Automated external defibrillator

Abstract

To provide an automatic external defibrillator capable of determining accurately the state of the heart.SOLUTION: An automatic external defibrillator includes: a pair of pads pasted on a chest of a rescuee and for applying an electric shock; and an ultrasonic sensor for outputting an ultrasonic signal, and receiving the ultrasonic signal reflected from at least either of the heart and a great vessel of the rescuee.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an automated external defibrillator, and more particularly to an automated external defibrillator equipped with an evaluation function in the mechanical activity of the heart.

Background Art

[0002] In recent years, the spread of automated external defibrillators (AEDs) has been progressing. AEDs are widely installed in commercial facilities, schools, etc. An AED automatically analyzes ventricular fibrillation and other life-threatening arrhythmias of a rescued person, and attempts to restore the function of the heart by giving an electrical shock (defibrillation) according to the analysis result.

[0003] As an example of an automated external defibrillator, Patent Document 1 describes an automated external defibrillator including a pair of defibrillation pads attached to the chest of a rescued person to apply an electrical shock to the heart, and a sensor unit that detects a pulse wave at the head of the rescued person.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] This invention has been made in view of these problems, and aims to provide an automated external defibrillator capable of accurately determining the condition of the heart. [Means for solving the problem]

[0007] This invention relates to a pair of devices that are attached to the chest of a person being rescued to deliver an electric shock. of electric Extreme The system comprises a head, an ultrasonic sensor that outputs an ultrasonic signal and receives ultrasonic signals reflected from at least one of the rescued person's heart and major blood vessels, an electrocardiogram (ECG) signal acquisition unit that receives the rescued person's ECG signal, and a control unit that determines the state of the rescued person's heart based on the ECG signal and the ultrasonic signal received by the ultrasonic sensor. The control unit determines whether the state of the rescued person's heart is normal, ventricular fibrillation, ventricular tachycardia, pulseless electrical activity, or asystole based on the ECG signal and the ultrasonic signal received by the ultrasonic sensor. Our This determines which one it is.

[0008] Furthermore, the present invention comprises a pair of electrode pads that are attached to the chest of a person being rescued to deliver an electric shock, and a microphone that detects at least one of the person's heart sounds and the sounds of blood flow in major blood vessels. [Effects of the Invention]

[0009] According to the present invention, the condition of the rescued person's heart is determined based on the electrocardiogram signal from the electrode pads and the ultrasound echo signal reflected from the rescued person, as well as the heart sound and blood flow signals from the microphone. This allows for a more accurate determination of the rescued person's heart condition compared to determining the condition based solely on the electrocardiogram signal. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram illustrating an automated external defibrillator (AED). [Figure 2] This is a diagram illustrating ultrasonic sensors (ultrasonic Doppler sensors). [Figure 3] This is a block diagram showing the configuration of the first embodiment. [Figure 4] It is a flowchart showing an example of control in the first embodiment. [Figure 5A] It is a diagram for explaining an appropriate attachment position of the ultrasonic pad. [Figure 5B] It is another diagram for explaining an appropriate attachment of the ultrasonic pad. [Figure 6] It is a subroutine in the control example of FIG. 4. [Figure 7] It is a diagram for explaining detection of heart sound by a microphone. [Figure 8] It is a block diagram showing the configuration of the second embodiment. [Figure 9] It is a flowchart showing an example of control in the second embodiment. [Figure 10] It is a subroutine in the control example of FIG. 9. [Figure 11] It is a diagram showing a modified example of the block diagram of FIG. 3. <​​​​​​​​​​​​​​​​​​​In addition, the automated external defibrillator 1 in the present embodiment also includes an ultrasonic sensor 7. The ultrasonic sensor 7 is connected to the main body 2 via an ultrasonic cable 8. The ultrasonic sensor 7 includes a transmitting vibrator 7a that transmits ultrasonic waves into the body of the rescued person P, and a receiving vibrator 7b that receives the reflected ultrasonic waves reflected by the heart or large blood vessels of the rescued person P. The ultrasonic sensor 7 is provided integrally with an ultrasonic pad 9. The ultrasonic pad 9 is attached to a position corresponding to the heart of the rescued person P. Note that the attachment positions of the electrode pads 3, 4 and the ultrasonic pad 9 shown in FIG. 1 are only schematically shown, so they are approximate positions.

[0014] Also, as shown in FIG. 1, the main body 2 includes a display unit 21 and an operation unit 22. The display unit 21 includes, for example, a liquid crystal display and a drive circuit. The operation state of the automated external defibrillator 1, the state (pathological condition) of the heart of the rescued person, etc. are displayed on the display unit 21. Further, the operation unit 22 includes various operators such as buttons operated by the operator (i.e., rescuer) of the automated external defibrillator 1.

[0015] FIG. 2 is an explanatory diagram of the ultrasonic sensor 7. FIG. 2 shows a cross-sectional view around the heart H of the rescued person P. Note that FIG. 2 shows the heart H in the diastolic phase. As shown in FIG. 2, blood flows into the left ventricle Hb through the mitral valve Ha. The ultrasonic sensor 7 (ultrasonic pad 9) is attached to the body surface S at a position corresponding to the heart H. In this state, when ultrasonic waves (ultrasonic signals) are transmitted from the transmitting vibrator 7a, the ultrasonic waves are reflected by the blood flowing through the heart and large blood vessels including the vicinity of the mitral valve Ha, and the reflected waves (ultrasonic echo signals) are received by the receiving vibrator 7b. The ultrasonic echo signals received by the receiving vibrator 7b include the ultrasonic echo signals reflected by the heart H or large blood vessels (e.g., aorta Hc) as described above. Further, not limited to blood cells, the ultrasonic echo signals reflected by myocardial activity and other tissues in the heart (e.g., aortic valve Hd) are included. Therefore, the automated external defibrillator 1 of the present embodiment extracts the ultrasonic echo signals by blood and obtains the blood flow velocity by Doppler analysis. This process will be described later.

[0016] Figure 3 is a block diagram showing the functional configuration of the automated external defibrillator 1. As shown in Figure 3, the main unit 2 includes, in addition to the display unit 21 and operation unit 22 described above, a control unit 12, a storage unit 13, an ultrasonic transmitting / receiving unit 14, an audio output unit 15, a high voltage generation unit 16, an electrocardiogram signal acquisition unit 17, a state detection unit 18, and a power supply unit 19. The ultrasonic transmitting / receiving unit 14, under the control of the control unit 12, issues an output instruction for an ultrasonic signal to the ultrasonic sensor 7, and receives an ultrasonic echo signal from the ultrasonic sensor 7 and sends the received ultrasonic signal to the control unit 12. The audio output unit 15 is a sound-emitting device such as a speaker, which, for example, outputs voice guidance or voice warnings under the control of the control unit 12.

[0017] The control unit 12 includes a processor such as a CPU and can execute various programs stored in the storage unit 13. The control unit 12 may include one processor or multiple processors. Furthermore, the control unit 12 includes a gate array and an A / D converter.

[0018] Furthermore, as shown in Figure 3, the control unit 12 includes a Doppler analysis unit 121. The Doppler analysis unit 121 is a functional unit realized by the processor executing a program stored in the memory unit 13. The Doppler analysis unit 121 receives the reflected wave signal (ultrasonic echo signal) from the person being rescued P, received by the receiving transducer 7b, via the ultrasonic transmitting / receiving unit 14. Then, as described above, the Doppler analysis unit 121 extracts only the ultrasonic echo signals corresponding to blood cells from the ultrasonic echo signals and determines the blood flow velocity based on the extracted ultrasonic echo signals. Specifically, the Doppler analysis unit 121 determines the blood flow velocity using the ultrasonic Doppler method. There are two methods of ultrasonic Doppler: the pulsed Doppler method and the continuous wave Doppler method, and the Doppler analysis unit 121 may adopt either method. However, since the pulsed Doppler method requires specifying the positioning site, the continuous wave Doppler method, which allows blood flow detection over a wide area of ​​the entire ultrasonic beam, is preferred.

