Plasma probe

Abstract

To provide an improved instrument for argon plasma surgery with a low environmental burden.SOLUTION: An instrument 10 comprises a hose 15 and a conductor 17, the conductor being formed by a thread of carbon fibers 23 or including carbon fibers. The carbon fibers serve for thermal cooling of a plasma foot point that forms directly at the end of the conductor at the carbon fibers or in a compact body in contact with the conductor. The conductor is arranged inside a lumen 16 of the hose without forced contact with the inner wall of the hose. The high thermal conductivity of the conductor in the longitudinal direction results in low thermal stress of the hose and provides high durability of the instrument. By this construction, the instrument can be provided with halogen-free plastics, and thermal disposal of the instrument after use causes no problems. This applies when the instrument is configured to contain no metal or substantially no metal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an instrument for performing surgical procedures on a human or animal patient. In particular, the instrument according to the invention is useful for argon plasma coagulation of living tissue. [Background technology]

[0002] An instrument for tissue coagulation configured as an argon plasma probe is known from EP 3769707 A1. This probe comprises a flexible plastic hose with a lumen extending along its entire length. A supply device is connected to the proximal end of the hose, through which argon can be supplied, flowing through the hose toward the distal end. An electrical conductor is arranged inside the hose, and at the proximal end of the instrument, the conductor is also connected to a pole of a generator contained within the device, thus providing an electrical high-frequency voltage for plasma generation. The other pole of the generator is connected to a neutral electrode. The electrical conductor extends through the lumen of the hose to an electrode, which is formed by a metal platelet supported on both diametrically opposed edges of the inside of the hose, thus providing a central support. The distally facing tip of the electrode provides an electrical discharge, thus ionizing the passing argon stream and generating a plasma stream.

[0003] To reduce thermal stress in the hose due to improved electrode cooling, the electrodes are provided with coatings that support heat distribution and heat transfer to the passing gas stream. However, the electrodes create significant thermal stresses in plastic hoses, necessitating the use of thermally robust plastic materials for the hoses. Such plastic materials often contain chlorine or fluorine compounds, which can cause difficulties in disposing of such equipment. In particular, the combustion of such materials can produce substances that can pose significant environmental and health hazards due to their toxicity and / or durability.

[0004] A low-temperature plasma device is known from US 2021 / 0145499 A1, which has an outlet nozzle through which the plasma is electrically drawn out. Aluminum or graphene are also considered as materials for the electrodes.

[0005] Additionally, from the general industry it is known to form small electrodes from graphite, for which reference is made to EP 0 476 572 A1 and JP 2018-098122 A1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent Application Publication No. 3769707 [Patent Document 2] U.S. Patent Application Publication No. 2021 / 0145499 [Patent Document 3] European Patent Application Publication No. 0476572 [Patent Document 4] Japanese Patent Application Publication No. 2018-098122 Summary of the Invention [Problem to be solved by the invention]

[0007] Starting from the above, it is an object of the present invention to provide an appliance with a low environmental impact. [Means for solving the problem]

[0008] This object is solved by an apparatus according to claim 1.

[0009] The instruments according to the present invention are configured for medical treatment of living tissue. Preferably, the instruments are configured as flexible probes that can be inserted into a patient's body through the working channel of an endoscope. However, the instruments can also have a rigid, inflexible shank and a handle at the proximal end for use as, for example, a laparoscopic instrument. Optionally, the instruments can also be configured with a handle having a short shank for open surgical use.

[0010] The instrument preferably comprises a hose configured to be flexible for endoscopic use. If the instrument is configured as a laparoscopic instrument, the hose may also be configured as a rigid tubular shank. This also applies if the instrument is configured for open surgical use.

[0011] A lumen extends through the hose, extending from the proximal end to the distal end of the hose. A connection means is provided at the proximal end so that the hose can be connected to a gas source to provide a gas flow to the lumen. Additionally, an electrical connection configured to provide an electrical current in the electrical conductors extending through the lumen to the distal end of the hose is provided at the proximal end. A combined connector can function as the connection means and the electrical connector, including a gas connection pin and at least one electrical pin. However, the electrical connection can also be configured separately from the gas connection means as a separate connector.

