper plates, for exam- ple a diameter of about 5 cm. Preferably, the upper surface of the lower plate and/or a lower surface of the upper plate are smooth and/or covered with a material that has a reduced friction with the sensor array or film. In this way, the force sensor may be embodied in a simple and reliable manner for sensing the perpendicular component of the applied force.

According to a particularly preferred embodiment of the invention, the force sensor comprises or is a force-sensing resistor (FSR) film. Force-sensing resistors are con- figured as a film or foil comprising a conductive material, in particular a conductive polymer, that changes resistance depending on the application of force to the surface of the film or foil. Usually FSR sensors comprise conducting electrodes provided, for example, as crossed or interlacing comb-like structures in a lower and an upper layer, separated by a force-sensitive layer that comprises the conductive material having force-dependent resistance. By employing an FSR sensor the force-transmission unit can be designed in a particularly simple and cost-efficient form. Further, an FSR sen- sor is robust and simple to operate with an electronic control. The FSR sensor can be provided as a thin film having a thickness of, for example, about or less than 0.5 mm, and having about the same size and shape as the lower and the upper plates. The FSR sensor can be thus easily mounted in a floating manner by simply placing the film between the surfaces of the lower and the upper plate, which both preferably are smooth and have low friction with the film.

Preferably, the force transmission unit comprises two rubber plates between which the lower and the upper plate and the force sensor are embedded. The two rubber plates may be formed of natural rubber, for example. The two rubber plates may be approximately circular. In particular, the force transmission unit is formed by a lower rubber plate, the lower plate, the floatingly arranged force sensor, the upper plate, and an upper rubber plate, wherein the lower plate may be glued to an upper side of the lower rubber plate and the upper side of the upper plate may be glued to an un- derside of the upper rubber plate. Further, the lower and the upper rubber plates may have a larger diameter than the lower and the upper plate and may be glued to each other, encompassing the lower and the upper plates and the force sensor. In this way usability and robustness of the apparatus can be improved, and a more even distribu tion of an exerted force can be achieved. Further, the force sensor can be more safely embedded in a water-tight manner.

Advantageously, the flexible mat comprises a textile layer on its upper side, which is printable or printed. The textile layer may be glued to the upper side of the upper layer of the mat. In this way instructions to the user and/or markings for alignment of the apparatus with respect to physical features of the patient can easily be placed on a surface of the apparatus that is visible during use. Preferably the mat is configured to be foldable and to this end comprises at least a first section and a second section which are foldable with respect to each other. The first and the second section of the mat are connected directly or indirectly to one an- other via at least one predetermined fold line. The at least one fold line may be con- figured as a groove or cut and may be formed by embossing or by cutting to a part of its thickness into one or both layers of the mat, providing reduced stiffness at the fold line and thus making the mat bendable at the fold line. The at least two sections of the mat can be folded atop one other, lying flat in this state, and can then be corre- spondingly unfolded. In this way storage, packaging, transportation, and carrying of the apparatus can be facilitated.

In a particularly preferred embodiment the mat is configured so as to be essentially rectangular and has only two sections and one fold line running parallel to two oppo- site edges dividing the surface of the mat into the two sections of approximately equal size. When the mat is folded up, i.e. the apparatus is closed, one section is su- perposed on the other section; in this state, the upper side of the mat which may bear instructions and markings, is on the inside, and the lower side of the mat, which may have a non-slip configuration, is on the outside of the closed configuration. For use, the mat is unfolded, i.e. the apparatus is opened, requiring only one simple working step. The mat in its unfolded state can have a width of about 15 cm and a length of about 20 cm, and the apparatus in its closed state can have a length of about 15 cm and a width of about 10 cm; these dimensions have turned out to be well suited for cardiopulmonary resuscitation of an adult. Further, this embodiment is particularly suitable for storage and transportation in a motor vehicle first aid kit such as accord- ing to DIN 13157. An apparatus configured in this manner can easily be included in such a first aid kit so that it can be immediately and simply accessed in case of an accident.

Preferably, the force sensor is connected to the electronic control device by a flex cable having at least one predetermined folding position, which may be a short trans- verse fold line, coinciding with the fold line of the mat. In particular, one single flex cable with only two electric lines may be sufficient for connecting the force sensor, which may be an FSR sensor, to the electronic control device. The predetermined folding position may be formed by a transverse line of reduced thickness of the flex cable. In this way safe transmission of the sensor signal to the control device can be achieved without obstructing the folding and unfolding of the mat.

Preferably, the apparatus comprises a battery for supplying the control device and thus also the force sensor and the signaling device with electric energy. The appa- ratus may comprise a battery compartment for accommodating the battery, which may be, for example, part of the control device. The apparatus further comprises a battery contact for electrically contacting the battery, the battery contact being elec- trically connected to the electronic control device. The battery contact may be, for example, a flexible metal flap pressed by an elastic force to a terminal of the battery. The battery contact preferably is part of the battery compartment; the apparatus may comprise two battery contacts contacting both terminals of the battery and being electrically connected to the control device.

