Monitoring and diagnosis by electrocardiography

Abstract

An electrocardiogram chest attachment device (100) that is usable in emergency scenarios comprises a stretchable main body (101) and a plurality of electrodes. The electrodes comprise chest electrodes supported by the body (101) of the device (100) and limb electrodes housed on and extendable away from the body (101). The body (101) of the device (100) is extendable to fit various chest sizes so that the chest electrodes are placed at the appropriate positions on a subject's chest to obtain an accurate electrocardiogram measurement. A skeleton frame (113) imparts differential rigidity to the body (101) so that the body (101) is relatively rigid before being stretched and relatively flexible after being stretched. This facilitates ease of use and fast and accurate placement of the electrodes at the correct positions, especially during fast-paced, high-intensity emergency healthcare situation.

Description

[0001] MONITORING AND DIAGNOSIS BY ELECTROCARDIOGRAPHY

[0002] FIELD OF THE INVENTION

[0003] This invention relates to systems and methods for medical monitoring and diagnosis, in particular biomedical systems and methods for monitoring a subject’s heart.

[0004] BACKGROUND OF THE INVENTION

[0005] Electrocardiography is commonplace for monitoring cardiac electrical profiles and for diagnosing heart health. It is used both in life-threatening situations, such as those encountered by ambulance teams and in hospital emergency departments, and in relatively relaxed situations such as in doctor’s surgeries and when performing medical examinations.

[0006] Electrocardiogram (ECG) systems for monitoring activity of a subject’s heart in real time are used and interpreted by medical practitioners to diagnose heart-related disorders including arrhythmias, coronary diseases, heart attacks and cardiomyopathy. An ECG is a graphical representation of the heart’s electrical activity obtained from electrodes applied to the subject’s body. It is non-invasive, inexpensive and widely accepted with a well-established standard.

[0007] The most important requirement to obtain a reliable ECG is to arrange the necessary electrodes on a subject’s body correctly. This requires anatomical landmarks on the subject’s chest or abdomen to be identified before placing an electrode at each location. Each electrode typically comprises a thin metal strip located centrally on a small adhesive disc that is stuck to a subject’s skin. Each electrode is connected by a wire to an ECG machine that processes the signals to generate and display an ECG output on a monitor.

[0008] By way of example, the most commonly used ECG arrangement is the so-called ‘12-lead ECG’, which comprises twelve ‘leads’ being electrical pictures of the heart, obtained via ten electrodes. The ten electrodes comprise six precordial or chest electrodes and four auxiliary or limb electrodes to be placed on a subject at specific respective positions. It is from these ten electrodes that the different electrical comparisons are generated into the twelve leads, or views, that make up the 12-lead ECG. With reference to Figure 1 of the accompanying drawings, the six chest electrodes are placed at positions V1 to V6 over the centre and to the left of the thorax. Electrode positions V1 and V2 are located either side of the sternum at the level of the fourth intercostal space, as shown by line D, where the fourth rib of a subject joins the sternum. Electrode position V4 is located at the intersection of the fifth intercostal space and the midclavicular line, denoted by line A. V3 is the midpoint between V2 and V4. V5 and V6 are also on the fifth intercostal space but positioned laterally to V4 on the anterior axillary line, denoted by line B and the mid axillary line denoted by line C, respectively. By medical convention, the intercostal space of a given rib is the area between it and the next rib below.

[0009] The four limb electrodes are placed at respective positions in one of two conventional configurations. In one of those configurations, the limb electrodes are placed one on each wrist at positions RA and LA and one on each ankle at positions LL and RL as shown in Figure 2. In the other of those configurations, the limb electrodes are not placed on the limbs but are instead placed one on each shoulder at positions RA and LA and one each side of the lower abdomen at positions LL and RL, as shown in Figure 3, which is known in the art as the Mason-Likar placement.

[0010] Attachment of electrodes individually to a subject is a methodical, laborious and repetitive process that requires time and care to ensure accurate placement. This is a significant drawback, especially in a fast-paced, high-intensity emergency scenario, such as during emergency patient transport or in a hospital emergency department or intensive care unit.

[0011] Applying the various electrodes quickly and accurately can become all the more difficult if the electrode wires become tangled. The numerous wires also clutter the area of the subject’s chest or abdomen, potentially hindering performance of other emergency procedures that may be required.

[0012] TW202103633A discloses a scalable electrode patch including a main body and a plurality of electrode portions formed on the main body. The main body is extendable to adjust its size according to a subject’s body proportion such that the electrode portions are accurately positioned when applied to the subject’s torso. However, the device of TW202103633A may be difficult to use in a high-intensity emergency scenario where there is a threat to life. The invention disclosed herein, as defined by the claims and further described in the nonlimiting detailed description, contributes substantial improvements to the current state of the art.

[0013] SUMMARY OF THE INVENTION

[0014] Against this background, the invention resides in an ECG device comprising a body that supports a set of chest electrodes. The chest electrodes may be arranged in series across the body. The body is extensible from a compact configuration in which there is a lesser spacing between the chest electrodes to an extended configuration in which there is a greater spacing between the chest electrodes, wherein the body is relatively stiff in the compact configuration and is relatively flexible in the extended configuration.