[0019] In addition to the display unit 21 and the operation unit 22, the control unit 12 controls the operation of the memory unit 13, the ultrasonic transmission / reception unit 14, the audio output unit 15, and the high voltage generation unit 16. The control unit 12 performs tasks such as analyzing electrocardiograms, determining the condition of the heart and major blood vessels using ultrasonic echo signals, and controlling the output of electric shocks.

[0020] The memory unit 13 includes non-volatile memory such as ROM and volatile memory such as RAM, and information such as electrocardiogram signals is stored in this memory unit 13.

[0021] Electrode pads 3 and 4 are connected to a high-voltage generator 16, an electrocardiogram signal acquisition unit 17, and a state detection unit 18, respectively, via electrode cables 5 and 6. The high-voltage generator 16 generates high-voltage pulses for the electric shock delivered to the person being rescued P from the electrode pads 3 and 4 based on a control signal from the control unit 12. The electrocardiogram signal acquisition unit 17 filters out noise contained in the electrocardiogram signal from the electrode pads 3 and 4, and amplifies the filtered electrocardiogram signal. The electrocardiogram signal amplified by the electrocardiogram signal acquisition unit 17 is sent to the control unit 12 and used for electrocardiogram analysis, etc.

[0022] The state detection unit 18 detects the attachment status of the electrode pads 3 and 4 to the person being rescued P by, for example, measuring the impedance between the electrode pads 3 and 4 and the body surface of the person being rescued P. The state detection unit 18 also outputs a signal to the control unit 12 indicating the attachment status of the electrode pads 3 and 4 to the person being rescued P. The state detection unit 18 outputs one of two signals: an appropriate signal indicating that the electrode pads 3 and 4 are properly attached, and an inappropriate signal indicating that they are not properly attached.

[0023] The power supply unit 19 includes a battery with an output voltage of approximately 12V. In addition to the battery, the power supply unit 19 may also include a charger that charges using AC power supplied from a commercial power source. Furthermore, as shown in Figure 3, the power supply unit 19 is connected to the high voltage generation unit 16 and supplies power to operate the high voltage generation unit 16. Although not shown, the power supply unit 19 is also connected to the display unit 21, operation unit 22, control unit 12, memory unit 13, ultrasonic transmitting / receiving unit 14, electrocardiogram signal acquisition unit 17, state detection unit 18, power supply unit 19, and audio output unit 15, and supplies power to operate each of these units.

[0024] Next, the control performed in this embodiment will be described. Conventional automated external defibrillators (AEDs) measure electrocardiogram signals from electrode pads attached to the chest of the person being rescued and analyze the measured electrocardiogram signals. Based on the analysis results, if a conventional AED determines that the person is in a state close to being unable to pump blood (ventricular fibrillation or pulseless ventricular tachycardia), it determines that an electric shock is necessary for the person being rescued and instructs the operator to deliver the electric shock. In other words, conventional AEDs determine whether or not to deliver an electric shock to the person being rescued based solely on the electrocardiogram signal. In the case of ventricular fibrillation (Vf) and pulseless ventricular tachycardia (pulseless VT), an electric shock is deemed appropriate, while in the case of pulseless electrical activity (PEA) and asystole, an electric shock is deemed not appropriate.

[0025] However, in pulseless ventricular tachycardia (pulseless VT) and pulseless electrical activity (PEA), the presence or absence of mechanical activity of the heart is an important factor in the decision. Therefore, in conventional automated external defibrillators (AEDs) that determine the appropriateness of an electric shock based solely on electrocardiogram signals, the judgment may be inaccurate or insufficient. Consequently, AEDs (compared to current, i.e., conventional AEDs) are required to more accurately determine the state of the heart. Therefore, in the AED 1 of this embodiment, the state of the heart is determined by acquiring information on the mechanical activity of the heart (including information on heart sounds) in addition to the electrocardiogram signal, thereby more accurately and comprehensively determining the electrical and mechanical activity of the heart.

[0026] Figure 4 is a flowchart showing an example of control in this embodiment. The control shown in Figure 4 is executed, for example, when the power to the automated external defibrillator 1 is turned on by the operator (or when the power is turned on automatically, such as when the automated external defibrillator 1 is removed from its housing case). The specific details of the control are described below.

[0027] First, the control unit 12 instructs the voice output unit 15 to output an audio instruction to attach the electrode pads 3 and 4 and the ultrasonic pad 9 (step S1). In response, the voice output unit 15 outputs an audio message such as, "Please attach the two electrode pads and the ultrasonic pad to the positions indicated on the pads," or a warning sound to that effect. It is assumed that the back surface of each pad has an image drawn on it indicating the position where each pad should be attached. Next, the control unit 12 determines whether the electrode pads 3 and 4 are properly attached to the predetermined positions (drawn positions) on the person being rescued P (step S2). Specifically, the control unit 12 determines that they are properly attached if it receives an appropriate signal from the state detection unit 18. Conversely, the control unit 12 determines that they are not properly attached if it receives an inappropriate signal from the state detection unit 18. It is also determined that they are not properly attached if the attachment of the electrode pads 3 and 4 is insufficient.

[0028] If the control unit 12 determines in step S2 that the electrode pads 3 and 4 are not properly attached, it instructs the audio output unit 15 to output an audio instruction to prompt the proper attachment of the electrode pads 3 and 4 (step S3). In response, the audio output unit 15 outputs an audio instruction to attach the electrode pads 3 and 4, or a warning sound indicating this. After executing the process in step S3, the control unit 12 returns to the process in step S2.

[0029] On the other hand, if the control unit 12 determines in step S2 that the electrode pads 3 and 4 are properly attached, it determines whether the ultrasonic pad 9 for transmitting and receiving ultrasonic signals is attached to the appropriate position on the person being rescued P (i.e., whether the attachment position is appropriate) (step S4). Here, the appropriate position is a position corresponding to the heart and also including the intercostal spaces sufficiently. Figures 5A and 5B are diagrams illustrating the appropriate position of the ultrasonic pad 9. If the transmitting transducer 7a and receiving transducer 7b mounted on the ultrasonic pad 9 are not positioned corresponding to the heart and also corresponding to the intercostal spaces, the ultrasonic echo signal corresponding to blood cells will be weakened, and accurate information on blood flow may not be obtained. For example, as shown in Figure 5A, suppose the transmitting transducer 7a is positioned corresponding to the intercostal spaces, but the receiving transducer 7b is not positioned corresponding to the ribs B. In this case, the ultrasonic transmitting beam is irradiated into the heart, but the ultrasonic echo signal reflected within the heart is blocked by the ribs B, and the signal received by the receiving transducer 7b becomes weak. Furthermore, as shown in Figure 5B, if the receiving transducer 7b is positioned in a location corresponding to the intercostal space, but the transmitting transducer 7a is positioned in a location corresponding to rib B, the ultrasonic transmitting beam will be blocked by rib B and will not reach the heart (or will be weakened even if it does reach the heart), and the reflected wave (received signal) reflected within the heart will also be weakened.

