Chest compression device

Abstract

A chest compression device for delivering cardiopulmonary resuscitation to a patient. The device comprises an actuator and a retaining member. The retaining member is configured, in use, to receive an external counter force so as to fix the retaining member against an external surface to maintain a position of the actuator relative to the patient.

Description

[0001] CHEST COMPRESSION DEVICE

[0002] Field of invention

[0003] The invention relates generally to a chest compression or CPR device. More particularly, but not exclusively, the invention relates to a device for delivering cardiopulmonary resuscitation (CPR), including chest compressions, to a patient suffering from Cardiac Arrest (CA), using an actuator secured in position on the patient.

[0004] Background

[0005] A patient suffers from CA when their heart suddenly stops pumping blood around the body. In the UK, it is estimated that CA causes at least 480 deaths per day. An effective way to treat a patient suffering from CA is to deliver CPR to the patient, which often includes giving chest compressions to the patient. However, outside clinical settings, the delivery of chest compressions remains very low, often due to bystanders’ inaction driven by panic, lack of knowledge, or insufficient physical stamina to provide high-quality compressions.

[0006] . Consequently, the survival rate for patients suffering from Out-of-Hospital Cardiac Arrest (OHCA) is less than 10%.

[0007] Heart rhythms associated with CA are divided into two groups: shockable rhythms (e.g., ventricular fibrillation (VF)) and non-shockable rhythms (e.g., asystole and pulseless electrical activity (PEA)). Defibrillators are often used to treat a patient suffering from CA by applying an electric charge or current to their heart to restore a normal heartbeat. However, defibrillators can only be used to treat CA associated with shockable rhythms and cannot be used to treat CA associated with non-shockable rhythms. While defibrillation can be lifesaving, it must be combined with effective chest compression. When it comes to first aid response, society tends to be over-reliant on bystanders whose skills, stamina, and experience, often fall short of the required standards.

[0008] The effectiveness of chest compression delivered to a patient is determined by three main factors. Firstly, the deliverer of CPR must place their hands in suitable position relative to the patient’s torso. Secondly, the deliverer must compress the patient’s chest at an appropriate rhythm. Finally, the deliverer must compress the patient’s chest to a suitable depth. Therefore, the deliverer must possess a sufficient amount of strength to achieve these three main factors, and it is especially important to compress the patient’s chest to a suitable depth, making it difficult for many people to deliver effective CPR over long periods of time. Further, an average person may panic if faced with a patient suffering from OHCA (i.e., in public), especially if they are not trained to deliver effective CPR whilst waiting for an ambulance to arrive to their location.

[0009] Various chest compression devices for delivering CPR to a patient exist. However, such devices require multiple users of the device to lift and move the patient to an appropriate position relative to the device. This often requires more than one person to set up the device to deliver CPR. Further, many of these devices are impractical, unintuitive and lack portability. Many of these devices can only be operated and used effectively by healthcare professionals.

[0010] The present invention has been devised with the foregoing in mind.

[0011] Summary of Invention

[0012] According to a first aspect of the invention, there is provided a chest compression device for delivering cardiopulmonary resuscitation to a patient.

[0013] The device may comprise an actuator. The actuator may comprise one or more of a mechanical, electric, hydraulic, pneumatic, piezoelectric, thermal or magnetic mechanism, or any other suitable mechanism. Suitable mechanical mechanisms include, but are not limited to, foot pumps, rod cranks, and rack and pinion assemblies. The actuator may be configured to move the device substantially linearly, e.g., perpendicularly to the chest of a patient. The actuator may be configured to move the device in a manner to compress the patient’s thorax.

[0014] The actuator may be configured, in use, to deliver compression onto the patient’s chest.

[0015] The actuator may directly engage with the patient’s chest by directly exerting a force onto the patient’s chest. The actuator may engage other parts of the device to indirectly engage the patient’s chest and deliver compressions.

[0016] The device may comprise a retaining member. The retaining member may be configured, in use, to receive an external counter force. The retaining member may be configured, in use, to receive an external counter force so as to fix the retaining member against an external surface and maintain a position of the actuator relative to the patient.

[0017] The external counter force may be the weight of a person who is using the device to apply chest compressions to the patient. The retaining member may be configured such that, when a patient is lying on a surface, the retaining member can be placed on one or more sides of the patient and fixed against the surface using an external counter force. The retaining member may be flexible such that it can be partially wrapped around a patient and fixed to a surface using an external counter force for a variety of different patient sizes. The retaining member may be semi-flexible. The retaining member may comprise a plurality of rigid sections connected via flexible material. The retaining member may be rigid and comprise a frame. The retaining member may be semi-flexible or rigid such that it provides a structure to secure the device relative to the patient’s chest when under the influence of the external counter force.

[0018] The device may comprise a strap configured to engage with the actuator. The strap may be the retaining member. The retaining member may comprise a pair of straps. The strap may extend through or around the actuator and / or the device from one side to an opposite side. The retaining member may comprise exposed retaining member regions to which the external counter force is applied. The exposed retaining member regions may comprise exposed strap regions configured to, in use, secure the actuator in position on the patient. The strap may be configured and / or sized to secure the device on the chest of a patient positioned on the ground or floor. The strap preferably has a width that can be secured on the ground with a user’s feet by providing sufficient area for a user to stand on. The strap preferably has a width that can be secured on the ground with a user’s knees by providing sufficient area for a user to kneel on. The strap preferably has a width that can be secured on the ground with a user’s body by providing sufficient area for a user to sit on. For example, the strap may be approximately 180cm long (or approximately 250cm, 240cm, 230cm, 220cm, 210cm, 200cm, 190cm, 170cm, 160cm, 150cm, 140cm, 130cm, 120cm, 110cm, 100cm, 90cm, or 80cm. The strap may be approximately 18cm wide (or approximately 25cm, 24cm, 23cm, 22cm, 21cm, 20cm, 19cm, 17cm, 16cm, 15cm, 14cm, 13cm, 12cm, 11cm or 10cm).

