RU2243005C1 - Device for applying electrotherapy - Google Patents

Abstract

FIELD: medical engineering.

SUBSTANCE: device has electrodes, in series connected unit for producing treatment signal and unit for controlling action amplitude, in series connected units for restricting treatment current density matching the number of electrodes and multi-contact connector for connecting electrodes introduced between unit for controlling action amplitude level and the electrodes. Each of the electrodes is connected to output of its multi-contact connector. Other contacts of the connectors have cross-pieces on the same side with the electrode depending on electrode areas. The contacts are connected to inputs of their units for restricting treatment current density.

EFFECT: enhanced effectiveness of treatment; high level of patient safety.

2 dwg

Description

The proposed device relates to medical equipment, in particular to devices for electrotherapy, and can be used for medical-rehabilitation and medical-prophylactic procedures, for example, in physiotherapy.

The regulation of the electrotherapy procedure [1] provides for the imposition of removable electrodes of various shapes and sizes on the patient’s skin through moist pads that ensure reliable contact of the electrode with the patient’s body and exclude the possibility of damage to the patient’s skin due to loose contact with the electrode and local excess of the maximum allowable current density. The magnitude of the current through the electrodes is determined by the medical staff according to the subjective sensations of the patient at the beginning of the electrotherapy session, by changing the output voltage (current) of the electrotherapy device, to the output of which electrodes applied to the patient’s body are connected.

When the staff is working with a device for electrotherapy, errors associated with the replacement of electrodes are possible. For example, if, with the device settings unchanged (patient’s current value), one electrode is replaced with another having a smaller area, then the maximum permissible current density of 0.1 mA / cm [1] can be exceeded, causing the patient to feel a burning sensation or shooting during procedures and leading to burns of the patient’s skin surface under the electrodes. A similar effect can occur during malfunction or accident of the electrotherapy device during the session with an uncontrolled increase in the intensity of exposure (current through the electrodes applied to the patient’s body).

Known devices for electrotherapy [2-4], providing effects on the affected organs of the patient with currents of various shapes through the electrodes for the purpose of their treatment, prevention, training and strengthening. A common feature of the known devices is the presence in their composition of the actual device for electrotherapy and a set of replaceable electrodes with lead cables. Replaceable electrodes have a different area and are connected with their lead cables equipped with single-contact connectors to the corresponding connectors of the device.

The closest in the totality of common features is an electric stimulator [5], which contains a series-connected driver of the signal of exposure, a regulator of the level of amplitude of exposure and electrodes.

This device (prototype) does not ensure patient safety during the procedure, both during errors of the medical staff when setting the exposure intensity, and during malfunctioning of the exposure signal shaper or exposure amplitude level regulator.

The aim of the invention is to increase patient safety during the electrotherapy procedure by limiting the permissible current density under the electrode at a level safe for the patient for any area of the connected electrode.

To achieve this goal, the device selected as a prototype additionally introduced series-connected limiters of the current density of the action by the number of electrodes and multi-contact connectors for connecting electrodes connected between the level regulator of the amplitude of the effect and the electrodes, each electrode being connected to the output of its limiter of the current density of the action through the first contact of its multi-pin connector, the other contacts of the connectors on the side of the electrodes are equipped with a jumper E for various values of the area of the electrodes, on the other hand are connected to inputs of their impact limiters current density.

Thus, the combination of the above signs allows us to solve the problem - improving the patient’s safety during the electrotherapy procedure by limiting the permissible current density under the electrode at a level safe for the patient for any area of the connected electrode, both for medical personnel errors when setting the exposure intensity, and in case of malfunction of the impact signal shaper or the impact amplitude level controller.

Figure 1 presents a block diagram of the proposed device.

The device for electrotherapy contains a device 1, consisting of a series of connected signal shaper 2, a regulator of the level of the amplitude of the effect 3 and a set of limiters of the current density 4-5 connected by inputs to each of the output of its regulator of the level of the amplitude of the impact 3, and outputs (a) each the first contact (a) of its multi-pin connector 6-7. Other contacts (b-e) of multi-contact connectors 6-7 are connected respectively to the inputs of the same name (b-e) of their current density limiters 4-5. The device also includes a set of replaceable electrodes of different sizes 8-9, each of which is connected to the first contact (a) of its multi-contact connector 12-13 through its lead cable 10-11. The area of the electrodes 8-9 is encoded by a set of jumpers installed between contact b and contacts c, d, e of multi-contact connectors 6-7, respectively. So, for example, for an electrode 8 having a minimum area, a jumper on the connector 6 is installed only between contacts b and c, and for an electrode 9 having a maximum area, jumpers on a connector 7 are installed between contacts b and c, b and d, b and e.

Figure 2 presents an embodiment of a circuit diagram of the current density limiters 4-5.

The limiter of the current density of the action contains an input 14 connected to the limiting channel of the current flowing into the patient’s electrode 15 with the anode of the diode 16. The cathode of the diode 16 is connected to the collector of the first npn transistor 17 and one of the terminals of the resistor 18, the other terminal of which is connected to the base the first npn transistor 17 and the collector of the second npn transistor 19, the base of which is connected to the emitter of the first npn transistor 17 and one of the terminals of each of the resistors 20, 21, 22, the other terminals of the resistors 20, 21, 22 are each connected to the anode of their diode 23, 24, 25. The cathodes of di Odes 23, 24, 25 are connected respectively to the outputs indicated by the letters c, d, e. The emitter of the second npn transistor 19 is connected to the anode of the diode 26, and the cathode of the diode 26 is connected to the outputs indicated by the letters a and b.