[0030] Therefore, in step S4, the control unit 12 determines whether the ultrasonic pad 9 is attached in the correct position. Specifically, the control unit 12 starts transmitting ultrasound using the transmitting transducer 7a, and if the intensity of the ultrasound echo signal received by the receiving transducer 7b is less than a preset threshold, it determines that the ultrasonic pad 9 is not attached in the correct position. Conversely, if the ultrasound echo signal is above the threshold, the control unit 12 determines that the ultrasonic pad 9 is attached in the correct position. If the control unit 12 determines in step S4 that the pad is attached in the correct position, it analyzes the electrocardiogram signal and the ultrasound echo signal and outputs the analysis results as audio (step S6). The processing in step S6 will be described later.

[0031] On the other hand, if the control unit 12 determines in step S4 that the ultrasonic pad 9 is not attached in the correct position, it instructs the audio output unit 15 to output an audio instruction to attach the ultrasonic pad 9 again (step S5). That is, it outputs an audio instruction to adjust the position to encourage attachment in the correct position. In response, the audio output unit 15 outputs an audio instruction to attach the ultrasonic pad 9 or a warning sound indicating this. In this embodiment, the control unit 12 repeats the processes of steps S4 and S5 until it determines in step S4 that the ultrasonic pad is attached in the correct position. However, as another example, the control unit 12 may determine that there is no pulse after executing the process of step S5 a predetermined number of times (for example, about 3 times) and proceed to step S6.

[0032] As described above, the automated external defibrillator 1 in this embodiment is equipped with an ultrasonic sensor 7 and transmits an ultrasonic signal into the heart of the person being rescued P and receives the reflected wave in order to more accurately and comprehensively understand the condition of the person being rescued P. Specifically, the control unit 12 drives the ultrasonic transmitting transducer 7a to transmit ultrasonic waves into the heart of the person being rescued P. The ultrasonic waves transmitted into the heart are reflected by the blood cells in the heart, and the reflected ultrasonic waves are received by the receiving transducer 7b.

[0033] In step S6, the control unit 12 analyzes the state of the heart more accurately and comprehensively than before by analyzing the electrocardiogram signal and the ultrasound echo signal, and outputs the analysis results as audio. Figure 6 is a flowchart of the subroutine for step S6. In this process, the control unit 12 determines which of the following lethal arrhythmias (i.e., ventricular fibrillation, pulseless ventricular tachycardia, pulseless electrical activity, or asystole) the state of the rescued person P's heart corresponds to. First, the control unit 12 detects the waveform pattern of the electrocardiogram signal (step S60) and detects the blood flow velocity using an ultrasound Doppler (step S61). The control unit 12 controls the process of step S60 and step S61 to be executed simultaneously in parallel. Specifically, in step S60, the control unit 12 acquires the electrocardiogram signal from the electrocardiogram signal acquisition unit 17 and detects the waveform pattern of the electrical activity of the heart from the electrocardiogram signal. That is, the control unit 12 acquires the electrical activity of the rescued person P's heart from the electrocardiogram signal. In step S61, the Doppler analysis unit 121 of the control unit 12 performs Doppler analysis on the ultrasound echo signals reflected within the major blood vessels of the heart and detects the blood flow velocity. In this way, the control unit 12 obtains the mechanical activity of the rescued person P's heart from the ultrasound echo signals. Steps S60 and S61 may be performed simultaneously, or they may be performed in the order of S60 then S61, or in the reverse order.

[0034] Once steps S60 and S61 are completed, the control unit 12 proceeds to step S62. The processes shown in steps S62 to S71 represent an algorithm for comprehensively determining the state of the heart based on the waveform pattern of the electrocardiogram signal and the blood flow velocity. The control unit 12 performs a comprehensive analysis of the electrocardiogram signal and blood flow velocity (step S62). Specifically, it estimates the waveform pattern based on the electrocardiogram signal and determines whether the blood flow velocity based on the Doppler analysis of the ultrasound echo signal is smaller than a predetermined threshold. The specific analysis of blood flow velocity will be described later. First, the estimation of the waveform pattern based on the electrocardiogram signal will be explained. The control unit 12 estimates whether the waveform pattern of the electrocardiogram signal detected in step S60 corresponds to a normal waveform pattern or to the waveform pattern of one of the lethal arrhythmias: ventricular fibrillation (Vf), pulseless ventricular tachycardia (pulseless VT), pulseless electrical activity (PEA), or asystole. Each waveform pattern is pre-stored in the memory unit 13, and the control unit 12 estimates the corresponding waveform pattern by comparing each waveform pattern with the waveform pattern of the electrocardiogram signal of the person being rescued P. However, if the state of the heart is determined based solely on the electrocardiogram signal, it may not be possible to accurately determine whether or not it corresponds to one of the lethal arrhythmias mentioned above. When making a judgment based on the electrocardiogram signal, the waveform for a normal heart, the waveform for ventricular fibrillation (Vf), and the waveform for asystole can be identified. However, in the judgment of ventricular tachycardia (VT) and pulseless electrical activity (PEA), judgment based solely on the electrocardiogram signal may lead to errors in judging the mechanical activity of the heart. Ventricular tachycardia (VT) includes pulseless VT and pulsed VT, and it is difficult to determine whether or not there is a pulse from the electrocardiogram signal alone. Furthermore, it is also difficult to determine whether or not there is a pulse by carotid artery palpation by the rescuer. Even when assessing pulseless electrical activity (PEA), if pulseless electrical activity is suspected based on the electrocardiogram signal, and mechanical activity is confirmed in the heart, depending on the degree of that mechanical activity, it may not be classified as PEA. Thus, determining which state of lethal arrhythmia is present based solely on the electrocardiogram signal can be difficult in emergency situations requiring life-saving measures.

[0035] In the comprehensive analysis of the electrocardiogram signal and blood flow velocity in step S62, if the waveform pattern of the person being rescued P matches a normal waveform pattern, the control unit 12 identifies that the heart is in a normal state (step S63). Also, in the comprehensive analysis of the electrocardiogram signal and blood flow velocity in step S62, if the waveform pattern of the electrocardiogram signal matches a waveform pattern of asystole, the control unit 12 identifies that the heart is in asystole (step S64). Also, in the comprehensive analysis of the electrocardiogram signal and blood flow velocity in step S62, if the waveform pattern of the electrocardiogram signal matches a waveform pattern of ventricular fibrillation, the control unit 12 identifies that the heart is in ventricular fibrillation (Vf) (step S65). In each step from S63 to S65, the control unit 12 identifies the heart state and outputs information indicating the identified heart state via voice output. This allows the operator of the automated external defibrillator 1 to recognize the state of the person being rescued P. Furthermore, in each of steps S63 to S65, the cardiac state (normal, asystole, ventricular fibrillation) can be identified based on the electrocardiogram signal. Another example is that the control unit 12 may more accurately identify the cardiac state by further considering the blood flow velocity detected in step S61. For example, if the cardiac state is estimated to be normal based on the electrocardiogram signal, and the blood flow velocity is less than a predetermined threshold, the control unit 12 can make a more detailed judgment that the heart is normal but the pulse is weak. Also, for example, if the cardiac state is estimated to be asystole based on the electrocardiogram signal, and the blood flow velocity is greater than a predetermined threshold, the control unit 12 can determine that the heart is asystole but a pulse remains. In this way, the control unit 12 can more accurately grasp the cardiac state of the person being rescued P by comprehensively determining not only the waveform pattern of the electrocardiogram signal but also mechanical cardiac activity such as blood flow velocity obtained from the ultrasound echo signal.

