JP7493865B1 - Automated External Defibrillator - Google Patents

Abstract

The automatic external defibrillator (AED) includes a power supply unit (19), a high-voltage generating unit (16) that boosts a voltage applied from the power supply unit (19) to generate a high-voltage pulse, and a pair of electrodes (30A, 30B) that apply an electric shock based on the high-voltage pulse to a rescuee. The high-voltage generating unit (16) includes a full-bridge inverter circuit (161) that converts a DC voltage applied from the power supply unit (19) to an AC voltage, a transformer (163) that boosts the converted AC voltage, and a first driver (162). The control unit (14) transmits a PWM signal to the first driver (162) to PWM-control the full-bridge inverter circuit (161) and change the output voltage of the full-bridge inverter circuit (161) in a time series according to a set waveform.

Description

The present invention relates to an automated external defibrillator.

Automated external defibrillators (AEDs) are widely used as defibrillators that deliver a high-voltage pulse of electric shock to the recipient's spasming heart, defibrillating it and encouraging normal heartbeats. Conventional AEDs are relatively large devices and are often installed in stations, public facilities, commercial buildings, etc., making them difficult to carry around.

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.

JP 2022-182010 A

The AED described in Patent Document 1 uses a simple mechanism of turning on and off a single switch installed between the power supply unit and the transformer to supply power to the 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.

The present invention has been made in consideration of the above-mentioned situation, and aims to provide an automatic external defibrillator that is small and capable of generating high-voltage pulses suitable for defibrillation.

In order to achieve the above object, the automated external defibrillator according to the present disclosure comprises:
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;
a transformer that boosts the AC voltage converted by the inverter 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 electric energy supplied from the inverter circuit to the transformer by supplying the switching control signal to the inverter circuit and controlling a duty ratio of a switching operation of the inverter circuit ;
Equipped with.

Furthermore, a memory unit may be provided that stores data representing changes in the duty ratio over time in response to the 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 inverter circuit, for example, in accordance with the data stored in the memory unit.

The memory unit stores data representing the change in duty ratio over time, for example, corresponding to each of a plurality of voltage waveforms of the electric shock to be applied to the recipient. In this case, a selection means for selecting one of the plurality of voltage waveforms may be further provided. The duty ratio control means controls the duty ratio of the inverter circuit according to the data corresponding to the voltage waveform selected by the selection means.

The device may include a measuring means for measuring the impedance between the electrodes attached to the recipient, and a means for storing a fundamental waveform of an applied voltage , and the duty ratio control means may correct the fundamental waveform based on the impedance measured by the measuring means, and supply the switching control signal to the inverter circuit based on the corrected fundamental waveform to control the duty ratio of the switching operation of the inverter circuit, thereby controlling the electrical energy supplied from the inverter circuit to the transformer .

The device may further include a means for updating data indicating the change in duty ratio over time stored in the memory unit.

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.

The device may further include a memory unit that stores data indicating the polarity of the applied voltage corresponding to the voltage waveform of the electric shock to be applied to the recipient. In this case, the polarity control means controls the polarity reversal circuit in accordance with the data stored in the memory means.

The device may further include a smoothing circuit that smoothes the voltage output by the rectifier circuit.

The duty ratio control means may generate multiple voltage pulses by driving the inverter circuit multiple times at predetermined time intervals.

The electrode may have a needle-like or pad-like outer shape and be attached to the person being rescued.

The present invention makes it possible to achieve compact size and easily generate high-voltage pulses with complex waveforms.

FIG. 1 is a diagram showing an example of the appearance of an AED according to an embodiment of the present disclosure. 1A and 1B are diagrams illustrating examples of electrode attachment positions of an AED according to an embodiment of the present disclosure. FIG. 2 is a circuit block diagram of an AED according to an embodiment of the present disclosure. 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. 4 is a diagram showing an example of a circuit configuration of a high voltage generating unit shown in FIG. 3 . 6A to 6D are timing charts illustrating the operation of the full-bridge inverter circuit shown in FIG. 5 . 6 is a diagram showing an example of a circuit configuration of a first driver shown in FIG. 5 . FIG. 4 illustrates an example of a functional configuration of a storage unit illustrated in FIG. 3 . 6A to 6F are timing charts illustrating the operation of the high voltage generating unit shown in FIG. 5 . 4 is a flowchart of a high-voltage pulse application process executed by the AED according to the embodiment. 11 is a flowchart showing details of the waveform table generation process shown in FIG. 10 . 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. 11 is a flowchart for explaining an example of operation of the AED in a dual shock mode according to an embodiment of the present disclosure. FIG. 13 is a diagram showing an example of the appearance of an AED according to a modified example. 13 is a diagram showing an example of an electrode structure of an AED according to a modified example. FIG.

