Automated external defibrillator

Abstract

To provide a compact automated external defibrillator capable of generating a high-voltage pulse suitable for defibrillation.SOLUTION: An automated external defibrillator (AED) includes a power supply part 19, a high-voltage generation part 16 for boosting a voltage applied from the power supply part 19 and generating a high-voltage pulse, and a pair of electrodes 30A and 30B for imparting electric shock based on the high-voltage pulse to a person to be rescued. The high-voltage generation part 16 includes a DC-AC conversion circuit 161 for converting a DC voltage applied from the power supply part 19 to an AC voltage, a transformer 163 for boosting the converted AC voltage, and a first driver 162. A control part 14 transmits a control signal and changes an output voltage of the DC-AC conversion circuit 161 according to a set waveform in a time-series manner.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to automated external defibrillators. [Background technology]

[0002] Automated External Defibrillators (AEDs) are widely used as defibrillators that deliver a high-voltage pulse of electric shock to the recipient's spasming heart to stimulate normal heartbeat. Conventional AEDs are relatively large devices and are often installed in stations, public facilities, commercial facilities, etc., making them difficult to carry around.

[0003] A technology for miniaturizing AEDs is known from Patent Document 1. The AED described in Patent Document 1 generates a high-voltage pulse by boosting the output voltage of the power supply unit with a transformer. The AED described in Patent Document 1 can be miniaturized because it does not need to be equipped with a high-voltage, large-capacity capacitor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-182010 A Summary of the Invention [Problem to be solved by the invention]

[0005] The AED described in Patent Document 1 supplies power to a transformer using a simple mechanism of turning on and off a single switch provided between a power supply unit and a transformer. Therefore, it is difficult for the AED described in Patent Document 1 to generate a high-voltage pulse with a complex waveform suitable for defibrillation, which can be generated by conventional AEDs.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide an automatic external defibrillator that is small and capable of generating a high-voltage pulse suitable for defibrillation. [Means for solving the problem]

[0007] In order to achieve the above object, the automated external defibrillator according to the present disclosure comprises: A DC / AC conversion circuit; a transformer that boosts the AC voltage converted by the DC-AC conversion circuit; a rectifier circuit that rectifies the voltage boosted by the transformer; an electrode for applying an electric shock to a rescuee based on an output voltage of the rectifier circuit; a duty ratio control means for controlling the DC / AC conversion circuit to control the electric energy supplied from the DC / AC conversion circuit to the transformer; Equipped with.

[0008] The device may further include a memory unit that stores data representing a change in duty ratio over time in accordance with a voltage waveform of the electric shock to be applied to the rescuee. In this case, the duty ratio control means controls the duty ratio of the switching operation of the DC-AC conversion circuit in accordance with the data stored in the memory unit.

[0009] The storage unit stores data representing a change in duty ratio over time corresponding to each of a plurality of voltage waveforms of an electric shock to be applied to a rescuee, for example. In this case, the device may further include a selection means for selecting one of the plurality of voltage waveforms. The duty ratio control means controls the duty ratio of the DC-AC conversion circuit according to the data corresponding to the voltage waveform selected by the selection means.

[0010] The device may include means for measuring the impedance between the electrodes attached to the recipient, means for storing a fundamental waveform of an applied voltage, and means for correcting the fundamental waveform based on the impedance measured by the measuring means, and for generating data indicating a change in duty ratio with respect to time based on the corrected waveform.

[0011] The device may further comprise a means for updating data indicating a change in duty ratio with respect to time stored in the storage unit.

[0012] The device may further include a polarity reversal circuit that applies the output voltage of the rectifier circuit to the electrodes in a forward or inverted manner in accordance with a polarity control signal, and a polarity control means that transmits the polarity control signal to the polarity reversal circuit to apply a voltage of a polarity corresponding to the set waveform to the electrodes.

[0013] The device may further include a memory unit for storing data indicating the polarity of the applied voltage corresponding to the voltage waveform of the electric shock to be applied to the rescuee. In this case, the polarity control means controls the polarity reversing circuit in accordance with the data stored in the memory means.

[0014] The power supply may further include a smoothing circuit that smoothes the voltage output from the rectifier circuit.

[0015] The duty ratio control means may generate a plurality of voltage pulses by driving the DC / AC conversion circuit a plurality of times at a predetermined time interval.

[0016] The electrodes may have a needle-like or pad-like outer shape and may be attached to the person being rescued. Effect of the Invention

[0017] According to the present invention, it is possible to realize miniaturization and easily generate high voltage pulses with complex waveforms. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing an example of the appearance of an AED according to an embodiment of the present disclosure. [Diagram 2] 1A to 1C are diagrams showing examples of electrode attachment positions of an AED according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a circuit block diagram of an AED according to an embodiment of the present disclosure. [Figure 4]1A to 1C are diagrams showing examples of waveforms of high-voltage pulses that can be applied by an AED according to an embodiment of the present disclosure. [Diagram 5] 4 is a diagram illustrating an example of a circuit configuration of a high voltage generating unit illustrated in FIG. 3. [Figure 6] 6(A) to 6(D) are timing charts illustrating the operation of the full-bridge inverter circuit shown in FIG. [Figure 7] 6 is a diagram illustrating an example of a circuit configuration of a first driver illustrated in FIG. 5. [Figure 8] 4 is a diagram illustrating an example of a functional configuration of a storage unit illustrated in FIG. 3. [Figure 9] 6(A) to 6(F) are timing charts illustrating the operation of the high voltage generating unit shown in FIG. [Figure 10] 1 is a flowchart of a high-voltage pulse application process executed by an AED according to an embodiment. [Figure 11] 11 is a flowchart showing details of the waveform table generation process shown in FIG. 10. [Figure 12] FIG. 13 is a diagram showing an example of a waveform of a high-voltage pulse in a dual shock mode of an AED according to an embodiment of the present disclosure. [Figure 13] 11 is a flowchart for explaining an example of operation of an AED in a dual shock mode according to an embodiment of the present disclosure. [Figure 14] FIG. 13 is a diagram showing an example of the appearance of an AED according to a modified example. [Figure 15] 13 is a diagram showing an example of an electrode structure of an AED according to a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an automated external defibrillator according to an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are given the same reference numerals. In the following description, the automated external defibrillator is also referred to as an AED (Automated External Defibrillator).