[0036] On the other hand, in the comprehensive analysis of the electrocardiogram signal and blood flow velocity in step S62, if the waveform pattern of the person being rescued P matches the waveform pattern of ventricular tachycardia (VT), the control unit 12 checks whether the blood flow velocity detected in step S61 is smaller than a predetermined threshold α (step S66). As mentioned above, ventricular tachycardia includes pulseless VT and pulsed VT. Therefore, the control unit 12 needs to determine which state the heart of the person being rescued P is in. The control unit 12 checks whether the blood flow velocity of the person being rescued P detected in step S61 is smaller than a predetermined threshold α. The threshold α is predetermined through clinical trials and various experiments.

[0037] If the control unit 12 confirms in step S66 that the blood flow velocity of the person being rescued P is less than the threshold α, it identifies the cardiac condition as pulseless VT (step S67). Conversely, if the blood flow velocity of the person being rescued P is confirmed to be greater than or equal to the threshold α in step S66, the control unit 12 identifies the cardiac condition as pulsed VT (step S68). In this way, the control unit 12 can accurately distinguish between pulseless VT and pulsed VT by comprehensively determining mechanical cardiac activity such as blood flow velocity obtained from ultrasound echo signals in addition to the waveform pattern of the electrocardiogram signal. Here, the criterion that the blood flow velocity is less than the threshold α is an example of a predetermined condition, and the process in step S66 is an example of a process that determines whether the blood flow in the great vessels of the person being rescued meets a predetermined condition.

[0038] On the other hand, in the comprehensive analysis of the electrocardiogram signal and blood flow velocity in step S62 described above, if the waveform pattern of the person being rescued P matches the waveform pattern of pulseless electrical activity (PEA), the control unit 12 checks whether the blood flow velocity detected in step S61 is smaller than a predetermined threshold β (step S69). As described above, it is usually difficult to determine whether or not it is pulseless electrical activity based solely on the electrocardiogram signal; in other words, there is room for doubt as to whether or not it is pulseless electrical activity based solely on the electrocardiogram signal. This point is extremely important because automated external defibrillators are ineffective against pulseless electrical activity. Therefore, in this embodiment, if the condition of the heart of the person being rescued P is estimated to be pulseless electrical activity (PEA), the control unit 12 makes a comprehensive judgment in conjunction with the ultrasound echo signal. Specifically, the control unit 12 checks whether or not the blood flow velocity of the person being rescued P is smaller than a predetermined threshold β. The threshold β is predetermined through clinical trials and various experiments.

[0039] If the control unit 12 confirms that the blood flow velocity of the person being rescued P is less than the threshold β, it identifies the cardiac condition as pulseless electrical activity (PEA) (step S70). Conversely, if the blood flow velocity of the person being rescued P is confirmed to be greater than or equal to the threshold β, the control unit 12 identifies the cardiac condition as not pulseless electrical activity (PEA) (step S71). Here, the criterion for determining that the blood flow velocity is greater than or equal to the threshold β is an example of a predetermined condition, and the process in step S69 is an example of the process of determining whether the blood flow in the great vessels of the person being rescued meets the predetermined conditions. If the control unit 12 confirms that the cardiac condition of the person being rescued P is not PEA, it may be possible to confirm the pulse of the person being rescued P, but if the pulse is clinically judged to be weak and insufficient, it instructs the voice output unit 15 to check for consciousness (e.g., response to calls) and respiratory movement. As described above, the control unit 12 can accurately determine whether or not pulseless electrical activity (PEA) is present by referring to the waveform pattern of the electrocardiogram signal as well as the state of mechanical activity such as blood flow velocity obtained from the ultrasound echo signal.

[0040] Conventional automated external defibrillators (AEDs) identify the state of the heart solely from the waveform pattern of the electrocardiogram (ECG). However, relying solely on the ECG may not accurately identify the state of the heart. In particular, when distinguishing between pulseless ventricular tachycardia (PAD) and pulsed ventricular tachycardia (VT), and when determining whether or not pulseless electrical activity (PEA) is present, relying solely on the ECG can lead to misjudgments. In contrast, as described above, the control unit 12 of this embodiment refers to the blood flow velocity in the major vessels of the heart obtained from the ultrasound echo signal in addition to the ECG signal, allowing for a more comprehensive and accurate determination of the state of the heart. In other words, the control unit 12 identifies the state of the heart (i.e., the mechanical activity of the heart) not only based on the waveform pattern of electrical activity, but also on blood flow velocity, etc., and identifies the state of the heart through a comprehensive judgment of these electrical and mechanical activities.

[0041] In this embodiment, the control unit 12 determines whether the condition that the blood flow velocity is less than a threshold α is met when it estimates ventricular tachycardia (VT) based on the electrocardiogram signal, and identifies it as pulseless ventricular tachycardia (pulseless VT) when that condition is met. However, the conditions for determining pulseless ventricular tachycardia (pulseless VT) when it estimates ventricular tachycardia (VT) based on the electrocardiogram signal are any conditions related to blood flow velocity that allow it to be determined that there is no pulse, and the specific conditions for this are not limited to this embodiment. As another example, the control unit 12 may identify it as pulseless ventricular tachycardia (pulseless VT) when it meets the condition that the blood flow velocity remains below a threshold α for a predetermined period of time.

[0042] Furthermore, in this embodiment, the control unit 12 determines whether the condition that the blood flow velocity is less than a threshold β is met when pulseless electrical activity (PEA) is estimated based on the electrocardiogram signal, and identifies it as pulseless electrical activity (PEA) when that condition is met. However, the conditions for identifying pulseless electrical activity (PEA) when pulseless electrical activity (PEA) is estimated based on the electrocardiogram signal are any conditions related to blood flow velocity that allow it to be determined that there is no pulse, and the specific conditions for this are not limited to this embodiment. As another example, the control unit 12 may identify pulseless electrical activity (PEA) when the condition that the blood flow velocity remains below a threshold β for a predetermined period of time is met.

[0043] Returning to the flowchart in Figure 4, the control unit 12 evaluates (or determines) the analysis results of the cardiac condition of the person being rescued P (step S7). In other words, it determines the cardiac condition of the person being rescued P as identified in the subroutine in Figure 6. If the analysis in step S6 determines that the cardiac condition of the person being rescued P is ventricular fibrillation or pulseless ventricular tachycardia (step S7), the control unit 12 determines that an electric shock is appropriate. In this case, the control unit 12 instructs the voice output unit 15 to output an electric shock instruction instructing the person to press the electric shock operation button (step S8).

[0044] Next, the control unit 12 instructs the voice output unit 15 to output a voice command indicating that cardiopulmonary resuscitation (CPR) should also be performed (step S9). In response, the voice output unit 15 outputs a voice guide indicating that CPR should be performed, i.e., chest compressions and chest blows. Next, the control unit 12 proceeds to step S6 to continuously monitor the progress of the heart's condition over time. This allows for real-time monitoring of the rescued person P's response to CPR over time. In this case, in step S6, the control unit 12 re-determines the heart's condition and outputs a voice message regarding the heart's condition. For example, if the blood flow velocity has increased due to pulseless VT or pulseless electrical activity compared to the previous analysis, the control unit 12 outputs a voice message to that effect. Thus, the information regarding the heart's condition includes information indicating the changes in the heart's condition over time.

[0045] Furthermore, if the control unit 12 determines, based on the analysis in step S6, that the cardiac condition of the person being rescued P is pulseless electrical activity (PEA) or asystole (step S7), it determines that an electric shock is not appropriate. In this case, the control unit 12 proceeds to step S9, instructs the output of a voice command for cardiopulmonary resuscitation, then proceeds to step S6, continues to monitor changes in the cardiac condition, and outputs information regarding the cardiac condition via voice.

[0046] Furthermore, if the control unit 12 determines, based on the analysis in step S6, that the cardiac condition of the person being rescued P is normal or has a pulse (VT) (step S7), it determines that an electric shock is not appropriate and terminates the control shown in Figure 4.

