RU2149040C1 - Electrostimulator - Google Patents

Abstract

FIELD: medical engineering. SUBSTANCE: electrostimulator is used in physiotherapy for performance of multichannel electric stimulation of patients. Electrostimulator has channel former including controller, digital indication unit and keyboard unit. Electrostimulator also includes channel switch, power supply unit and unit of n output channels. Each of output channels contains amplitude modulator and output amplifier with output terminals for connection of electrode. EFFECT: simultaneous stimulation of several patients. 1 cl, 9 dwg

Description

 The invention relates to medical equipment and can be used in physiotherapy to affect the electrically excitable physiological systems of a living organism. The invention extends the functionality of the device and increases the efficiency and safety of its use.

 A device for low-frequency physiotherapy is known, which contains a signal conditioner, a PWM modulator and n-output channels, a channel commutator, an inverter, a selective filter, a current transformer, n electromagnetic relays, a DC voltage converter and two DC voltage input terminals. The signal conditioner is based on a controller, a digital display unit and a keyboard unit [RF Patent 2112565, cl. A 61 N 1/36, 1996].

 The mentioned device has a significant drawback, limiting the possibility of its use in medical practice. Each of the n channels has only one terminal (5.1, 5.2 ... 5.n) for connecting a stimulating, active electrode. Therefore, the second electrode, providing a closed circuit of the stimulating current, is connected to terminal 6 of the common bus. As a result, this electrode is common to all n channels.

 Such a multichannel stimulation scheme is functional only under the condition that the path of the stimulating current through the patient’s body from the active electrode to the passive passes only through the stimulated organ, without affecting other organs on which it could have a negative effect. If this condition is met, then the method of multichannel monopolar stimulation is implemented.

 However, in many cases, a device having one common passive electrode for all channels is not applicable.

 Consider a typical case of electrotherapeutic effects on the muscles of both hands, for example, on the right and left biceps. When stimulating the right biceps, the active electrode of the first channel is fixed across this muscle, and the common passive electrode is fixed in the region of the right shoulder joint. In this case, the stimulating current of the first channel passes from the active electrode through the main part of the biceps to the shoulder joint and ends on a common passive electrode.

 Further, the active electrode of the second channel should be fixed on the left biceps. In this case, the stimulating current of the second channel passes from the left bicep to the right shoulder joint, affecting the organs of the chest cavity and neck along the way.

 The passage of current, under normal conditions, stimulating biceps through the heart, can cause myocardial fibrillation and death of the patient.

 The passage of current through the sinuses of the carotid arteries in the neck can cause a sharp drop in blood pressure and death from shock.

 The passage of current through the muscles of the larynx can cause airway spasm and death from suffocation.

 When two active electrodes are located on the right and left biceps, the described situation is created with almost any arrangement of a common passive electrode.

 The presence of a single common electrode generates another significant drawback: the inability to use a multichannel device for conducting treatment sessions for several patients at the same time.

 Therefore, in practice, bipolar, rather than monopolar, multichannel stimulation is used, in which each output channel has two electrodes and both of these electrodes are placed in zones strictly defined for each channel. In this case, the outputs (pairs of electrodes) of individual channels are isolated from each other, which excludes the appearance of a stimulating current between the outputs of different channels.

 A device for low-frequency physiotherapy is also known, comprising a signal driver, a PWM modulator, a channel commutator, a DC voltage converter and n-output channels. The signal generator is based on a controller, a digital display unit and a keyboard unit.

 Each of the n channels of the device is made in the form of a series-connected inverter, a selective filter, the corresponding channel of the current transformer and the output terminal [RF Patent N 2114650, A 61 N 1/36, 1996]. A single output terminal that closes the external circuit of each channel is connected to a common bus.

 Like the previous device, this multichannel device implements only the monopolar stimulation scheme, and therefore it has the same disadvantages as the previous device.