[0019] The actuator may be configured to engage the strap such that, when an external counter force fixes the ends of the strap in place, the actuator engages the strap to increase the tension in the strap. The strap may be positioned over the patient such that, as the tension increases, the strap compresses the patient’s chest.

[0020] Each strap region may comprise a loose end. The loose ends may be the ends which are distal from the actuator. Having strap regions with loose ends may enable the retaining member to be positioned over patients, covering the patient’s chest, to meet the requirements of the patient and / or the environment, without moving the patient. The strap may be formed of, or comprise, a flexible material. The strap may be or be formed of a sheet of fabric. The strap may be or be formed of plastic. The strap may comprise multiple layers. The strap may comprise an inner layer formed of a suitable material to reinforce the strap. The inner layer may comprise memory-foam material or any shape memory material to allow the fabric to self deploy when the device is used. The strap may comprise one or more rigid portions. The inner layer may be formed of or comprise one or more rigid portions. For example, the rigid portions may be or be formed of one or more wood or plastic panels, or any other suitable rigid material. The rigid portions may be placed in a parallel arrangement across the length of the strap, and each rigid portion may extend across the width of the strap. The rigid portions may be a suitable shape to match the shape of the strap. For example, the rigid portions may be rectangular. Having rigid portions not only reinforces the strap, but facilitates self-deployment of the strap and packaging of the device e.g. inside a casing. Rigid portions may also help to secure the device to the patient when in use. The strap may comprise an outer layer. The outer layer may be formed of fabric or a flexible plastic. The outer layer may be or formed of a material with a suitably high coefficient of friction, such that once the fabric is deployed and the user steps on the fabric, the strap does not slip against a surface on which each exposed region is placed. The strap / outer layer of the strap may comprise one or more visual markings to facilitate the positioning of the strap on a patient. Having a flexible strap, e.g. a thin, flexible strap, enables the strap to flex and extend through or around the actuator.

[0021] Advantageously, the strap may be configured to, in use, secure the actuator to patients of various body types and anthropometric mensurations. Example patient body types include, but are not limited to, ectomorph, mesomorph and endomorph. In the case of a patient suffering from sudden cardiac arrest (SCA), the user of the device would have no prior knowledge of a patient’s body type or composition, and patients of all types of body type or composition can suffer from SCA. It is therefore important that the device conforms with all body types with various or compositions and mensuration.

[0022] The device / actuator may be configured to apply a compression force on the chest. The direction of compression force may define a first axis. The first axis may extend through the centre of the device and through the chest of the patient. The device may be configured to provide a substantially linear compression to the chest of a patient when lying on a surface. The device may be configured to provide a substantially 3D compression to the chest of a patient when lying on a surface. The compression force applied by the device may be large enough to compress the patient’s chest by a depth of at least 4cm, maybe approximately 5cm or up to approximately 6cm. However, to deliver effective chest compressions in some patients or methods, a compression depth of less than 4cm may suffice. An adequate compression depth ensures that the patient’s heart and / or thorax is compressed enough to create sufficient blood flow, preventing organ damage due to oxygen deprivation. If a person were to deliver chest compressions manually, they may not be strong enough to provide an adequate compression depth, or may be able to initially provide an adequate compression depth but not be able to sustain an adequate compression depth when delivering chest compressions for long periods of time as the deliverer begins to tire.

[0023] The device / actuator may be configured to, in use, apply the compression force periodically. The frequency of compressions may be approximately 0.6s or 0.5s or less to provide at least 100 - 120 compressions per minute. The frequency of compressions may be approximately 0.6s or 0.5s or less to provide at least 70 compressions per minute. The frequency may be predetermined.

[0024] Each exposed retaining member region (e.g., exposed strap region) may be configured to, in use, secure the actuator in position when a counter force is applied to each exposed strap region along the first axis. The counter force may be applied by a user of the device by stepping, kneeling, sitting, or otherwise exerting their weight, on one or more of each of the exposed retaining member regions. By stepping on the exposed retaining member regions, the counter force may be applied by the weight of the user. The counter force may be applying an alternative form of weight applied to one or more of the exposed retaining member regions. Advantageously, the device can be secured to a patient suffering from CA without having to lift the patient.

[0025] The counter force may compensate for the reaction force resulting from the compression force. The reaction force may be exerted by the patient’s chest on the device. The counter force may compensate for any additional forces applied to the device. The reaction forces and any additional forces may act in a substantially opposite direction the applied compression force. Any additional forces may be caused by friction, wind, movement of the patient or by any other suitable means.

[0026] The strap may be configured to engage with the actuator. The actuator may comprise a first shaft. The actuator may comprise a barrel. The first shaft may be disposed in the barrel. The first shaft may extend through the barrel along a second axis, wherein the second axis is perpendicular to the first axis,

[0027] The strap may engage with the first shaft, wherein the strap wraps or extends partially around the first shaft. The strap may engage with the barrel. The strap may extend in a tortuous path between the barrel and first shaft. The first shaft may be configured to rotate about the second axis. A tensile force may be applied to the strap on rotation of the first shaft to apply the compression force to the chest. The barrel may comprise one or more openings. The strap may extend through the one or more openings. The barrel may be formed of a translucent or opaque material, such that the first shaft and portion of strap that is wrapped around the first strap is unseen. The device may further comprise a rotary actuator configured to drive the rotation of the first shaft.

[0028] The first shaft may be configured to, in use, rotate in a first direction about the second axis. Rotation of the first shaft in the first direction may shorten one or more of the exposed strap regions. Shortening one or more of the exposed strap regions may translate the actuator along the first axis towards the chest and apply the compression force to the chest. Shortening one or more of the exposed strap regions may increase the tensile force applied to the strap.

[0029] The first shaft may be configured to, in use, rotate in a second direction about the second axis. Rotation of the first shaft in the second direction may lengthen one or more of the exposed strap regions and translates the frame along the first axis away from the chest to decompress the chest. Lengthening one or more of the exposed strap regions may decrease the tensile force applied to the strap.

[0030] As an alternative to the shaft and barrel arrangement, a single piece component may be provided for the strap to pass through / around e.g. a unitary component with a channel provided therein / therethrough e.g. an arcuate channel.

