Automated external defibrillator

Abstract

Depending on the treatment being administered to the subject, the presence or absence of body movement in the subject can be detected more appropriately. [Solution] In the automated external defibrillator 1, the treatment control unit 132 controls the treatment to the subject. The detection unit 133 detects the subject's body movements. The detection unit 133 also changes the method of detecting the subject's body movements according to the type of treatment period corresponding to the type of treatment performed by the treatment control unit 132.

Description

Technical Field

[0001] The present disclosure relates to an automated external defibrillator.

[0002] In Non-Patent Document 1, it is stipulated that after electrocardiogram analysis and electrical shock are performed using an automated external defibrillator (AED) (hereinafter also referred to as "AED"), chest compression and artificial respiration for the subject should be continued.

[0003] An AED having a function of detecting the body movement of a subject is also known. In an AED having such a function, for example, based on the presence or absence of the body movement of the subject, it is determined whether chest compression is being performed on the subject, and if it is determined that chest compression is not being performed, an instruction to perform chest compression can be output.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, during the period before performing an electrical shock, it is desirable to detect that the rescuer is not touching the subject and that the subject is not making spontaneous movements. That is, during such a period, it is desirable that the body movements to be detected include not only the body movements due to chest compression but also the body movements caused by the rescuer touching the subject and the spontaneous body movements of the subject.

[0006] This disclosure aims to provide an automated external defibrillator that can more appropriately detect whether or not a subject is moving, depending on the status of the treatment being performed on the subject. [Means for solving the problem]

[0007] An automated external defibrillator relating to one aspect of this disclosure is: An automated external defibrillator that performs electrocardiogram analysis and discharge processing on a subject, A treatment control unit that controls the treatment of the subject, The system includes a detection unit that detects the body movements of the subject, The detection unit changes the method for detecting the subject's body movements according to the type of treatment period corresponding to the type of treatment performed by the treatment control unit. [Effects of the Invention]

[0008] According to this disclosure, it is possible to more appropriately detect whether or not a subject is moving, depending on the circumstances of the treatment being performed on the subject. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an external view of an AED according to an embodiment of this disclosure. [Figure 2] Figure 2 is a block diagram showing the configuration of the AED shown in Figure 1. [Figure 3] Figure 3 is a flowchart showing the control flow by the control unit shown in Figure 2. [Figure 4] Figure 4 is a table showing the criteria used when detecting body movement by the detection unit shown in Figure 2. [Figure 5] Figure 5 is a graph showing an example of a waveform illustrating the change in impedance when chest compressions are being performed on a subject. [Figure 6] Figure 6 is a graph showing an example of a waveform illustrating the change in impedance when the subject is being shaken. [Figure 7]Figure 7 is a graph showing an example of a waveform illustrating the change in impedance when the subject is making voluntary body movements. [Modes for carrying out the invention]

[0010] The following describes an example of an automated external defibrillator (AED1) according to this disclosure, using drawings. For the sake of clarity, the description of components with the same reference numerals as those already described in the description of the embodiments will be omitted. Furthermore, the dimensions of the components shown in these drawings may differ from the actual dimensions of the components, for the sake of clarity.

[0011] [AED Configuration] Figure 1 is an external view of an AED1 according to an embodiment of the present disclosure. As shown in Figure 1, the AED1 comprises an AED body 10, a battery pack 11, a cover 12, a cable 13, and a pair of electrode pads 14 and 15.

[0012] The battery pack 11 supplies power to the AED unit 10 to operate it. The battery pack 11 is also connected to the back side of the AED unit 10 in a removable manner, for example.

[0013] The lid 12 is structured to cover the AED body 10. When the lid 12 changes from a closed state to an open state, the main power supply of the AED 1 turns ON and the AED 1 starts up. Conversely, when the lid 12 changes from an open state to a closed state, the main power supply of the AED 1 turns OFF. Note that the AED 1 is not limited to a configuration that switches the main power supply ON / OFF in accordance with the opening and closing of the lid 12; for example, a power button for switching the main power supply ON / OFF may be provided on the AED body 10.