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

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, 30B, and cables 40A, 40B that electrically connect the main body 10 to the electrodes 30A, 30B, respectively.

When using the AED1, the electrodes 30A and 30B are inserted near the right chest and flank of the person being rescued, respectively, as shown in Fig. 2. The positions of the electrodes 30A and 30B are not limited to the example shown in Fig. 2, and may be any positions that are paired with the heart, i.e., 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, by inserting the electrodes 30A and 30B into the left and right shoulders, individual differences can be reduced.

Returning to FIG. 1, the main body 10 of the AED 1 has an easily portable shape and size similar to, for example, 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.

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 that instructs the rescuee to apply a high-voltage pulse, a waveform selection button that selects the waveform of the high-voltage pulse to be applied, and a mode selection button that selects the operating mode.

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.

The power supply unit 19 includes a DC power supply with an output voltage V1 of approximately 100 to 110 V. This DC power supply is, for example, configured by connecting multiple 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 various parts other than the high voltage generation unit 16, and supplies operating power to these parts.

The high voltage generating unit 16, under the control of the control unit 14, boosts the output voltage of the power supply unit 19 and adjusts the boosted voltage to generate a high voltage pulse (more specifically, a potential difference between the electrodes 30A and 30B) to be applied to the recipient 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 the monophasic waveform shown in FIG. 4(A), the biphasic BTE waveform shown in FIG. 4(B), and the 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 the "set waveform".

An example of the circuit configuration of the high voltage generating unit 16 is shown in Figure 5. Note that Figure 5 shows only the main circuit configuration, and the ground connection parts 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.

The full-bridge inverter circuit 161 includes four switching elements Q1 to Q4 that form the four sides of the 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.

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

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

As shown in Fig. 6(A) and (B), by repeating the process of alternately setting the switching control signals S1 and S2 to a high level, the set of switching elements Q1 and Q4 and the set of switching elements Q2 and Q3 are alternately and repeatedly turned on. As a result, as shown in Fig. 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, as shown in Fig. 6(D), an AC primary current _Iin flows through the primary winding 163a. The effective value of the primary current _Iin is determined by the ratio of the on-period PW1 or PW2 to the on-off cycle λ of the switching elements Q1 to S4, that is, the duty ratios (PW1/λ) and (PW2/λ). Therefore, by adjusting the duty ratios (PW1/λ) and (PW2/λ), that is, by PWM-controlling the switching operations of the switching elements Q1 to Q4, the amount of electrical energy supplied to the transformer 163 can be adjusted. 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 as or different from each other.

A large pulsed, instantaneous current flows through the switching elements Q1 to Q4. For this reason, it is desirable to use a large Si-MOSFET that can tolerate a pulsed, instantaneous current of, for example, about 300 A and is capable of high-speed switching.

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

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 NR 13.8. It is also desirable to use low-loss Litz wire for the secondary winding 163b, and to make the winding thick. As a result, for example, the resistance of the primary winding 163a can be about 0.025 Ω, and the resistance of the secondary winding 163b can be about 1.93 Ω, and the impedance of the transformer 163 can be suppressed to 1/10 or less of the bioimpedance (50 to 1000 Ω), which is sufficiently small, 3 Ω or less.

The rectifying and smoothing circuit 164 comprises a full-wave rectifying circuit 164a composed of diodes D1 to D4, which are rectifying elements, and a smoothing capacitor C1 that constitutes a smoothing circuit.

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. It is preferable that the diodes D1 to D4 are SiC Schottky type diodes that can tolerate large currents and high-frequency switching operations. In order to ensure the withstand voltage, multiple diode elements may be connected in series and used as the diodes D1 to D4.

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 desirable for the smoothing capacitor C1 to have a high withstand voltage and a relatively small capacity. For example, a withstand voltage of 1,600V and a capacity of about 12μF is desirable. The smoothing capacitor C1 can suppress pulsations in the output voltage. However, it is also possible to perform rectification only by the full wave rectifier circuit 164a without providing the smoothing capacitor C1.

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.

The polarity reversal circuit 165 is a circuit that switches the voltage V2 output by the rectifying and smoothing circuit 164 between the electrodes 30A and 30B in either the forward or reverse direction. The polarity reversal 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, IGBT, or the like, made of SiC for large currents. In the following explanation, they are referred to as MOSFETs.