[0031] The rotary actuator may comprise a first gearwheel. The first shaft may engage with the first gearwheel. The rotary actuator may comprise a second gearwheel. The second gearwheel may engage with the first gearwheel, wherein rotation of the second gearwheel may cause the rotation of the first gearwheel about the second axis. The second gearwheel may be vertically offset from the first gearwheel along the first axis. The second gearwheel may be horizontally offset from the first gearwheel along a third axis, wherein the third axis is perpendicular to the first and second gearwheel. The first gearwheel and / or the second gearwheel may comprise a plurality of teeth. The number of teeth comprised by the first gearwheel may equal to the number of teeth comprises by the second gearwheel. Alternatively, the number of teeth comprised by the first gearwheel may not be equal to the number of teeth of the second gearwheel. For example, the first gearwheel may comprise 20 teeth and the second gearwheel may comprise 15 teeth. The dimensions of the first gearwheel may be the same or substantially the same as the dimensions of the second gearwheel. The first gearwheel and / or second gearwheel may comprise a plurality of gaps between each of the plurality of teeth. Each gap of the first gearwheel may be large enough to fit each of the plurality of teeth on the second gearwheel, such that the first gearwheel engages with the second gearwheel and rotation of the first gearwheel causes rotation of the second gearwheel. Each gap of the second gearwheel may be large enough to fit each of the plurality of teeth on the first gearwheel, such that the first gearwheel engages with the second gearwheel and rotation of the first gearwheel causes rotation of the second gearwheel.

[0032] The rotary actuator may further comprise a motor. The motor may engage with the second shaft, wherein the motor may be configured to, in use, drive the rotation of the second shaft. The motor may be powered electrically. The rotation of second shaft may be driven by any other suitable means. Other suitable means to drive the rotation of the second shaft include, but are not limited to, pneumatic, hydraulic, mechanical and magnetic systems.

[0033] The rotary actuator may be configured to drive the rotation of the first shaft using any other suitable means. Other suitable means to drive the rotation of the second shaft include, but are not limited to, pneumatic, hydraulic, mechanical and magnetic systems.

[0034] The device may comprise a controller. The controller may be connected to / communicate with the motor. The controller may be configured to control the speed, direction and / or torque of the motor. The controller may be connected to the motor via a switch e.g. a Fl-Bridge for switching the polarity of voltage applied across the motor, such the direction of the motor is controlled. The speed of the motor may be proportional to the time period of the applied compression force. The controller may comprise a processor. The processor may be programmed with a set of instructions used to control the motor. The controller may be powered by a battery. The battery may be rechargeable. Alternatively, the controller may be remote from the device. The torque of the motor may be controlled to achieve a suitable chest compression depth. The motor may be connected to the second shaft via gearbox, such that gearbox increases the torque of the motor.

[0035] The motor may be connected to the first shaft via a mechanical clutch. When the clutch is engaged, the motor may be configured to drive the rotation of rotation of the second shaft, and therefore, drive the rotation of the first shaft in a first direction about the second axis to translate the actuator towards the chest to compress the chest. When the clutch is disengaged, the second shaft may no longer be configured to drive the rotation of the second shaft. Once the clutch is disengaged, elastic energy stored in the strap may be released and cause the one or more of the exposed strap regions to lengthen, to translate the actuator away from the chest to decompress the chest.

[0036] The actuator may comprise a ring gear. The ring gear may comprise a ring gear bearing. The ring gear may comprise a ring gear shaft. The ring gear may comprise a ring gear airflow support.

[0037] The actuator may comprise a motor. The actuator may comprise an airflow mount. The actuator. The actuator may comprise a gear system. The gear system may be, or comprise, a planetary system. The planetary system may comprise a planet carrier. The planetary gear system may comprise a sun gear. The planetary gear system may comprise planet bearings. The planetary gear system may comprise planet gears. The planetary gear system may comprise a planet carrier support.

[0038] The planet carrier support and ring gear airflow support may be fixed in place. In use, the motor may drive rotation of the ring gear shaft. In use, the motor may drive rotation of the ring gear shaft via the planetary gear system and an Epicycloid train arrangement. The epicycloid train arrangement may comprise the sun gear, planet gears, and ring gear shaft. The motor may deliver a rotational output, which may drive reduction gear systems (which, in examples, can be harmonic, cycloidal, or epicyclic gear systems), then at a final reduction stage, the sun gear may act as an input, the planet carrier support may be fixed, and there may be rotational output to the ring gear shaft.

[0039] The device may comprise a clutch. The clutch may be configured to enable selective engagement between the motor and the gear system. The clutch may be configured to enable selective engagement between the motor and different components of the gear system. The clutch may be configured to enable selective engagement between the motor and different components of the planetary gear system.

[0040] The device may comprise a spring mechanism. The spring mechanism may be configured to oppose the compression force and enable decompression of the patient’s chest.

[0041] The motor may be reversible so as to enable reverse rotation of the shaft to allow decompression of the patient’s chest. The motor may be configured to drive reverse rotation of the shaft via a reverse gear which is connected through the clutch.

[0042] The motor may directly drive rotation of a sun gear, which in turn directly drives rotation of the planetary gears. The planetary gears may directly drive rotation ring gear shaft via engagement with teeth of the ring gear.

[0043] The ring gear shaft may comprise a slot. In use, two straps (which form the retaining member) may extend from inside the shaft through the slot. The ring gear shaft may comprise two slots. A strap may extend through the ring gear shaft between the two slots.

[0044] The straps may be configured to receive a counter force, such as a user’s weight, to fix them in place on the ground either side of a patient. As the shaft rotates, tension may increase in the straps to exert a downwards force on a patient’s chest

[0045] The controller may be configured to control defibrillation technology.

[0046] Any part of the device, such as the retaining member (e.g., strap) and / or the housing of the device may comprise defibrillation pads, or any surface configured to deliver defibrillation shocks through the patient’s chest to restart the heart.