[0015] The body of the device may have a stiffening structure comprising a plurality of elements that are connected together in the compact configuration and are separable from each other by extension of the body into the extended configuration. The elements of the stiffening structure could, for example, be interengaged in the compact configuration and disengaged from each other by extension of the body into the extended configuration. The elements of the stiffening structure may be arranged dendritically.

[0016] The body of the device could comprise substantially parallel inner and outer layers of extensible material. In that case, a cavity defined between the inner and outer layers can contain the stiffening structure. The cavity may further contain an ECG processor that is electrically connected to each of the set of chest electrodes. The inner layer may have an adhesive surface.

[0017] A thumb pad may be positioned for a user to apply application force to a chest electrode at an end of the series of chest electrodes. The thumb pad may, for example, be on the outer layer and the ECG processor can be in the cavity directly beneath the thumb pad or housed within the thumb pad.

[0018] The body may comprise a series of modules, each module supporting at least one chest electrode of the set of chest electrodes and comprising at least one element of the stiffening structure. Each module of the body can be extensible and the modules may be extensible individually, for example sequentially along the series. Each module may comprise at least two chest electrodes of the set of chest electrodes and a pinch grip formation that is associated with one of those chest electrodes and is configured for a user to apply extension force to that module. The pinch grip formation can be in fixed relation to the associated chest electrode.

[0019] Electrical conductors can extend to respective ones of the chest electrodes along, beside or through the elements of the stiffening structure. For example, the conductors may be chest wires that are deflectable by extension of the body into the extended configuration. In that case, the device may comprise belay guides that act on the chest wires to guide the chest wires around the chest electrodes during extension of the body.

[0020] The device of the invention may further comprise a set of four limb electrodes that are stowed on and deployable from the body. Each limb electrode may be electrically connected to a limb wire that is stowed on the body in a compact configuration and is extensible away from the body by deployment of the associated limb electrode. Each limb wire could have an adhesive surface. Each limb wire may be stowed in a blister on the body and the associated limb electrode may be supported by a top removable wall portion of that blister.

[0021] The inventive concept also embraces a corresponding method of obtaining an ECG, the method comprising: applying a body of an ECG device to a subject's chest, the body of the device then being in a compact configuration and relatively stiff; and extending the body of the device across the subject's chest, that act of extension causing the body of the device to become relatively flexible while increasing mutual spacing between a series of chest electrodes that are supported by the body of the device. For this purpose, the method may comprise separating two or more elements of a stiffening structure of the device as the body of the device is extended.

[0022] The method may comprise attaching a first chest electrode to the subject's chest, pulling a second chest electrode away from the first chest electrode to extend the body of the device, and attaching the second chest electrode to the subject's chest. In that case, the method may further comprise positioning an intermediate chest electrode on the subject's chest, the intermediate chest electrode being disposed on the body of the device between the first and second chest electrodes attached to the subject's chest.

[0023] The first and second chest electrodes may be disposed on an extensible first module of the body of the device, and that first module may be extended by pulling the second chest electrode away from the first chest electrode. The method may further comprise pulling a third chest electrode away from the second chest electrode to extend a second module of the body of the device, and attaching the third chest electrode to the subject's chest.

[0024] The method of the invention can also comprise separating at least one limb electrode from the body of the device while deploying a limb wire that connects the or each limb electrode to the body of the device, and attaching the or each limb electrode to the subject. The limb wire could be adhered to the subject along a length of the limb wire.

[0025] The present invention is defined by the following claims, and nothing in the foregoing summary should be taken as a limitation on those claims.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which:

[0028] Figure 1 is a schematic front view of the thorax of a human subject, showing target locations for placing chest electrodes;

[0029] Figure 2 is a schematic diagram of a human subject showing target locations for placing limb electrodes on the subject’s wrists and ankles for the conventional 12-lead ECG set-up;

[0030] Figure 3 corresponds to Figure 2 but shows alternative and clinically equally acceptable target locations for the limb electrodes in a Mason- Li kar placement;

[0031] Figures 4a and 4b are schematic plan views of a device of the invention shown respectively in contracted and extended states, where a dashed lead line indicates that the related feature resides on the reverse side of the device;

[0032] Figure 5 is a schematic wiring diagram of the device when in the extended state shown in Figure 4b; Figure 6a is a schematic plan view that shows the device in the contracted and extended states and further shows a skeletal structure of the device when in those states;

[0033] Figures 6b to 6e are schematic plan views that show variants of the skeletal structure of the device and also show, in Figures 6c to 6e, wiring of the device;

[0034] Figure 7 is a enlarged schematic detail plan view of part of the device when in the contracted state shown in Figure 4a, in conjunction with an elevation view of that part of the device;

[0035] Figure 8 corresponds to the elevation view of Figure 7 and shows that part of the device being gripped by a user and about to be stretched into the extended state;