[0014] Each of the electrode pads 14 and 15 contains a viscous gel. When the AED 1 is not in use, the electrode pads 14 and 15 are stored in a bag with release paper attached to each gel. Also, the bag containing the electrode pads 14 and 15 is attached, for example, inside the lid portion 12. A rescuer using the AED 1 removes the bag from the lid portion 12 and takes out the electrode pads 14 and 15 from the bag. Then, the rescuer attaches the gel portion to the subject's skin with the electrode pads 14 and 15 peeled off from the release paper.

[0015] The cable 13 electrically connects the AED main body 10 and the electrode pads 14 and 15. The AED main body 10 performs processes such as electrocardiogram analysis and electric shock (hereinafter referred to as "discharge process") on the subject in a state where the electrode pads 14 and 15 are attached to the subject.

[0016] FIG. 2 is a block diagram showing the configuration of the AED 1 shown in FIG. 1. As shown in FIG. 2, the AED main body 10 includes a sound output unit 101, a control unit 103, a storage unit 104, a high-voltage unit 105, and an electrocardiogram analysis unit 106. The storage unit 104 stores programs and the like for controlling various operations of the AED 1.

[0017] When the AED 1 is activated, the control unit 103 reads out and executes programs and the like stored in the storage unit 104 to control various operations of the AED 1. More specifically, the control unit 103 functions as an output control unit 131, a treatment control unit 132, and a detection unit 133.

[0018] The output control unit 131 reads out sound data such as voice guidance and warning sounds for the rescuer from the storage unit 104 and outputs the read sound data to the sound output unit 101. The sound output unit 101 is, for example, a speaker, and when it receives the sound data output from the output control unit 131, it outputs a voice or a warning sound based on the sound data.

[0019] The treatment control unit 132 controls the treatment for the subject. For example, the treatment control unit 132 controls the electrode pads 14, 15 and the electrocardiogram analysis unit 106 so as to cause the electrocardiogram analysis unit 106 to perform electrocardiogram analysis. The electrocardiogram analysis unit 106 performs electrocardiogram analysis of the subject through the electrode pads 14, 15 by being controlled by the treatment control unit 132.

[0020] Also, after the electrocardiogram analysis, the treatment control unit 132 controls so that a discharge process to the subject is performed. More specifically, the treatment control unit 132 charges the internal capacitor of the high-voltage unit 105 with the battery cell 11A included in the battery pack 11, and controls the battery cell 11A and the internal capacitor so as to discharge from the electrode pads 14, 15.

[0021] The detection unit 133 detects the body movement of the subject. For example, the detection unit 133 acquires the impedance between the pair of electrode pads 14, 15 at intervals of 4 milliseconds. Then, the detection unit 133 calculates at least one of the amplitude and the period of the waveform indicating the change in the impedance acquired in, for example, one second, and detects the presence or absence of the body movement of the subject based on at least one of the calculated amplitude and period. Hereinafter, the amplitude of the waveform indicating the change in the impedance is simply referred to as the "amplitude of the impedance". Also, the period of the waveform representing the change in the impedance is simply referred to as the "period of the impedance".

[0022] [Flow of Control by the Control Unit] FIG. 3 is a flowchart showing the flow of control by the control unit 103 shown in FIG. 2. As shown in FIG. 3, during the treatment period in which the treatment for the subject is controlled by the treatment control unit 132 in the control unit 103, two or more types of periods are included.

[0023] Here, as an example of two or more treatment periods, we will explain by dividing them into the period from the start of electrocardiogram analysis to the end of the discharge process (the first period) and the cardiopulmonary resuscitation (CPR) period in which chest compressions are performed on the subject after the discharge process (the second period). Hereafter, the period from the start of electrocardiogram analysis to the end of the discharge process will be referred to as the "weaning period," and the cardiopulmonary resuscitation period will be referred to as the "CPR period."

[0024] Referring to Figures 1 to 3, first, the main power of AED1 is switched ON (step S11), and the electrode pads 14 and 15 are attached to the subject (step S12). In this case, the treatment control unit 132 controls the electrocardiogram analysis unit 106 to perform electrocardiogram analysis, and the electrocardiogram analysis begins. That is, the weaning period begins. When the weaning period begins, the output control unit 131 outputs a weaning instruction D1 from the sound output unit 101 to instruct the rescuer to move away from the subject. For example, the voice output for the weaning instruction D1 is "Please move away from the body" (step S13).