[0020] 1 is a diagram showing an example of the appearance of an AED 1 according to an embodiment of the present disclosure. The AED 1 includes a main body 10, a pair of electrodes 30A and 30B, and cables 40A and 40B that electrically connect the main body 10 to the electrodes 30A and 30B, respectively.

[0021] When using the AED1, the electrodes 30A and 30B are inserted near the right chest and flank of the rescuee, respectively, as shown in Fig. 2. The positions of the electrodes 30A and 30B are not particularly limited to the example shown in Fig. 2, and may be any positions that are paired with the heart, that is, positions that allow an electric shock to be given to the heart. Specifically, the electrodes 30A and 30B are attached at any positions that allow a current generated by a high voltage pulse to pass from one of the electrodes 30A and 30B through the heart and reach the other. For example, individual differences can be reduced by inserting the electrodes 30A and 30B into the left and right shoulders.

[0022] Returning to Fig. 1, the main body 10 of the AED 1 has a shape and size that is easy to carry, for example, similar to a mobile terminal, tablet, etc. A display unit 11 and an operation unit 12 are provided on the surface of the main body 10. The display unit 11 includes, for example, a liquid crystal display and its drive circuit. The display unit 11 displays information indicating the operation state of the AED 1, the waveform of the high voltage pulse to be applied, the operation mode, etc.

[0023] The operation unit 12 includes an operation knob 12a and a button group 12b. The button group 12b includes various operation buttons such as a power button, a voltage application button for instructing the rescuee to apply a high-voltage pulse, a waveform selection button for selecting the waveform of the high-voltage pulse to be applied, and a mode selection button for selecting an operation mode.

[0024] As shown in FIG. 3, inside the main body 10 of the AED 1, in addition to the display unit 11 and operation unit 12 described above, there are provided a memory unit 13, a control unit 14, a communication unit 15, a high-voltage generation unit 16, an electrocardiogram signal acquisition unit 17, a status detection unit 18, a power supply unit 19, and an audio output unit 20.

[0025] The power supply unit 19 includes a DC power supply with an output voltage V1 of about 100 to 110 V. This DC power supply is configured, for example, by connecting a plurality of semi-solid lithium batteries in series. The power supply unit 19 supplies DC power to the high voltage generation unit 16. Although not shown in FIG. 3, the power supply unit 19 is also connected to each unit other than the high voltage generation unit 16 and supplies operating power to each of these units.

[0026] The high voltage generating unit 16 boosts the output voltage of the power supply unit 19 and adjusts the boosted voltage in accordance with the control of the control unit 14 to generate a high voltage pulse (more specifically, a potential difference between the electrodes 30A and 30B) to be applied to the rescuee between the electrodes 30A and 30B. This high voltage pulse has a waveform suitable for defibrillation. In this embodiment, the operator operates the operation unit 12 to set the waveform of the high voltage pulse to be generated from among a monophasic waveform shown in FIG. 4(A), a biphasic waveform, a BTE waveform shown in FIG. 4(B), and an RLB waveform shown in FIG. 4(C). In the following description, the waveform of the high voltage pulse currently set as the application target is also referred to as a "set waveform."

[0027] An example of the circuit configuration of the high voltage generating unit 16 is shown in Fig. 5. Note that Fig. 5 shows only the main circuit configuration, and the ground connection part and the like are omitted as appropriate. The high voltage generating unit 16 includes a full bridge inverter circuit 161, a first driver 162, a transformer 163, a rectifying and smoothing circuit 164, a polarity reversing circuit 165, and a second driver 166.

[0028] The full-bridge inverter circuit 161 includes four switching elements Q1 to Q4 that form the four sides of a bridge circuit. The switching elements Q1 to Q4 are each composed of a MOSFET, an IGBT, or the like. In the following description, it is assumed that the switching elements Q1 to Q4 are composed of an N-channel MOSFET. One end (drain) of the current path of the switching elements Q1 and Q3 is connected to the positive terminal of the power supply unit 19. One end (source) of the current path of the switching elements Q2 and Q4 is connected to the negative terminal of the power supply unit 19. A connection node N1 between the other end (source) of the current path of the switching element Q1 and the other end (drain) of the current path of the switching element Q2 is connected to one end of the primary winding 163a of the transformer 163. A connection node N2 between the other end (source) of the current path of the switching element Q2 and the other end (drain) of the current path of the switching element Q4 is connected to the other end of the primary winding 163a of the transformer 163.

[0029] A switching control signal S1 is applied from the first driver 162 to the gates of the switching elements Q1 and Q4, and a switching control signal S2 is applied from the first driver 162 to the gates of the switching elements Q2 and Q3.

[0030] The switching elements Q1 and Q4 are turned on when the switching control signal S1 is at a high level. At this time, a current flows from the positive terminal of the power supply unit 19 to the switching element Q1 to the connection node N1 to the primary winding 163a of the transformer 163 to the connection node N2 to the switching element Q4 to the negative terminal of the power supply unit 19. On the other hand, the switching elements Q2 and Q3 are turned on when the switching control signal S2 is at a high level. At this time, a current flows from the positive terminal of the power supply unit 19 to the switching element Q3 to the connection node N2 to the primary winding 163a of the transformer 163 to the connection node N1 to the switching element Q2 to the negative terminal of the power supply unit 19.

[0031] As shown in Figures 6(A) and (B), by repeating the process of alternately setting the switching control signals S1 and S2 to a high level, the pair of switching elements Q1 and Q4 and the pair of switching elements Q2 and Q3 are alternately and repeatedly turned on. As a result, as shown in Figure 6(C), an AC voltage is applied to the primary winding 163a of the transformer 163. The voltage applied to the primary winding 163a is approximately -V1 to +V1. As a result, an AC primary current I in The primary current I in The effective value of is determined by the ratio of the on-period PW1 or PW2 to the on-off cycle λ of the switching elements Q1 to Q4, i.e., the duty ratios (PW1 / λ) and (PW2 / λ). ​​Therefore, by adjusting the duty ratios (PW1 / λ) and (PW2 / λ), i.e., by PWM-controlling the switching operations of the switching elements Q1 to Q4, it is possible to adjust the amount of electrical energy supplied to the transformer 163. Note that the on-period PW1 of the pair of switching elements Q1 and Q4 and the on-period PW2 of the pair of switching elements Q2 and Q3 may be the same or different from each other.