[0036] Figure 9 corresponds to Figure 1 by showing target locations for placing chest electrodes on the thorax;

[0037] Figure 10 corresponds to Detail X of Figure 9;

[0038] Figures 11a to 11 d are a sequence of schematic views corresponding to Figure 10 and showing application of the device to a subject to bring electrodes of the device into alignment with respective target locations on the thorax as the device is stretched in stages from the contracted state into the extended state;

[0039] Figure 12 is a schematic front view of a human subject showing limb electrodes attached to the target locations shown in Figure 3 while remaining connected to the device by their respective limb wires;

[0040] Figure 13 corresponds to Figure 12 but shows the device in use, transmitting signals derived from the electrodes for display as an electrocardiogram;

[0041] Figures 14a and 14b are schematic elevation views showing a limb electrode being pulled away from the device and its application to the subject’s skin, the electrode remaining connected to the device by a limb wire; Figure 15 is a sequence of schematic elevation views showing further detail of the steps shown in Figures 14a and 14b; and

[0042] Figure 16 contains schematic bottom and elevation views of a limb electrode while attached to its housing and after it is detached from its housing, respectively.

[0043] DETAILED DESCRIPTION OF THE INVENTION

[0044] The following description and the accompanying drawings sufficiently illustrate embodiments of the invention to enable those skilled in the art to practice them. Other embodiments can incorporate structural, logical, electrical, process, or other changes. Portions and features of some embodiments can be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.

[0045] The invention is exemplified here by an ECG chest attachment device (100). The device

[0046] (100) is designed for ease of use by medical practitioners in emergency scenarios but can also be used with benefit in more relaxed circumstances, such as when performing routine medical examinations or investigations.

[0047] Referring to Figures 4a and 4b, the device (100) comprises an elongate strip-like main body

[0048] (101). The body (101) can be stretched or elongated from a relatively short, contracted state as shown in Figure 4a into a lengthened, extended state as shown in Figure 4b.

[0049] The body (101) supports a plurality of electrodes (A to J). In this example, the electrodes are grouped into two sets. The first set of electrodes comprises a series of chest electrodes (A to F), in this example six such electrodes, exposed on an inner surface (111b) of the body (101). The chest electrodes (A to F) are distributed along the length of the body (101) in an elongate array or series such that the spacing between them increases as the body (101) is stretched from the contracted state into the extended state. With that increased spacing, the chest electrodes (A to F) can be adhered to the subject’s chest at the respective chest electrode positions V1 to V6 shown in Figure 1 , as will be explained with reference to Figures 11a to 11d.

[0050] The body (101) comprises three modules or sections, each of which supports two of the chest electrodes (A to F), namely: a sternal section (102) that supports chest electrodes (A and B) corresponding to chest electrode positions V1 and V2; a precordial section (103) that supports chest electrodes (C and D) corresponding to chest electrode positions V3 and V4; and an axilla section (104) that supports chest electrodes (E and F) corresponding to chest electrode positions V5 and V6.

[0051] The sternal (102), precordial (103) and axilla (104) sections are conjoined in series. Each of those sections may be generally planar. When the body (101) of the device (100) is in the contracted state, all of those sections may lie substantially in a common plane.

[0052] The sternal section (102) is generally rectangular and elongate parallel to a longitudinal axis that joins the chest electrodes (A and B). When the sternal section (102) is stretched along that axis, the mutual spacing between the chest electrodes (A and B) is such that they may be placed at the corresponding chest electrode positions V1 and V2.

[0053] The precordial section (103) extends along a longitudinal axis that intersects the longitudinal axis of the sternal section (102) at an obtuse angle, defining a first inflection in the elongate shape of the device (100). The orientation of the precordial section (103) relative to the sternal section (102) accommodates breast contours of a subject and allows the chest electrodes (C and D) to be placed at the corresponding chest electrode positions V3 and V4, when the precordial section (103) is stretched along its longitudinal axis.

[0054] An arcuate junction between the axilla section (104) and the precordial section (103) defines a second inflection in the elongate shape of the device (100), in a direction opposed to that of the first inflection. This allows the axilla section (104), when stretched along its longitudinal axis, to curve around the ribs and beneath the armpit of a subject such that the chest electrodes (E and F) can be placed at the corresponding chest electrode positions V5 and V6.

[0055] The second set of electrodes comprises a plurality of limb electrodes (G to J), such as four limb electrodes as shown. The limb electrodes (G to J) are supported initially on the sternal section (102) of the device (100). As will be explained with reference to Figures 12, 13, 14a and 14b, the limb electrodes (G to J) can be detached and pulled away from the body (101) of the device (100) to be adhered to the subject’s shoulders and lower abdomen in the positions RA to RL shown in Figure 3, as per the Mason-Likar ECG lead system. In principle, the limb electrodes (G to J) could be adhered to the subject’s wrists and ankles in the positions RA to RL shown in Figure 2. Once deployed in this way, the limb electrodes (G to J) remain connected to wiring in the body (101) of the device (100) via respective flying limb wires (106).