According to an aspect of the invention which is also claimed independently from the above mentioned first aspect, the mat is configured to be foldable, comprising at least a first section and a second section, as mentioned above. Further, the apparatus corn- prises a battery for supplying electric energy to the electronic control device, and a battery contact for electrically contacting the battery, the battery contact being elec- trically connected to the electronic control device, as described above. Further ac- cording to this aspect of the invention, the battery contact is arranged in the first sec- tion of the flexible mat, and the apparatus comprises an insulation strip, wherein a first end section of the insulation strip is arranged for insulating the battery from the battery contact, and a second end section of the insulation strip is fixed to the second section of the mat such that by unfolding the mat the insulation strip is automatically withdrawn from the battery contact and the battery contact electrically contacts the battery. The insulation strip thus has a length that is small enough so that by opening the apparatus, i.e. by unfolding the second section of the mat from the first section, the second end section of the insulation strip, which is opposite to the first end sec- tion, moves a sufficient distance to pull away the first end section from the battery contact. In other words, the distance travelled in unfolding the mat by a point of fixa- tion of the insulation strip on the second section of the mat is sufficiently large to pull the insulation strip away from the battery contact. The insulation strip preferably comprises or consists of an electrically insulating plastic material, such as a biaxial- ly-oriented polyethylene terephthalate (Mylar), for example. The first end section of the insulation strip may be inserted between the battery and the battery contact or cover the battery contact, such that upon withdrawal of the insulation strip the battery contact, due to an elastic force, contacts the respective terminal of the battery. The other battery terminal preferably is electrically connected to the electronic control device in the opened as well as in the closed state of the apparatus. The battery compartment may have for example, a fixed battery contact to make electric contact with a first battery terminal, and an elastic contact flap to make electric contact with a second battery terminal opposing the first battery terminal, such that the battery is held in place by the elastic force of the contact flap. The first end section of the insu- lation strip may be inserted between the fixed battery contact and the first battery terminal, or between the elastic contact flap and the second battery terminal. The first end section of the insulation strip can be held in place by the elastic force of the con- tact flap to insulate one of the battery terminals and can be withdrawn upon exerting a force such that both battery terminals have electric contact. The electronic control device preferably is configured to be activated and to reach its working mode auto- matically after being electrically connected to the battery. In this way it can be achieved that the electronic control device is switched on automatically and the appa- ratus reaches its working condition simply by opening the apparatus, without requir- ing any further working step. Moreover, the electric energy consumption of the elec- tronic control device before it is activated can be minimized in this way, reducing the energy consumption effectively to zero and thus maximizing a lifetime of the battery.

Preferably the second end of the insulation strip is fixed to an underside of the second section of the mat, in particular to an area near a front edge of the second section, the front edge being that edge at which the mat is unfolded. The insulation strip may be fixed, for example, by means of a pin or a bolt, or may be glued to the under- side of the mat. Thus, in a closed state of the apparatus, the insulation strip is fixed on an outer side of the folded mat, while in the working mode of the apparatus, the insulation strip is placed on a underside of the mat, extending away from the force transmission unit, and thus does not interfere with the actions to be taken by the user.

The control device is preferably configured such that the apparatus can be used only once, after the apparatus has been opened and the battery has been contacted to the electronic control device. For this purpose, for example, one can set a time period during which, after the last exertion of a compressive force or after the control device has been switched on, no more compressive force has been exerted, and after a preset maximum duration of such inactivity is reached, the signaling device is permanently deactivated. The preset maximum duration of inactivity may be selected such to make sure that a resuscitation once initiated has ended and that the battery capacity is sufficient to support full functionality of the apparatus during active resuscitation, for example 10 or 15 minutes. In this way it can safely be avoided that an apparatus that is no longer fully functional due to energy consumption is used again. Further, a seal can be provided that must be broken when the apparatus is opened, and/or the appa- ratus may be provided in a sealed package.