 Another significant drawback of this device is that since at any given moment the output signal can be present at the output of only one of n channels, the signal period must be n times longer than its duration. It follows that the device does not allow simultaneous stimulation of several organs (for example, muscles) or act on them with such a time shift when the stimulus of one channel is completely or partially blocked by stimuli supplied to other channels. However, it is precisely such a temporary structure of actions that the so-called functional stimulation requires, which is used, in particular, to restore or artificially compensate for lost motor functions after a stroke, after spinal cord injuries, etc.

The present invention solves the problem of conducting controlled multi-channel electrical stimulation, eliminating the above disadvantages and while providing:
- the possibility of multichannel electrical stimulation, excluding the formation of an uncontrolled current path to the common electrode;
- the possibility of simultaneously conducting a stimulation session for several patients;
- the ability to stimulate several zones simultaneously or with an arbitrary temporal shift of stimuli in different channels.

 The solution to this problem is achieved by the fact that in an electric stimulator containing a signal driver, including a digital display unit, a keyboard unit and a controller connected by a multi-bit bus to the input of the device’s channel switch, a power supply unit and an n-output channel unit with electrodes, according to the present invention, each of n -output channels of the device contains an amplitude modulator connected by its 2-bit output to the first input of the output amplifier with two output terminals. The first input of the amplitude modulator of each channel is connected to the corresponding output of the controller. The second input of the amplitude modulator of each channel is connected to the 2-bit output of the controller, the third input of the amplitude modulator of each channel is connected to the corresponding output of the channel switch, and the fourth input is to the first output of the power supply. The second and third inputs of the output amplifiers of each channel are connected respectively to the first and second outputs of the power supply. The controller, digital display unit and keyboard unit are connected by a common bidirectional multi-bit bus. The first inputs of the controller, digital display unit, keyboard unit and channel switch are connected to the first output of the power supply.

 The technical result of the present invention is that due to the proposed circuit solution of the stimulator, it is possible to carry out both monopolar and bipolar multichannel stimulation. Stimulating effects can go in various combinations: simultaneously on several output channels, alternately on each channel or with an arbitrary time shift. Stimulating currents can have a pulsed form, a form of oscillations of a sinusoidal or other form.

The invention is illustrated by the following description and drawings:
FIG. 1 is a block diagram of the proposed stimulator,
FIG. 2 - electrical diagram of controller 2 for option 2-channel electrical stimulator,
FIG. 3 - electric circuit block digital indication (BCR) 3,
FIG. 4 - electrical circuit block keyboard (BKL) 4,
FIG. 5 - electrical diagram of the switch 5 for the option of a 2-channel electrical stimulator,
FIG. 6 - electrical diagram of the power supply 6,
FIG. 7 is a circuit diagram of an amplitude modulator 8.1 (8.2 ... 8.n),
FIG. 8 is a circuit diagram of an output amplifier 9.1 (9.2 ... 9.n),
FIG. 9 - enlarged algorithm of the controller 2.

 The stimulator (Fig. 1) contains a signal driver 1, including a controller 2 connected by a bi-directional multi-bit bus, a digital display unit (BCR) 3 and a keyboard unit (BKL) 4, a channel 5 switch, a power supply 6 and an output channel block 7 containing n output stimulator channels. Each of the n output channels contains an amplitude modulator. The amplitude modulator of the first channel is 8.1, the second is 8.2, the third is 8.3, and the n is 8.n. Each channel also contains an output amplifier with two terminals. Accordingly: the output amplifier of the first channel 9.1 with output terminals 10.1.1 and 10.1.2. The output amplifiers of the second, third, fourth (n-th) channels are 9.2, respectively, with terminals 10.2.1 and 10.2.2, 9.3 with terminals - 10.3.1 and 10.3.2, 9.4 (n) with terminals 10.4.1 and 10.4. 2 (10.n.1 and 10.n.2).

 Signal conditioner 1 is intended for generating the following signals: stimulating signals with time characteristics set by the operator; PWM signal proportional to the set amplitude for each of n channels, a control digital code for the channel switch. Shaper 1 can be implemented in the form of a coupled bidirectional multi-bit bus controller 2, a digital display unit 3 and a keyboard unit 4.

