Patent Application
20250152952
The present invention relates generally to automated external defibrillators (AEDs) with automatic selection between adult and paediatric defibrillation doses.
Existing AEDs are configured to provide adult and paediatric doses of defibrillation shocks having different energies using two electrodes on two defibrillation pads respectively. Most AEDs have visual guides for pad placement that rely on placing the electrodes at different specific locations for adult and paediatric patients.
Adult doses of defibrillation shocks are typically delivered with the two pads placed on an adult patient in an anterior-anterior orientation so that one of the two electrodes is a sternal electrode and the other is an apex electrode. Lower-energy paediatric doses of defibrillation shocks are typically delivered with the two pads placed on a child patient in an anterior-posterior orientation so that one of the two electrodes is a front chest electrode and the other is a back electrode.
Conventional AEDs suffer several shortcomings. The selection between adult and paediatric doses for child patients is not fully automated but instead requires caregivers to manually select child doses, and prevent incorrect operation with adult doses. For example, the use of press buttons or key inserts that manually set operation of the AED to “child mode,” or child-specific pads and/or leads that manually hardwire the AED to operate in “child mode.”
One of the key requirements for AEDs is a compact device form factor with small pad footprints. This creates an internal packaging space constraint that limits battery size, which in turn limits the cycle life and shelf life of conventional AEDs.
The arrangements used in conventional AEDs to manually select between adult and paediatric defibrillation doses reduce the internal space available for packaging batteries, which in turn further limits the cycle life and shelf life of compact AEDs.
One such configuration of defibrillator using motion sensors for electrode placement determination and dosage administration is disclosed in EP 3679353.
However, some of the drawbacks of the method and apparatus of EP 3679353 include the following.
In view of this background, there is an unmet need for AEDs having improved arrangements for selecting between adult doses and paediatric doses of defibrillation shocks. In addition, there is also an unmet need for AEDs capable of therapeutic use in non-hospital or medical settings, where the users do not have training or expert knowledge on the use of AEDs.
It is an object of the disclosure to provide an improved automatic dosage adjustment system and automated external defibrillator having the same which addresses or ameliorates one or more disadvantages or limitations associated with the prior art, or at least which provides the public with a useful choice.
In one aspect the present disclosure may provide an AED with a small form factor having a housing, and all of the components located in or on the housing, the AED comprising two or more angular motion sensors that allow the AED to determine the relative orientation of the AED electrodes and to automatically select between adult doses and paediatric doses of defibrillation shocks based on the orientations of the AED electrodes.
In one aspect, the present disclosure may provide an AED, comprising
According to a further aspect, the disclosure may provide an AED, comprising
In another aspect the disclosure provides a method of using an AED, comprising
In another aspect the disclosure provides a method of using an AED, comprising
The following configurations may relate to any of the above aspects.
In one configuration each angular motion sensor may comprise one or more of an inertial measurement unit (IMU), a gyroscope sensor, and an accelerometer.
In one configuration the infant dose of defibrillation shocks may have lower energy than the adult dose of defibrillation shock.
In one configuration the processor may be configured to automatically select the adult dose of defibrillation shock if the two pads are determined to have an anterior-anterior orientation so that one of the two electrodes is a sternal electrode and the other is an apex electrode.
In one configuration the processor may be configured to automatically select the infant dose of defibrillation shocks if the two pads are determined to have an anterior-posterior orientation so that one of the two electrodes is a front chest electrode and the other is a back electrode.
In one configuration the process may be further configured to provide a fail-safe indication of whether the patient is an adult or an infant.
In one configuration transthoracic impedance (TTI) measurements may be acquired from the two electrodes, and the processor may be further configured to analyse the TTI measurements to provide a fail-safe indication of whether the patient is an adult or an infant.
In one configuration the processor may be further configured to automatically select between the adult dose and the paediatric dose of defibrillation shock to be delivered by the two electrodes based on a combination of the relative orientation of the two pads, and the analysis of the TTI measurements from the two electrodes.