[0047] Next, the effects of this embodiment will be described. As described above, in the automated external defibrillator 1 of this embodiment, when assessing the condition of the heart of the person being rescued P, the electrical activity of the heart obtained from the electrocardiogram signal and the mechanical activity of the heart obtained from the ultrasound echo signal are acquired. Then, the automated external defibrillator 1 makes a comprehensive judgment of the electrical and mechanical activity of the heart and determines the condition of the heart of the person being rescued P (more appropriately than conventional devices). Therefore, the automated external defibrillator 1 of this embodiment can determine the condition of the heart more accurately than conventional automated external defibrillators that make judgments based only on the electrocardiogram signal. For example, even in cases where it is difficult to determine the condition of the heart based on the electrocardiogram signal alone, such as distinguishing between pulseless VT and pulsed VT, or determining whether or not there is pulseless electrical activity (PEA), accurate judgments can be made. In other words, it is possible to accurately determine whether or not to apply an electric shock to the person being rescued P. Furthermore, by accurately determining whether or not to apply an electric shock to the person being rescued P, it is possible to avoid giving an electric shock to the person being rescued P unnecessarily and harmfully. Thus, the automated external defibrillator 1 of this embodiment can comprehensively judge the electrical activity of the heart (evaluation by electrocardiogram) and its mechanical activity (evaluation by ultrasound), and provide information that is even more useful for saving lives.

[0048] Furthermore, by continuously identifying the state of the heart based on a comprehensive assessment of its electrical and mechanical activity, the operator of the automated external defibrillator 1 (i.e., the rescuer) can be informed more accurately and in real time of the condition of the person being rescued P and its physiological progression (changes over time). This provides the operator of the automated external defibrillator 1 with even more useful information for saving lives. In addition, the automated external defibrillator 1 in this embodiment can grasp the state of the mechanical activity of the person being rescued P's heart by receiving ultrasonic echo signals reflected within the heart, allowing for effective combination of the automated external defibrillator 1 with other measures to save the person being rescued P (e.g., chest compressions, chest blows, administration of vasoconstrictors, administration of antiarrhythmic drugs, etc.). By performing such effective combined measures, the resuscitation rate of the person being rescued P can be improved, as can the rate of the person being rescued P's return to society where they can perform daily activities.

[0049] (Second embodiment) Next, a second embodiment will be described. The automated external defibrillator 300 of the second embodiment is equipped with a microphone instead of the ultrasonic sensor in the first embodiment for detecting the condition of the heart of the person being rescued P. The automated external defibrillator 300 of the second embodiment acquires audio signals (heart sounds and blood flow sounds of major vessels) from the heart of the person being rescued P using the microphone, and detects the condition of the heart based on the audio signals and electrocardiogram signals. In the second embodiment, components similar to those in the first embodiment are denoted by the same reference numerals, and descriptions of components similar to those in the first embodiment are omitted. Furthermore, in the following description, unless otherwise specified, the audio signal from the heart will be referred to as heart sounds.

[0050] The audio signal is detected by the microphone. Figure 7 is an explanatory diagram of the microphone 200. Figure 7 shows a cross-sectional view of the area around the heart H of the person being rescued P. As shown here, blood flows into the left ventricle Hb through the mitral valve Ha. The microphone 200 is mounted on the microphone pad 100 that receives the audio signal. That is, the microphone 200 is integrated with the microphone pad 100. The microphone 200 is connected to the main unit 301 via a microphone cable 201. The microphone pad 100 is attached to the body surface S at a position corresponding to the heart H. The heart has four valves, and during systole, the mitral valve Ha in the left ventricle Hb and the tricuspid valve (not shown) in the right ventricle He close. The sound when these valves close is the first heart sound, and the closing of the valves ejects blood from the heart. Subsequently, during diastole, when the heart expands and blood flows into it, the mitral valve (Ha) and tricuspid valve open, while the aortic valve (Hd) and pulmonary valve (not shown) close. The sound heard at this time is the second heart sound, and because the second heart sound follows the first heart sound, it sounds like "thump-thump." The presence of this normal sound is evidence that the heart is performing normal mechanical functions, and this is evidence that blood is being properly pumped throughout the body. In other words, if this normal sound is not heard, it can be concluded that blood is not being pumped properly.

[0051] Figure 8 is a block diagram showing the configuration of the automated external defibrillator 300 in the second embodiment. In the configuration of the automated external defibrillator 300 shown in Figure 8, the configuration related to the ultrasonic echo signal of the automated external defibrillator in the first embodiment has been replaced with a configuration related to the audio signal, but the other configurations are the same. Therefore, only the configuration related to the audio signal will be described here.

[0052] Specifically, the main unit 301 of the automated external defibrillator 300 is equipped with a heart sound receiver 101. The heart sound receiver 101 receives the heart sounds of the person being rescued P via a microphone 200. The received heart sounds are sent to the control unit 120.

[0053] The control unit 120 also includes a heart sound analysis unit 122, as shown in Figure 8. The heart sound analysis unit 122 is a functional unit realized by the processor executing a program stored in the memory unit 13. The heart sound analysis unit 122 receives heart sounds (audio signals) from the person being rescued P via the heart sound receiving unit 101 and analyzes the heart sounds. The heart sound analysis unit 122 performs filtering processing, such as detecting only a predetermined frequency band.

[0054] Next, the control performed in the second embodiment will be described. As mentioned above, conventional automated external defibrillators (AEDs) determine the need for an electric shock based solely on the electrocardiogram signal, which can sometimes lead to inaccurate judgments. Therefore, in the AED 300 in this second embodiment, the cardiac condition is determined more accurately by referring to the heart sounds obtained from the microphone 200 in addition to the electrocardiogram signal.

[0055] Figure 9 is a flowchart illustrating an example of control in the second embodiment. This control example shown in Figure 9 is executed, for example, when the power supply of the automated external defibrillator 300 is turned on by the operator (or when the power supply is turned on automatically, such as by removing the automated external defibrillator 300 from its housing case), similar to the control example described in Figure 4. In this control example shown in Figure 9, the explanation of the same steps as in the control example in Figure 4 of the above-described embodiment is omitted or simplified, and the same step numbers are used for the same steps. The specific details of the control are described below.

[0056] First, the control unit 120 instructs the voice output unit 15 to output an audio instruction to attach the electrode pads 3 and 4 and the microphone pad 100 (step S100). In response, the voice output unit 15 outputs an audio message such as, "Please attach the two electrode pads and the microphone pad to the positions indicated on the pads," or a warning sound to that effect. Next, the control unit 120 determines whether the electrode pads 3 and 4 are properly attached to the predetermined positions on the person being rescued P. If it determines that they are not properly attached, it instructs the voice output unit 15 to output an audio instruction to encourage the proper attachment of the electrode pads 3 and 4 (steps S2-3).

[0057] On the other hand, if the control unit 120 determines that the electrode pads 3 and 4 are properly attached, it determines whether the microphone pad 100 is attached to the appropriate position on the person being rescued P (step S400). Specifically, if the intensity of the heart sounds (or blood flow sounds of major vessels) received by the microphone pad 100 is less than a preset threshold, the control unit 120 determines that the microphone pad 100 is not attached to the appropriate position. If the control unit 120 determines in step S400 that the microphone pad 100 is not attached to the appropriate position, it instructs the audio output unit 15 to output an audio instruction to prompt adjustment of the microphone pad 100's position (step S500). In response, the audio output unit 15 outputs an audio instruction to attach the microphone pad 100 or a warning sound indicating this. In this embodiment, the control unit 120 repeats the processes of steps S400 and S500 until it determines that the device is attached in the appropriate position in step S400. However, as another example, the control unit 120 may determine that the heart sound itself is weak after executing the process of step S500 a predetermined number of times, and proceed to step S600.