In general, the control device is configured for activating the signaling device as dis- closed in WO 2016/188629 Al. The generation of a signal perceivable by the user thus depends, for example, on a detected maximum force exerted on the force trans- mission unit, a minimum force, a difference between the maximum and the minimum force, and/or the frequency of fluctuations in the detected force, the force being a force component perpendicular to the surface of the chest. In particular, the control device can be configured to continuously detect the compressive force exerted on the force transmission unit. Maximum and minimum values of the exerted force can be determined therefrom, with these values allowing compression strokes to be identi- fied. Further, a force amplitude can be determined based on the difference between the maximum and the minimum values. The signaling device can be controlled to generate a signal that depends on the maximum detected force, the minimum force, the force amplitude, and/or the frequency of fluctuations in the force or the compres- sions, for example by generating sounds of different loudness and/or different pitch or optical signals of different brightness and/or colors. Preferably, a plurality of sig- nals perceptible via different sensory channels can be generated simultaneously. It is also preferable for the control device to be configured such that the detected value of the compressive force exerted on the force transmission unit is compared with one or a plurality of predetermined target values. The signaling device can comprise a suita- ble sound generator and/or a suitable light source. For example, a suitable light source can be composed of a plurality of LEDs of different colors, such as red, yel- low, and green. The sound generator may be suitable for generating speech com- mands guiding the user. This allows the user to obtain clear feedback during cardiac massage on the compressive force exerted, the relaxation time between two compres- sions, and as to whether the compressions are performed with sufficient frequency.

According to a preferred embodiment of the invention, the control device is config- ured to activate the signaling device to indicate the necessity of ventilation after a predetermined number of strokes of a predetermined force. Thus, for example, after about 30 strokes characterized by a maximum force exerted on the force transmission unit and a consecutive minimum force, having at least a pre-determined difference between the maximum and the minimum force, a special signal is generated by the signaling device. After a predetermined number of ventilation cycles have been per- formed, another signal is generated to indicate that cardiac massage is to be resumed. In this way it can be made easily discernible for a user how to apply correct ventila- tion to the patient.

In using the apparatus according to the invention, the apparatus may first be removed from a package, in which the apparatus may be shrink-wrapped, for example. If the package has a seal, the seal is destroyed, so that it is recognizable that the apparatus has been used. In a following step, the apparatus is opened by unfolding the sections of the mat that are folded onto one another, in a preferred embodiment the mat hav- ing only two sections which can be unfolded in one single working step. Further, according to a preferred embodiment of the apparatus, the insulation strip is automat- ically withdrawn from the battery contact when the mat is unfolded, thereby switch- ing the electronic control device on without requiring a further action by the user. The apparatus automatically reaches its working mode. The optical and acoustic in- dicators may then be immediately activated.

The apparatus is placed by the user on the chest of a patient and aligned by means of the markings printed on the upper side of the mat and/or provided by means of the shape of the mat. In this manner, one can ensure that a compression area marked on the upper side of the apparatus and at which site the transmission unit is embedded in the mat is placed over that area of the patient's chest on which the compressive force must be exerted in cardiac massage. As soon as the user exerts a compressive force on this area, this is detected by the force sensor of the force transmission unit, and the sensor signal is evaluated by the control device of the apparatus. If the preset target force for cardiac massage, for example 41 kp, is not reached, this may be indi- cated by a colored optical signal, such as a red optical signal, and/or a sound with decreasing frequency. If the exerted force is above the target range, this may be indi- cated by a yellow light and/or a rising frequency, and if the exerted force is in the target range, a green light may be shown and/or a sound with a constant frequency generated. The force amplitude and/or the frequency of compressions can also be measured and compared with a target range, and a corresponding signal or corresponding signals depending on whether a target range has been reached or not may be generated. A target frequency of the compressions to be performed may also be indicated by a further light or sound.

After a preset number of compressions, a signal can be generated that indicates that ventilation is needed. After a pre-determined number of ventilation cycles have been performed, this may be indicated by a further signal. The user thereafter resumes cardiac massage.

According to a method for manufacturing an apparatus for assisting a user during cardiopulmonary resuscitation of a patient, the apparatus preferably being configured as described above, a force sensor which preferably is an FSR sensor film, a lower plate, and an upper plate are provided, the lower and the upper plate preferably each being of roughly circular shape with approximately identical diameters and being made of a hard plastic material, to be elastically bendable to some degree. The FSR sensor film, which has approximately the same area as the lower and the upper plate, is placed in a floating manner between the lower and the upper plate. In a preferred manner, a lower and an upper rubber plate, each having roughly circular shape and a diameter larger than that of the lower and upper plates, are provided, and the assem- bly of the FSR sensor film and the lower and the upper plates is arranged between the lower and the upper rubber plate; thereafter the upper rubber plate is glued to the lower rubber plate on its margin that exceeds the lower and the upper plates. The assembly constituted by the FSR sensor film and the lower and the upper plates and, if provided, the lower and the upper rubber plates, forms a force transmission unit.