[0047] Any part of the device, such as the retaining member (e.g., strap) and / or the housing of the device may comprise sensors. The sensors may be configured to inform the resuscitation process including, but not exclusively, to assist with: the proper placement of the retaining member, the proper placement of the device on the patient, the compression zone depth and rhythm of the device onto the patient, reading the patient vital signs (e.g., heart rhythm, blood pressure, blood oxygenation etc.).

[0048] The device may comprise a first input means. The first input means may be connected to the controller. On activation, the device may begin to apply a periodic compression force. The first input means may be, but is not limited, a push button, switch, touch sensor or any suitable alternative. The device may comprise a second input means. The second input means may be connected to the controller. On activation of the second input means, the second input means may adjust the strap length, by extending the strap to loosen it or shortening the strap to tighten it, to help secure the device in position. The second input means may be, but is not limited, a push button, switch, touch sensor or any suitable alternative.

[0049] The device may further comprise a housing. The actuator may be disposed within the housing. The controller may be disposed within the housing. The housing may be formed of a rigid material. The housing may comprise a first and second section. The first section may be detachable from the second section, such that the components disposed within the housing can be accessed.

[0050] The housing may comprise one or more openings at opposite sides of the housing. The openings may be a part of a contact zone between the housing and the patient’s chest. The strap may extend through the opening(s). The housing may be configured e.g. otherwise closed such that only specific sections of the strap are exposed. The housing may comprise one or more visual markings to facilitate the positioning of the device on a patient’s body.

[0051] According to a second aspect, the device according to the first aspect of the invention may be included in apparatus. The apparatus may comprise a casing. The casing may be mounted e.g. on a wall or other location accessible by a user. The device may be disposed within the casing. The device may be detachable from the casing. The device may comprise one or more tabs, configured such that pulling the / each tab(s) detaches the device from the casing. The device may be detached from the casing by any other suitable means. When the device is disposed within the casing, each exposed region of the strap may be folded over the housing of the device. The strap may be formed of or comprise memory-foam material or memoryshape material. Advantageously, when the device is detached from the casing, the straps may be unfolded into a suitable position to facilitate the positioning of the device and secure the actuator in position on the patient. The apparatus may comprise a cutting means. The cutting means may be detachable to the casing. The suitable cutting means, such as a pair of scissors, may be used to cut and remove the patient’s clothing such that the actuator can be secured to the patient and effective chest compressions can be delivered to the patient.

[0052] According to a third aspect, a method of delivering cardiopulmonary resuscitation using the device of any of claims 1 to 13 may be provided. The device may be positioned on the chest of a patient. The device may be secured to the actuator in position on the patient with the exposed retaining member regions (e.g., strap regions) operating the device to deliver cardiopulmonary resuscitation to the patient.

[0053] According to a fourth aspect, a method of delivering cardiopulmonary resuscitation using the apparatus according to the second aspect of the invention may also be provided. The method may comprise aligning the casing on the user’s torso. The method may comprise detaching the device from the casing. The method may comprise aligning the device on the user’s torso. The method may comprise securing the device to the patient. The method may comprise triggering the device to deliver chest compression.

[0054] Optional features of any of the above aspects may be combined with the features of any other aspect, in any combination. For example, features described in connection with the device of the first aspect may have corresponding features definable with respect to the apparatus of the second aspect, the method of the third aspect and / or the method of the fourth aspect, and these embodiments are specifically envisaged. Features which are described in the context or separate aspects and embodiments of the invention may be used together and / or be interchangeable wherever possible. Similarly, where features are, for brevity, described in the context of a single embodiment, those features may also be provided separately or in any suitable sub-combination.

[0055] Brief description of drawings

[0056] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0057] Figure 1 shows a schematic of the chest compression device;

[0058] Figure 2 shows a schematic of the chest compression device;

[0059] Figure 3 shows a perspective view of the actuator of the chest compression device of Figure 1;

[0060] Figure 4 shows a schematic of the chest compression device of Figure 1, further comprising a housing and a rotary actuator;

[0061] Figure 5 shows a perspective view of the chest compression device of Figure 3; Figure 6 shows another perspective view of the chest compression device of Figure 3;

[0062] Figure 7 shows a schematic of a chest compression device secured to a patient;

[0063] Figures 8(a) and 8(b) respectively show force diagrams relative to the patient when the device translates towards the patient to compress the chest and when the device translates away from the patient such that the chest is decompressed;

[0064] Figure 9 shows a number of different body types;

[0065] Figure 10 shows a schematic of another chest compression device;

[0066] Figures 11(a) and 11(b) respectively show a perspective view and an enlarged perspective view of another chest compression device;

[0067] Figure 12 shows a perspective view of the chest compression device of Figure 11;

[0068] Figure 13 shows a perspective view of a casing configured to receive a chest compression device;

[0069] Figures 14(a) and 14(b) respectively show how a chest compression device can be removed from a casing to be positioned on a patient;

[0070] Figures 15(a) and 15(b) show perspective views of chest compression devices comprising a rigid retaining member;

[0071] Figures 16(a) and 16(b) respectively show perspective views of chest compression devices comprising with rigid and flexible retaining members;

[0072] Figure 17 shows a perspective view of a chest compression device comprising a semi-flexible retaining member;

[0073] Figures 18(a) and 18(b) show perspective views of an actuator demonstrating the generation of a compression force; and

[0074] Figure 19 shows a perspective exploded view of an actuator. Detailed description

[0075] Figure 1 shows a schematic view of a chest compression device 10. The device 10 is used to apply chest compressions to a patient 5. The device 10 comprises an actuator 12 and a retaining member 14.

[0076] In use, the device is positioned such that the actuator 12 is disposed on the chest of the patient 5. To perform a chest compression, the actuator exerts a compression force (indicated via arrow 1) upon the chest of the patient 5. In turn, the patient’s chest exerts an opposing reaction force (indicated via arrow 2) on the actuator 12.

[0077] To compensate for the reaction force 2, the retaining member 14 is configured to receive an external counter force (indicated via arrow 3). The counter force 3 negates the reaction force (i.e., balances the resultant forces acting on the device 10) so as to maintain the position of the actuator 12 against the patient’s chest and to ensure the actuator 12 is able to apply a sufficiently strong / deep chest compression.