 Controller 2 (Fig. 2) is designed to control the BCI 3, BKL 4, channel switch 5. It can be implemented on the basis of a single-chip microcomputer KR1830BE51 [Boborykin A.V., Lipovetsky G.P., Litvinsky G.V. and other single-chip microcomputers. M. MIKAP, 1994.] p. 107- p. 218.

 The block of digital indication BTS 3 (Fig. 3) is a set of digital seven-segment indicators and single LEDs. The BCI serves to display information about the parameters of the output signals, the procedure time, the number of the current treatment program, the channel operation mode, the STOP, START or PAUSE state. It can be performed on indicators HDSP-5621G and AL307 or other similar elements.

 The keyboard unit BKL 4 (Fig. 4) is a matrix of N x M elements. It serves to transmit control information directly to the controller and can be performed on buttons such as PKN159 or other buttons without fixing.

 Channel switch 5 (Fig. 5) is designed to connect the required output channels and can be performed on one or n (depending on the number of switched channels) registers of the type IR27 or other registers with data capture. Channel 5 switch with its outputs is connected respectively to the third input of the amplitude modulator of each channel, and its multi-bit input is connected to the multi-bit output of the controller.

 The power supply 6 (Fig. 6) is designed to convert mains voltage 220V 50 Hz to voltage for supplying circuits of microcircuits and supply voltage of output amplifiers. The power supply unit 6 is connected with its first output to the second inputs of the output amplifiers of each channel, to the fourth inputs of the amplitude modulators of each channel, to the first inputs of the controller, digital display unit and channel switch. The second output of the power supply 6 is connected to the third inputs of the output amplifiers of each channel.

 The pacemaker has a block of n output channels 7. The number of output channels is regulated by the specifics of medical tasks and can range from 1 to 8 channels. The output channels of the stimulator form stimulating pulses with predetermined time, amplitude parameters and the desired shape, and also provide isolation of the power supply channels from the patient's circuits. Each output channel contains an amplitude modulator (8.1, 8.2, ... 8.n, respectively) and an output amplifier (9.1, 9.2, ... 9.n, respectively). The amplitude modulator (Fig. 7) provides the modulation of the signal coming from the output of the driver, in amplitude and its arrival at the input of the output amplifier, if the modulator is opened by a signal from the switch. The amplitude modulator can be performed on a 561KTZ chip and an integrating chain.

 The output amplifiers of each channel (9.1, 9.2, ... 9.n) are designed to amplify the current of the stimulating signal to the required value, to ensure isolation of the power supply circuits of the amplifier from the patient circuit and to ensure the independence of the amplitude of the current of the stimulating signal from changes in the resistance of the patient circuit. The output amplifiers (Fig. 8) are made according to a bipolar circuit, which makes it possible to obtain stimulating signals in the form of monophasic pulses of positive and negative polarity, two-phase pulses, and also alternating current with a sinusoidal or other shape at the output of each channel.

 The output amplifier works according to the current source circuit and can be performed on a 1401UD2A chip and KT815 transistors.

 The output transformer as part of the amplifier isolates the patient’s power and circuit, as well as matching with the load. The primary windings of the transformer are included in the collector circuits of the transistors, and the secondary winding is connected to the output terminals.

 A pair of output terminals of the first channel (10.1.1 and 10.1.2, respectively) and each channel (10.2.1, 10.2.2, ... 10.n.1,10.n.2, respectively) is used to connect a patient cable with a pair electrodes.

 The stimulator works as follows. (An enlarged algorithm of the controller is shown in Fig. 9).

 The operator applies electrodes to stimulated areas of the patient’s body.

 When the stimulator is connected to the network, the output voltages 1 and 2 of the power supply unit show the supply voltage of the analog and digital circuits of the device. Almost simultaneously with the supply of power to input 1 of controller 2, the latter installs on the multi-bit bus connecting it to switch 5 a digital code that disconnects all channels. Thus, there is no voltage at the output terminals of the channels. At the same time, zero values are displayed on the current indicators of the BTS 3 channels. In addition, the program indicator shows the default treatment program number, the timer shows the default treatment time, the mode indicator shows the default mode. The STOP indicator is on.