[0025] Next, once the electrocardiogram analysis is complete (step S14), the treatment control unit 132 determines, based on the results of the electrocardiogram analysis, whether or not a discharge procedure is necessary for the subject (step S15). Here, let's assume that the treatment control unit 132 has determined that a discharge procedure is necessary (YES in step S15). In this case, the output control unit 131 causes the sound output unit 101 to output a discharge notification D2 to inform the rescuer that a discharge procedure will be performed. For example, the discharge notification D2 may say, "An electric shock will be performed" (step S16).

[0026] Next, the detection unit 133 in the control unit 103 checks whether or not the subject's body movement has been detected (step S17). If no body movement is detected (NO in step S17), the treatment control unit 132 controls the system to perform the discharge treatment on the subject (step S20).

[0027] On the other hand, if body movement of the subject is detected (YES in step S17), it is possible that the subject is moving spontaneously, or that the rescuer is touching the subject, such as by performing chest compressions or shaking. In such cases, the treatment control unit 132 delays the timing of executing the discharge process. Then, the output control unit 131 outputs the release instruction D1 again (step S18).

[0028] Next, the control unit 103 checks whether a predetermined time T has elapsed since the timing at which it was determined that discharge processing was necessary (step S19). If the predetermined time has not elapsed since the above timing (NO in step S19), the operations from step S17 onward are repeated.

[0029] On the other hand, if a predetermined time has elapsed since the withdrawal instruction D1 was output again (YES in step S19), the treatment control unit 132 controls the system to perform the discharge process on the subject (step S20).

[0030] Once the discharge process is performed on the subject, the CPR period begins. When the CPR period begins, the output control unit 131 causes the sound output unit 101 to output a chest compression instruction D3 to instruct the subject to perform chest compressions. For example, the voice output for chest compression instruction D3 is "Please begin chest compressions and artificial respiration" (step S21).

[0031] Next, the detection unit 133 checks whether or not body movement of the subject has been detected (step S22). If no body movement of the subject is detected ("NO" in step S22), it is highly likely that chest compressions have not been performed on the subject. In this case, the output control unit 131 outputs the chest compression instruction D3 again (step S23).

[0032] Then, when a predetermined time has elapsed from the start of the CPR period (if "YES" is answered in step S24), the CPR period ends (step S25). The withdrawal period then starts again, and the actions from step S13 onwards are repeated.

[0033] Furthermore, if body movement is detected in step S22 (YES in step S22), the actions from step S24 onward will proceed without the chest compression instruction D3 being re-output.

[0034] Furthermore, it may be determined in step S15 that discharge processing is not necessary ("NO" in step S15). In this case, the operations from step S21 onward will proceed without discharge processing.

[0035] In the above explanation, even if the subject's body movement is detected (YES in step S17), if a predetermined time has elapsed since it was determined that discharge processing is necessary (YES in step S19), the discharge processing will be performed (step S20). However, the operation is not limited to this. For example, if the subject's body movement is detected, the operation from step S21 onwards may be performed without performing the discharge processing (step S20), prioritizing the safety of any rescuers who may be in contact with the subject.

[0036] [Detection of subject's body movement] As described above, the detection unit 133 detects the subject's body movements during each treatment period, including the withdrawal period and the CPR period. During the CPR period, it is necessary to determine whether or not chest compressions are being performed on the subject. In contrast, during the withdrawal period, it is desirable that the body movements to be detected include not only body movements caused by chest compressions, but also body movements caused by the rescuer touching the subject, and spontaneous body movements of the subject.

[0037] Here, assuming that a suitable threshold is used to detect the subject's body movements to determine whether or not chest compressions are being performed during the withdrawal period, it may be difficult to detect the subject's body movements caused by the rescuer shaking the subject, or the subject's spontaneous body movements.

[0038] Therefore, in the AED1 of this disclosure, the detection unit 133 changes the method of detecting body movement depending on the type of treatment period. More specifically, the detection unit 133 changes the method of detecting the subject's body movement so that more types of body movement are detected during the withdrawal period than during the CPR period. In this embodiment, as an example, a case will be described in which the detection unit 133 changes at least one of the amplitude determination criteria and the period determination criteria that serve as the basis for detecting body movement between the withdrawal period and the CPR period.

