RU2183946C2 - Device for treating biological tissue with plasma - Google Patents

Abstract

FIELD: medicine. SUBSTANCE: device has anode unit and cathode unit separated with insulating inserts and connected to power supply source. Space between electrodes built by anode and cathode unit electrodes communicates with air supply source by means of main tube. The cathode electrode is thermochemical cathode press-fitted flush into holder manufactured from heat-insulating and current-conducting material. EFFECT: enhanced effectiveness of treatment; controlled air plasma flow stability. 12 cl, 5 dwg

Description

 The invention relates to medicine, in particular medical equipment, and relates to a device for exposure to plasma on biological tissue.

 Currently known devices for plasma exposure to biological tissue, which are very limitedly used in surgery, for example, abdominal, thoracic, purulent, burn, in liver and spleen surgery, in urology and oncological surgery, etc. mainly for bloodless dissection of biological tissues, coagulation of extensive diffusely bleeding wound surfaces, thermal destruction of pathologically altered biological tissues, sterilization of infected wounds, etc.

 For example, a plasma arc scalpel is known for dissecting and simultaneously coagulating biological tissue (see US Pat. No. 3,991,764). The scalpel contains a cylindrical body with a tubular anode placed therein. Inside the anode, concentric with respect to it, is the cathode. Between the cathode and the anode there is a shell that allows the coolant to flow through separate channels to cool the latter. In addition, for longitudinal movement of the cathode and bringing it into contact with the anode, a plunger is provided with which an electric arc is ignited. After ignition of the arc, the inert gas flowing through it leaves the small anode hole in the form of a hot plasma jet and at the same time has a temperature sufficient for simultaneous dissection and coagulation of living biological tissue.

 However, the above-described device, due to its implementation according to a two-electrode circuit, is not able to provide a stable and reproducible effect on biological tissue. The instability of the plasma flow flowing from the output channel of the device, and often its complete disappearance due to arc shunting, significantly complicates the surgeon's work, reduces the effectiveness of the plasma exposure, and sometimes makes it impossible to perform the operation. Shunting processes are especially active at low plasma-forming gas consumption, but an increase in it in surgical devices is impossible due to the increased likelihood of a gas embolism, drying of the surgical field, blood spatter, etc.

 In addition, two-electrode plasma devices with a self-stabilizing arc length due to low efficiency are not able to provide highly enthalpy plasma flows, often necessary for effective surgical intervention.

 The use of the proposed device in practical medicine requires either in the apparatus itself or in the operating or preoperative rooms at least one cylinder with a supply of argon, as well as the need for periodic renewal of the supply of consumed gas, which is argon. It should be noted that the smaller the volume of the vessel with argon, the more often it needs to be replaced.

 In addition, the use of an inert gas as a working plasma-forming substance limits or makes it impossible to use the proposed device in military field surgery and in disaster medicine.

 Another device is known for exposing plasma to biological tissue (see, for example, US Pat. No. 3,434,476).

 This device comprises a cylindrical body, which is an anode, at the working end having an outlet opening in communication with an internal channel in which a pointed central electrode, which is a cathode, is axially located. The housing has an internal concentric channel into which water is supplied to cool the anode. In addition, the device is equipped with an external tube (sheath) concentric with respect to the housing, forming with the latter an annular channel ending at the working end with an aperture concentric with the anode outlet. An inert gas is supplied through the internal (axial) channel — argon or helium, which forms a plasma jet when an electric arc is ignited between the cathode and anode from a DC power source. To control the shape of the plasma jet, cold gas is supplied through an external annular channel with a flow rate that provides a flow rate at the outlet of it greater than the flow rate of hot ionized argon or helium.

 Because the design described above is similar to the design of a plasma arc scalpel (see US Pat. No. 3,991,764), it has all the drawbacks inherent in the plasma tissue application apparatus described in US Pat. No. 3,991,764, namely, the instability of the plasma flow acting on the tissue (2-electrode scheme) and the use of an inert gas (argon or helium) as a working plasma-forming substance. The use of a cold gas mantle claimed in the patent for controlling the shape of a plasma jet does not eliminate the noted drawbacks of the device, but, on the contrary, only exacerbates them due to an increased risk of gas embolism.