[0078] The counter force can be the weight of a person. For example, a person who is using the device to apply chest compressions to a patient can place their weight onto the retaining member 14 (e.g., by standing or kneeling on the retaining member 14). In other examples, the counter force can be provided by the weight of an object with sufficient mass to compensate for the reaction force 2.

[0079] The actuator 12 can comprise one or more of: a hydraulic piston actuator, a pneumatic piston actuator, a crankshaft actuator, and cylindrical cam actuator, a scotch yoke actuator, scotch crank mechanism, a Cam and follower actuator, a pinion and rack actuator, a rail driven mechanism, a chain driven mechanism, a solenoid, or any other suitable actuator mechanism.

[0080] In some examples, the actuator 12 is configured to deliver chest compression according to the cardiac pump theory. In such examples, the actuator 12 can be configured to apply pressure to a local area of the chest, such as over the sternum. Such an actuator may be a piston actuator.

[0081] In some examples, the actuator 12 is configured to deliver chest compression according to the thoracic pump theory. In such examples, the actuator 12 can be configured to apply pressure across a large area (or the entire) area of the chest. Such an actuator may comprise straps or other elongated members which exert a downwards force across the width of the patient’s chest.

[0082] The actuator can be any of electric, thermal, electromagnetic, linear pneumatic, linear or hydraulic.

[0083] In the example of Figure 1, the retaining member 14 is substantially rigid. In other examples, the retaining member 14 can be at least partially flexible. In some examples, the device comprises multiple retaining members.

[0084] In the example of Figure 1, the actuator 12 directly contacts the patient 5. However, in other examples this is not necessary, and one or more components may be disposed between the actuator 12 and the patient 5 as long as the actuator is still able to exert a sufficient compression force 1 to the patient 5.

[0085] In the example of Figure 1, the actuator 12 is directly connected to the retaining member 14. However, in other examples this is not necessary, and one or more components may be disposed between the actuator 12 and the retaining member 14. For example, the device 10 may comprise a casing which houses the actuator 12, and the retaining member 14 may be configured to fix the position of the casing relative to the patient 5.

[0086] Examples of alternative devices 10 are shown in Figures 15-17 and are explained below.

[0087] Figure 15a shows a perspective view of a device 10 comprising a rigid retaining member 14, similarly to the example device 10 of Figure 1. The retaining member 14 extends from one side of the actuator 12 and comprises foot portions 14-1. In use, a user can stand on the foot portions 14-1 to provide the counter force. The rigid retaining member 14 can be, for example, a frame formed of a strong rigid material, such as a metal, plastic, wood. The frame needs to be sufficiently strong to not break or significantly deform when subject to the counter force and reaction force.

[0088] Figure 15b shows a perspective view of another device 10 comprising a rigid retaining member 14. The retaining member 14 extends from two opposing sides of the actuator 12 and comprises foot portions 14-1. In use, a user can stand on the foot portions 14-1 to provide the counter force. In the example of Figure 15b the retaining member 14 is continuous and extends across / through the actuator 12. In other examples, multiple retaining members 14 can be used, and separate retaining members 14 can extend from opposing sides of the actuator 12.

[0089] Figure 16a shows a perspective view of a device 10 comprising a rigid retaining member 14. The retaining member 14 extends from a single side of the actuator 12 and splits to form foot portions 14-1. The device 10 of Figure 16a is substantially similar to the device 10 of Figure 15a, but the foot portions 14-1 are spaced further apart so as to enable their placement either side of a patient’s head and / or shoulders.

[0090] Figure 16b shows a device 10 comprising a flexible retaining member 14. The flexible retaining member 14 can be formed of, or comprise, any suitable material. For example, the retaining member 14 can comprise fabric straps. In the example of Figure 16b, the retaining member 14 is formed of two straps which extend from opposing sides of the actuator 12. In use, a user can stand (or kneel in the examples of Figures 15a or 16a) on the fabric straps so as to provide the counter force required to maintain the position of the actuator 12 relative to the patient.

[0091] Figure 17 shows a device 10 comprising a semi-flexible retaining member 14. The semiflexible retaining member 14 can be formed of, or comprise, a plurality of rigid segments which are rotatably connected. In the example of Figure 17, the retaining member 14 is formed of two portions which extend from opposing sides of the actuator 12, and each portion comprises a plurality of rigid segments which are rotatably connected.

[0092] For any of the example devices shown herein, such as the example devices shown in Figures 15-17, any retaining members 14 is shown with separated foot portions can be instead comprise single foot portions onto which both feet of a bystander can be placed. Similarly, any body part instead of a foot, such as a knee, can be used to provide the counter force to the retaining member.

[0093] Figure 2 shows a schematic of a chest compression device 100. In this embodiment, the device 100 comprises an actuator 102 and a strap 104. The strap 104 is an example of a retaining member 14. The strap 104 is configured, in use, to extend through or around the actuator 102 from one side to an opposite side, wherein a first exposed strap region 106a and a second exposed strap region 106b are configured to, in use, secure the actuator 102 in position on the patient. The device 100 and / or the actuator 102 is configured to apply a compression force to the chest of the patient, wherein the direction of compression force defines a first axis. The device 100 and / or the actuator 102 is configured to, in use, apply the compression force periodically.

[0094] First exposed strap region 106a and second exposed strap region 106b are configured to, in use, secure the actuator 102 in position when a counter force applied to each exposed strap region 106a, b along a direction parallel to the first axis, wherein the counter force compensates for the reaction force resulting from the compression force, wherein the reaction force is exerted by the patient’s chest on the device 100 and / or actuator 102.

[0095] Figure 3 shows a perspective view of the actuator 102 used in one example. The actuator 102 comprises a first shaft 160 and a barrel 140. Although shown separated from each other in Figure 3, the first shaft 160 is disposed in the barrel 140 such that the first shaft 160 extends through the barrel 140 along a common second axis, wherein the second axis is perpendicular to the first axis. That is, the first shaft 160 sits within the cavity of the barrel 140 with a gap therearound. The strap 104 wraps around or extends partially around the first shaft 160 in a tortuous path between the barrel 140 and first shaft 160. In this manner the strap 104 engages with the first shaft 160 and the barrel 140. The first shaft 160 is configured, in use, to rotate about the second axis, wherein a tensile force is applied by the strap 104 on rotation of the first shaft 160, to translate to a linear motion of the device 100 and apply the compression force to the chest.