One end of the current path of the switching elements Q5 and Q7 is connected to the positive terminal T3 of the rectifying 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 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 of the opposite polarity -V2 is applied between the electrodes 30A and 30B, resulting in a high-voltage pulse Vout that applies an electric shock.

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 Figures 6 (A) and (B) in accordance with the 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.

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 timing at which the switching control signals S1 and S2 are set to a 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.

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 voltage of FIG. 4(A) and the first half of the applied voltage of 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 voltage of 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.

The memory unit 13 shown in Figure 3 includes a non-volatile memory such as a Read Only Memory (ROM) and a volatile memory such as a Random Access Memory (RAM). The non-volatile memory stores the control program executed by the control unit 14 and fixed data. 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 electrocardiogram signals, etc.

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

The basic waveform table 132 is arranged in a non-volatile storage area of the storage unit 13, and stores the basic waveforms of high-voltage pulses selectable by the AED 1, for example, the waveform data of the voltage waveforms shown in Figures 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 the reference value Rr, the total energy applied to the rescuee is the 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 position of the electrodes, etc., and is about 1000Ω when the electrodes 30A and 30B are needle-shaped as shown in Figure 1, and about 20Ω to 200Ω when the electrodes are of the conventional pad type (see Figure 14). For this reason, in this embodiment, the reference value Rr of the bioimpedance is set to, for example, 1000Ω, and the reference waveform is set.

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 are sometimes collectively referred to as the waveform table 135, which means that they are tables that define the waveform of the high-voltage pulse to be applied.

More specifically, the PWM control table 133 stores the elapsed time ti (i = 0, 1, 2, ...) and the period λ and pulse widths PW1 and PW2 at that time in association with each other 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 rescued person. 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.

The polarity control table 134 stores the elapsed time ti in correspondence with the polarity of the voltage to be applied at that time in order to control the switching control signals S3 and S4 supplied to the polarity reversal circuit 165 for the high voltage pulse to be applied to the rescuee.

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 position where the electrodes are attached, etc. Therefore, when the bioimpedance Rb of the recipient is high, if the voltage Vi determined by the fundamental waveform is applied, the applied energy may be insufficient, while when the bioimpedance Rb is low, if the voltage Vi determined by the fundamental waveform is applied, the applied energy may be excessive. 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, and the total energy E applied to the recipient is made to match the reference value Er.

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 is expressed as ^V2 /R. Therefore, when the impedance R is k times larger, approximately the same energy E can be applied by multiplying the voltage by √k. Alternatively, approximately the same energy E can be applied by multiplying the application time (duration) of the high voltage pulse by k times.

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

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

On the other hand, 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.

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. 4B. For ease of understanding, it is assumed that the period λ of the switching control signals S1 and S2 is constant.

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/bioimpedance reference value Rr detected by the state detection unit 18 is 1.3. In this case, in order to apply the reference energy value Er to the rescuee, a voltage waveform Va obtained by correcting the voltage of the basic voltage waveform Vr by 1.14≒√1.3=√(Rb/Rr) times is applied to the rescuee. The voltage waveform Va obtained by correcting the voltage by 1.14 times is shown by a thick solid line in Figure 9(A) (the figure has been deformed for ease of viewing).
When the voltage waveform Va is obtained, the output voltage V2=|Va| of the rectifying and smoothing circuit 164 becomes a positive voltage waveform as shown in FIG. 9B.

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 at timing T1 so that V2=1.14Vr is obtained, and thereafter, the duty ratio is gradually decreased during timings T1-T2 and T4-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 constant, and the pulse widths PW1 and PW2 of the switching operation of the full-bridge inverter circuit 161 are appropriately set at timing T1, and thereafter, the pulse widths PW1 and PW2 are gradually decreased. Note that FIG. 9C and FIG. 9D are schematic diagrams illustrating the change in the duty ratio over time, and are different from the actual waveforms. 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.

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

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

The control unit 14 shown in FIG. 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 multiple computers. In addition, a portion of the control unit 14 may include hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

The control unit 14 operates according to the 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.

The control unit 14 includes a waveform control unit 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 the 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.

The waveform control unit 141 also generates a PWM control signal by referring to the stored data in 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 turn 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. 9B.

The waveform control unit 141 also 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 the period when a positive voltage should be applied to the rescuee, and sets the switching control signal S4 to a high level during the period when a negative voltage should be applied to the rescuee, as illustrated in Figs. 9(E) and (F). As a result, during the 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 the 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.