Further, a first and a second rubber layer are provided, wherein the first rubber layer may have an anti-slip underside, and/or the second rubber layer may have a printed textile layer on its upper side. The first and/or the second rubber layer may have a pre-determined fold line. The force transmission unit is placed on an upper side of the first rubber layer, an electronic control unit is provided and connected to the FSR sensor, and also arranged on the upper side of the first rubber layer. The force trans- mission unit and the electronic control unit are fixed on the first rubber layer, for example by gluing. Thereafter the second rubber layer, which may have window to accommodate the electronic control unit, is positioned above the first rubber layer and glued to it, such that at least the force transmission unit is partially or completely embedded between the first and the second rubber layers, which form a continuous mat. A battery is inserted into a battery compartment. The apparatus is then closed by folding the mat, preferably along the fold line, wherein, according to a preferred em- bodiment, an insulation strip is arranged such that the battery is insulated from a bat- tery contact of the electronic control unit, and fixed to an opposite margin of the un- derside of the first rubber layer such that it is automatically pulled away from the battery contact when the apparatus is opened. The apparatus may finally be packed and sealed in a plastic cover, such as a shrink-wrap. It is to be understood that the features mentioned above and to be explained below can be used not only in the respective combination given, but also in other combina- tions or alone, without departing from the scope of the present invention.

Further aspects of the invention are explained in the following description of two preferred embodiments and the attached drawing. The figures show the following:

Fig. 1 is a top view of an apparatus according to a first embodiment of the invention in an opened state;

Fig. 2 shows the apparatus according to Fig. 1 in a closed state;

Figs. 3a-3e show various details and assembly stages of the apparatus according to Fig. 1 ;

Fig. 4 is a top view of an apparatus according to a second embodiment of the inven- tion in an opened state;

Fig. 5 shows the apparatus according to Fig. 4 in a closed state;

Figs. 6a-6d show details of the apparatus according to Fig. 4.

As shown in a top view in Fig. 1, an apparatus 1 for assisting a user during cardio- pulmonary resuscitation, in accordance with a first embodiment of the present inven- tion, has an approximately rectangular overall shape. Fig. 1 shows the apparatus 1 in its opened, i.e. unfolded, state. The side lengths of the apparatus 1 may be approximately 15 cm x 20 cm, for example; these side lengths have proven particularly use- ful in an apparatus 1 adapted for cardiopulmonary resuscitation of an adult patient. The apparatus 1 comprises a continuous flexible mat 2, which is subdivided into a first section 3 and a second section 4 of approximately equal sizes by a fold line 5 running parallel to the short sides of the rectangular shape. The mat 2 is sufficiently flexible to adapt itself to the surface of the chest of a patient on whom the apparatus 1 is placed. The fold line 5 may be thinned out by stamping or cutting into the upper layer of the mat, thereby increasing flexibility as compared to the sections 3, 4.

The apparatus 1 further comprises a force transmission unit 10 that is embedded in the mat 2 approximately in the center of the second section 4. The site of the force transmission unit 10 is marked in a visible manner, for example by concentric circles and the wording "PUSH". This makes it easily discernible to a user where to apply a compressive force when the apparatus 1 is placed on the chest of the patient. In order to facilitate correct alignment on the patient’s chest, the upper surface of the mat 2 bears further markings, such as first lines 6, 6’ and second lines 7, 7’. Moreover, dia- grams and/or instructions for alignment and use of the apparatus 1 may be shown on the upper surface of the mat 2. Markings, instructions and diagrams may be printed on a textile layer of the mat 2. As shown in Fig. 1, the apparatus 1 comprises a sig- naling device having, for example, a multiplicity of LEDs 8 and/or a sound genera- tor, for generating a visible and/or an audible signal to the user. The apparatus 1 also comprises an electronic control device (see below).

The sections 3, 4 can be placed on top of one another by folding them up along the fold line 5. In Fig. 2, the apparatus 1 is shown in a folded state. The second section 4 is folded at the fold line 5 over the first section 3 of the mat 2 and rests on it. This gives rise to a compact apparatus that is easily portable and that in its folded state fits easily into a standard first aid kit according to DIN 13157, for example. As shown in Fig. 2, the second section 4 may have a flap 9 at its front edge in order to facilitate opening the apparatus 1 (not shown in Fig. 1). The apparatus 1 may be switched into working mode, for example, by a manual switch or a may be automatically activated when opened by means of a sensor that detects opening, such as described in WO 2016/188629 Al . In the folded state shown in Fig. 2 the printed side is on the inside.

For measuring the compressive force exerted by the user on the patient’s chest, the apparatus comprises a force-sensing resistor (FSR) type force sensor 1 1 depicted schematically in Fig. 3a. The FSR sensor 11 is configured as a circular film disk hav- ing a diameter of approximately 50 mm with a force-sensitive area 12. The force- sensitive area 12 is formed by a thin layer of a conductive material with force- dependent resistance, covered on both sides by thin layers having conducting electrodes, which may be arranged as crossed or interlacing comb-like structures. The conducting electrodes are electrically connected to an ultra-thin flex cable 13. The flex cable 13 has electric lines formed by silver on a PET film, for example.