 Thus, at present, none of the known devices for plasma exposure to biological tissue due to the use, firstly, of imperfect (non-optimal) technical solutions and, secondly, the use of inert gases, which are consumable components, as a working plasma-forming gas, found wide application in practical medicine, in particular surgery.

 The present invention is the creation of such a device for plasma exposure to biological tissue, which due to the structural design of the cathode assembly would allow the use of atmospheric air as a working plasma-forming gas and at the same time significantly increase the stability of the plasma flow acting on the tissue.

 This problem is solved in that in a device for plasma exposure to biological tissue containing an anode assembly made in the form of a hollow cylinder, which is the body of the entire device, with an output channel at its working end; a cathode assembly having a holder made in the form of a hollow cylinder of an electrically conductive material coaxially mounted in the housing using insulating inserts, and an electrode fixed to its working end; a power source to which both nodes are connected, and a cooling system, wherein the interelectrode space formed by the cathode electrode and the anode at its working end is connected via a line to a source of working plasma-forming gas, according to the invention, the cathode electrode is a thermochemical cathode, pressed flush into the holder made of heat-conducting and electrically conductive material, and air is used as a working plasma-forming gas.

 This design of the thermochemical electrode allows the use of ordinary atmospheric air as the working plasma-forming gas, as a result of which there is no need for cylinders to store inert gas, periodically replenishing the spent working substance, which, in turn, due to the autonomy of the device to increase its convenience and economy operation and the possibility of effective use of the device in field surgery and disaster medicine.

 The cooling system of the cathode and anode assemblies may include a heat sink that is made in the form of a sleeve mounted coaxially in the housing between the insulating inserts and covering the cathode holder in the immediate vicinity of the cathode electrode, as well as a cylindrical screen made of insulating material and located between the radiator and the housing .

 It is advisable, in the immediate vicinity of the inner surface of this sleeve, to carry out at least two through channels or two longitudinal flats forming channels with the screen for circulating coolant.

 This design of the cooling system of the cathode assembly provides efficient heat removal from the cathode holder and normalization of the temperature state of the electrode, which leads to a significant decrease in the rate of erosion of the cathode, eliminates the possibility of switching to a mode with intense erosion of the cathode insert, and allows hydraulically combining the cooling systems of the anode and cathode assembly, which, in turn, reduces the transverse size of the entire device.

 The device can be equipped with an interelectrode insert made in the form of a sleeve mounted coaxially in the housing in the interelectrode space between the cathode electrode and the anode and electrically isolated from them, and it is advisable to provide the interelectrode insert with its own cooling system hydraulically connected to the cooling system of the cathode and anode assemblies.

 The interelectrode insert provides stable burning of the electric arc in the interelectrode gap, which makes it possible to obtain an air-plasma stream that is stable in time and space, acting on biological tissue, at almost any and, most importantly, low consumption of working gas - atmospheric air, which, in in turn, minimizes the risk of gas embolism.

 The above technical result is also achieved by the fact that the device for plasma exposure to biological tissue containing an anode assembly made in the form of a hollow cylinder, which is the body of the entire device, with an output channel at its working end, a cathode assembly having a holder made in the form of a hollow cylinder from an electrically conductive material coaxially mounted in the housing using insulating inserts, and a cathode electrode fixed to its working end, a power source to which the anode connection is connected l and the cathode assembly and the cooling system, the interelectrode space formed by the cathode electrode and the anode at its working end being connected via a line to a source of working plasma-forming gas, in accordance with the invention, further comprises an interelectrode insert made in the form of a sleeve mounted coaxially in case in the interelectrode space between the cathode electrode and the anode and electrically isolated from them, the cathode electrode is a thermochemical cathode, pressed up to the holder made of heat-conducting and electrically conductive material, air is used as the working plasma-forming gas, the cooling system that provides cooling of the cathode and anode assemblies contains a heat sink that is made in the form of a sleeve mounted coaxially in the housing between the insulating inserts and covering the cathode holder in the immediate vicinity of the cathode electrode, as well as a cylindrical screen made of insulating material and located between the radiator and body.

 In this case, the sleeve may have at least two longitudinal flats forming channels with the inner surface of the screen, or at least two through longitudinal channels designed to circulate the coolant and passing in the immediate vicinity of its inner surface, and the interelectrode insert may be provided with its own a cooling system hydraulically connected to the cooling system of the cathode and anode assemblies.

 The device in both variants of its implementation can be equipped with a removable sterile cover that completely covers the body of the device.