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 voice, warning sounds, etc. that guide the operation of the AED 1 under the control of the control unit 14.

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

The electrocardiogram signal acquisition unit 17 filters 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 acquisition 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.

The condition detection unit 18 measures, for example, the impedance between the electrodes 30A and 30B, i.e., 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.

Next, the operation and usage of the AED 1 having the above configuration will be described.
The AED 1 is small and lightweight, so rescuers can easily carry it with them, and it does not require space even when it is installed.

When using the AED 1, the rescuer operates the operation unit 12 to turn on the power and insert electrodes 30A and 30B into positions that sandwich the recipient's heart, 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 electrodes 30A and 30B are attached correctly. 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 electrodes 30A and 30B. The status detection unit 18 measures the voltage between electrodes 30A and 30B and the current flowing through electrode 30A or 30B, measures the bioimpedance Rb, and notifies the control unit 14.

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 result of the determination via the display unit 11 and the audio output unit 20. The rescuer reattaches the electrodes 30A, 30B as necessary, following the notification.

If necessary, the rescuer checks the electrocardiogram of the person being rescued. In this case, with electrodes 30A and 30B attached to the person being rescued, the rescuer presses the electrocardiogram detection button in button group 12b. In response to this operation, the control unit 14 starts the electrocardiogram signal acquisition unit 17. The electrocardiogram signal acquisition unit 17 measures the voltage between electrodes 30A and 30B and supplies it to the control unit 14. The control unit 14 displays the waveform of the detected biovoltage on the display unit 11. The rescuer checks the electrocardiogram of the person being rescued by following the display.

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 preregistered 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 storage unit 13.
Next, the control unit 14 waits for the application button of the button group 12b to be pressed (step S13).

When the apply button is pressed (step S13: Yes), the waveform control unit 141 of the control unit 14 executes a waveform table generation process to generate a waveform table 135 (PWM control table 133 and polarity control table 134) (step S14).

The waveform table generating 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).
Next, the control unit 14 obtains the 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 applied to the recipient becomes the reference value E (step S23).
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).
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).
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.
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).
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.

Next, the control unit 14 supplies a PWM control signal to the first driver 162 based on the 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 of the switching elements Q1 to Q4, or the duty ratio.

In addition, 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).

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

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 then smoothed by the smoothing capacitor C1 and output as voltage V2. Voltage V2 has a waveform equal to the absolute value waveform of the correction voltage waveform Va, as shown in FIG. 9B.

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 the 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 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 the 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 electrodes 30A and 30B, and applies a negative high voltage pulse Vout to the rescuee.

In this way, a high-voltage pulse having a corrected voltage waveform Va as shown in Fig. 9 (A) is applied to the recipient. 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 recipient or variations in the attachment state of the electrodes 30A and 30B.

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, there is no need to use a high-voltage capacitor to hold 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 rectification smoothing circuit 164 is inverted by the polarity inversion circuit 165 controlled by the 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.

In addition, the AED 1 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.

In the above embodiment, an example is shown in which a high-voltage pulse is applied to the recipient once, but it may be applied multiple times. Hereinafter, the mode in which a high-voltage pulse is applied multiple times with a certain time interval between them 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, high-voltage pulses with different waveforms may be generated for the first and second pulses. Also, more than two high-voltage pulses may be generated consecutively and applied to the recipient.

In the dual shock mode, the AED 1 applies two successive high-voltage pulses to the recipient 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. The operator can also set the time interval between the two successive high-voltage pulses to be applied within the range of 0.25 s to 3.00 s by operating the operation unit 12.

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.
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.

If it is determined in step S32 that the process has ended, the process ends.

In the case of the processing of Figure 13, if the number of repetitions, the waveforms and order of the high voltage pulses to be applied, and the interval period are stored in advance in the memory unit 13, there is no need to store the entire waveform data for multiple pulses in the waveform memory area 131, and the capacity of the memory unit 13 can be reduced.

(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, monophasic waveform, BTE waveform, and 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 monophasic waveform, the polarity inversion circuit 165 does not need to be provided in the high voltage generating unit 16.

In addition, any high-voltage pulse waveform can be generated and edited by reading out the waveform data stored in the basic waveform table 132, processing and editing the waveform in accordance with the operation of the operation unit 12 while displaying the waveform on the 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 the memory unit 13 via the communication unit 15.

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 structures such as fine needles, blades, teeth, and irregularities to reduce contact resistance with the body surface of the person being rescued.