As shown in Fig. 3b in an explosion drawing, the FSR sensor is arranged between a lower plate 14 and an upper plate 15, both of which have a circular shape with a di- ameter of about 50 mm. The lower and the upper plate 14, 15 are thus shaped as cir- cular disks and may be composed of a hard plastic, for example polystyrene, and each have a thickness of approximately 1 mm. The plates 14, 15 are elastically bend- able, having a stiffness corresponding approximately to an ordinary credit card. Both plates 14, 15 have smooth surfaces on their sides facing the force sensor 11 to pro- vide low friction with the force sensor 11. The force sensor 11 is arranged in a float- ing manner between the plates 14, 15. In particular, the force sensor 11 is not glued or otherwise fixed to the plates 14, 15.

Further, the lower plate 14 is glued to a lower rubber plate 16, and the upper plate 15 is glued to an upper rubber plate 17. The lower and the upper rubber plates 16, 17 each have a diameter that is larger than that of the lower and the upper plates 14, 15, for example 75 mm. The rubber plates 16, 17 are also configured as flat circular disks that are arranged congruently to each other. The rubber plates 16, 17 each have a thickness of about 2 mm and have a shore hardness of about 65, for example. On their margins exceeding the area of the lower and the upper plate 14, 15, respective- ly, the lower and the upper rubber plates 16, 17 are glued to each other. The assem- bly formed by the force sensor 11, the lower and the upper plates 14, 15 and the lower and the upper rubber plates 16, 17 forms the force transmission unit 10.

The force transmission unit 10 is configured approximately in the form of a circular disk overall having a diameter of approximately 75 mm (see Fig. 3c). The force transmission unit 10 as a whole is flexible. As shown in Fig. 3c, the force transmission unit 10 is connected to an electronics unit 20 by means of the flex cable 13, which on its end close to the sensor 11 is also embedded between the lower and the upper rubber plates 14, 15. The electronics unit 20 comprises a printed circuit board (PCB) 21 on which a microcontroller 22, a signaling device 23, and a battery holder 24 are arranged, which are symbolically shown in Fig. 3c. The flex cable 13 may be connected to corresponding terminals of the PCB 21 by conductive adhesive tape. The microcontroller 22 is configured to receive and evaluate the sensor signal generated by the force sensor 11 and to control the signaling device 23. For this purpose, the microcontroller 22 comprises processing means with corresponding drivers and a storage unit in which the target values for the force of the compressions performed in cardiac massage and the frequency of said compressions are stored, as well as infor- mation pertaining to generating light signals and/or audible signals, such as spoken commands. The microcontroller 22 may comprise a further storage unit in which actually measured force values and time data are stored. The signaling device 23 may comprise a sound generator and/or a light source. The sound generator is, for exam- ple, a miniature speaker that is suitable for generating speech commands at a suffi- cient volume to be perceivable even in a noisy environment such as in road traffic. The light source may be a light-emitting diode (LED) or a plurality of LEDs 8 for generating light of various colors at a sufficient brightness to be perceivable even in bright daylight. Thus, for example three LEDs 8 may be provided to emit red, yellow and green light, respectively (see Fig. 1). The electronics unit 20 may have, in total, a thickness of approximately 2 to 3 mm.

As represented in Fig. 3d, the force transmission unit 10 and the electronics unit 20 connected by the flex cable 13 are arranged on a lower rubber layer 25, which forms a lower layer of the mat 2. Preferably the force transmission unit 10, the flex cable 13 and the PCB 21 of the electronics unit 20 are glued on the lower rubber layer 25. The flex cable 13 itself has a pre-determined folding position formed by a short transverse fold line which is arranged to coincide with the fold line 5 of the mat 2 (see Fig. 1). The underside of the lower rubber layer 25 has a slip-resistant coating or is roughened in order to improve positioning on the patient's chest. Fig. 3e shows an upper rubber layer 26 which is glued on top of the lower rubber layer 25, enclosing the force transmission unit 10 and the flex cable 13. The upper rubber layer 25 is cut in to a part of its thickness from its underside along a straight line defining the fold line 5 of the mat 2 (see Fig. 1). The electronics unit 20 fits into a window 27 of the upper rubber layer 26, the window 27 being adapted in shape and dimensions to the PCB 21, such that the electronics unit 20 is integrated into the up- per rubber layer 26. On the upper side of the upper rubber layer 26 a textile layer 28 is placed which is printed with the markings, instructions and/or diagrams for instructing the user and which covers the electronics unit 20, except for the signaling device 23 (see Fig. 1). The textile layer 28 may be woven polyester, for example.