In one configuration each pad may comprise at least three angular motion sensors, and the processor may be further configured to analyse angular motion signals from a majority of the angular motion sensors on each pad to provide a fail-safe indication of whether the patient is an adult or an infant.
In one configuration the processor may be further configured to automatically select between the adult dose and the paediatric dose of defibrillation shock to be delivered by the two electrodes based on a combination of the relative orientation of the two pads, and the analysis of the angular motion signals from the majority of the angular motion sensors on each pad.
In one configuration the method may further comprise providing a fail-safe indication of whether the patient is an adult or an infant.
In one configuration the method may further comprise
In one configuration the method may further comprise automatically selecting between the adult dose and the infant dose of defibrillation shock to be delivered by the two electrodes based on a combination of the relative orientation of the two pads, and analysis of the TTI measurements from the two electrodes.
In one configuration the method may further comprise
In one configuration the method may further comprise automatically selecting between the adult dose and the paediatric dose of defibrillation shock to be delivered by the two electrodes based on a combination of the relative orientation of the two pads, and the analysis of the angular motion signals from the majority of the angular motion sensors on each pad.
The term “axis” as used in this specification means the axis of revolution about which a line or a plane may be revolved to form a symmetrical shape. For example, a line revolved around an axis of revolution will form a surface, while a plane revolved around an axis of revolution will form a solid.
The term “comprising” as used in the specification and claims means “consisting at least in part of.” When interpreting each statement in this specification that includes the term “comprising,” features other than that or those prefaced by the term may also be present. Related terms “comprise” and “comprises” are to be interpreted in the same manner.
As used herein the term “and/or” means “and” or “or”, or both.
As used herein “(s)” following a noun means the plural and/or singular forms of the noun.
For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence.
The term “comprising” as used in the specification and claims means “consisting at least in part of.” When interpreting each statement in this specification that includes the term “comprising,” features other than that or those prefaced by the term may also be present. Related terms “comprise” and “comprises” are to be interpreted in the same manner.
This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.
To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.
Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.
Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings.
Referring to
An electronics module 150 may be packaged inside one or both of the two pads 110. The electronics module 150 may comprise a shock generation circuit to generate doses of defibrillation shocks, a processor with memory, and a power supply, such as a battery. Each of the shock generation circuit, the processor, and the power supply may be located in one pad 110 or distributed across the two pads 110. A suitable compact AED 100 is described in further detail in the present applicant's WO 2018/232450 which is hereby incorporated by reference in its entirety.
The processor may be configured to analyse angular motion signals from the two angular motion sensors 140 to determine orientations of the two pads 110 relative to one another. The processor may further be configured to automatically select between adult doses and paediatric doses (also referred to as infant doses, wherein the weight of the patient is within the range of about 1.5 kg to about 9.5 kg) of defibrillation shocks to be delivered by the two electrodes 130 based, at least in part, on the orientations of the two pads 110. The paediatric doses of defibrillation shocks may have lower energy than the adult doses of defibrillation shocks.
For example, as shown in
Alternatively, as shown in
The processor may also be configured to analyse ECG signals from the two electrodes 130 to determine shockable cardiac rhythms.
The AED 100 may be configured to provide or include a fail-safe indication of whether a patient is an adult or an infant.
If the processor establishes that the angular motion signals acquired from the at least two angular motion sensors 140 may not accurately determine the orientation of the two pads, or in cases where there is no affirmative indication of the orientation of the pads, or whether the patient is an adult or an infant, the AED may be configured to provide or include a fail-safe indication of whether a patient is an adult or an infant.
TTI measurements may also be acquired from the two electrodes, and the processor may be further configured to analyse the TTI measurements. One of the fail-safe indications provided in the AED may include, based on the TTI measurements values, determining the age group of a patient (i.e., whether the patient is an infant or an adult).