[0058] On the other hand, the control unit 120 determines that the microphone pad 100 is attached in the appropriate position if the heart sound intensity is above a threshold. If the control unit 120 determines in step S400 that the microphone pad is attached in the appropriate position, it analyzes the electrocardiogram signal and heart sounds, and further outputs the analysis results as audio (step S600). In step S600, the control unit 120 determines the state of the heart by analyzing the electrocardiogram signal and heart sounds. Figure 10 is a flowchart of the subroutine in step S600. Note that the flowchart shown in Figure 10 has almost the same control content as the flowchart in Figure 6 in the first embodiment described above, with the description of ultrasound replaced by heart sounds. Therefore, explanations of parts that are the same as the control content in Figure 6 are omitted or simplified, and the same step numbers are used for explanations of the same steps.

[0059] In this process, the control unit 120 determines which of the following lethal arrhythmias (i.e., ventricular fibrillation, pulseless ventricular tachycardia, pulseless electrical activity, or asystole) the cardiac condition of the person being rescued P falls under. First, the control unit 120 acquires an electrocardiogram signal from the electrocardiogram signal acquisition unit 17, detects the waveform pattern of the electrical activity of the heart from the electrocardiogram signal (step S60), and detects heart sounds using the microphone 200 (step S610). The control unit 12 controls the process of step S60 and step S61 to be executed simultaneously and in parallel. In step S60, the control unit 12 acquires the electrical activity of the heart of the person being rescued P from the electrocardiogram signal. In step S610, the heart sound analysis unit 122 of the control unit 120 detects heart sounds using the microphone pad 100. In other words, the control unit 120 acquires the mechanical activity of the heart of the person being rescued P from the heart sounds. Steps S60 and S610 may be performed simultaneously, or they may be performed in the order of S60 then S610, or in the reverse order.

[0060] After steps S60 and S61 are completed, the control unit 120 performs a comprehensive analysis of the electrocardiogram signal and heart sounds (step S62). Specifically, it estimates the waveform pattern based on the electrocardiogram signal and determines whether the heart sound intensity detected by the microphone 200 is less than a predetermined threshold. The specific analysis of heart sounds will be described later. First, let's explain the estimation of the waveform pattern based on the electrocardiogram signal. The control unit 120 estimates whether the waveform pattern of the electrocardiogram signal detected in step S60 corresponds to a normal waveform pattern or to the waveform pattern of one of the lethal arrhythmias: ventricular fibrillation (Vf), pulseless ventricular tachycardia (pulseless VT), pulseless electrical activity (PEA), or asystole. If the state of the heart is determined based only on the electrocardiogram signal, it may not be possible to accurately determine whether it corresponds to one of the above lethal arrhythmias. When making a judgment based on the electrocardiogram signal, the waveform for a normal heart, the waveform for ventricular fibrillation (Vf), and the waveform for asystole can be identified. However, in diagnosing ventricular tachycardia (VT) and pulseless electrical activity (PEA), relying solely on electrocardiogram signals can lead to misjudgments regarding the heart's mechanical activity. Ventricular tachycardia (VT) includes pulseless VT and pulsed VT, and determining whether or not there is a pulse is difficult based solely on electrocardiogram signals. Similarly, determining whether or not there is a pulse is difficult even through carotid artery palpation by rescuers. In diagnosing pulseless electrical activity (PEA), even if pulseless electrical activity is suspected based on the electrocardiogram signal, if mechanical activity is confirmed in the heart, it may not be classified as PEA depending on the degree of that mechanical activity. Thus, determining which state of lethal arrhythmia is present can be difficult in emergency situations requiring life-saving, based solely on electrocardiogram signals.

[0061] In the comprehensive analysis of the electrocardiogram signal and heart sounds in step S62, if the waveform pattern of the person being rescued P matches a normal waveform pattern, the control unit 120 identifies that the heart is in a normal state (step S63). Also, in the comprehensive analysis of the electrocardiogram signal and heart sounds in step S62, if the waveform pattern of the electrocardiogram signal matches a waveform pattern of asystole, the control unit 120 identifies that the heart is in asystole (step S64). Also, in the comprehensive analysis of the electrocardiogram signal and heart sounds in step S62, if the waveform pattern of the electrocardiogram signal matches a waveform pattern of ventricular fibrillation, the control unit 120 identifies that the heart is in ventricular fibrillation (Vf) (step S65). In each step from S63 to S65, the control unit 120 identifies the heart state and outputs information indicating the identified heart state via voice output. This allows the operator of the automated external defibrillator 300 to recognize the state of the person being rescued P. Furthermore, in each of steps S63 to S65, the cardiac state (clear, asystole, ventricular fibrillation) can be identified based on the electrocardiogram signal. Another example is that the control unit 120 may further consider the heart sounds detected in step S610 to more accurately determine the cardiac state. In this way, the control unit 120 can more accurately grasp the cardiac state of the person being rescued P by comprehensively determining not only the waveform pattern of the electrocardiogram signal but also the mechanical cardiac activity obtained from the heart sounds.

[0062] On the other hand, in the comprehensive analysis of the electrocardiogram signal and heart sounds in step S62, if the waveform pattern of the person being rescued P matches the waveform pattern of ventricular tachycardia (VT), the control unit 120 checks whether the intensity of the heart sounds detected in S610 is less than a predetermined threshold γ (step S660). As mentioned above, ventricular tachycardia includes pulseless VT and pulsed VT. Therefore, the control unit 120 needs to determine which state the heart of the person being rescued P is in. The control unit 120 checks whether the intensity of the heart sounds of the person being rescued P detected in step S610 is less than a predetermined threshold γ. The threshold γ is predetermined through clinical trials and various experiments.

[0063] If the control unit 120 confirms in step S660 that the heart sound intensity of the person being rescued P is less than the threshold γ, it identifies the cardiac condition as pulseless VT (step S67). Conversely, if the heart sound intensity of the person being rescued P is confirmed to be greater than or equal to the threshold γ in step S660, the control unit 120 identifies the cardiac condition as pulsed VT (step S68). In this way, the control unit 120 can accurately distinguish between pulseless VT and pulsed VT by comprehensively determining not only the waveform pattern of the electrocardiogram signal but also mechanical cardiac activity such as heart sounds. Here, the criterion that the heart sound intensity is less than the threshold γ is just one example of a predetermined condition, and the process in step S660 is just one example of the process of determining whether the heart sound intensity of the person being rescued P meets the predetermined condition.

[0064] On the other hand, in the comprehensive analysis of the electrocardiogram signal and heart sounds in step S62 described above, if the waveform pattern of the person being rescued P matches the waveform pattern of pulseless electrical activity (PEA), the control unit 120 checks whether the heart sound intensity is less than a predetermined threshold δ (step S690). As described above, determining whether or not it is pulseless electrical activity is usually difficult based solely on the electrocardiogram signal; in other words, a judgment based only on the electrocardiogram signal leaves room for doubt as to whether or not it is pulseless electrical activity. This point is extremely important because automated external defibrillators are ineffective against pulseless electrical activity. Therefore, in the second embodiment, if the condition of the heart of the person being rescued P is estimated to be pulseless electrical activity (PEA), the control unit 120 makes a comprehensive judgment by combining the heart sounds in addition to the electrocardiogram signal. Specifically, the control unit 120 checks whether or not the heart sound intensity of the person being rescued P is less than a predetermined threshold δ. The threshold δ is predetermined through clinical trials and various experiments.