In Fig. 4 an apparatus 31 according to second embodiment of the invention is shown in a top view in an opened state and in Fig. 5 in a closed state. The apparatus 31 is configured as the apparatus 1 described above and depicted in an exemplary manner in Figs. l-3e, with the exception of a plastic cap 32 being provided for covering the electronics unit 20, and an insulation strip 33 for insulating the battery, as described below with reference to Figs. 6a-6f. The insulation strip 33 is fixed to the second section 4 of the mat 2 by means of a bolt 34, as shown in Fig. 2. The plastic cap 32 is made of a translucent material, such that the LEDs of the signal- ing device 23 shine through the cap 32. Thus the light of the LEDs 8 is scattered into a wider angle improving their visibility. Further, the plastic cap 32 may serve to am plify the sound emitted by a sound generator of the signaling device 23 by resonance. The plastic cap 32 can be snapped onto the PCB 21. The cap 32 may be removable in a training version of the apparatus 31 for replacing the battery.

Fig. 6a shows the battery holder 35 of the apparatus 31 in a schematic enlarged view. As the battery holder 24 in the first embodiment (see Fig. 3d), the battery holder 35 is fixed to the PCB 21 of the electronics unit 20 and is made of bent sheet-metal shaped to form a pocket to accommodate a button cell battery. Electric contact to one terminal of the battery is made by two resilient flaps 36, 36’ extending from a top of the holder 35 to its downside. At the same time the resilient flaps 36, 36’ serve to press the battery against a contact on the PCB 21 (not shown in Fig. 6a) to provide electric contact to the opposite terminal of the battery. In the second embodiment the pocket of the battery holder 35 opens to that side of the PCB 21 that is opposite the fold line 5, i.e. the battery can be inserted in a direction from the front edge of the apparatus 31. In the view shown in Fig. 6a, the battery can be slid under the top of the battery holder 35 from a front left side. The insertion movement is limited by flaps 38, 38’ provided on the opposite side of the battery holder 35 (see Fig. 6b).

In Fig. 6b the electronics unit 20 is depicted which fits into the window 27 of the upper layer 26 of the mat 2 (see Fig. 3e). In the second embodiment the electronic components and the battery holder 35 of the electronics unit 20 protrude over the surface of the first section 3 and are covered by the cap 32 (see Fig. 4) which has been removed in Fig. 6b. As can be seen in Fig. 6b, the battery 37 has been inserted under the top part of the battery holder 35 from the left side until it contacts the flaps 38, 38’ acting as stops. The battery 37 preferably is a Lithium button cell battery. The battery 37 is held by the flaps 36, 36’ under the holder 35, which at the same time provide electric contact to the "+" terminal of the battery 37. An electric con- nection of the terminal of the battery 37 with a corresponding contact on the PCB 21, on the other hand, is interrupted by the end section of the insulation strip 33 which is placed under the battery 37 in the battery holder 35. The insulation strip preferably is a thin film consisting of biaxially-oriented polyethylene terephthalate (Mylar)

When the apparatus 31 is opened, the insulation strip 33 is pulled out of the battery holder 35, such that electric contact is made between the terminal of the battery and the corresponding battery contact on the PCB 21. Thus the microcontroller 22 is supplied with electric energy, switching it on such that the microcontroller 22 auto- matically initializes and activates the electrical and electronic functions of the appa- ratus 31, which thus reaches its working mode. In Fig. 6c an intermediate situation is shown during unfolding the mat 2, just before the insulation strip 33 is tightened and subsequently withdrawn. In Fig. 6c the cap 32 is not shown. Fig. 6d depicts the same intermediate state of the apparatus 31 including the cap 32. The cap 32 may have a slit or a recess to permit easy removal of the insulation strip 33. In the fully opened state, as shown in Fig. 4, the insulation strip 33 is completely pulled out of the elec- tronics unit 20, remaining connected to the mat 2 only by the bolt 34. The insulation strip 33 thus is held on the underside of the mat 2 and does not interfere with any action to be taken by the user when applying cardiopulmonary resuscitation. In this way the lifetime of the battery may be increased to about 10 years or more.

For using the apparatus 1, 31 to assist a user in cardiopulmonary resuscitation, the apparatus 1 , 31 is removed from a package in which it is sealed in a folded or closed state (see Figs. 2, 5). The apparatus 1, 31 is then unfolded or opened. If the apparatus 1 is configured according to the first embodiment, opening may be facilitated by the flap 9 (see Fig. 2), and during or after opening the apparatus 1 is switched on manually or automatically by means of a sensor that detects opening. If the apparatus 31 is configured according to the second embodiment, during opening the insulation strip 33 is automatically withdrawn from the battery contact, such that the microcontroller 21 is supplied with electric energy by the battery 37 (see Fig. 6c). In both cases the microcontroller 32 is placed in working mode, and the signaling device 23 is activat- ed. The signaling device 23 may be configured to start immediately or after a few seconds to generate acoustic and optical signals in a rhythm corresponding to the target frequency of the compressions during cardiac massage, for example signals with a duration of approximately 50 ms and a repetition frequency of approximately lOO/min. The apparatus 1, 31 thus opened and switched on is shown in Figs. 1 or 4, respectively, in a top view as seen by the user.