[0039] (a) Detection of body movement during withdrawal period (a-1) Detection of chest compressions or shaking Figure 4 is a table showing the criteria used when detecting body movement by the detection unit 133 shown in Figure 2. Figure 5 is a graph showing an example of a waveform indicating the change in impedance when chest compressions are being performed on the subject. Figure 6 is a graph showing an example of a waveform indicating the change in impedance when shaking is being performed on the subject. In the graphs shown in Figures 5 and 6, the vertical axis represents the amplitude of the impedance, and the horizontal axis represents time.

[0040] As shown in Figure 5, when chest compressions are being performed on the subject, the amplitude of the impedance acquired by the detection unit 133 exceeds the amplitude reference value A1. Similarly, as shown in Figure 6, when shaking is being performed on the subject, the amplitude of the impedance acquired by the detection unit 133 also exceeds the amplitude reference value A1. Therefore, as shown in Figure 4, during the withdrawal period, the amplitude reference value A1 is used as the amplitude determination criterion for detecting whether chest compressions or shaking is being performed on the subject.

[0041] Furthermore, for example, Non-Patent Document 1 specifies a recommended value for the period during which chest compressions are performed (hereinafter referred to as "period reference value T1"). That is, when chest compressions are being performed on the subject, the period of the impedance acquired by the detection unit 133 is estimated to be close to the period reference value T1.

[0042] Furthermore, as shown in Figure 6, if shaking is being performed on the subject, the period of the impedance acquired by the detection unit 133 is estimated to be shorter than the period reference value T1 described above (hereinafter referred to as "period reference value T2"). For this reason, as shown in Figure 4, period reference value T1 and period reference value T2 (< period reference value T1) are used as criteria for determining the period to detect whether chest compressions or shaking are being performed on the subject during the withdrawal period.

[0043] For example, the detection unit 133 determines that the first condition is met if the amplitude of the impedance is greater than or equal to the amplitude reference value A1. The detection unit 133 also determines that the second condition is met if the period of the impedance falls within the range from the value obtained by subtracting a margin M2 (for example, period reference value T2 × 10%) from the period reference value T2 to the value obtained by adding a margin M1 (for example, period reference value T1 × 10%) to the period reference value T1. Then, during the withdrawal period, if both the first and second conditions are met, the detection unit 133 determines that chest compressions or shaking are being performed on the subject.

[0044] Furthermore, during the withdrawal period, the detection unit 133 may be configured to determine that chest compressions or shaking are being performed on the subject if either the first or second condition is met.

[0045] (a-2) Detection of the subject's spontaneous body movements Figure 7 is a graph showing an example of a waveform illustrating the change in impedance when the subject is making voluntary body movements. In the graph shown in Figure 7, the vertical axis represents the amplitude of the impedance, and the horizontal axis represents time.

[0046] As shown in Figure 7, when the subject is breathing or making other spontaneous movements, the subject's body may move more significantly compared to when chest compressions are being performed as shown in Figure 5 or when shaking is being performed as shown in Figure 6. In other words, the amplitude of the impedance acquired by the detection unit 133 may significantly exceed the amplitude reference value A1.

[0047] On the other hand, even if the subject is not moving voluntarily, if the subject is being transported on a stretcher or the like, the subject's body will move even more significantly. In such cases, the amplitude of the impedance acquired by the detection unit 133 may exceed the amplitude reference value A2 (> amplitude reference value A1).

[0048] Therefore, as shown in Figure 4, for example, amplitude reference values ​​A1 and A2 are used as criteria for determining the amplitude of the impedance to detect whether the subject is making spontaneous body movements during the withdrawal period.

[0049] Furthermore, as shown in Figure 7, if the subject is performing spontaneous actions such as breathing, the impedance period acquired by the detection unit 133 is estimated to be longer than the period reference value T1 shown in Figure 5, i.e., the recommended period for performing chest compressions (hereinafter referred to as "period reference value T3").

[0050] Therefore, as shown in Figure 4, for example, the period reference value T3 is used as a criterion for determining the period of impedance to detect whether the subject is making spontaneous body movements during the withdrawal period.