 Such a case, sterilized by traditional methods separately from the device and worn on it immediately before surgery, ensures compliance with aseptic requirements during the operation of the surgeon.

The invention is further illustrated by the example of a preferred embodiment, illustrated by the drawings, which show the following:
figure 1 - schematic representation of the inventive device for exposure to plasma on biological tissue, General view, a longitudinal section;
figure 2 is a section along the line II-II in figure 1;
figure 3 is a section along the line III-III in figure 1;
figure 4 is a top view of the device of figure 1;
figure 5 is a section along the line VV in figure 1.

 A patented device for plasma exposure to biological tissue contains an anode assembly 1 (Fig. 1) and a cathode assembly 2, connected respectively to the positive and negative terminals of power supply 3.

 The anode assembly 1 is made in the form of a cylindrical body 4 with a working conical end 5, inside of which the anode 6 with an output cylindrical channel 7 is placed.

 The cathode assembly 2 is located coaxially in the housing 4 and is a cylindrical holder 8, on the working end of which is placed the actual electrode 9, pressed flush into the holder 8 and made of electrically and thermally conductive material, for example, copper. Inside the holder 8 there is a cylindrical channel 10, on the one hand connected via a line 11 with a source of working plasma-forming gas (not shown in the figures), which uses atmospheric air, and on the other hand communicates via radial channels 12 with the interelectrode space 13. Cathode electrode 9 is a thermochemical cathode made of a material of group IV of the periodic system, a subgroup of titanium IV B, for example, hafnium.

 The cathode assembly 2 is mounted coaxially in the cylindrical housing 4 of the anode assembly 1 using cylindrical insulating inserts 14 and 15 made of dielectric material, for example, plexiglass, on each of which there are two diametrically oppositely located flats 16, 16 'and 17, 17', respectively (Fig. 2 and Fig. 3), forming channels 18, 18 ', 19, 19', intended for the circulation of coolant in the cooling system of the anode 6, the supply and removal of which is through cylindrical channels 20 and 20 '(Fig. 3 and 4). In the simplest case, water can be used as a coolant.

 In the housing 4 (Fig. 1) of the anode assembly 1, a radiator is installed coaxially between the insulating inserts 14 and 15, which serves to remove heat from the cathode holder 8, made in the form of a sleeve 21 of heat-conducting material, for example, copper, and covering the cylindrical surface of the cathode holder 8 in the immediate proximity to the cathode electrode 9 with a minimum radial clearance to ensure optimal thermal contact between them. To prevent electrical contact between the radiator (21), which is under the potential of the cathode, and the housing 4, which is under the potential of the anode, the device has a cylindrical screen 22 made of dielectric material, such as plexiglass, and mounted coaxially between the radiator (21) and the case 4 . On the outer cylindrical surface of the sleeve 21 (figure 5) there are two diametrically oppositely located flats 23 and 23 ', forming channels 24 and 24' with the inner surface of the screen 22, intended for circulation about coolant in the cooling system of the cathode assembly 2.

 The sleeve 21 may have two diametrically opposed longitudinal channels extending in the immediate vicinity of its inner surface, intended for circulation of the coolant in the cooling system of the cathode assembly 2. This embodiment of the cooling of the cathode assembly is not shown in the figures.

 In the interelectrode space 13 (Fig. 1 and Fig. 3), an interelectrode insert 25 is arranged coaxially between the cathode assembly 2 and the anode assembly 1, made in the form of a sleeve of electrical and heat-conducting material, for example, copper, electrically isolated from them using an insulating insert 15, a cylindrical screen 22 and a high-temperature seal 26 made, for example, of silicone rubber.

 On the outer cylindrical surface of the interelectrode insert 25 there are diametrically opposed flats 27 and 21 '(Fig. 3), forming channels 28 and 28' with the inner surface of the screen 22, intended for circulation of the cooling liquid in the cooling system of the interelectrode insert 25.

 The cooling systems of the interelectrode insert 25, the cathode assembly 2 and the anode 6 are hydraulically connected to each other via channels 20, 18, 19, 24, 28 and 20 ', 18', 19 ', 24', 28 ', the circulation of the coolant through which is ensured annular cavity 29 (figure 1 and figure 3) around the anode 6.