[0056] The electrodes (A to J) may be of any form suitable for obtaining an ECG and may comprise any material suitable for use in an electrode such as a metallic material, a conductive polymer material, a conductive elastomeric sponge material or an elastomeric sponge material coated with a conductive polymer material. By way of example, the elastomeric sponge material could be a polydimethylsiloxane sponge material and the conductive polymer material could be a poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOTPSS).

[0057] Figure 5 shows that the body (101) of the device (100) contains or supports an ECG processor (107) and a plurality of wires, comprising a plurality of chest wires (105) and a plurality of limb wires (106), or other conductors that deliver electrical input signals from the various electrodes (A to J) to the ECG processor (107). Each of the electrodes (A to J) is connected to the ECG processor (107) by a respective single wire of the plurality of chest wires (105) or of the plurality of limb wires (106). The input signals conveyed by the plurality of wires (105, 106) correspond to electrical impulses that are picked up by the electrodes (A to J) from the subject’s skin. The ECG processor (107) receives and processes the input signals to generate an output signal that drives an ECG display or printer external to the device (100), that display or printer being connected to the ECG processor (107) through a wireless or wired connection such as a USB port (108). Alternatively, the device (100) could output unprocessed or partially processed data, which may then be processed externally before being printed or displayed. In that case, the device (100) need not have an onboard ECG processor (107).

[0058] The ECG processor (107) may comprise a power supply (109) such as a battery (109) that is configured to supply power to the device (100), or may be powered by an external power supply. For example, a USB port (108) may be used to connect an external power supply to the device (100) or to charge an on-board battery (109) of the device (100). The device (100) may comprise a wireless transmitter or transceiver (110) that may, for example, be operable according to Bluetooth specifications.

[0059] Each wire of the plurality of wires (105, 106) connects one electrode to the ECG processor (107) such that all limb and chest electrodes (A to J) are connected to the ECG processor (107) by a single individual wire. In this example, the body (101) of the device (100) comprises at least two layers of stretchable material defining respective exterior surfaces, namely an inner layer (111a) defining an inner surface (111b) that lies against the subject’s skin and on which the chest electrodes (A to F) are positioned, and an outer layer (112a) defining an outer surface (112b) that then faces away from the subject. The body (101) of the device (100) may be hollow or have a capacity for a potential space, with a cavity (121) defined between the inner (111a) and outer (112a) layers. Conveniently, the chest wires (105) connecting the chest electrodes (A to F) to the ECG processor (107) may be housed in the cavity (121) between the inner (111a) and outer (112a) layers. Each of those chest wires (105) may be shaped to be extensible, for example being coiled, curved or sinuously undulating. Thus, when the body (101) of the device (100) is stretched, the chest wires (105) may uncoil or straighten to the extent required to accommodate that elongation without exceeding a permissible level of strain. Conveniently, the chest wires (105) disposed within the body (101) may travel through or beside elements of a frame (113) that is also disposed within the body (101). Alternatively, the chest wires (105) may be comprised of a structure that is flexible and stretchable so as to stretch with the main body (101) of the device (100). In one example, the wires (105, 106) may comprise a bilayer liquid-solid conductor (BiLiSC) material.

[0060] Belay guides (114) may be situated at or around at least some of the chest electrodes (A to F). The belay guides (114) guide the chest wires (105) that connect each chest electrode (A to F) to the ECG processor (107) around any intervening chest electrodes (A to F). This prevents the chest wires (105) from cutting into the chest electrodes (A to F) or the stretchable material of the device (100) as the device (100) is stretched. Additionally, the belay guides (114) assist in maintaining the shape and structural integrity of the sections of the body (101) by allowing the chest wires to conform predictably to the changing shape and dimensions of the device (100) as it is stretched.

[0061] The stretchable material of the body (101) may comprise any suitable, flexible, stretchable, medical-grade material such as FixomullOStretch sold by Leukoplast®, or a silicone-based material, or a combination of more than one material. The body (101) may be stretchable at least in any two mutually orthogonal directions such that the device (100) may be variably stretched to any size required to fit a subject’s chest to place the chest electrodes (A to F) at the chest electrode positions V1 to V6. The inner surface (111 b) of the body (101) has an external adhesive layer (111c) for sticking the device (100) to a subject’s chest, thus holding the chest electrodes (A to F) in place once the device (100) is applied to the subject. The adhesive layer (111c) may comprise any suitable adhesive material such as a non-woven fabric. The non-woven fabric may be FixomullOStretch, or any other suitable material.

[0062] A removable cover web may be applied to the adhesive layer (111c) to protect the adhesive layer (111c) before use of the device (100) and can be peeled away from the adhesive layer (111c) to prepare the device (100) for use. The cover web may comprise three segments corresponding respectively to the sternal section (102), the precordial section (103) and the axilla section (104) of the device (100). Each of the three segments of the cover web can be removed independently from the adhesive layer (111c), selectively to expose the adhesive layer (111c) of any one of the three sections of the device (100) at any time, such that the sections may be applied to a subject’s chest sequentially. A cover web may also be applied to each of the electrodes (A to J) to protect the electrodes (A to J) before use of the device (100) and may be peeled away from the electrodes (A to J) to prepare the device (100) for use.