The input 14 is also connected in the restriction channel of the current 27 flowing from the patient’s electrode to the cathode of the diode 28. The anode of the diode 28 is connected to the collector of the first pnp transistor 29 and one of the terminals of the resistor 30, the other terminal of which is connected to the base of the first pn p of the transistor 29 and the collector of the second pnp of the transistor 31, the base of which is connected to the emitter of the first pnp of the transistor 29 and one of the terminals of each of the resistors 32, 33, 34, the other terminals of the resistors 32, 33, 34 are connected each with the cathode of its diode 35, 36, 37. The anodes of the diodes 35, 36, 37 are connected respectively to the output marked with the letters c, d, e. The emitter of the second pnp transistor 31 is connected to the cathode of the diode 38, and the anode of the diode 38 is connected to the outputs indicated by the letters a and b.

In order for the limiting of the inflowing and outflowing currents to occur at the same level, the resistances of the resistors of both channels connected to the outputs of the same name, indicated by the letters c, d, e, must be equal, i.e.

Let the electrode 8 having a minimum area S _min , to which the jumper shown in dashed line in the diagram of Fig. 2, is connected to the limiter of the current density of the action current.

The resistance of the resistor 20 R _{20 is} calculated by the formula (2)

where U _be - voltage saturation base-emitter of the second transistor 19;

I _max (S _min ) is the maximum allowable current for the electrode 8 having a minimum area S _min ; calculated by the formula (3)

where Is _max - the maximum allowable current density under the electrode, equal to 0.1 mA / cm ² [1].

Assuming the pitch reference electrode area equal to S _min, choose R ₂₁ = R _20/2 and R ₂₂ = R _20/4.

Using jumpers installed between pin b and three contacts c, d, and e of a multi-pin cable connector for each electrode, it is possible to code its area (and, accordingly, the current limit for this area) in the range from S _min to S _max = 7 · S _min , with a step equal to S _min . If it is necessary to reduce the step of setting the electrode area or increasing the range of setting the area of the electrodes, S _max / S _min , increase the number of contacts of the multi-pin connector of the lead cable of each of the electrodes used to encode the area of the electrode.

Device for electrotherapy works as follows. The voltage from the impact signal conditioner 2 is fed to the input of the influence amplitude level regulator 3, where the nursing staff sets the level of the amplitude of the current or voltage coming further from its outputs through the current density limiters 4-5 and, accordingly, the contacts (a) of the pairs of multi-contact connectors 6, 12-7, 13 through lead cables 10-11 to the electrodes 8-9.

If, due to a mistake in the medical staff or due to a malfunction of the exposure signal conditioner 2 or the exposure amplitude level 3 regulator, the amplitude of the outgoing current in the circuit of the electrode 8, which has a smaller area, arrives at the input of the exposure density limiter 4, exceeds the maximum value of I _max ( S _min), the voltage drop across resistor 20 applied to a transition base - emitter voltage of the second n-p-n transistor 19 opens and introduces it into saturation, the collector - emitter of transistor 19 is reduced, lowering the voltage ix applied to a transition base - emitter voltage of the first n-p-n transistor 17, closing the latter so that the current flowing from its emitter is limited to I _max (S _min). Similarly, if the level or amplitude of the incoming current in the circuit of the electrode 8, having a smaller area, supplied to the input of the current density limiter 4, exceeds the maximum value I _max (S _min ), then the voltage drop across the resistor 32 applied to the base-emitter junction of the second the pnp of the transistor 31 opens and enters it into saturation mode, the collector-emitter voltage of the transistor 31 decreases, lowering the voltage applied to the base-emitter junction of the first pnp of the transistor 29, closing the latter so that the current flowing into his emitt p, is limited to I _max (S _min).

For the electrode 9, which has a larger area than that of the electrode 8, current limitation in the current density limiter does not occur 5 because the voltage drop created by the flow of current I _max (S _min ) through parallel-connected resistors 20-22 (for current flowing into the electrode) or 32-34 (for current flowing from the electrode) is not enough to open transistors 19 or 31, respectively.

Thus, the proposed device for electrotherapy in all cases ensures the safety of the patient during the procedure both with errors of the medical staff when setting the intensity of exposure, and with malfunctioning of the shaper of the exposure signal or the level of the amplitude of the exposure.

USED SOURCES

1. A brief introduction to electrotherapy. Phisiomed Elektromedizin, Schnaittach-Laipersdorf, Germany. First printed 1995; Reprinted 1997, 1999, 2000.

2. The device for electrical muscle stimulation EMC-30-1 “Stimulus-1”, passport 1979

3. Electrical stimulator universal ESU-2, passport V / O “Medexport”.

4. Low-frequency therapy apparatus “Amplipulse-5”, passport V / O “Medexport”.

5. Electrical stimulator according to A.S. USSR SU No. 1819632 A1, class A 61 n 1/36, D.I.Dolgiy and M.V. Lukyanov, publ. 06/07/93, bull. No. 21 is a prototype.

Claims (1)

A device for electrotherapy, containing electrodes and a serially connected shaper of the exposure signal and a regulator of the level of the amplitude of the impact, characterized in that it additionally introduced serially connected limiters of the current density of the exposure by the number of patient electrodes and multi-contact connectors for connecting electrodes connected between the level of the amplitude of the exposure and the electrodes and each electrode is connected to the output of its current density limiter through its first contact of multicontact connector, the other connector contacts from the electrodes are provided with webs for various values of the area of the electrodes, on the other hand are connected to inputs of their impact limiters current density.

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