[0065] In step S690, if the control unit 120 confirms that the heart sound intensity of the person being rescued P is less than the threshold δ, it identifies the cardiac condition as pulseless electrical activity (PEA) (step S70). Conversely, in step S690, if the heart sound intensity of the person being rescued P is confirmed to be greater than or equal to the threshold δ, the control unit 120 identifies the cardiac condition as not pulseless electrical activity (PEA) (step S71). Here, the criterion that the heart sound intensity is greater than or equal to the threshold δ is an example of a predetermined condition, and the process in step S690 is an example of the process of determining whether the heart sound intensity of the person being rescued P meets the predetermined condition. If the control unit 120 determines that the heart of the person being rescued P is not in PEA, it may be possible to confirm the pulse of the person being rescued P, but if the pulse is clinically judged to be weak and insufficient, it instructs the voice output unit 15 to check for consciousness (e.g., response to calls) and respiratory movement. As a result, the control unit 120 can accurately determine whether or not pulseless electrical activity (PEA) is present by referring to the state of mechanical activity of the heart obtained from heart sounds, in addition to the waveform pattern of the electrocardiogram signal.

[0066] In this embodiment, the control unit 120 determines whether the condition that the heart sound intensity is less than threshold γ is met when ventricular tachycardia (VT) is estimated based on the electrocardiogram signal, and identifies it as pulseless ventricular tachycardia (pulseless VT) when this condition is met. However, the conditions for determining pulseless ventricular tachycardia (pulseless VT) when ventricular tachycardia (VT) is estimated based on the electrocardiogram signal can be any conditions related to heart sounds, and the specific conditions for this are not limited to this embodiment. As another example, the control unit 120 may identify it as pulseless ventricular tachycardia (pulseless VT) when the condition that the heart sound intensity remains below threshold γ for a predetermined period of time is met.

[0067] Furthermore, in this embodiment, the control unit 120 determines whether the condition that the heart sound intensity is less than a threshold δ is met when pulseless electrical activity (PEA) is estimated based on the electrocardiogram signal, and identifies it as pulseless electrical activity (PEA) when that condition is met. However, the conditions for identifying pulseless electrical activity (PEA) when it is estimated based on the electrocardiogram signal can be any conditions related to heart sounds, and the specific conditions for this are not limited to this embodiment. As another example, the control unit 120 may identify pulseless electrical activity (PEA) when the condition that the heart sound intensity remains less than a threshold δ for a predetermined period of time is met.

[0068] Next, returning to Figure 9, the control unit 120 executes steps S7 to S9. Note that the explanation of steps S7 to S9 is the same as in the first embodiment described above, so the explanation is omitted here.

[0069] Next, the effects of the second embodiment will be described. As described above, in the automated external defibrillator 300 of the second embodiment, when assessing the cardiac condition of the person being rescued P, the electrical activity of the heart obtained from the electrocardiogram signal and the mechanical activity of the heart obtained from the microphone 200 are acquired. The automated external defibrillator 300 then determines the cardiac condition of the person being rescued P based on a comprehensive judgment of the electrical and mechanical activity of the heart. Therefore, the automated external defibrillator 300 of the second embodiment (similar to the automated external defibrillator in the first embodiment) can determine the cardiac condition more accurately than conventional automated external defibrillators that make judgments based only on the electrocardiogram signal. For example, even in cases where it is difficult to determine the cardiac condition based solely on the electrocardiogram signal, such as distinguishing between pulseless VT and pulsed VT, or determining whether or not there is pulseless electrical activity (PEA), accurate judgments can be made. In other words, it is possible to accurately determine whether or not to apply an electric shock to the person being rescued P. Furthermore, by accurately determining whether or not to apply electric shock to the person being rescued P, it is possible to avoid inflicting harmful and useless electric shock on the person being rescued P when it is unnecessary.

[0070] Furthermore, similar to the first embodiment, the cardiac assessment is continuously performed based on a comprehensive judgment of the cardiac electrical and mechanical activity, allowing the operator of the automated external defibrillator 300 (i.e., the rescuer) to be more accurately and in real time informed of the rescued person P's condition and its physiological progression (changes over time). This provides the operator of the automated external defibrillator 1 with even more useful information for saving lives. In addition, the automated external defibrillator 300 in the second embodiment can grasp the mechanical activity of the rescued person P's heart by receiving heart sounds from within the heart, allowing the automated external defibrillator 300 to be effectively combined with other measures to rescue the rescued person P (e.g., chest compressions, chest blows, administration of vasoconstrictors, administration of antiarrhythmic drugs, etc.). By performing such an effective combination of measures, the resuscitation rate of the rescued person P can be improved, as can the rate of the rescued person P's return to society where they can perform daily activities.

[0071] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to these specific embodiments, and various forms that do not depart from the spirit of the invention are also included in the present invention. For example, in the first embodiment, the electrode pads 3 and 4 and the ultrasonic pad 9 are each separate components, and three pads, the pair of electrode pads 3 and 4 and the ultrasonic pad 9, are attached to the body of the person being rescued. With this configuration, the attachment positions of the electrode pads 3 and 4 and the ultrasonic pad 9 can be adjusted independently. In contrast, in the automated external defibrillator 310 shown in Figure 11, an ultrasonic sensor 7 may be mounted on one of the electrode pads 30 of the pair of electrode pads 30 and 4. The other components of the automated external defibrillator 310 are the same as those of the automated external defibrillator 1 (see Figure 1) according to the first embodiment, which has been described with reference to Figure 1. Thus, in the automated external defibrillator 310 shown in Figure 11, one of the electrode pads 30 also functions as an ultrasonic pad. This configuration means the automated external defibrillator 310 has only two pads, thus not increasing the number of pads compared to conventional automated external defibrillators. Furthermore, the fact that the number of pads does not increase makes it easier to attach the pads to the person being rescued in an emergency, and consequently shortens the time until an electric shock is delivered.

[0072] Furthermore, in the second embodiment, the electrode pads 3 and 4 and the microphone pad 100 are each separate components, and the three pads—the pair of electrode pads 3 and 4 and the microphone pad 100—are attached to the person being rescued. With this configuration, the attachment positions of the electrode pads 3 and 4 and the microphone pad 100 can be adjusted independently. On the other hand, in the automated external defibrillator 320 shown in Figure 12, a microphone 200 is mounted on one of the pair of electrode pads 31 and 4, specifically electrode pad 31. The other components of the automated external defibrillator 320 are the same as those of the automated external defibrillator 300 according to the second embodiment, which was described with reference to Figure 8. Thus, in the automated external defibrillator 320 shown in Figure 12, one of the electrode pads 31 also functions as a microphone pad. With this configuration, the number of pads in the automated external defibrillator 320 becomes two, thus avoiding an increase in the number of pads compared to conventional automated external defibrillators. Furthermore, because the number of pads does not increase, it becomes easier to attach the pads to the person being rescued in an emergency, and consequently, the time until an electric shock can be administered can be shortened.

[0073] Furthermore, in each of the embodiments described above, the order in which the electrode pads 3 and 4 and the ultrasonic pad 9 (or microphone pad 100) are attached is such that the electrode pads 3 and 4 are attached to the person being rescued P first, and then the ultrasonic pad 9 (or microphone pad 100) is attached. However, the order in which the electrode pads 3 and 4 and the ultrasonic pad 9 (or microphone pad 100) are attached may be reversed, or they may be attached simultaneously (for example, they can be attached simultaneously if there are multiple rescuers). Also, in each of the embodiments described above, although the control unit 120 determines whether the attachment position of the electrode pads 3 and 4 is appropriate in steps S2 and S3, it may be assumed that the electrode pads have already been properly attached. In other words, it is not necessary to determine whether the electrode pads 3 and 4 have been attached or not. Also, although the control unit 120 determines whether the attachment position of the ultrasonic pad 9 (or microphone pad 100) is appropriate in steps S4 and S5 (or steps S400 and S500), it may be assumed that the ultrasonic pad 9 (or microphone pad 100) has already been properly attached. In other words, it is not necessary to determine whether the ultrasonic pad 9 (or microphone pad 100) is attached in the correct position.