[0032] A large pulsed momentary current flows through the switching elements Q1 to Q4, and therefore it is desirable to use a large Si-MOSFET that can tolerate a pulsed momentary current of, for example, about 300 A and is capable of high-speed switching.

[0033] The transformer 163 shown in Fig. 5 includes a primary winding 163a and a secondary winding 163b. The primary winding 163a and the secondary winding 163b are wound around a core (iron core) made of ferrite or the like. One end of the primary winding 163a is connected to a connection node N1 of the full-bridge inverter circuit 161, and the other end of the primary winding 163a is connected to a connection node N2. One end of the secondary winding 163b is connected to an output terminal T1 of the transformer 163, and the other end of the secondary winding 163b is connected to an output terminal T2 of the transformer 163.

[0034] It is desirable that the number of turns of the primary winding 163a is relatively small, for example, about 10 turns, and the number of turns of the secondary winding 163b is, for example, about 100 to 200 turns. In this case, the turn ratio NR of the primary winding 163a and the secondary winding 163b is 1:10 to 1:20. In this example, the number of turns of the primary winding 163a is 10, the number of turns of the secondary winding 163b is 138, and the turn ratio is NR13.8. It is also desirable to use a low-loss Litz wire for the secondary winding 163b, and to make the winding thick. Thereby, for example, the resistance of the primary winding 163a can be about 0.025Ω, and the resistance of the secondary winding 163b can be about 1.93Ω, and the impedance of the transformer 163 can be suppressed to 1 / 10 or less of the bioimpedance (50 to 1000Ω), which is sufficiently small, 3Ω or less.

[0035] The rectifying smoothing circuit 164 includes a full-wave rectifying circuit 164a constituted by diodes D1 to D4, which are rectifying elements, and a smoothing capacitor C1 that constitutes a smoothing circuit.

[0036] The input terminal of the full-wave rectifier circuit 164a is connected to the output terminals T1 and T2 of the transformer 163, and the voltage between the output terminals T1 and T2 is full-wave rectified, and the pulsating voltage is applied between the positive terminal T3 and the negative terminal T4 of the smoothing capacitor C1. The diodes D1 to D4 are preferably SiC Schottky type diodes that allow large current and high-frequency switching operation. In order to ensure the withstand voltage, a plurality of diode elements may be connected in series and used as the diodes D1 to D4.

[0037] The smoothing capacitor C1 smoothes the pulsating voltage after full wave rectification applied between the positive terminal T3 and the negative terminal T4. It is preferable that the smoothing capacitor C1 has a high withstand voltage and a relatively small capacity. For example, it is preferable that the withstand voltage is 1,600V and the capacity is about 12μF. The smoothing capacitor C1 can suppress the pulsation of the output voltage. However, it is also possible to perform only the rectification by the full wave rectifier circuit 164a without providing the smoothing capacitor C1.

[0038] For example, if the output voltage of the power supply unit 19 is 110 V and the turns ratio NR of the transformer 163 is 13.8, the voltage V2 between the positive terminal T3 and the negative terminal T4 changes with the duty ratio, but is approximately 1500 V at maximum, which is sufficient for use as a high-voltage pulse for the AED 1. It is possible to obtain a higher voltage by adjusting the power supply voltage V1 and the turns ratio NR.

[0039] The polarity reversing circuit 165 is a circuit that switches between applying the voltage V2 output by the rectifying and smoothing circuit 164 in a forward direction or a reverse direction between the electrodes 30A and 30B. The polarity reversing circuit 165 has a configuration similar to that of the full-bridge inverter circuit 161, and includes four switching elements Q5 to Q8 that form the four sides of the full-bridge circuit. The switching elements Q5 to Q8 are each composed of an N-channel MOSFET, an IGBT, or the like, made of SiC for large currents. In the following description, they are referred to as MOSFETs.

[0040] One end of the current path of the switching elements Q5 and Q7 is connected to the positive terminal T3 of the rectifying and smoothing circuit 164. One end of the current path of the switching elements Q6 and Q8 is connected to the negative terminal T4 of the rectifying and smoothing circuit 164. A connection node N3 between the other end of the current path of the switching element Q5 and the other end of the current path of the switching element Q6 is connected to the electrode 30A via a cable 40A. A connection node N4 between the other end of the current path of the switching element Q7 and the other end of the current path of the switching element Q8 is connected to the electrode 30B via a cable 40B. As a result, a voltage V2 or a voltage -V2 of the opposite polarity is applied between the electrodes 30A and 30B, resulting in a high-voltage pulse Vout that applies an electric shock.

[0041] The first driver 162 is a drive circuit that controls the on and off of the switching elements Q1 to Q4 of the full-bridge inverter circuit 161. The first driver 162 controls the period λ and pulse widths PW1, PW2 of the switching control signals S1 and S2 illustrated in Fig. 6(A) and (B) in accordance with a PWM control signal supplied from the control unit 14. In other words, it controls the duty ratio of the switching operation of the full-bridge inverter circuit 161.

[0042] An example of the configuration of the first driver 162 is shown in FIG. In the illustrated example, the first driver 162 includes an oscillator circuit 1621 and a frequency divider circuit 1622 including a plurality of counters. The oscillator circuit 1621 includes, for example, an oscillator, and outputs a clock signal of about 1 MHz. The frequency divider circuit 1622 counts the number of clocks of the clock signal output from the oscillator circuit 1621 according to the PWM control signal, and measures the period λ shown in FIG. 6. The frequency divider circuit 1622 measures the initial timings at which the switching control signals S1 and S2 are set to high level within each period λ, and further measures the pulse widths PW1 and PW2 to output the switching control signals S1 and S2. As a result, the period λ and pulse widths PW1 and PW2 of the switching control signals S1 and S2 are controlled in units of one clock (1 μS). The period λ and pulse widths PW1 and PW2 are updated and set in the frequency divider circuit 1622 as needed by the PWM control signal. As a result, the full-bridge inverter circuit 161 is PWM-controlled, and the amount of electric energy supplied from the full-bridge inverter circuit 161 to the transformer 163 is controlled.