The apparatus 1, 31 is then placed on the chest of a patient such that the force transmission unit 10, which is marked on the upper side of the mat 2, comes to rest on the sternum in the area in which the compressive force must be exerted in cardiac massage. The correct location of the apparatus 1, 31 on the patient’s chest is shown in the diagrams printed on the textile layer 28 (see Figs. 1, 4). The lines 6, 6’, 7, T provide further help to align the mat 2 correctly. The user then begins the cardiac massage, and for this purpose exerts a compressive force on the area marked on the upper side of the mat 2 by the wording "PUSH". The compressive force exerted is continually monitored by the force sensor 1 1 of the force transmission unit 10, and maximum and minimum values of the compressive force are detected, and compression strokes are identified. Depending on the maxi- mum detected force, the minimum force, the force amplitude, and/or the frequency of fluctuations in the force or the compressions, the LEDs 8 and a sound generator of the signaling device 23 are activated, wherein, colors of the activated LEDs 8 and increasing or decreasing frequency of the generated sounds depend on whether pre- determined target values are achieved or, if there are deviations from the target val- ues, which amount and direction the deviations have.

After about 30 compressions that fulfill the target conditions, an acoustic or optical signal is generated that indicates that ventilation is needed. After a preset time, a fur- ther signal is emitted, indicating that the cardiac massage should be continued.

After no further compressions have been performed for an extended period of time, the signaling device 22 is no longer activated by the microcontroller 32, and the mi- crocontroller 32 may be switched off permanently or switched into a rest state in which it is only available for reading out the stored data.

In manufacturing the apparatus according to the embodiments described above, the force sensor 11 (see Fig. 3a), the lower plate 14, and the upper plate 15 are provided. Further, the lower rubber plate 16 and the upper rubber plate 17 are provided, the lower plate 14 is glued to the lower rubber plate 16, the upper plate 15 is glued to the upper rubber plate 17. The force sensor 11 is placed in a floating manner between the lower and the upper plates 14, 15 and is not glued or bonded to the lower or the up- per plate 14, 15. All components are centered (see Fig. 3b). The upper rubber plate 17 is glued to the lower rubber plate 16 on its margin that exceeds the lower and the upper plates 14, 15 to form the force transmission unit 10. Further, the first rubber layer 25 and the second rubber layer 26 are provided, the second rubber layer 25 being cut to a fraction of its thickness from its underside along a straight line, defining the pre-determined fold line 5. To the upper side of the first rubber layer 25 glue is evenly applied. The force transmission unit 10 is con- nected to the electronic control unit 20 by the flex cable 13, and the force transmis- sion unit 10 and the control unit 20 are precision positioned on the upper side of the first rubber layer 25. The force transmission unit 10, the electronic control unit 20, and preferably also the flex cable 13 are glued on the first rubber layer 25. Thereafter the second rubber layer 26 is arranged on the first rubber layer 24 such that the electronic control unit 20 is accommodated by the window 27. The second rubber layer 26 is aligned over the first rubber layer and both rubber layers 25, 26 are pressed together. Thus, the second rubber layer 26 is glued onto the first rubber layer 26, such that the force transmission unit 10 is completely embedded between the first and the second rubber layers 25, 26. A battery 37 is inserted under a battery holder 35 of the electronic control unit 20 before or after gluing the second rubber layer 26 onto the first rubber layer 25. The apparatus 1 is then closed by folding the mat. If the apparatus 31 is configured in accordance with the second embodiment, before closing the apparatus 31 completely, an insulation strip 33 is arranged under the bat- tery 37 to insulate a battery contact of the electronic control unit 20 from the battery 37, and the insulation strip 33 is fixed to an opposite edge of the first rubber layer 25 on its underside such that it is automatically pulled away from the battery contact when opening the apparatus 31. Finally the apparatus may be packed and sealed in a plastic cover, such as a shrink- wrap. During manufacturing, or already in manufacturing the electronic control unit 20, data may be loaded to the microprocessor 21, including program code, to perform the functions described above. For purposes of clarity, not all of the reference symbols are shown in all of the figures. Reference symbols in a figure that are not explained have the same meaning as in the remaining figures. List of reference symbols