[0063] Turning next to Figures 6a to 6e, these drawings shows that the body (101) of the device

[0064] (100) may contain or comprise a skeleton frame (113), or other stiffening structure (113), for imparting differential rigidity to the body (101), for example disposed in a cavity (121) defined between inner (111a) and outer (112a) layers of stretchable material. In this respect, the body

[0065] (101) is relatively rigid and compact for ease of handling when in the contracted state before being applied to a subject and then becomes relatively flexible upon being stretched into the extended state during application before the device (100) is fully attached to a subject’s chest. This combines the convenience of relative rigidity before application of the device (100) to the subject with the advantage of relative flexibility during and after its application to the subject. This is particularly advantageous in fast-paced and stressful emergency situations where there is a threat to the subject’s life. In such situations, any solution that enables care to be delivered more speedily and efficiently could significantly improve the likelihood of the subject surviving.

[0066] Controlled flexibility is highly beneficial during application of the device (100) as a device (100) that is too flexible or floppy could too easily fold back over on itself before or during application to a subject, impeding quick and efficient application. Also, before application, and when the device (100) is stored in a wrapper or pack, it is advantageous for the body (101) of the device (100) to maintain a substantially planar shape overall.

[0067] The skeleton frame (113) comprises a set of elongate elements such as tubes and / or rods that may be arranged to follow or to define the general shape of the device (100). The elements of the frame may be made of any suitable material, such as a polymer or polymer- based material, and may themselves be flexible.

[0068] The elements of the skeleton frame (113) may, for example, comprise male and female interlocking or telescoping segments such that when the device (100) is in the contracted position before stretching, the segments interlock to impart rigidity to the device (100). Upon stretching the device (100), the elements of the frame may disengage and separate from each other as seen in Figure 6a, thus reducing the rigidity of the device (100). The reduction in rigidity of the device (100) may be localised to where the elements disengage from each other, with the elements themselves continuing to confer relative stiffness to the device (100) elsewhere along the length and / or width of the device (100).

[0069] The skeleton frame (113) helps a user to apply the device (100) quickly and accurately to a subject’s chest by making it easy to stretch each section of the device (100) sequentially before applying each stretched section of the device (100) in turn after applying the previous stretched section to the chest. As each section of the device (100) is stretched, elements of the frame within that section separate from each other, increasing the flexibility or decreasing the stiffness or rigidity of the stretched section. This makes it easy to conform and to fix the stretched section to the subject’s chest while the positions of other sections of the device (100), already fixed to the subject or not yet stretched, remain under control. Sections of the device (100) not yet stretched maintain their rigidity as the elements of the skeleton frame (113) in those sections remain interlocked.

[0070] When the body (101) of the device (100) is stretched longitudinally, its increase in length may cause a corresponding reduction in its width along an axis transverse to the direction of stretch. To allow for this change in shape or profile of the body (101), the skeleton frame (113) may have a dendritic configuration in some embodiments like that shown in Figure 6a. For example, at least some of the elements of the frame may branch out, imparting integral rigidity before application of the device (100) to a subject while allowing enough flexibility to facilitate application of the device (100). Figures 6b to 6e show that the skeleton frame (113) may have various other forms. Moving on now to Figures 7 and 8, these drawings show that the sternal section (102) of the device (100) comprises a thumb pad (115) with a concave outer depression that is shaped to be engaged by a user’s thumb as shown in Figure 8. This enables a user to anchor the device (100) to a subject’s chest by applying pressure to the chest via the thumb pad (115). The thumb pad (115) protrudes from the outer surface (112b) of the body (101) of the device (100) and may be made of any suitable medical-grade material such as a polymer material or a silicone-based material. Conveniently, the thumb pad (115) may house the aforementioned ECG processor (107) and / or the USB port (108) and / or the battery (109) and / or the Bluetooth transmitter (110).

[0071] In this example, the thumb pad (115) is aligned with the chest electrode A. This allows a user to anchor the device (100) by applying the electrode A to position V1 before stretching the body (101) of the device (100) to bring the other electrodes (B to F) progressively into alignment with their respective positions V2 to V6.

[0072] The body (101) of the device (100) is stretched and adhered to the subject’s chest section by section. For this purpose, each section comprises at least one pinch grip (116) that can be gripped between a user’s thumb and forefinger as shown in Figure 8 and then pulled away from a previously anchored chest electrode to stretch that section. Conveniently, each pinch grip (116) coincides with another of the chest electrodes (B to F), allowing the user easily to press the associated electrode against the subject’s skin after pulling it into alignment with the appropriate position V2 to V6. In Figures 7 and 8, for example, the pinch grip (116) of the sternal section (102) coincides with the chest electrode B and is used to pull that electrode B into alignment with position V2. The adhesive used is of such a quality that sliding of the material over the skin is not possible when applied correctly.