[0043] The second driver 166 is a drive circuit that controls the on and off of the switching elements Q5 to Q8 of the polarity reversal circuit 165. More specifically, the second driver 166 responds to a polarity control signal from the control unit 14, and when applying a positive voltage to the electrode 30A and a negative voltage to the electrode 30B as in the applied voltages in Fig. 4(A) and the first half of the applied voltages in Fig. 4(B) and (C), for example, the second driver 166 sets the switching control signal S3 to a high level so as to turn on the switching elements Q5 and Q8. On the other hand, when applying a negative voltage to the electrode 30A and a positive voltage to the electrode 30B as in the second half of the applied voltages in Fig. 4(B) and (C), the second driver 166 sets the switching control signal S4 to a high level so as to turn on the switching elements Q6 and Q7.

[0044] 3 includes a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). The non-volatile memory stores a control program and fixed data executed by the control unit 14. The volatile memory is used by the control unit 14 as a work area when executing the control program. In addition, the volatile memory temporarily stores an electrocardiogram signal and the like.

[0045] In addition, a waveform memory area 131 is secured in the storage unit 13 as shown in FIG. In the waveform memory area 131, a basic waveform table 132, a PWM control table 133, and a polarity control table 134 are stored.

[0046] The basic waveform table 132 is arranged in a non-volatile storage area of ​​the storage unit 13, and stores waveform data of basic waveforms of high voltage pulses selectable by the AED 1, for example, the voltage waveforms shown in Figs. 4(A) to (C). The waveform data of each basic waveform is designed so that when the impedance (biological impedance) between the electrodes 30A and 30B is a reference value Rr, the total energy applied to the rescuee is a reference value Er. The basic waveform table 132 is stored in a non-volatile storage area. The bioimpedance Rb varies depending on the shape of the electrodes, the attachment position of the electrodes, etc., and is about 1000Ω when the electrodes 30A and 30B are needle-shaped as shown in Fig. 1, and about 20Ω to 200Ω when the electrodes are of the conventional pad type (see Fig. 14). For this reason, in this embodiment, the reference waveform is set with the reference value Rr of the bioimpedance set to, for example, 1000Ω.

[0047] The PWM control table 133 and the polarity control table 134 are tables that are generated by customizing the basic waveforms stored in the basic waveform table 132 for the rescuee. The PWM control table 133 and the polarity control table 134 may be collectively referred to as a waveform table 135, which means a table that defines the waveform of the high-voltage pulse to be applied.

[0048] More specifically, the PWM control table 133 stores the elapsed time ti (i=0, 1, 2...) in association with the period λ and pulse widths PW1 and PW2 at that time in order to control the switching control signals S1 and S2 supplied to the full-bridge inverter circuit 161 for the high-voltage pulse applied to the rescuee. In other words, data indicating the duty ratio in the switching operation of the full-bridge inverter circuit 161 at the elapsed time ti is stored.

[0049] The polarity control table 134 stores the elapsed time ti and the polarity of the voltage to be applied at that time in association with each other in order to control the switching control signals S3 and S4 supplied to the polarity reversing circuit 165 for the high voltage pulse to be applied to the rescuee.

[0050] The waveform table 135 will now be described in more detail. The bioimpedance Rb between the electrodes 30A and 30B varies depending on the shape of the electrodes, the attachment position of the electrodes, etc. Therefore, when the bioimpedance Rb of the recipient is high, applying a voltage Vi determined by the fundamental waveform may result in a shortage of applied energy, while applying a voltage Vi determined by the fundamental waveform may result in an excessive amount of applied energy when the bioimpedance Rb of the recipient is low. Therefore, the bioimpedance Rb between the electrodes 30A and 30B is measured by the state detection unit 18, and the waveform of the fundamental waveform is adjusted according to the magnitude of the bioimpedance Rb of the recipient to generate an applied waveform, so that the total energy E applied to the recipient is made to match the reference value Er.

[0051] The energy E applied to a living body is expressed as the product I·V of the applied voltage V and the current I. Also, I=V / R. Therefore, the applied energy E=V 2 / R. Therefore, if the impedance R is k times larger, the voltage can be multiplied by √k to apply approximately the same energy E. Alternatively, if the application time (duration) of the high voltage pulse is multiplied by k, the same energy E can be applied.

[0052] In this embodiment, when the measured bioimpedance is Rb and the reference value of the bioimpedance is Rr, the voltage Vi of the fundamental waveform at timing ti is corrected to √(Rb / Rr)·Vi to form an application waveform and apply it to the person being rescued.

[0053] The PWM control table 133 stores the period λ and the pulse widths PW1 and PW2 required to generate a voltage √(Rb / Rr)·Vi at the timing of the elapsed time ti. In other words, it stores a PWM control signal that indicates the duty ratio of the switching operation of the full-bridge inverter circuit 161 at the timing ti.

[0054] Meanwhile, the polarity control table 134 stores data indicating the polarity of the voltage to be applied at the timing of the elapsed time ti. Note that data indicating positive polarity instructs the switching control signal S3 to be set to a high level, and data indicating negative polarity instructs the switching control signal S4 to be set to a high level.

[0055] The data stored in the PWM control table 133 and the polarity control table 134 will be explained based on a specific example. Here, it is assumed that the pulse voltage waveform to be applied is the BTE voltage exemplified in Fig. 4(B) For ease of understanding, it is assumed that the period λ of the switching control signals S1 and S2 is constant.

[0056] An example of a fundamental voltage waveform Vr of the BTE voltage waveform is shown by a thin dashed line in FIG. Here, let us assume that the bioimpedance Rb / reference value Rr of bioimpedance detected by the state detection unit 18 is 1.3. In this case, in order to apply the reference value Er of energy to the rescuee, a voltage waveform Va in which the voltage of the basic voltage waveform Vr is corrected to 1.14 ≒ √1.3 = √(Rb / Rr) times is applied to the rescuee. The voltage waveform Va in which the voltage is corrected to 1.14 times is shown by a thick solid line in Fig. 9(A) (the figure has been deformed for ease of viewing). When obtaining the voltage waveform Va, the output voltage V2=|Va| of the rectifying smoothing circuit 164 becomes a positive voltage waveform as shown in FIG. 9(B).