[0096] Figure 4 shows a schematic view of a chest compression device 100 similar to the device of Figure 2, but further comprising a housing 108 and a rotary actuator 110. The rotary actuator 110 is configured to, in use, drive the rotation of the first shaft 160. The actuator 102 is disposed within the housing 108 and engages with the housing 108. The housing 108 comprises a plurality of openings, e.g. one or more at opposite sides of the housing, wherein the strap 104 extends through the openings.

[0097] Figure 5 shows a perspective view of the chest compression device of Figure 4. The actuator 102 is disposed in the housing 108. A first exposed strap region 106a and a second exposed strap region 106b are configured to, in use, secure the device 100 in position on the patient. The housing 108 comprises a plurality of openings e.g. one or more on each side of the housing 108. The strap 104 is configured to extend through openings. Figure 6 shows another perspective view of the chest compression device of Figure 4. The housing 108 further comprises one or more visual markings 114 to facilitate the positioning of the device 100 on a patient.

[0098] Figure 7 shows a schematic of a chest compression device 100 in position on / secured to a patient 134. The device 100 comprises an actuator 102, The device 100 comprises a strap 104. The strap 104 engages with the actuator 102. The strap 104 is configured in use, to extend though or around the actuator 102 from one side to an opposite side, wherein a first exposed strap region 106a and second exposed strap region 106b are configured to, in use, secure the actuator 102 in position on the patient.

[0099] The first exposed strap region 106a and second exposed strap region 106b are configured to, in use, secure the actuator 602 in position when a first counter force 116a and a second counter force 116b are applied to the first exposed strap region 106a and second exposed strap region 116b respectively along the first axis. The counterforces may be provided by a user standing on the exposed strap regions 106a, 106b. The device 100 is configured to apply a compression force 117 to the chest, wherein the direction of compression force defines a first axis. The first counter force 116a and second counter force 116b compensate for the reaction force resulting from the compression force 117, wherein the reaction force is exerted by the patient’s chest on the device. The actuator 102 comprises a first shaft (not shown), wherein the strap 104 wraps around the first shaft and engages with the first shaft, wherein the compression force 117 is generated by a tensile force 119 (indicated by the red arrows) is applied to the strap 104. A rotary actuator 110 (not shown) is configured to drive the rotation of the first shaft. The compression force 117 is applied periodically. The actuator 102 comprises a first shaft, wherein the strap 104 wraps around the first shaft and engages with the first shaft, wherein the compression force is generated by the tensile force 119 applied to the strap 104.

[0100] Figures 8(a) and 8(b) respectively show force diagrams relative to the patient when the device translates towards the patient 234 to compress the chest and when the device translates away from the patient 234 such that the chest is decompressed. When the chest is compressed, a compression force is applied to the patient 234 by a chest compression device, and because of this compression force, the device experiences a reaction force exerted on the device by the chest.

[0101] Figure 8(b) shows the force diagram for a situation wherein the external counter force is not applied. The resultant force, in the absence of an external counter force, is insufficient for compressing the patient’s chest. Figure 8(a) shows the force diagram when the external counter force is applied, increasing the resultant downward force on the patient’s chest to enable chest compressions.

[0102] Figure 9 shows a number of different patient body types. In some embodiments, the strap may be configured to, in use, secure the actuator to patients of various body types and compositions. Example patient body types include, but are not limited to, ectomorph 318, mesomorph 320 and endomorph 322.

[0103] Figures 10 to 12 show a chest compression device 400, similar to that of figures 1 to 7. Features of devices 100 and 400 may be used interchangeable / in conjunction with each other.

[0104] Figure 10 shows a schematic of a chest compression device 400. The device 400 comprises an actuator 402 and strap 404. The strap 404 is configured to, in use, engage with the actuator 402. The strap 404 is configured in use, to extend though or around the actuator 402 from one side to an opposite side, wherein a first exposed strap region 406a and second exposed strap region 406b are configured to, in use, secure the actuator 402 in position on the patient 434. The device 400 comprises a housing 408. The actuator 402 is disposed within the housing 408. The device 400 comprises a rotary actuator 410 configured to drive the rotation of a first shaft (not shown). The device 400 comprises a controller 450 configured to drive one or more components of the rotary actuator 410.

[0105] Figures 11(a) and (b) respectively show a perspective view and an enlarged perspective view of the chest compression device 400. The device 400 comprises an actuator 402 and strap 404. The strap 404 is configured to, in use, engage with the actuator 402. The strap 404 is configured in use, to extend though or around the actuator 402 from one side to an opposite side. A first exposed strap region 406a and second exposed strap region 406b are configured to, in use, secure the actuator 402 in position on the patient 434. The device 400 comprises a housing 408. The actuator 402 is disposed within the housing 408. The device 400 may comprise a controller (not shown).

[0106] The device 400 and / or actuator 402 is configured to apply a compression force to the chest, wherein the direction of compression force defines a first axis 411. wherein the device 400 and / or actuator 402 is configured to, in use, apply the compression force periodically. First exposed strap region 406a and second exposed strap region 406b are configured to, in use, secure the actuator when a counter force is applied to each exposed strap region along the first axis 411, wherein the counter force compensates for the reaction force resulting from the compression force, wherein the reaction force is exerted by the patient’s chest on the device 400.

[0107] The actuator 402 comprises a first shaft (not shown) and a barrel 440. The first shaft is disposed in the barrel 440 and the first shaft extends through the barrel 440 along a second axis, wherein the second axis 413 is perpendicular to the first axis 411.