[0051] For example, the detection unit 133 determines that the third condition is met if the change amount Ad, which is the difference between the maximum and minimum amplitudes of the impedance, is greater than or equal to the difference between the amplitude reference value A2 and the amplitude reference value A1 (= amplitude reference value A2 - amplitude reference value A1). Alternatively, the detection unit 133 may be configured to determine that the third condition is met if the change amount Ad is greater than or equal to the amplitude reference value A2.

[0052] Furthermore, the detection unit 133 determines that the fourth condition is met if the impedance period falls within a range from the period reference value T3 minus a margin M3 (for example, period reference value T3 × 10%) to the period reference value T3 plus the margin M3. Then, during the withdrawal period, the detection unit 133 determines that there is spontaneous action by the subject if both the third and fourth conditions are met.

[0053] Furthermore, during the withdrawal period, the detection unit 133 may be configured to determine that there is a spontaneous action by the subject if either the third or fourth condition is met.

[0054] As described above, by setting criteria for the amplitude and period of impedance, it is possible to detect all body movements that should be detected during the withdrawal period, namely, body movements of the subject due to chest compressions, body movements of the subject due to shaking, and spontaneous body movements of the subject.

[0055] Furthermore, the detection unit 133 may be configured to detect the subject's body movements due to chest compressions, the subject's body movements due to shaking, and the subject's spontaneous body movements during the withdrawal period, using parameters other than the amplitude and period of impedance.

[0056] (b) Detection of body movement during CPR As described above, during the CPR period, it is necessary to determine whether or not chest compressions are being performed on the subject. Therefore, referring to Figures 4 and 5, the amplitude reference value A1 is used as the criterion for determining the amplitude of the impedance to detect whether or not chest compressions are being performed on the subject during the CPR period. In addition, the period reference value T1 is used as the criterion for determining the period of the impedance to detect whether or not chest compressions are being performed on the subject during the CPR period.

[0057] For example, the detection unit 133 determines that the fifth condition is met if the impedance period falls within a range from the period reference value T1 minus a margin M1 (for example, period reference value T1 × 10%) to the period reference value T1 plus the margin M1. Then, during the CPR period, the detection unit 133 determines that chest compressions are being performed on the subject if both the first condition and the fifth condition described above are met.

[0058] Furthermore, during the CPR period, the detection unit 133 may be configured to determine that chest compressions are being performed on the subject if either the first condition or the fifth condition is met.

[0059] As described above, by setting criteria for the amplitude and period of impedance, it is possible to detect the body movements that should be detected during the CPR period, i.e., the body movements of the subject caused by chest compressions.

[0060] Furthermore, the detection unit 133 may be configured to detect the subject's body movement during chest compressions during the CPR period using parameters other than the amplitude and period of impedance.

[0061] In the example described above, two types of treatment periods were explained: the weaning period and the CPR period. However, the period during which treatment is controlled by the treatment control unit 132 is not limited to these two types. For example, the CPR period may be divided into a chest compression period and a ventilation period. In such a case, the detection unit 133 can change the method of detecting the subject's body movements between the chest compression period and the ventilation period.

[0062] As described above, in AED1, the treatment control unit 132 controls the treatment to the patient. The detection unit 133 detects the patient's body movements. Furthermore, the detection unit 133 changes the method of detecting the patient's body movements according to the type of treatment period corresponding to the type of treatment performed by the treatment control unit 132. This configuration allows the detection of the subject's body movements to be altered according to the treatment being administered to the subject. Therefore, the presence or absence of subject movement can be detected more accurately.

[0063] Furthermore, in the AED1, the detection unit 133 detects whether or not the subject is moving based on at least one of the amplitude and period of a waveform that shows the change in impedance between the pair of electrode pads 14 and 15 of the AED1. Depending on the type of treatment period, the detection unit 133 changes the method of detecting the subject's body movement by changing at least one of the amplitude criteria and period criteria that serve as the basis for determining whether or not body movement is present. This configuration allows for easy and appropriate modification of the method for detecting the subject's body movements.