1 Apparatus

2 Mat

3 Section

4 Section

5 Fold line

6, 6’ Line

7, T Line

8 LED

9 Flap

10 Force transmission unit

11 Sensor

12 Force-sensitive area

13 Flex cable

14 Plate

15 Plate

16 Rubber plate

17 Rubber plate

20 Electronics unit

21 PCB

22 Microcontroller

23 Signaling device

24 Battery holder

25 Rubber layer

26 Rubber layer

27 Window

28 Textile layer

31 Apparatus

32 Cap

33 Insulation strip

34 Bolt Battery holder, 36’ Flap

Battery, 38’ Flap

Claims

1. Apparatus (1, 31) for assisting a user during cardiopulmonary resuscitation of a patient, comprising a force transmission unit (10) with a lower plate (14), an upper plate (15) and a force sensor (11) arranged between the lower plate (14) and the upper plate (15) for detecting a force exerted on the patient's chest by means of the upper plate (15) and the lower plate (14), a flexible mat (2) in which the force transmission unit (10) is partially or completely embedded, a signaling de- vice (8, 23) for generating at least one signal perceivable by the user, and an electronic control device for controlling the signaling device (8, 23) based on the force detected by the force sensor (11), characterized in that the force sensor (11) is arranged in a floating manner between the lower plate (14) and the upper plate (15).

2. Apparatus (1, 31) according to claim 1, characterized in that the force sensor (11) is a sensor array or sensor film comprising substantially a complete interface between the lower plate (14) and the upper plate (15).

3. Apparatus (1, 31) according to claim 1 or 2, characterized in that the force sensor (11) comprises or is a force-sensing resistor (FSR) film.

4. Apparatus (1, 31) according to any one of the preceding claims, characterized in that the force transmission unit (10) comprises a lower and an upper rubber plate (16, 17) between which the lower plate (14), the force sensor (11) and the upper plate (15) are embedded.

5. Apparatus (1, 31) according to any one of the preceding claims, characterized in that the mat (2) has a printable or printed textile layer (28) on its upper side.

6. Apparatus (1, 31) according to any one of the preceding claims, characterized in that the mat (2) is foldable, comprising at least a first section (3) and a second section (4) connected via a predetermined fold line (5), and that the force sensor (1 1) is connected to the electronic control device by a flex cable (13) having a predetermined folding position coinciding with the fold line (5) of the mat (2).

7. Apparatus (31) according to any one of the preceding claims or according to the generic clause of claim 1 , characterized in that the mat (2) is foldable, compris- ing at least a first section (3) and a second section (4), and that the apparatus comprises a battery (37) for supplying electric energy to the electronic control device, a battery contact for electrically contacting the battery (37), the battery contact being electrically connected to the electronic control device, and an insu- lation strip (33), wherein the battery contact is arranged in the first section (3) of the mat (2), wherein a first end section of the insulation strip (33) is arranged for insulating the battery (37) from the battery contact, and wherein a second end section of the insulation strip (33) is fixed to the second section (4) of the mat (2) such that by unfolding the mat (2) the insulation strip (33) is automatically with- drawn from the battery contact and the battery (37) electrically contacts the bat- tery contact.

8. Apparatus (31) according to claim 7, characterized in that the second end sec- tion of the insulation strip (33) is fixed to an underside of the second section (4) of the mat (2).

9. Apparatus (1, 31 ) according to any one of the preceding claims, characterized in that the electronic control device is configured to activate the signaling device (8, 23) to indicate the necessity of ventilation after a predetermined number of strokes of a predetermined force.

10. Method for assisting a user during cardiopulmonary resuscitation of a patient, wherein the control device of an apparatus (1, 31) configured according to any one of the preceding claims is automatically switched to a working mode when the mat (2) of the apparatus (1, 31) is unfolded, a force exerted on the force transmission unit (10) of the apparatus (1, 31) is detected by the force sensor (11) of the force transmission unit (10), and the signaling device (8, 23) of the appa- ratus (1, 31) is activated by the electronic control device based on the force de- tected.

11. Method for manufacturing an apparatus (1, 31) for assisting a user during cardio- pulmonary resuscitation of a patient, comprising the steps of:

providing a force sensor (11), a lower plate (14), and an upper plate (15), placing the force sensor (11) between lower and the upper plate (15) in a floating manner to form a force transmission unit (10),

providing a first and a second rubber layer (25, 26),

- connecting the force sensor (11) to an electronic control unit (20) and fixing the force transmission unit (10) and the electronic control unit (20) on the first rubber layer (25),

gluing the second rubber layer (26) on the first rubber layer (25) to embed at least the force transmission unit (10) between the first and the second rubber layer (25, 26) and to form a flexible mat (2),

folding the flexible mat (2) into a folded state.

12. Method according to claim 11 comprising the additional step of inserting a bat- tery (37) into a battery holder (35), placing a first end section of an insulation strip (33) between the battery (37) and a battery contact and fixing a second end section of the insulation strip (33) to an opposite margin on an underside of the first rubber layer (25), wherein the insulation strip (33) has such a length that it is automatically withdrawn from the battery contact by unfolding the apparatus