[0108] The strap 404 engages with the first shaft and the barrel 440, wherein the strap 404 wraps or extends partially around the first shaft and extends in a tortuous path between the barrel 440 and first shaft, wherein the first shaft is configured, in use, to rotate about the second axis 413, wherein a tensile force is applied by the strap on rotation of the first shaft to apply the compression force to the chest.

[0109] The device 400 further comprises a rotary actuator configured to, in use, drive the rotation of the first shaft. The first shaft is configured to, in use, rotate in a first direction about the second axis 413. Rotation of the first shaft in the first direction shortens one or more of the exposed strap regions, to translate the actuator 402 along the first axis 411 towards the patient’s chest and apply the compression force to the chest.

[0110] The first shaft is configured to, in use, rotate in a first direction about the second axis 413. Rotation of the first shaft in the second direction lengthens of the first exposed strap region 404a and second exposed strap region 404band translates the actuator 402 away from the patient’s chest along the first axis 411, wherein translating the actuator 402 away from the chest decompresses the chest.

[0111] The rotary actuator comprises a first gearwheel 436. The first gearwheel 436 engages with the first shaft. The rotary actuator further comprises a second gearwheel 438 that engages with the first gearwheel 436, wherein rotation of the second gearwheel 438 causes rotation of the first gearwheel 436 about the second axis 413. The second gearwheel 438 is vertically offset from the first gearwheel 436 along the first axis 411. The rotary actuator further comprises a second shaft (not shown). The motor 442 is engaged with the second shaft, and the motor is configured to, in use, drive the rotation of the second shaft. A controller 450 is configured to, in use, control the speed, direction and / or torque of the motor

[0112] Figure 12 shows a perspective view of the chest compression device 400. The device 400 comprises a battery 441 configured to power the electronic components of the device 400. The rotary actuator comprises a motor 442 configured to, in use, drive the rotation of the second shaft. The controller 410 is configured to, in use, control the speed, direction and / or torque of the motor. The controller 410 instructs an H-bridge 450 to change the direction, torque, and power of the motor 442.

[0113] Features of the chest compression devices 100 shown in Figures 1 to 7 may be combined or interchanged with features of device 400 of Figures 10 to 12.

[0114] Figures 18a and 18b show perspective views of the device 400 of Figure 12. These figures are described below to further explain how the compression force is generated.

[0115] Each exposed strap region 406a, b extends from a slit extending along the length of the barrel 440. In some examples the strap regions 406a, b are connected to each other inside the barrel 440 but, in other examples, the strap regions 406a, b are separate and are connected to an internal surface of the barrel 440.

[0116] The first gear wheel 436 is configured to rotate the barrel 440, as shown in Figure 18b. As the barrel 440 rotates, the tension increases in both exposed strap regions 406a, b. The combined effect of the tension in the exposed strap regions 406a, b produces a downwards force onto the patient’s chest, which is the compression force.

[0117] Figure 19 shows a perspective exploded view of an example actuator 602 which can be used in some examples of a chest compression device. The actuator 602 is suitable for use with chest compression devices which comprise two exposed strap regions. The two exposed strap regions can be opposing ends of a single strap, or can be ends of separate straps.

[0118] The actuator 602 comprises a ring gear comprising a ring gear bearing 611, a ring gear shaft 613, and a ring gear airflow support 631. The actuator 602 comprises a motor 615 and an airflow mount 617. The actuator 602 comprises a planetary gear system 619 comprising a planet carrier 621, a sun gear 623, planet bearings 625, planet gears 627, and a planet carrier support 629.

[0119] The planet carrier support 629 and ring gear airflow support 631 are fixed in place. In use, the motor 615 drives rotation of the ring gear shaft 613 via the planetary gear system 619 and an Epicycloid train arrangement comprised of the sun gear 623, planet gears 627, and shaft 613. The motor 615 delivers a rotational output, driving reduction gear systems (which, in examples, can be harmonic, cycloidal, or epicyclic gear systems), then at a final reduction stage, the sun gear 623 acts as an input, the planet carrier support 629 is fixed, and there is rotational output to the ring gear shaft.

[0120] The ring gear shaft 613 comprises a slot 609. In use, two straps (which form the retaining member) extend from inside the shaft 613 through the slot 609. The straps can receive a counter force, such as a user’s weight, to fix them in place on the ground either side of a patient. As the shaft 613 rotates, tension will increase in the straps to exert a downwards force on a patient’s chest.

[0121] In other examples, the ring gear shaft comprises two slots 609. The second slot can be disposed on an opposing side of the ring gear shaft to the first slot. Each exposed strap region may extend through a corresponding slot.

[0122] In the present example, the teeth of the ring gear are disposed at one end of the ring gear shaft 613. However, this is only an example and, in other examples, the ring gear teeth can be placed anywhere inside / along the ring gear shaft 613, for example in the centre of the ring gear shaft, or there can be teethed sections on the same shaft 613 configured to, in use, drive rotation of the ring gear shaft 613. Such arrangements can improve efficiency and reduce torsion forces in the shaft.

[0123] In some examples, the actuator 602 comprises a clutch mechanism (not shown). The clutch mechanism can be disposed, for example, at the output of the motor. In other examples, the clutch can be disposed in alternative positions.

[0124] In some examples, the actuator 602 comprises a loaded spring mechanism (not shown). The spring-loaded mechanism may be a back drivable mechanism configured to allow or optimise chest decompression.

[0125] Figure 13 shows a perspective view of a casing 550 configured to receive a chest compression device 100, 400. A chest compression device (100, 400 (not shown)) is disposed in casing 550. The casing 550 comprises one or more visual markings to facilitate positioning of the casing 550 on the patient. The chest compression device 100, 400 is detachable from the casing 550. The device comprises a tab 552. Pulling the tab 552 detaches the device from the casing 550. A cutting means (not shown) is detachable to the casing 550. Suitable cutting means, such as a pair of scissors, may be used to cut and remove the patient’s clothing such that the actuator can be secured to the patient and effective chest compressions can be delivered to the patient. Figures 14(a) and 14(b) respectively show how a chest compression device can be removed from a casing and how the device positioned on the patient. Figure 14(a) shows a casing 550, wherein a chest compression device is disposed within the casing 550. The casing 550 is positioned on the chest of patient 534. The chest compression device is detached from the casing 550. The straps 534 are unfolded to a position around the patient that is pre-determined due to the straps comprising memory-foam material. The actuator is then be aligned on the patient. The device is secured to the patient ready to begin chest compression.