The processor may be further configured to automatically select between adult doses and paediatric doses of defibrillation shocks to be delivered by the two electrodes 130 based on a combination of the orientations of the two pads 110, and analysis of the TTI measurements from the two electrodes 130.
It is noted that the main factors of concern with respect to determining whether a patient is an adult or an infant relate to pad size, body dimensions, age and to a lesser extent, pilosity, as other factors are consistent between the two groups. Body dimensions and age are often linked in that as people age they increase in size, but also people who are larger overall will have higher TTIs than their smaller counterparts. Pilosity is the amount of hair on the chest, affects the ability for the electrode pads to fully contact the chest resulting in increased possible range for adult TTIs.
In order to determine the accurate dosage (i.e., paediatric dosage or adult dosage) of defibrillation shock, the processor may be configured to analyse both the orientation data received from the angular motion signals from the at least two angular motion sensors, and the TTI measurements to determine whether the patient is an adult or an infant.
The processor may establish that the data received from both the at least two angular motion sensors 140, and the TTI measurements are not in agreement as to whether the patient is an adult or an infant. The processor may be configured to switch the dosage to that of an adult patient. This is so that while there are potential risks associated with delivering an adult dosage to an infant, defibrillation will still be effective and achieve the desired result of arresting the arrythmia. Conversely, if an adult received an infant dosage they may not receive sufficient defibrillation energy and the shock will be ineffective.
TTI requires either a test pulse (current) to be sent between the pads or a shock to be delivered. Of notable importance to the utility of TTI as a determinant of patient age (adult vs. infant) is the effect of pad size on TTI measurement. In traditional defibrillators there are typically separate pads for paediatric (i.e., infants) and adult patients, with paediatric pads typically being smaller to account for the smaller body size. Decreasing pad size has been shown to increase TTI, with results obtained showing similar or even higher TTI for infant/paediatric compared to adults with traditional pads. This would make it near impossible for traditional defibrillators, especially the ones with different sized pads for adult and infant patients, to differentiate between dosage based on TTI as the two ranges would overlap significantly.
The present disclosure may provide a AED which uses integrated pads, and hence the pad size is held constant for all patients. As TTI is known to increase with increasing body size, the TTI for adults vs children vs infants would be expected to reflect this relationship. The claimed AED is configured to employ additional safety features in the form of a failsafe measure for its automatic dose selection that is not available in other defibrillators.
Furthermore, as the measure of TTI is so variable and related to multiple factors, it would be difficult to accurately detect the age or size of the patient with any significant granularity based on this measure alone. Consequently, in the present disclosure the measure of TTI is treated as a threshold value, above which the person is considered an adult and below, an infant.
Referring to
As will be appreciated by a skilled addressee, these coordinate systems are examples only, i.e., the sensors can feasibly be placed in any orientation within the pads provided that orientation is known. For example, in a situation, if it is thought to be necessary to put the sensors in an orientation that does not align with the AED 100 directly, a mathematical transformation is applied to address the ambiguity.
Consequently, the AED 100 may provide an indication of the relative location of the pads in space based on the orientation of the coordinate systems. The initial orientation of the pads is shown in
For an adult patient, the pads may be expected to broadly be in alignment in the z-direction. In both the
Referring to
The method for orientation determination of the sensors may vary slightly between sensors. However, in majority of cases the requirement may be to collect data and then process the collected data to get the resultant outputs. Consequently, the extent of the data needed may differ between each use-case scenario.
An accelerometer, for example, may be configured to measure the acceleration due to gravity to orient itself. As gravity always acts in the same direction, the AED 100 at rest (placed gel side down on a surface, not moving) may register an acceleration of −9.8 ms−2 in the z-direction or −1 g. If that orientation is altered but the device left in position (e.g. placed on its side) then that acceleration would register across multiple axes to create a resultant acceleration vector of the same value. Based on the above values, and by also knowing the initial orientation of the sensors within the device, the orientation of the accelerometer vertically may be determined from the gravity vector alone, and therefore, may not strictly require the recording of data from the snap event of the AED 100.