[0057] In order to obtain the voltage waveform |Va| shown in FIG. 9B, as shown in FIG. 9C and FIG. 9D, the duty ratio of the switching operation of the full-bridge inverter circuit 161 is set so that V2=1.14Vr is obtained at the timing T1, and the duty ratio is gradually decreased from the timing T1 to T2 and from T4 to T5 as the voltage of the basic voltage waveform Vr decreases. In other words, the period λ of the switching control signals S1 and S2 is fixed, and the pulse widths PW1 and PW2 of the switching operation of the full-bridge inverter circuit 161 are appropriately set at the timing T1, and the pulse widths PW1 and PW2 are gradually decreased thereafter. Note that FIG. 9C and FIG. 9D are schematic diagrams for illustrating the time change of the duty ratio, and are different from the actual waveform. For example, in reality, the switching control signals S1 and S2 are out of phase with each other by π, as shown in FIG. 6A and FIG. 6B.

[0058] The PWM control table 133 stores data in table format indicating the period λ and pulse widths PW1, PW2, i.e., the duty ratio, at each elapsed time ti from the start timing T0 thus obtained. The data format can be any format, such as a set of the elapsed time ti, period λ, and pulse widths PW1, PW2, a set of the elapsed time ti and pulse widths PW1, PW2 assuming that the period λ is fixed, or the elapsed time ti and the duty ratio of the switching control signals S1 and S2.

[0059] 9(A), it is necessary to turn on the switching elements Q5 and Q8 of the polarity reversing circuit 165 so as to output a positive voltage between timings T0 and T3, and turn on the switching elements Q6 and Q7 so as to output a negative voltage between timings T3 and T6. For this reason, as shown in FIG. 9(E) and (F), the switching control signal S3 is set to a high level between timings T0 and T3, and the switching control signal S4 is set to a high level between timings T3 and T6. The polarity control table 134 stores data thus obtained indicating the polarity of the applied voltage at each elapsed time ti from the start timing T0.

[0060] 3 includes a processor such as a CPU (Central Processing Unit), i.e., a computer. The control unit 14 may include a single computer or may include multiple computers. In addition, a part of the control unit 14 may include hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0061] The control unit 14 operates in accordance with a control program stored in the memory unit 13, thereby controlling each of the display unit 11, operation unit 12, memory unit 13, communication unit 15, high voltage generation unit 16, ECG signal acquisition unit 17, status detection unit 18, and audio output unit 20, thereby performing ECG analysis, electric shock output control, etc.

[0062] The control section 14 includes a waveform control section 141 as a functional configuration. The waveform control unit 141 includes a DSP (Digital Signal Processor). When a waveform to be applied (a set waveform) is selected and a bioimpedance Rb is measured, the DSP obtains data for controlling the duty ratio of the switching operation of the full-bridge inverter circuit 161 and data for controlling the polarity reversal circuit 165, and stores the data in the PWM control table 133 and the polarity control table 134.

[0063] Moreover, the waveform control section 141 generates a PWM control signal by referring to the stored data of the PWM control table 133, and supplies the generated PWM control signal to the first driver 162. The first driver 162 alternately turns on and off the pair of switching elements Q1 and Q4 and the pair of switching elements Q2 and Q3 at the indicated duty ratio by the switching control signals S1 and S2 illustrated in Figs. 6(A), (B), 9(C), and (D) in accordance with the PWM control signal. As a result, as illustrated in Fig. 6(C), an AC voltage having an effective value corresponding to the duty ratio is applied to the primary winding 163a of the transformer 163, and as illustrated in Fig. 6(D), an AC primary current Iin having an effective value corresponding to the duty ratio flows. As a result, a high voltage AC voltage corresponding to the turns ratio NR is generated in the secondary winding 163b. This high voltage AC voltage is full-wave rectified by the full-wave rectifier circuit 164a and converted into a DC voltage, which is then smoothed by the smoothing capacitor C1 and output as shown in FIG. 9(B).

[0064] Moreover, the waveform control section 141 refers to the stored data in the polarity control table 134 and supplies the generated polarity control signal to the second driver 166. In response to the polarity control signal, the second driver 166 sets the switching control signal S3 to a high level during a period when a positive voltage should be applied to the rescuee, and sets the switching control signal S4 to a high level during a period when a negative voltage should be applied to the rescuee, as illustrated in Figs. 9(E) and (F). As a result, during a period when a positive voltage should be applied to the rescuee, the switching elements Q5 and Q8 are turned on to apply a positive voltage to the rescuee, and during a period when a negative voltage should be applied to the rescuee, the switching elements Q6 and Q7 are turned on to apply a negative voltage to the rescuee. As a result, an electric shock with a bipolar voltage waveform is applied to the rescuee.

[0065] 3 is a communication interface that performs wireless or wired communication with an external device (not shown) such as a server device under the control of the control unit 14. The audio output unit 20 includes a sound output device such as a speaker. The audio output unit 20 outputs a voice, a warning sound, etc. that guides the operation of the AED 1 under the control of the control unit 14.

[0066] The electrodes 30A and 30B are needle-shaped electrodes attached to a recipient in a state of cardiac arrest. The electrode 30A is connected to the high voltage generating unit 16, the electrocardiogram signal acquiring unit 17, and the state detecting unit 18 via a cable 40A. The electrode 30B is connected to the high voltage generating unit 16, the electrocardiogram signal acquiring unit 17, and the state detecting unit 18 via a cable 40B. By using the needle-shaped electrodes 30A and 30B, it is possible to ensure a connection between the recipient and the electrodes 30A and 30B, unlike normal pad-type electrodes, even if the body surface of the recipient is wet.

[0067] The electrocardiogram signal acquiring unit 17 performs filtering of noise contained in the electrocardiogram signal from the electrodes 30A and 30B, and amplifies the electrocardiogram signal from which the noise has been filtered. The electrocardiogram signal amplified by the electrocardiogram signal acquiring unit 17 is sent to the control unit 14 and used for electrocardiogram analysis, etc. The control unit 14 also appropriately displays the electrocardiogram signal on the display unit 11.