[0126] In some examples, part of the device, such as the retaining member (e.g., strap) and / or the housing of the device may comprise defibrillation pads, or any surface configured to deliver defibrillation shocks through the patient’s chest to restart the heart. A controller may be configured to control defibrillation technology. The controller may be user adjustable so as to control the frequency and or strength of the shocks delivered through defibrillation.

[0127] Any part of the device, such as the retaining member (e.g., strap) and / or the housing of the device can comprise one or more sensors. The sensors may be configured to inform the user’s and assist them during the resuscitation process. For example, the sensor can obtain data which is subsequently provided to a user (e.g., via a display or third party device) to assist with one or more of: the proper placement of the retaining member, the proper placement of the device on the patient, the compression zone depth and rhythm of the device onto the patient, reading the patient vital signs (e.g., heart rhythm, blood pressure, blood oxygenation etc.).

[0128] Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

[0129] Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The applicant hereby gives notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present application or of any further application derived therefrom. For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several means recited in the claims and any reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

Claims1. A chest compression device for delivering cardiopulmonary resuscitation to a patient, the device comprising: an actuator; and a retaining member configured, in use, to receive an external counter force so as to fix the retaining member against an external surface to maintain a position of the actuator relative to the patient.

2. The device of claim 1, wherein the retaining member is a strap, and wherein the strap comprises exposed strap regions configured to, in use, secure the actuator in position on the patient by receiving the external counter force.

3. The device of claim 1 or claim 2, wherein the exposed strap regions are at least partially flexible and comprise loose ends.

4. The device of any preceding claim, wherein the strap extends through or around the actuator from one side to an opposite side.

5. The device of any of claims 1-4, wherein the device and / or the actuator is configured to apply a compression force to the chest periodically.

6. The device of any of claims 2-5, wherein the strap comprised a memory-foam or any shape memory material.

7. The device of any of claims 2-6, wherein the actuator comprises a motor, a gear system, a ring gear, and a shaft; wherein the motor is configured to drive rotation of the gear system which in turn drives rotation of the ring gear; wherein the ring gear is part of, or connected to, the shaft such that the shaft rotates in unison with the ring gear; and wherein the shaft comprises one or more slots through which the exposed strap regions extend.

8. The device of claim 7, wherein the gear system is, or comprises, a planetary gear system, a harmonic gear system, or a cycloidal gear system.

9. The device of claim 7 and or claim 8, further comprising one or more of: a clutch configured to enable selective engagement between the motor and the gear system; a spring mechanism configured to oppose the compression force and enable decompression.

10. The device of any of claims 7-9, wherein the motor is reversible so as to enable reverse rotation of the shaft to allow decompression.

11. The device of any of claims 5 to 6, wherein the actuator comprises a first shaft and a barrel, wherein the first shaft is disposed in the barrel and the first shaft extends through the barrel along a second axis, wherein the second axis is perpendicular to the first axis.

12. The device of claim 11, wherein the strap engages with the first shaft and the barrel, wherein the strap wraps or extends partially around the first shaft and extends in a tortuous path between the barrel and first shaft, wherein the first shaft is configured, in use, to rotate about the second axis, wherein a tensile force is applied by the strap on rotation of the first shaft to apply the compression force to the chest.

13. The device of claim 11 or claim 12, further comprising a rotary actuator configured to in use, drive the rotation of the first shaft.

14. The device of claim 13, wherein the first shaft is configured to, in use, rotate in a first direction about the second axis, and wherein the rotation of the first shaft in the first direction shortens one or more of the exposed strap regions to translate the actuator along the first axis towards the patient’s chest and apply the compression force to the chest.

15. The device of any of claims 13 to 14, wherein the first shaft is configured to, in use, rotate in a second direction about the second axis, and wherein rotation of the first shaft in the second direction lengthens one or more of the exposed strap regions to translate the actuator along the first axis away from the patient’s chest.

16. The device of any of claims 13 to 15, wherein the rotary actuator comprises a first gearwheel, and wherein the first shaft engages with the first gearwheel; wherein the rotary actuator further comprises a second gearwheel that engages with the first gearwheel, wherein rotation of the second gearwheel causes rotation of the first gearwheel about the second axis; andwherein the second gearwheel is vertically offset from the first gearwheel along the first axis.

17. The device of claim 15 or claim 16, wherein the rotary actuator comprises a second shaft and a motor engaged with the second shaft, wherein the motor is configured to, in use, drive the rotation of the second shaft.

18. The device of claim 17, further comprising a controller configured to, in use, control the speed, direction and / or torque of the motor.

19. The device of any preceding claim, further comprising a housing, wherein the actuator is disposed within the housing and engages with the housing.

20. The device of claim 18, wherein the housing comprises a plurality of openings, wherein the strap extends through the plurality of openings.

21. The device of claim 19 or claim 20, wherein the housing further comprises visual markings to facilitate the positioning of the device on a patient.

22. The device of any of claims 18 to 22, further comprising a first input means connected to the controller, whereon upon activation of the first input means, the controller is configured to, in use, control the device to begin chest compression.

23. The device of any of claims 18 to 23 further comprising a second input means connected to the controller, wherein upon activation of the second input means, the controller is configured to, in use, to extend the length of the plurality of exposed regions to loosen the strap or shorten the length of the plurality of regions to tighten the strap and to secure the actuator in position.

24. The device of any preceding claim, wherein the device comprises one or more of: one or more sensors configured to monitor patient vital signs; one or more sensors configured to detect proper alignment of the device with a patient’s chest; and / or one or more defibrillation pads.

25. A method of delivering cardiopulmonary resuscitation to a patient using the apparatus of any preceding claim, the method comprising:positioning the device on the chest of a patient; secure the actuator in position on the patient with the exposed strap regions; operating the device to deliver cardiopulmonary resuscitation to the patient.

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