For a gyroscope-based sensor, the orientation detection method may vary from the above. For example, in the case of gyroscope based sensors, the determination of the orientation is based on having known where the sensors are placed initially, and recording the snap event to track changes in orientation up until pad placement. As relative orientation is the main concern of this application any error introduced by the snap can be accounted for by comparing the two pads.
Referring to
Some of the difficulties in accurately measuring the orientation of the sensors, especially for the sensor types which require recording from the snap event to placement, include additional processing power. For example, the data from such type of sensors would need to be stored for processing or processed live, which may decrease the storage requirements but increase the computational power.
Furthermore, in the case of an infant placement there may be additional steps involved in placing the pads in the posterior side (roll the body over, removal of clothes from back versus front), which may increase the time sensors need to record to be able to track the orientation/position of the pad. This in turn may increase the computational power required. Further, if the motion sensors provide a new determination after each classification cycle (in the event of multiple shocks) then this data may need to be collected continually.
The flow of information through the AED towards determining orientation and the requisite shock may take two paths. In the first path, the data may be processed using the processor (also referred to as the main processor).
In an alternate path, the data may be processed using the dedicated motion analysis processor to avoid any delay in the classification of the data received from the angular motion sensors, as this is the most important process for therapy, and is time-sensitive.
As depicted in
Furthermore, it will be appreciated that there is often noise present in data collected from motion sensors. The present disclosure may provide a AED configured to measure the noise from the sensors and removed said noise by applying signal processing techniques, such as digital or analog filters. In some instances, the filters may be hardware filters. In other instances, the filters may be software based.
Referring to
TTI block (step 805) may measure and compares the TTI values in order to determine if the pads are placed on an adult or an infant, with additional existing checks for whether the TTI indicates incorrect placement, prompting adjustment. Motion sensor block (step 806) may process the received data from the angular motion sensors in order to determine the relative orientation of the two pads. At the next phase, the determination of patient obtained based on the orientation of the pads is compared with the determination of patient obtained based on the TTI values.
At step 807, the ECG block may be configured to determine if there is a shockable rhythm. If no shockable rhythm is detected then the device may prompt according to its usual protocols, including, but not limited to commencing CPR. On the contrary, if a shockable rhythm is detected, the shock generation circuit may commence charging the pads for a shock.
While charging the pads, at step 810 processor may select the appropriate dosage based on the Table 1. As illustrated in Table 1, the device may be configured to prioritise an adult dosage over an infant dosage in cases where the measurements from the motion sensors and the TTI are not in agreement with each other.
Additionally, the classification stage also has check at step 808, wherein if no shockable rhythm is detected and the TTI or motion sensors indicate poor placement the user may be directed to adjust the pad placement. Further check is also performed at step 809, wherein if it is determined during the classification stage that no shockable rhythm is detected, then this information may be relayed, such that the user may perform alternate therapeutic measures such as CPR, etc.
In the use-case scenarios where the determined orientation of the sensors may indicate out of range values, the device may be configured to default to an adult shock.
The AED 100 may further be configured to provide a fail-safe indication of whether a patient is an adult or an infant based on data received from
The AED 100 may further comprise at least three angular motion sensors placed in each of the pads. In these implementations, the AED may be configured to provide a fail-safe indication of whether a patient is an adult or an infant based on the data received from each sensor to enable redundancy in case of sensor failure or calibration issues.
In the above implementation where at least three angular motion sensors are placed in each of the pads, the results from all the three sensors would be calculated separately and a majority rule (i.e. two out of three sensors indicate an agreement in the orientation) may be used to select the dosage. It may be preferable in this scenario that at least one sensor is an IMU as these can combine output from an accelerometer and gyroscope for greater accuracy. Furthermore, in this implementation, due to the increased number of sensors it may be possible to increase the threshold for infant TTI values to enable greater accuracy in selecting dosage.