[0064] Furthermore, the treatment period using AED1 includes a withdrawal period during which electrocardiogram analysis is performed and a CPR period during which chest compressions are performed on the subject. This configuration allows for a change in the method of detecting the subject's body movement between the withdrawal period during which electrocardiogram analysis is performed and the CPR period during which chest compressions are performed on the subject, enabling more accurate detection of whether or not body movement is present.

[0065] Furthermore, in AED1, the detection unit 133 modifies the method of detecting the subject's body movements so that more types of body movements are detected during the withdrawal period than during the CPR period. With this configuration, for example, during the withdrawal period, body movements caused by chest compressions, body movements caused by shaking the subject, and spontaneous body movements of the subject can be detected, while during the CPR period, only body movements caused by chest compressions can be detected.

[0066] In addition, in the AED1, the detection unit 133 detects the body movement of the subject due to chest compressions based on the impedance between the pair of electrode pads 14 and 15. With this configuration, for example, by calculating the amplitude and period of the waveform showing the change in impedance between electrode pads 14 and 15, it is possible to determine whether or not chest compressions are being performed on the subject and to appropriately give instructions for chest compressions.

[0067] In addition, in the AED1, the detection unit 133 detects the body movement of the subject caused by shaking, based on the impedance between the pair of electrode pads 14 and 15. With this configuration, for example, by calculating the amplitude and period of the waveform showing the change in impedance between electrode pads 14 and 15, it is possible to determine whether or not shaking is being performed on the subject and to appropriately instruct the subject to withdraw.

[0068] In addition, in the AED1, the detection unit 133 detects the subject's spontaneous body movements based on the impedance between a pair of electrode pads 14 and 15. With this configuration, for example, by calculating the amplitude and period of the waveform showing the change in impedance between a pair of electrode pads 14 and 15, it is possible to determine whether or not chest compressions are being performed on the subject and to appropriately perform the discharge treatment on the subject.

[0069] Although embodiments of this disclosure have been described above, the technical scope of this application should not be interpreted as being limited by the description of these embodiments. These embodiments are examples, and it will be understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the invention described in the claims. The technical scope of this application should be determined based on the scope of the invention described in the claims and the scope of its equivalents. [Explanation of symbols]

[0070] 1: AED (Automated External Defibrillator), 10: AED main unit, 11: Battery pack, 11A: Battery cell, 12: Cover, 13: Cable, 14, 15: Electrode pads, 101: Sound output unit, 103: Control unit, 104: Memory unit, 105: High-voltage unit, 106: Electrocardiogram analysis unit, 131: Output control unit, 132: Treatment control unit, 133: Detection unit

Claims

1. An automated external defibrillator that performs electrocardiogram analysis and discharge processing on a subject, A treatment control unit that controls the treatment of the subject, The system includes a detection unit that detects the body movements of the subject, An automated external defibrillator, wherein the detection unit changes the method of detecting the subject's body movements according to the type of treatment period corresponding to the type of treatment performed by the treatment control unit.

2. The detection unit is Based on at least one of the amplitude and period of the waveform showing the change in impedance between the pair of electrode pads of the automated external defibrillator, the presence or absence of body movement of the subject is detected. An automated external defibrillator according to claim 1, wherein, depending on the type of treatment period, the method for detecting the subject's body movement is modified by changing at least one of the criteria for determining the amplitude and the criteria for determining the period, which are used as the basis for determining whether body movement is present.

3. The automated external defibrillator according to claim 1, wherein the treatment period includes a first period during which the electrocardiogram analysis is performed and a second period during which chest compressions are performed on the subject.

4. The automated external defibrillator according to claim 3, wherein the detection unit modifies the method for detecting the subject's body movements so that the detection of body movements during the first period is greater than the detection of body movements during the second period.

5. The automated external defibrillator according to claim 1 or 2, wherein the detection unit detects the movement of the subject due to chest compressions on the subject based on the impedance between a pair of electrode pads of the automated external defibrillator.

6. The automated external defibrillator according to claim 1 or claim 2, wherein the detection unit detects the body movement of the subject due to shaking of the subject based on the impedance between a pair of electrode pads of the automated external defibrillator.

7. The automated external defibrillator according to claim 1 or 2, wherein the detection unit detects the subject's spontaneous body movement based on the impedance between a pair of electrode pads of the automated external defibrillator.

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