 To comply with aseptic requirements, the patented device is equipped with an easily removable and put on sterile cover 30 (Fig. 1), made in the form of a thin-walled cylindrical tube 31 with a conical end 32 and an opening 33 in it, completely covering the outer surface of the anode assembly 1, and the cover 30 can be both disposable and reusable. To simplify the drawings, the case 30 is shown only in figure 1.

 The device for exposure to plasma on biological tissue, shown in Fig.1-5, works as follows.

 Before starting operation, the device is connected to flexible electro-gas lines, switching it with power supply, cooling and plasma working gas supply systems, which use atmospheric air (these communications are not shown in the figures). Before starting work - a surgical operation - a sterile cover 30 is put on the device and fixed on it so that the end surfaces of the conical end 5 of the anode assembly 1 and the conical end 32 of the cover 30 are at the same level (in one plane), and the outer surface of the cylindrical body 4 would be completely closed by a cylindrical tube 31 of the cover 30, which ensures compliance with aseptic requirements during the operation of the surgeon.

 Next, coolant is supplied, which through channels 20 and 18 enters the channel 24, through which it flows along the radiator (21), cools it, and through the channel 19 enters the channel 28, through which it flows along the interelectrode insert 25, cools it and enters the annular cavity 29 around the anode 6, cools it and is removed from the device through diametrically opposed channels 28 ', 19', 24 ', 18' through a cylindrical channel 20 '.

 The combination of cooling systems of the interelectrode insert 25, cathode 2 and anode 1 nodes into a single, hydraulically coupled system allows for a minimum transverse dimension of the device and a small flow rate of the coolant to effectively remove heat from all of the mentioned structural elements, which ensures a long service life and also maintain "comfortable" for the surgeon's hand temperature of the outer surface of the housing 4 of the entire device.

 When the cooling system is in good condition (tightness), a working plasma-forming gas is supplied - atmospheric air and at the same time the device’s power supply system is turned on.

 Plasma-forming gas through line 11 through a cylindrical channel 10, the radial channels 12 of the cathode assembly 2 enters the interelectrode space 13 and from there into the outlet cylindrical channel 7 of the anode 6.

 Simultaneously with the supply of a plasma-forming working gas from the power supply 3, anode voltage 1 and cathode power 2 are supplied with the supply voltage of the device. Between the end face of the holder 8 with the cathode 9 pressed into it and the inner cylindrical surface of the output channel 7 of the anode 6, an auxiliary high-voltage pulse discharge is initiated, which stimulates the ignition of the main arc between the thermochemical cathode 9 and the anode 6. The interelectrode insert 25, which is essentially the third electrode under "floating" potential, fixes the average length of the arc, thus ensuring stable operation of the device with an arc length greater than self-settling, and excludes the development of the process and shunting, providing stable arc burning at low (almost any) flow rates of the working gas and stable outflow of air-plasma stream from the output channel 7 with the plasma flow parameters necessary for surgical treatment at low operating discharge currents and high electrical efficiency of the device.

 Thus, for the first time in domestic and world practice, a device has been created for plasma exposure to biological tissues, which due to its design and use of atmospheric air as a plasma-forming gas allows not only to remove the obstacles that stand in the way of the development of traditional "plasma" surgery associated with the use of technically imperfect 2 electrode devices or requiring consumable working substances - inert gases for their work, but also significantly expand the use of plasma devices in medicine, in particular in field surgery and disaster medicine.

 Prototypes of the patented device have successfully passed clinical trials in the departments of thoracic, abdominal, purulent surgery, in the trauma departments of civil and military medical institutions, as well as in specialized oncology clinics, which confirmed its high performance.

 It is noted that the device reliably provides the generation of a stable air-plasma flow in time and space at any and, most importantly, low working gas flow rates, which eliminates the occurrence of gas embolism, drying of the surgical field, blood spatter, etc., allows you to effectively perform bloodless dissection of biological tissues, coagulation of extensively bleeding wound surfaces, destruction of pathologically altered tissues, sterilization of infected wounds. In addition, in clinical trials of the device, a new effect of plasma-dynamic non-drug stimulation of reparative regeneration was discovered, leading to accelerated healing of complicated wounds of almost any origin.

 Of particular note is the small size and weight of the equipment, ease of operation and maintenance, safety for the patient and staff.