[0068] The condition detection unit 18 measures, for example, the impedance between the electrodes 30A and 30B, that is, the impedance (biological impedance) of the current passing portion of the rescue recipient. The condition detection unit 18 outputs the measured impedance to the control unit 14.

[0069] Next, the operation and usage of the AED1 having the above configuration will be described. The AED1 is small and lightweight, making it easy for rescuers to carry and does not require space when installed.

[0070] When using the AED 1, the rescuer operates the operation unit 12 to turn on the power and insert the electrodes 30A and 30B into positions that sandwich the heart of the rescuee, for example, the positions shown in FIG. 2. In this state, the rescuer presses the status detection button in the button group 12b of the operation unit 12 to determine whether the electrodes 30A and 30B are correctly attached. In response to this operation, the control unit 14 causes the high voltage generation unit 16 to generate a preset voltage and applies it between the electrodes 30A and 30B. The status detection unit 18 measures the voltage between the electrodes 30A and 30B and the current flowing through the electrode 30A or 30B, measures the bioimpedance Rb, and notifies the control unit 14.

[0071] The control unit 14 determines whether the electrodes 30A, 30B are attached correctly (whether the bioimpedance is within a predetermined range) based on the measured bioimpedance. The control unit 14 notifies the determination result via the display unit 11 and the audio output unit 20. The rescuer reattaches the electrodes 30A, 30B as necessary in accordance with the notification.

[0072] The rescuer checks the electrocardiogram of the rescuee as necessary. In this case, with electrodes 30A and 30B attached to the rescuee, the rescuer presses the electrocardiogram detection button in button group 12b. In response to this operation, control unit 14 starts up electrocardiogram signal acquisition unit 17. Electrocardiogram signal acquisition unit 17 measures the voltage between electrodes 30A and 30B and supplies it to control unit 14. Control unit 14 displays the waveform of the detected biovoltage on display unit 11. The rescuer checks the electrocardiogram of the rescuee according to the display.

[0073] Next, the process of applying a high voltage pulse to a rescuee will be described with reference to the flow chart of FIG. When applying a high-voltage pulse to a rescuee, the rescuer operates the operation unit 12 to display a list of pre-registered high-voltage pulse waveforms (step S11). The rescuer selects one of the displayed waveforms (step S12: Yes). The selected waveform is the set waveform. Note that steps S11 and S12 may be skipped by selecting a high-voltage pulse waveform to be applied in advance and storing it in the memory unit 13. Next, the control unit 14 waits for the application button of the button group 12b to be pressed (step S13).

[0074] When the apply button is pressed (step S13: Yes), the waveform control section 141 of the control section 14 executes a waveform table generation process for generating the waveform table 135 (the PWM control table 133 and the polarity control table 134) (step S14).

[0075] The waveform table generation process will be described in detail with reference to the flowchart of FIG. First, the control unit 14 controls the high voltage generating unit 16 and the state detecting unit 18 to measure the bioimpedance (step S21). Specifically, the control unit 14 causes the high voltage generating unit 16 to generate a predetermined voltage and measures the current flowing through the electrode 30A or 30B, thereby measuring the bioimpedance Rb (step S21).

[0076] Next, the control unit 14 obtains a ratio Rb / Rr of the measured bioimpedance value Rb to the reference value Rr of the bioimpedance expected by the basic waveform stored in the basic waveform table 132 (step S22). Next, the waveform control unit 141 of the control unit 14 multiplies the square root of the bioimpedance ratio √(Rb / Rr) by the peak value of the set waveform selected in step S14 to obtain a corrected voltage waveform Va so that the energy of the high-voltage pulse to be applied to the recipient becomes the reference value E (step S23).

[0077] Next, the waveform control section 141 sets t=0 (step S24). Next, the waveform control section 141 determines the period λ and pulse widths PW1, PW2 of the switching control signals S1 and S2 based on the peak value of the correction voltage waveform Va at the timing t (step S25).

[0078] Next, the waveform control section 141 obtains polarity data based on the polarity of the fundamental voltage waveform Vr at the timing t (step S26). Next, the waveform control section 141 determines whether or not t reaches the timing of ending the voltage application (step S27).

[0079] If t has not reached the end timing (step S27: No), t is updated to t=t+1 (step S28), and the process returns to step S25 to perform the same process for the next timing t.

[0080] If t has reached the end timing (step S27: Yes), the PWM control signals at the series of timings t obtained by multiple processing of step S25 are stored in the PWM control table 133, and the polarity control signals at the series of timings t obtained by multiple processing of step S26 are stored in the polarity control table 134 (step S29).

[0081] In this manner, the PWM control table 133 and the polarity control table 134 are formed by high speed calculation processing by the DSP of the waveform control section 141 . Next, the process proceeds to step S15 in FIG. 10, where the control unit 14 starts an internal timer.

[0082] Next, the control unit 14 supplies a PWM control signal to the first driver 162 based on data for the measurement time t of the internal timer among the PWM control signals stored in the PWM control table 133 (step S16). The PWM control signal indicates the period λ and pulse widths PW1 and PW2 or the duty ratio of the switching elements Q1 to Q4.

[0083] Furthermore, the control unit 14 supplies a polarity control signal to the second driver 166 based on the data for the measurement time t among the polarity control signals stored in the polarity control table 134 (step S17).

[0084] Next, the control unit 14 determines whether or not the application of the high voltage pulse has ended based on the time t measured by the internal timer (step S18).

[0085] If not completed (step S18: No), the process returns to step S16, and the application of the high voltage pulse continues. On the other hand, if the high-voltage pulse application process has ended (step S18: Yes), the process of measuring and displaying an electrocardiogram may be started automatically.

[0086] In response to the PWM control signal output in step S16, the first driver 162 alternately turns on and off the pair of switching elements Q1 and Q4 and the pair of switching elements Q2 and Q3 at the indicated duty ratio. As a result, an AC primary current Iin having a magnitude corresponding to the duty ratio flows through the primary winding 163a of the transformer 163, and a high-voltage AC voltage corresponding to the turn ratio is generated in the secondary winding 163b. This high-voltage AC voltage is full-wave rectified by the full-wave rectifier circuit 164a and converted into a high-voltage DC voltage, which is further smoothed by the smoothing capacitor C1 and output as a voltage V2. The voltage V2 has a waveform equal to the absolute value waveform of the correction voltage waveform Va, as shown in FIG. 9(B).