[0073] A device (100) of the invention may be packaged in any suitable packaging. The packaging can also contain other accessories that may be required or helpful for applying the device (100) to a patient’s chest for the purpose of measuring an ECG, or for using the device (100) when so applied. For example, the packaging may contain a razor for shaving a subject’s chest and / or a medical-grade alcohol wipe for cleaning the subject’s chest before applying the device (100) to the chest. The packaging may also contain a pen marker for marking relevant electrode landmark points (V1 to V6) on the subject’s chest. In one mode of use, the device (100) may be used in the 12-lead configuration. Therefore, a medical practitioner may open a package containing a device (100) of the invention and the abovementioned accessories. The practitioner can use the razor to remove any hair that could impede application of the device (100) to the subject’s chest and may then clean the skin of the chest with the alcohol wipe. The practitioner can also use the pen marker to mark at least landmark chest electrode positions V1 , V2, V4 and V6 on the chest. In this respect, Figures 9 and 10 show the chest electrode positions V1 to V6 marked on a subject’s chest. The practitioner may also use the pen marker to mark the limb electrode position RA, RL, LL and LA, for example on the shoulders and lower abdomen of the subject.

[0074] On removing the device (100) from the package, the practitioner firstly removes the cover web from the adhesive layer (111c) of the sternal section (102). For example, the practitioner can remove the cover web with one hand while holding the pinch grip (116) on the sternal section (102) using the other hand. The practitioner then places the chest electrode A over the electrode position V1 marked on the subject’s chest, as shown in Figure 11a, before pressing on the thumb pad (115) to fix the chest electrode A to the subject’s chest. This anchors one end of the sternal section (102) to the subject.

[0075] Next, as shown in Figure 11b, the practitioner stretches the sternal section (102) of the device (100) above, over and across the subject’s chest by pulling on the pinch grip (116) attached to the chest electrode B. The practitioner can continue to press on the thumb pad (115) to ensure that chest electrode A remains adhered to V1. When the chest electrode B is brought into alignment with electrode position V2, electrode B is landed or bought down on this point and pressure is applied to the chest electrode B to adhere it to the chest at V2. The practitioner can then also apply pressure to the sternal section (102) between and around the chest electrodes (A and B) to adhere the remainder of the sternal section (102) to the skin of the subject’s chest.

[0076] With the sternal section (102) and its chest electrodes (A and B) thereby secured firmly to the subject’s chest, the practitioner may hold the pinch grip (116) corresponding to chest electrode D with one hand and remove the cover web from the adhesive layer (111c) of the precordial section (103) with the other hand. The practitioner then uses the pinch grip (116) of chest electrode D to stretch the precordial section (103) to the length required for the chest electrode D to be placed on the subject’s chest at electrode position V4, as shown in Figure 11c. This can be done in a lifting, stretching action with the chest electrode D located over the V4 location before its application to skin. Conveniently, the practitioner can apply pressure to that pinch grip (116) to adhere the chest electrode D to the chest at V4.

[0077] Elegantly, aligning the chest electrode D with V4 also brings chest electrode C into alignment with electrode position V3 that is disposed between V4 and V2. After ensuring that chest electrode C is at V3, the practitioner can then also apply pressure to the remainder of the precordial section (103) between and around the chest electrodes (C and D) to adhere the precordial section (103) securely to the subject’s chest.

[0078] With the precordial section (103) and its chest electrodes (C and D) thereby secured firmly to the subject’s chest, the practitioner can hold the pinch grip (116) corresponding to chest electrode F with one hand and remove the cover web from the adhesive layer (111c) of the axilla section (104) with the other hand. The practitioner then uses the pinch grip (116) of chest electrode F to stretch the axilla section (104) to the length required for the chest electrode F to be placed under the subject’s armpit at electrode position V6, as shown in Figure 11 d. This can be done in a lifting and stretching action of the axilla section (104) to locate the chest electrode F over the V6 point before applying the chest electrode F. Conveniently, the practitioner can apply pressure to that pinch grip (116) to adhere the chest electrode F to the chest at V6.

[0079] Again, elegantly, aligning the chest electrode F with V6 also brings chest electrode E into alignment with electrode position V5 that is disposed between V6 and V4. After ensuring that chest electrode E is at V5, the practitioner can then also apply pressure to the remainder of the axilla section (104) between and around the chest electrodes (E and F) to adhere the axilla section (104) securely to the subject’s chest.

[0080] Thus, the configuration of the device (100) enables a practitioner to use the four landmark electrode positions V1, V2, V4 and V6 to apply the device (100) quickly and accurately to the chest of a subject of any reasonable size, with minimal repetitive movements. Once all of the chest electrodes (A to F) are adhered to the correct corresponding chest electrode positions V1 to V6, the practitioner can press the body (101) of the device (100) against the subject’s chest to ensure the device (100) is securely attached to the subject.