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 grasps the gripping portion 301 of the electrode 30 to open the holding portion 302, inserts and pinches the skin K between the holding portions 302, 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.

Furthermore, multiple needle-shaped parts 303, such as a pin holder, may be arranged on the gripping part 302. At least a part of the needle-shaped parts 303 is present inside the skin K.

Needle-shaped electrodes, clothespin-shaped electrodes, pad-shaped electrodes with fine needles, etc. are effective in ensuring a stable electrical connection between the electrode and the person being rescued, even in environments where the anterior chest is continually wet, such as in rainy weather.

In addition, the circuits and operations can be modified as appropriate. For example, although the description has been primarily based on positive logic, the circuits may also be designed using negative logic. Furthermore, the materials and numerical values given as examples in the embodiments are merely examples and are not limiting.

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

In addition, a correction table may be prepared that associates the total amount of loss with the correction content, 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.

In the above description, the voltage to be applied at each timing t was obtained by correcting the basic voltage waveform Vr. This disclosure is not limited to this. For example, it is also possible to obtain the 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.

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.
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 reversal circuit 165 is an example of 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. Therefore, the switching control signals S3 and S4 are examples of polarity control signals.

The waveform control unit 141 and the first driver 162 are an example of a duty ratio control unit 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 representing changes 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 representing 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 rescue recipient.
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.
The waveform control section 141 and the 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.

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

1...AED, 10...main body, 30A, 30B, 50A, 50B...electrodes, 40A, 40B...cable, 11...display, 12...operation, 13...storage, 131...waveform table, 14...controller, 141...waveform control, 15...communication, 16...high voltage generating unit, 161...full bridge inverter circuit, 162 first driver, 163 transformer, 163a...primary winding, 163b...secondary winding, 164 rectifying 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 (10)

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;
a transformer that boosts the AC voltage converted by the inverter 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 electric energy supplied from the inverter circuit to the transformer by supplying the switching control signal to the inverter circuit and controlling a duty ratio of a switching operation of the inverter circuit ;
An automated external defibrillator comprising: a memory unit for storing data representing a change in duty ratio over time in accordance with a voltage waveform of an electric shock to be applied to a rescuee;
The duty ratio control means controls a duty ratio of a switching operation of the inverter circuit in accordance with the data stored in the storage unit.
2. The automated external defibrillator of claim 1. The memory unit stores data representing a change in duty ratio with respect to time corresponding to each of a plurality of voltage waveforms of an electric shock to be applied to a rescuee,
A selection means for selecting one of the plurality of voltage waveforms is further provided,
the duty ratio control means controls the duty ratio of the inverter circuit in accordance with data corresponding to the voltage waveform selected by the selection means .
3. The automated external defibrillator of claim 2. A measuring means for measuring impedance between the electrodes attached to the rescuee;
A means for storing a fundamental waveform of an applied voltage ,
the duty ratio control means corrects the fundamental waveform based on the impedance measured by the measurement means, and supplies the switching control signal to the inverter circuit based on the corrected fundamental waveform to control a duty ratio of a switching operation of the inverter circuit, thereby controlling the electric energy supplied from the inverter circuit to the transformer.
2. The automated external defibrillator of claim 1 . The device further includes a means for updating data indicating a change in the duty ratio with respect to time stored in the storage unit.
4. An automated external defibrillator according to claim 2 or 3. a polarity inversion circuit that applies the output voltage of the rectifier circuit to the electrodes in a forward or reversed state in accordance with a polarity control signal;
a polarity control means for transmitting the polarity control signal to the polarity reversal circuit to apply a voltage having a polarity corresponding to a voltage waveform of an electric shock to be applied to the electrode;
3. The automatic external defibrillator of claim 1 or 2, further comprising: a memory unit for storing data indicating a polarity of an applied voltage corresponding to a voltage waveform of an electric shock to be applied to a rescuee;
The polarity control means controls the polarity reversing circuit in accordance with the data stored in the storage unit .
7. The automated external defibrillator of claim 6 . Further comprising a smoothing circuit for smoothing the voltage output from the rectifier circuit.
3. An automated external defibrillator according to claim 1 or 2. The duty ratio control means generates a plurality of voltage pulses by driving the inverter circuit a plurality of times at a predetermined time interval.
3. An automated external defibrillator according to claim 1 or 2. The electrode has a needle-like, pad-like, or scissors-like shape and is attached to the person being rescued.
3. An automated external defibrillator according to claim 1 or 2.