[0087] In response to the polarity control signal output in step S17, the second driver 166 sets the switching control signal S3 to a high level during a period when a positive high-voltage pulse should be applied, turns on the pair of switching elements Q5 and Q8, applies a forward voltage V2 between the electrodes 30A and 30B, and applies a positive high-voltage pulse Vout to the rescuee. Also, the second driver 166 sets the switching control signal S4 to a high level during a period when a negative high-voltage pulse should be applied, turns on the pair of switching elements Q6 and Q7, applies a forward voltage V2 between the electrodes 30A and 30B, and applies a negative high-voltage pulse Vout to the rescuee.

[0088] In this way, a high-voltage pulse having a corrected voltage waveform Va as shown in Fig. 9(A) is applied to the rescuee. The high-voltage pulse of the corrected voltage waveform Va applies a substantially constant energy E regardless of variations in bioimpedance caused by individual differences in the rescuee, variations in the attachment state of the electrodes 30A and 30B, and the like.

[0089] As described above, according to the AED1 of the embodiment of the present invention, since a high voltage is generated using DC / AC conversion by an inverter circuit and a transformer, it is not necessary to use a high-voltage capacitor for holding the high voltage, and it is possible to reduce the size. In addition, the voltage of the high-voltage pulse is adjusted in a time series by the full-bridge inverter circuit 161 controlled in units of one pulse by a PWM signal. Therefore, it is possible to easily generate a high-voltage pulse with a complex waveform suitable for defibrillation. Furthermore, the polarity of the voltage V2 output by the rectifying and smoothing circuit 164 is inverted by the polarity inversion circuit 165 controlled by a polarity inversion signal at an appropriate timing according to the set waveform. This makes it possible to easily generate a high-voltage pulse with a biphasic waveform such as a BTE waveform or an RLB waveform.

[0090] In addition, the AED1 according to this embodiment is equipped with a smoothing circuit that smoothes the voltage boosted by the transformer 163, making it possible to suppress pulsating current and generate a high-voltage pulse with a more ideal waveform.

[0091] In the above embodiment, an example in which a high-voltage pulse is applied to the recipient once has been shown, but it may be applied multiple times. Hereinafter, a mode in which a high-voltage pulse is applied multiple times with a certain time interval therebetween is called a dual shock mode. FIG. 12 shows an example of a high-voltage pulse generated by the high-voltage generating unit 16 in the dual shock mode. In this example, two high-voltage pulses with an RLB waveform are generated consecutively with a time interval of 2 s. Note that in the dual shock mode, the first and second high-voltage pulses may have different waveforms. Also, more than two high-voltage pulses may be generated consecutively and applied to the recipient.

[0092] In the dual shock mode, the AED 1 applies two consecutive high voltage pulses to the rescuee at a preset time interval. For example, the operator can switch the operation mode of the AED 1 to the dual shock mode by operating the operation unit 12. In addition, the operator can set the time interval between the two consecutive high voltage pulses to be applied within a range of 0.25 s to 3.00 s by operating the operation unit 12.

[0093] In this case, for example, the entire waveform data for a plurality of times may be stored in the waveform memory area 131 and applied by the high-voltage pulse application process shown in FIG.

[0094] Also, as shown in the flow of FIG. 13, a high voltage pulse of a set waveform is applied (step S31), and then it is determined whether or not the high voltage pulse has been applied a preset number of times (step S32). If not, a certain interval time is measured (step S33), and the process returns to step S31 to apply the next high voltage pulse. The waveform of the next high voltage pulse to be applied may be the same as or different from the waveform of the high voltage pulse applied previously. Furthermore, when applying three or more times, the length of the interval may be different or the same each time. Furthermore, it may be possible to edit the waveforms to be applied and the order in which they are applied.

[0095] If it is determined in step S32 that the process is to end, the process ends.

[0096] In the case of the process of FIG. 13, if the number of repetitions, the waveforms and order of the high voltage pulses to be applied, and the interval periods are stored in advance in memory unit 13, it is not necessary to store all of the waveform data for multiple pulses in waveform memory area 131, and the capacity of memory unit 13 can be reduced.

[0097] (Modification) The above embodiment can be modified in various ways. For example, in the above embodiment, the waveform of the high voltage pulse can be set from among three types, namely, the monophasic waveform, the BTE waveform, and the RLB waveform, but the types of waveforms that can be set are not limited to these. In addition, the waveform of the high voltage pulse that the AED1 can output may be fixed to only one. For example, when the waveform of the high voltage pulse that the AED1 can output is fixed to only the monophasic waveform, the polarity inversion circuit 165 may not be provided in the high voltage generation unit 16.

[0098] Moreover, any high-voltage pulse waveform can be generated and edited by reading out the waveform data stored in basic waveform table 132, processing and editing it in accordance with the operation of operation unit 12 while displaying the waveform on display unit 11, and overwriting or saving it under a different name. Furthermore, waveform data generated or edited by an external computer or the like may be stored in storage unit 13 via communication unit 15.

[0099] The electrodes 30A and 30B of the AED 1 are not limited to the needle-shaped electrodes shown in Fig. 1, and electrodes of various shapes can be used. For example, as shown in Fig. 14, the AED 1 may have pad-shaped electrodes 50A and 50B instead of the needle-shaped electrodes 30A and 30B. In addition, the surfaces of the pad-shaped electrodes 50A and 50B may have a structure such as fine needles, blades, teeth, or irregularities to reduce contact resistance with the body surface of the person being rescued.

[0100] Moreover, the electrodes 30A, 30B to which the present invention is applied may each have a clothespin-type configuration, as exemplified in Fig. 15. The electrode 30 shown in Fig. 15 has a gripping portion 301 and a holding portion 302. The rescuer holds the gripping portion 301 of the electrode 30 to open the holding portion 302, inserts the skin K between the holding portions 302 and pinches it, and releases the grip of the gripping portion 301 to allow the holding portion 302 to hold the skin K, thereby attaching the electrode 30 to the skin K.