[0081] Next, as shown in Figures 12 and 13, the practitioner can pull the limb electrodes (G to J) away from their housings (117) on the sternal section (102) into the corresponding limb electrode positions RA, LR, LL and LA. Limb wires (106) connecting the limb electrodes (G to J) to the ECG processor (107) of the device (100) are paid out from the housings (117) of the limb electrodes (G to J) on the sternal section (102). The practitioner can also flatten the limb wires (106) against the subject’s skin. The limb wires (106) could have an adhesive coating (122) to hold them against the skin.

[0082] Figure 13 shows the device (100) in use, communicating with an ECG machine, monitor or printer via a wireless link between the ECG processor (107) of the device (100) and an intermediate receiver. The practitioner can thereby view the subject’s cardiac electrical profile and assess the subject’s heart health.

[0083] Turning finally to Figures 14a, 14b, 15 and 16, these drawings show exemplary details of how the limb electrodes (G to J) may be housed as shown in Figure 14a and deployed as shown in Figure 14b. The limb electrodes (G to J) are implemented in grapnel arrangements, each comprising a housing or blister (117) that houses the associated limb wire (106) in a compact folded or coiled configuration. The blister (117) comprises a tubular side wall (118) whose open top is closed by a top removable wall portion (119) that comprises the limb electrode (G to J). A line of weakness (120) provides for the top removable wall portion (119) and limb electrode (G to J) to be torn away from the tubular wall (118) of the blister (117) when a pinch grip (116) of the limb electrode (G to J) is pulled by a user as shown in Figure 14a. The limb wire (106) then unfolds or uncoils through the open top of the blister (117) as shown in Figure 14b.

[0084] The limb wire (106) deploys only to the length required to place the limb electrode (G to J) at the appropriate position, thus reducing clutter of the subject’s chest and abdomen. The limb wire (106) can also be coated in an adhesive substance that may be activated upon exposure to air allowing the limb wire (106) to stick to the subject’s skin, thus reducing the profile of the device (100) during use and further reducing clutter of the chest and abdomen area.

[0085] In other modes of use, the device (100) may be used in any other convenient configuration as judged appropriate by the skilled practitioner, for example the 6-lead configuration or the 3-lead configuration. The process of attaching the device (100) to the chest of a subject in the 3-lead configuration is similar to that of the 12-lead configuration, wherein the only chest electrode (A to F) which is attached to the subject’s chest is chest electrode A at chest position V1. Therefore, only the cover web of the sternal section (102) requires removal, or partial removal, from the adhesive layer (111c) of the sternal section (102) before attachment to a subject’s chest. The limb electrodes (G to J) are attached to the corresponding limb electrode positions RA to RL to complete the 3-lead configuration attachment. An advantage of this mode of use is that the device (100) may be used to obtain an ECG sufficient for monitoring purposes, for example during emergency transport, where the most accurate ECG reading may not be necessary as judged by a skilled medical practitioner. The invention may also be used in any other mode of use as judged useful by a skilled medical practitioner.

[0086] In an emergency scenario, speedy and accurate application of an ECG device to monitor the cardiac activity of a subject may be crucial to effective patient care, for example to detect the occurrence of cardiac arrest or cardiac arrhythmia. The present invention has a key advantage over a traditional ECG device by reducing the need to place numerous electrodes in individual and repetitive operations. The invention also mitigates the problem of clutter and obstruction caused by the numerous individual wires of a traditional ECG device. In contrast, the invention neatly encapsulates the chest wires (105) within the main body (101) of the device (100) and manages the limb wires (106) using the same compact component.

[0087] While the invention has been described above by reference to various embodiments, it will be understood that many changes and modifications can be made without departing from the scope of the invention. The foregoing detailed description should therefore be understood as an illustration of presently preferred embodiments of the invention and not as a definition of the invention. Similarly, modes of use have been described for obtaining an ECG of a subject. Those modes of use indicate how a device of the invention can be used but are intended for illustrative purposes only and are not intended to limit the scope of the invention. Any other mode of use, as deemed appropriate by a medical practitioner, may also be appropriate as a mode of use of the device. It is only the following claims, including all equivalents, that are intended to define the scope of this invention.

Claims

CLAIMS1. An ECG device (100) comprising a body (101) that supports a set of chest electrodes (A - F) and is extensible from a compact configuration in which there is a lesser spacing between the chest electrodes (A - F) to an extended configuration in which there is a greater spacing between the chest electrodes (A - F), wherein the body (101) is relatively stiff in the compact configuration and is relatively flexible in the extended configuration.

2. The device (100) of Claim 1 , wherein the body (101) has a stiffening structure (113) comprising a plurality of elements that are connected together in the compact configuration and are separable from each other by extension of the body (101) into the extended configuration.

3. The device (100) of Claim 2, wherein the elements of the stiffening structure (113) are interengaged in the compact configuration and are disengageable from each other by extension of the body (101) into the extended configuration.

4. The device (100) of Claim 2 or Claim 3, wherein the body (101) comprises a series of modules (102, 103, 104), each module supporting at least one chest electrode of the set of chest electrodes (A - F) and comprising at least one element of the stiffening structure (113).