Furthermore, in implementations where multiple sensors are used, it may be possible that multiple sensors may malfunction or return incorrect results. This could be due to a number of reasons, however, under a majority rule system two faulty sensors on one pad could result in a number of different scenarios. In most of the cases, the pad positioning would become indeterminate which would result in an adult dose as that is the best therapy selection.
In an alternate scenario where two faulty sensors may override the functioning sensor and return the opposite orientation of the pads
TTI tends to increase under most factors that differentiate adults from infants and as such it is unlikely that TTI would also fail to return an accurate reading.
An additional scenario may be defibrillation on a small child, who may have a sufficiently low TTI to register as infant. In this case, an infant dose may be administered to a child, however this is of low risk as many defibrillators deliver low dose shocks to children, not just infants. Due to this however, TTI would be unable to be removed as a failsafe measure.
Therefore, in the present device, the use of multiple sensors would create a more accurate reading and may lead to being able to increase the TTI threshold due to greater confidence in the motion sensor result.
In the present disclosure, as the sensors may be configured to measure the relative orientation of the pads they can be placed in any known, fixed position and orientation within the pads. That said, however, it may be preferable to mount the sensors on the PCB itself as it may provide the most stable attachment point for the sensors.
The AED may comprise one sensor placed on the controller side of the board (with the battery and processors) and the other on a capacitor bank side. The device may also comprise an additional wire added to the cable connecting the two pads to transmit the data to the controller side.
Each pad of the present defibrillator may have a volume of about 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 cm3, and useful ranges may be selected from any of these values (for example, about 100 to about 200, about 100 to about 180, about 100 to about 160, about 100 to about 150, about 110 to about 200, 110 to about 190, about 110 to about 170, about 110 to about 150, about 120 to about 200, about 120 to about 180, about 120 to about 150, about 130 to about 200, about 130 to about 180, about 130 to about 150, about 140 to about 200, about 140 to about 180, about 140 to about 160 or about 140 to about 150 cm3).
Each pad of the present defibrillator may have a surface area of about 50, 60, 70, 80, 90 or 100 cm2, and useful ranges may be selected from any of these values (for example, about 50 to about 100, about 50 to about 80, about 50 to about 70, about 50 to about 60, about 60 to about 100, about 60 to about 80, about 60 to about 70 or about 50 to about 60 cm2).
Described is a compact AED configured for a single use defibrillation therapy and resuscitation of a patient. The device is configured to automatically select between an adult dose and an infant dose of defibrillation shock to be delivered by the two electrodes based, at least in part, on the relative orientation of the two pads. The resultant device is user friendly, requires minimal training or knowledge in terms of its operational use. Thus, removing points of confusion for the user unfamiliar with the device.
For example, the volume of each of the pads may be about 9.7 cm×9.3 cm×1.7 cm to give a total volume of 153 cm3, and the surface area may be about 8.2 cm×8.6 cm to give a total surface area of 70.5 cm2
Embodiments of the present invention provide AEDs that are both generally and specifically useful for automatically selecting between adult and paediatric doses of defibrillation shocks.
Embodiments of the present invention advantageously omit the space-consuming, manual fail-safe arrangements used in conventional AEDs to manually select between adult and paediatric doses of defibrillation shocks. The omission of manual fail-safe arrangements may advantageously increase (or “buy back”) internal packaging space available for batteries, which in turn may increase the cycle life and shelf life of compact AEDs.
In other words, the automatic selection between adult and paediatric doses may facilitate optimal use of internal packaging space in compact AEDs for power supply. For example, embodiments of the present invention may facilitate compact AEDs having a target shelf life of up to at least one or two years.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention as herein described with reference to the accompanying drawings.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022900264 | Feb 2022 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2023/051187 | 2/9/2023 | WO |