 Clinical testing of the patented device was carried out in the treatment of gunshot wounds in the conditions of the Special Medical Unit (696 MOSN, Mozdok). The device is recommended for adoption for the supply of the Armed Forces of the Russian Federation and the organization of mass production.

Claims (12)

 1. A device for plasma action on biological tissue containing an anode assembly (1), made in the form of a hollow cylinder (4), which is the body of the entire device, with an output channel (7) at its working end (5), a cathode assembly (2) having a holder (8), made in the form of a hollow cylinder of an electrically conductive material, coaxially mounted in the housing (4) using insulating inserts (14.15), and a cathode electrode (9) fixed to its working end, a source (3) power supply, to which the anode assembly (1) and the cathode assembly (2) are connected, and the cooling system moreover, the interelectrode space (13) formed by the cathode electrode (9) and the anode (6) at its working end (5) is connected via a line (11) to the source of the working plasma-forming gas, characterized in that the cathode electrode (9) is a thermochemical cathode pressed flush into the holder (8) made of heat-conducting and electrically conductive material, and air was used as the working plasma-forming gas.  2. The device according to claim 1, characterized in that the cooling system comprises a heat sink for heat removal, made in the form of a sleeve (21) installed coaxially in the housing (4) between the insulating inserts (14.15) and covering the cathode holder (8) in close proximity to the cathode electrode (9), as well as a cylindrical screen (22) made of insulating material and located between the radiator and the casing (4).  3. The device according to claim 2, characterized in that the sleeve (21) has at least two longitudinal flats (23.23 ') forming channels (24.24') with the inner surface of the cylindrical screen (22) for circulation coolant.  4. The device according to claim 2, characterized in that the sleeve (21) has at least two through longitudinal channels for circulating coolant and passing in the immediate vicinity of its inner surface.  5. The device according to claim 1, characterized in that it is provided with an interelectrode insert (25) made in the form of a sleeve mounted coaxially in the housing (4) in the interelectrode space (13) between the cathode electrode (9) and the anode (6) and electrically isolated from them.  6. The device according to p. 5, characterized in that the interelectrode insert (25) is equipped with its own cooling system, hydraulically connected to the cooling system of the cathode (2) and anode (1) nodes.  7. The device according to any one of paragraphs. 1-6, characterized in that it is provided with a removable sterile cover (30), completely covering the body (4) of the device.  8. A device for plasma action on biological tissue containing an anode assembly (1) made in the form of a hollow cylinder (4), which is the body of the entire device, with an output channel (7) at its working end (5), a cathode assembly (2) having a holder (8), made in the form of a hollow cylinder of an electrically conductive material, coaxially mounted in the housing (4) using insulating inserts (14.15), and a cathode electrode (9) fixed to its working end, a source (3) power supply, to which the anode assembly (1) and the cathode assembly (2) are connected, and the cooling system moreover, the interelectrode space (13) formed by the cathode electrode (9) and the anode (6) at its working end (5) is connected via a line (11) to the source of the working plasma-forming gas, characterized in that it further comprises an interelectrode insert (25) ), made in the form of a sleeve mounted coaxially in the housing (4) in the interelectrode space (13) between the cathode electrode (9) and the anode (6) and electrically isolated from them, the cathode electrode (9) is a thermochemical cathode pressed flush into holding spruce (8) made of heat-conducting and electrically conductive material, air is used as the plasma-forming gas, the cooling system contains a heat sink for heat dissipation, made in the form of a sleeve (21) mounted coaxially in the housing (4) between the insulating inserts (14.15) ) and covering the cathode holder (8) in the immediate vicinity of the cathode electrode (9), as well as a cylindrical screen (22) made of insulating material and located between the radiator and the casing (4).  9. The device according to p. 8, characterized in that the sleeve (21) has at least two longitudinal flats (23,23 ') forming channels (24, 24') with the inner surface of the cylindrical screen (22) for circulation coolant.  10. The device according to p. 8, characterized in that the sleeve (21) has at least two through longitudinal channels for circulating coolant and passing in the immediate vicinity of its inner surface.  11. The device according to any one of paragraphs. 8-10, characterized in that the interelectrode insert (25) is equipped with its own cooling system, hydraulically connected to the cooling system of the cathode (2) and anode (1) nodes.  12. The device according to any one of paragraphs. 8-11, characterized in that it is provided with a removable sterile cover (30), completely covering the body (4) of the device.

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