5. The device (100) of Claim 4, wherein each module (102, 103, 104) of the body (101) is extensible.

6. The device (100) of Claim 5, wherein the modules (102, 103, 104) of the body (101) are extensible individually.

7. The device (100) of Claim 6, wherein the modules (102, 103, 104) of the body (101) are extensible sequentially along the series.

8. The device (100) of any of Claims 4 to 7, wherein each module (102, 103, 104) comprises at least two chest electrodes of the set of chest electrodes (A - F) and a pinch grip formation (116) that is associated with one of those chest electrodes (A - F) and is configured for a user to apply extension force to that module (102, 103, 104).

9. The device (100) of Claim 8, wherein the pinch grip formation (116) is in fixed relation to the associated chest electrode (A - F).

10. The device (100) of any of Claims 2 to 9, further comprising electrical conductors (105) that extend to respective ones of the chest electrodes (A - F) along, beside or through the elements of the stiffening structure (113).

11. The device (100) of Claim 10, wherein the conductors (105) are chest wires (105) that are deflectable by extension of the body (101) into the extended configuration.

12. The device (100) of Claim 11 , further comprising belay guides (114) acting on the chest wires (105) to guide the chest wires (105) around the chest electrodes (A - F) during extension of the body (101).

13. The device (100) of any of Claims 2 to 12, wherein the elements of the stiffening structure (113) are arranged dendritically.

14. The device (100) of any of Claims 2 to 13, comprising substantially parallel inner (111a) and outer (112a) layers of extensible material.

15. The device (100) of Claim 14, comprising a cavity (121) that is defined between the inner (111a) and outer (112a) layers and that contains the stiffening structure (113).

16. The device (100) of Claim 15, wherein the cavity (121) further contains an ECG processor (107) that is electrically connected to each of the set of chest electrodes (A - F).

17. The device (100) of any of Claims 14 to 16, wherein the inner layer (111a) has an adhesive surface (111c).

18. The device (100) of any preceding claim, wherein the chest electrodes (A - F) are arranged in series across the body (101).

19. The device (100) of Claim 18, further comprising a thumb pad (115) that is positioned for a user to apply application force to a chest electrode (A - F) at an end of the series.

20. The device (100) of Claim 19 when appendant to Claim 16, wherein the thumb pad (115) is on the outer layer (112a) and the ECG processor (107) is in the cavity (121) beneath the thumb pad (115).21 . The device (100) of any preceding claim, further comprising a set of limb electrodes (G - J) that are stowed on and deployable from the body (101).

22. The device (100) of Claim 21 , wherein each limb electrode (G - J) is electrically connected to a limb wire (106) that is stowed on the body (101) in a compact configuration and is extensible away from the body (101) by deployment of the associated limb electrode (G - J).

23. The device (100) of Claim 22, wherein the limb wire (106) of each limb electrode (G to J) has an adhesive surface (122).

24. The device (100) of Claim 22 or Claim 23, wherein the limb wire (106) of each limb electrode (G - J) is stowed in a blister (117) on the body (101) and the associated limb electrode (G - J) is supported by a top removable wall portion (119) of that blister (117).

25. A method of obtaining an ECG, the method comprising: applying a body (101) of an ECG device (100) to a subject's chest, the body (101) of the device (100) then being in a compact configuration and relatively stiff; and extending the body (101) of the device (100) across the subject's chest, that act of extension causing the body (101) of the device (100) to become relatively flexible while increasing mutual spacing between a series of chest electrodes (A - F) that are supported by the body (101) of the device (100).

26. The method of Claim 25, comprising separating two or more elements of a stiffening structure (113) as the body (101) of the device (100) is extended.

27. The method of Claim 25 or Claim 26, comprising attaching a first chest electrode (A - F) to the subject's chest, pulling a second chest electrode (A - F) away from the first chest electrode (A - F) to extend the body (101) of the device (100), and attaching the second chest electrode (A - F) to the subject's chest.

28. The method of Claim 27, comprising positioning an intermediate chest electrode (A - F) on the subject's chest, the intermediate chest electrode (A - F) being disposed on the body (101) of the device (100) between the first and second chest electrodes (A - F) attached to the subject's chest.

29. The method of Claim 27 or Claim 28, wherein the first and second chest electrodes (A and B) are disposed on an extensible first module (102) of the body (101) of the device (100) and that first module (102) is extended by pulling the second chest electrode (A - F) away from the first chest electrode (A - F).

30. The method of Claim 29, comprising pulling a third chest electrode (C - D) away from the second chest electrode (C - D) to extend a second module (103) of the body (101) of the device (100), and attaching the third chest electrode (C - D) to the subject's chest.

31. The method of any of Claims 25 to 30, comprising separating at least one limb electrode (G - J) from the body (101) of the device (100) while deploying a limb wire (106) that connects the or each limb electrode (G - J) to the body (101) of the device (100), and attaching the or each limb electrode (G - J) to the subject.

32. The method of Claim 31 , comprising adhering the limb wire (106) to the subject along a length of the limb wire (106).

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