[0074] Furthermore, in the first embodiment, the control unit 12 may, instead of blood flow velocity, identify the rate of change in myocardial activity or the operating speed of valves within the heart from the ultrasonic echo signal received by the ultrasonic sensor 7, and detect the presence or absence of a pulse based on these. Also, since the first embodiment is performed to determine whether or not the heart is functioning, it is preferable that the blood flow to be detected is the blood flow within the heart, but the blood flow to be detected may also be the blood flow of major blood vessels other than the heart. In this case, the ultrasonic pad 9 is attached to a position corresponding to a major blood vessel other than the heart. Furthermore, in the second embodiment, although the control unit 120 detects heart sounds with the microphone 200, it is sufficient to obtain information on the mechanical activity of the heart, and therefore, as described above, blood flow sounds may be obtained instead of heart sounds.

[0075] Furthermore, in each of the embodiments described above, the waveform pattern of the electrical activity of the rescued person P's heart was detected from the electrocardiogram signal to estimate whether it was normal or a lethal arrhythmia. However, the parameters for estimating the state of the heart are not limited to the waveform pattern, and may include, for example, the amplitude (wave height).

[0076] Furthermore, in each of the embodiments described above, the operation guide and announcements regarding the cardiac status of the automated external defibrillator are not limited to voice output such as voice guidance or warning sounds, but may also be output on the display unit 21 in the form of images, text, etc.

[0077] In the embodiments described above, the Doppler analysis unit 121 (or heart sound analysis unit 122) is included in the same hardware as the control units 12 and 120, but they may be separate hardware units, and all functions may be performed by a single processor. Furthermore, the control unit 12, the ultrasonic transmitting / receiving unit 14, the electrocardiogram signal acquisition unit 17, and the state detection unit 18 may all be independent hardware units, or at least two of the control unit 12, ultrasonic transmitting / receiving unit 14, electrocardiogram signal acquisition unit 17, and state detection unit 18 may be implemented by the same hardware unit. Thus, the hardware configuration is not limited to the embodiments described above. [Explanation of symbols]

[0078] 1,300,310,320 Automated External Defibrillators 2,301 Main body 3,4,30,31 Electrode pads 5,6 Electrical Cables 7. Ultrasonic Sensor 7a Transmitting transducer (ultrasonic) 7b Receiving transducer (for ultrasound) 8 Ultrasonic Cable 9 Ultrasonic pads 12,120 Control Unit 13 Storage section 14. Ultrasonic Transceiver Unit 15 Audio output section 16 High-voltage generation unit 17. ECG signal acquisition unit 18 State detection unit 19 Power supply section 21 Display section 22 Control section 100 Microphone Pads 121 Doppler Analysis Department 122 Heart Sound Analysis Department 200 microphones 201 Microphone Cable

Claims

1. A pair of electrode pads that are attached to the chest of the person being rescued to deliver an electric shock, An ultrasonic sensor that outputs an ultrasonic signal and receives an ultrasonic signal reflected from at least one of the heart and major blood vessels of the person being rescued, An electrocardiogram signal acquisition unit that receives the electrocardiogram signal of the person being rescued, A control unit that determines the condition of the person being rescued based on the electrocardiogram signal and the ultrasonic signal received by the ultrasonic sensor, Equipped with, The control unit determines, based on the electrocardiogram signal and the ultrasound signal received by the ultrasound sensor, whether the cardiac condition of the person being rescued is normal, ventricular fibrillation, ventricular tachycardia, pulseless electrical activity, or asystole. Automated external defibrillator.

2. An automated external defibrillator according to Claim 1, The control unit determines from the electrocardiogram signal whether the state of the rescued person's heart is normal, ventricular fibrillation, ventricular tachycardia, pulseless electrical activity, or asystole, based on a predetermined waveform pattern. If the cardiac condition of the person being rescued is determined to be ventricular tachycardia, the blood flow velocity of the major vessels obtained from the ultrasound signal received by the ultrasound sensor is determined to be either pulseless ventricular tachycardia or ventricular tachycardia with a pulse, based on whether or not it is greater than a predetermined first threshold. If it is determined that the cardiac condition of the person being rescued is pulseless, the presence or absence of pulseless electrical activity is determined by whether or not the blood flow velocity of the major vessel obtained from the ultrasound signal received by the ultrasound sensor is greater than a predetermined second threshold. Automated external defibrillator.

3. An automated external defibrillator according to Claim 1, The control unit determines from the electrocardiogram signal whether the state of the rescued person's heart is normal, ventricular fibrillation, ventricular tachycardia, pulseless electrical activity, or asystole, based on a predetermined waveform pattern. If the cardiac condition of the person being rescued is determined to be ventricular tachycardia, then, based on the blood flow velocity of the major vessels obtained from the ultrasound signal received by the ultrasound sensor and the conditions related to the blood flow velocity that can be determined to be absent, it is determined whether it is pulseless ventricular tachycardia or ventricular tachycardia with a pulse. If it is determined that the cardiac condition of the person being rescued is pulseless, then it is determined whether or not it is pulseless electrical activity based on the blood flow velocity of the major vessel obtained from the ultrasound signal received by the ultrasound sensor and the conditions related to the blood flow velocity that can be determined to be pulseless. Automated external defibrillator.

4. An automated external defibrillator according to any one of claims 1 to 3, The control unit determines whether or not to administer the electric shock based on the electrocardiogram signal and the ultrasound signal. Automated external defibrillator.

5. An automated external defibrillator according to claim 4, The control unit, If a predetermined waveform pattern of the electrical activity of the rescued person's heart is detected from the electrocardiogram signal, the ultrasonic sensor determines whether or not to administer the electric shock based on whether the mechanical activity of the heart or the blood flow in the major vessels, obtained from the ultrasonic signal received by the ultrasonic sensor, meets predetermined conditions. Automated external defibrillator.

6. An automated external defibrillator according to any one of claims 1 to 5, The ultrasonic sensor is mounted on one of the electrode pads of the pair of electrodes. Automated external defibrillator.

7. An automated external defibrillator according to any one of claims 1 to 5, The ultrasonic pad further comprises the ultrasonic sensor mentioned above, The ultrasonic pad and the pair of electrode pads are separate components. Automated external defibrillator.

8. An automated external defibrillator according to any one of claims 1 to 5, The system further includes an output unit that outputs information regarding the state of the heart. Automated external defibrillator.

9. An automated external defibrillator according to claim 2 or 3, If pulseless ventricular tachycardia is detected, the control unit will output an audio message to the audio output unit instructing the delivery of an electric shock. Automated external defibrillator.

10. An automated external defibrillator according to claim 9, The control unit, after delivering an electric shock, re-executes the process of measuring the electrocardiogram signal and blood flow velocity. Automated external defibrillator.

11. An automated external defibrillator according to claim 2 or 3, If the control unit determines that cardiac arrest or pulseless electrical activity is present, it instructs cardiopulmonary resuscitation, re-executes the process of measuring the electrocardiogram signal and blood flow velocity, and if the blood flow velocity becomes faster than the previously measured blood flow velocity, it causes the audio output unit to notify the unit of this fact. Automated external defibrillator.

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