[0101] Furthermore, a plurality of needle-shaped parts 303 like a pin holder may be arranged on the grip part 302. At least a part of the needle-shaped parts 303 is present inside the skin K.

[0102] Needle-shaped electrodes, clothespin-shaped electrodes, pad-shaped electrodes having fine needles, etc. are effective in ensuring stable electrical connection between the electrode and the recipient even in environments where the front of the chest is continually wet, such as in rainy weather.

[0103] In addition, the circuits and operations can be modified as appropriate. For example, although the description has been given mainly in terms of positive logic, the circuits may be designed in terms of negative logic. Furthermore, the materials and values ​​exemplified in the embodiments are merely examples and are not limiting.

[0104] In addition to the bioimpedance, there are also losses in the internal impedance of the battery, the inverter, the transformer, and the rectifier circuit. Therefore, based on the measured output current and output voltage, the peak value and pulse length of the basic voltage waveform Vr may be corrected so that the energy of the applied high voltage pulse matches the target value.

[0105] Also, a correction table that associates the total amount of loss with the correction content may be prepared, the total loss may be calculated, the correction content may be calculated using the calculated total loss as a key, and the basic voltage waveform Vr may be corrected in accordance with the calculated correction content.

[0106] In the above description, the voltage to be applied at each timing t is obtained by correcting the basic voltage waveform Vr. This disclosure is not limited to this. For example, it is also possible to obtain a high voltage waveform to be applied without using the basic voltage waveform Vr. For example, the basic waveform table 132 is removed, and the envelope of the high voltage pulse voltage and the total amount of electrical energy to be applied are stored in the waveform memory area 131. The waveform control unit 141 obtains the applied voltage at each timing based on the measured bioimpedance value Rb so that the total energy of the high voltage pulse to be applied matches the target value E and the envelope matches the basic envelope stored in advance.

[0107] In the above embodiment, the full-bridge inverter circuit 161 is an example of an inverter circuit that converts a DC voltage into an AC voltage by performing a switching operation with a duty ratio according to a switching control signal.

[0108] The transformer 163 is an example of a transformer that boosts the AC voltage converted by the inverter circuit. The full-wave rectifier circuit 164a is an example of a rectifier circuit that rectifies the boosted voltage. The smoothing capacitor C1 is an example of a smoothing circuit that smoothes the voltage output by the rectifier circuit. The electrodes 30A and 30B are examples of electrodes that apply an electric shock to the recipient based on the output voltage of the rectifier circuit. The polarity reversing circuit 165 is an example of a polarity reversing circuit that applies the output voltage of the rectifier circuit to the electrodes in a forward or inverted manner in accordance with a polarity control signal. Therefore, the switching control signals S3 and S4 are an example of a polarity control signal.

[0109] The waveform control unit 141 and the first driver 162 are an example of a duty ratio control means that supplies a switching control signal to the inverter circuit and controls the electric energy supplied from the inverter circuit to the transformer. The PWM control table 133 is an example of a storage unit that stores data indicating the change in duty ratio over time in accordance with the voltage waveform of the electric shock to be applied to the recipient. The polarity control table 134 is also an example of a storage unit that stores data indicating the polarity of the voltage of the electric shock to be applied to the recipient. The operation unit 12 and the control unit 14 are an example of a selection means for selecting one of a plurality of voltage waveforms to be applied. The control unit 14 and the state detection unit 18 are an example of a measuring means for measuring the impedance between the electrodes attached to the rescuee. The operation unit 12, the control unit 14, and the communication unit 15 are an example of a means for updating the data indicating the change in the duty ratio with respect to time stored in the storage unit. Waveform control section 141 and second driver 166 are an example of a polarity control means that transmits a polarity control signal to a polarity inversion circuit to apply a voltage of a polarity corresponding to the set waveform to the electrodes.

[0110] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and the present invention includes the inventions described in the claims and their equivalents. The inventions described in the original claims of this application are listed below. [Explanation of symbols]

[0111] 1...AED, 10...main body, 30A, 30B, 50A, 50B...electrodes, 40A, 40B...cable, 11...display unit, 12...operation unit, 13...storage unit, 131...waveform table, 14...control unit, 141...waveform control unit, 15...communication unit, 16...high voltage generation unit, 161...full bridge inverter circuit, 162 first driver, 163 transformer, 163a...primary winding, 163b...secondary winding, 164 rectification smoothing circuit, 165 polarity inversion circuit, 166 second driver, Q1 to Q8...switching elements, D1 to D4...diodes, C1...capacitor, 17...electrocardiogram signal acquisition unit, 18...state detection unit, 19...power supply unit, 20...audio output unit

Claims

1. A DC-AC conversion circuit that converts a DC voltage to an AC voltage and controls the amplitude, A boost circuit that increases the AC voltage output by the DC-AC conversion circuit, A rectifier circuit that rectifies the voltage boosted by the aforementioned boost circuit, An application unit that enables the application of an electric shock to a person being rescued by applying a voltage between electrodes based on the output voltage of the rectifier circuit, An automated external defibrillator equipped with [a specific feature].

2. The DC-AC conversion circuit generates AC voltages for multiple electric shocks in succession with intervals between them. An automated external defibrillator according to claim 1.

3. The DC-AC conversion circuit generates an AC voltage such that the voltage waveforms of multiple consecutive electric shocks include voltage waveforms that are different from each other. The automated external defibrillator according to claim 2.

4. Further comprising a control circuit that controls the operation of the DC-AC conversion circuit and generates AC voltages for multiple electric shocks, The control circuit causes the DC-AC conversion circuit to generate AC voltages for multiple electric shocks by executing a control program for generating AC voltage for one electric shock multiple times. The automated external defibrillator according to claim 2.

5. The DC-AC conversion circuit further comprises a control circuit that generates AC voltages for multiple electric shocks according to a preset number of repetitions, the voltage waveform and sequence of electric shocks, and the interval period. The automated external defibrillator according to claim 2.

6. The boost circuit is composed of a transformer, and its impedance is 3Ω or less. An automated external defibrillator according to any one of claims 1 to 5.

7. The application unit includes a polarity reversal circuit that reverses the polarity of the output voltage of the rectifier circuit and applies it to the electrode. An automated external defibrillator according to any one of claims 1 to 5.

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