 In this state, the operator can use the keyboard to set the program number, another channel synchronization mode, and change the procedure time. In the STOP state, the buttons for setting the amplitude of the stimulating current in the channels are locked. After setting all the required values, the operator presses the "START" button and controller 2 starts to execute the specified program. In this case, the operator, using the buttons for setting the current amplitude in each channel (BKL 4), sets the output current values necessary for each channel, which are displayed on the corresponding indicators of the BCI 3.

 At the inputs 1 of each of the n amplitude modulators (8.1, 8.2, ..., 8.n), a PWM signal corresponding to the set pulse amplitude is supplied from controller 2. The inputs 2 of each of the n channels receive pulses with the required time parameters. In the amplitude modulator 8.1 (8.2, ..., 8.n), the pulses are modulated in amplitude and, if an enable signal from switch 5 is present at input 3 of the modulator 8.1 (8.2, ..., 8-n), then the pulses are input 1 output amplifier 9.1 (9.2, ..., 9.n). The voltage at the output of modulator 8.1 (8.2, ..., 8.n) and, respectively, at the input of amplifier 9.1 (9.2, ..., 9-n)) rises and falls smoothly. This is due to the presence of an integrating chain in modulator 8.1 (8.2, ..., 8.n).

 The output amplifier (9.1, ..., 9.n) (Fig. 8) consists of two arms. Pulses corresponding to the positive polarity of the output signal are fed to the input of one arm, and pulses corresponding to the negative polarity are fed to the input of the other. Thanks to such a circuit, monopolar pulses of positive and negative polarity, bipolar pulses and alternating current oscillations can be obtained at the amplifier output. The simultaneous presence of pulses at the input of both arms of the amplifier is eliminated by software. Feedback resistance is included in the emitter circuit of the output transistors. Feedback voltage proportional to the current in the emitter, and therefore in the collector circuit of the transistors, is supplied to the comparison element (which is made on the operational amplifier 140UD2A), where it is compared with the signal from the output of the amplitude modulator. The error signal is supplied to the base of the transistor. Thus, the output amplifier works as a current source and the signal in the patient circuit is little dependent on load changes.

 During the procedure, the operator can adjust the current amplitude values in each channel. Changing the channel synchronization modes, program number and duration of the procedure in the "START" state is blocked.

 For short-term suspension of the procedure, it is necessary to press the "PAUSE" button in BCL 4. In this case, the corresponding LED turns on, the generation of stimulating signals stops, the timer stops. In this case, the codes of all parameters are saved.

 When you press the "START" button again, the work resumes. Due to the presence of integrating circuits in the output amplifiers, the current in the patient's circuits increases smoothly, without creating discomfort.

 At the end of the procedure time, the timer is reset, the current in the patient's circuit decreases to zero, work stops and the stimulator goes into the STOP state.

 The procedure can be stopped at any time by pressing the STOP button. Pressing it will reset all parameters.

Claims (1)

 An electrical stimulator comprising a signal driver, including a digital display unit, a keyboard unit and a controller connected by a multi-bit bus to the input of the device’s channel switcher, a power supply unit and a block of n output channels with electrodes, characterized in that each of the n output channels of the device contains an amplitude modulator connected its two-bit output to the first input of the output amplifier with two output terminals, for connecting the electrodes, the first input of the amplitude modulator of each channel is connected to the corresponding output of the controller, the second input of the amplitude modulator of each channel is connected to the two-bit output of the controller, the third input is connected to the corresponding output of the channel switch, and the fourth input is to the first output of the power supply, the second and third inputs of the output amplifier of each channel are connected to the first and second output, respectively power supply, controller, digital display unit and keyboard unit are connected by a common bi-directional multi-bit bus, the first inputs of the controller, digital display unit and switching torus channels are connected to the first output of the power supply.

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