[0012] The conductor terminating in or at the outlet opening is made entirely or partially of or comprises carbon fiber. Carbon fiber has a high thermal conductivity and is therefore suitable for dissipating heat introduced into the end of the conductor by the plasma accumulating therein in a proximal direction, away from the distal conductor end, and distributing the heat over most of its length, an amount that is a multiple of the conductor's diameter. Gas passing through the conductor in the reverse direction then contributes efficiently to cooling. This results in a conductor temperature that is lower than would be tolerated by plastics that are not high-temperature resistant. As a result, the hose can be made of low-temperature resistant plastic, particularly a halogen-free plastic. The plastic can be particularly chlorine-free and / or fluorine-free. This allows for simple and environmentally friendly disposal of used equipment by combustion. During combustion, no long-lasting, toxic, or otherwise environmentally harmful substances are produced.

[0013] This also applies in relation to electrical conductors that consist of, or at least contain, relevant amounts of carbon fibers, which can also be oxidized to CO2 without producing problematic chemicals, metals or metal oxides.If desired, devices according to the invention can be free of nickel, chromium, molybdenum, cobalt, silver, copper or other expensive or toxic metals, especially heavy metals.

[0014] The carbon fibers, when oriented primarily in the luminal direction, correspond to the thermal conductivity of the conductor, and therefore the thermal conductivity of the conductor is substantially along the longitudinal direction of the fibers, i.e., in the direction of the preferred thermal conductivity of the carbon fibers.

[0015] The carbon fibers can be embedded in a rigid body. However, it is preferred to configure the conductor as a thread, strand, twisted thread, cord, or string. The carbon fibers can also be provided as a spun-around roving, a braided string, or as fibers adhesively connected to one another, either wholly or only partially. The conductor thus formed is flexible and can therefore adapt to any bends in the hose without resistance.

[0016] The yarn can be a multifilament yarn consisting of several monofilaments, each containing many carbon fibers that extend continuously over the entire length of the conductor. However, this does not completely exclude the individual carbon fibers from having shorter lengths.

[0017] However, it is also possible to use staple fiber yarns made of carbon fibers with a limited length that is shorter than the entire length of the conductor. In any case, good heat transfer in the longitudinal direction of the conductor is achieved due to the strong lateral contact between the fibers, e.g., resulting from the spinning process.

[0018] The conductor can have a constant cross-section throughout its entire length, and the conductor can include or consist of carbon fiber from its proximal end to its distal end. In such cases, the instrument according to the present invention can be particularly easily adapted to the desired length required for a particular use. For example, the instrument can be provided in a standard length equal to the maximum required length (e.g., 3 m). If a shorter length of the instrument is needed, a section can be separated from the distal end, thereby making the instrument immediately ready for use. Also, instruments with used ends, e.g., instruments damaged thermally or due to tissue buildup, can be quickly made ready for use again by minimal shortening, which means cutting off the damaged end.

[0019] In both cases mentioned above, the conductor containing or made of carbon fiber not only serves to conduct current along the length of the device. Rather, its distal end serves as an electrode for supplying the plasma. Because argon flows around the conductor, thus keeping oxygen away from it, the carbon fiber exhibits a long life and does not exhibit interference erosion. Also, centering of the conductor inside the lumen is not required, so thermal stresses in the hose at its distal end in the plasma region remain low.

[0020] It should be noted that a metal electrode can be attached to the distal end of a conductor made of or containing carbon fibers. For example, this electrode can be an uncoated stainless steel electrode, a silver-coated stainless steel electrode, a graphite electrode, an electrode made of a material with good thermal conductivity properties such as tungsten carbide (a hard metal), or an electrode made of tungsten. The electrode can be a brush, a pen with a pointed or blunt end, a needle, a loop, or another suitable type of shape.

[0021] Regardless of the material properties of the conductor and the configuration of the distal end, the conductor can have a proximal section formed by a metallic conductor, such as aluminum wire, steel wire, or wire made of another metal. Aluminum or steel wire construction has the advantage that no toxic residues are produced during combustion of the used instrument. Iron, iron oxide, aluminum, and aluminum oxide are considered harmless residues.

[0022] The conductor is preferably provided with an insulating material that forms the inner insulation of the device, while the hose is the outer insulation. Preferably, the insulating material extends over the entire length of the conductor, thus ensuring its insulating strength. Therefore, the insulating material is preferably made of a plastic from the polyimide group. Other plastics with high insulating capacity and low electrical loss angles can also be used.

[0023] If the conductor is wrapped with a suitable material for electrical insulation, such as a polyimide plastic band, the flexibility of the conductor is not significantly affected, and the instrument remains very flexible. Therefore, this conductor can also be used in endoscopes where these instruments require large bending.

[0024] The winding is preferably cross-wound, meaning that one winding is wound around the conductor in a right-handed spiral, while the layer above or below it is wound in a left-handed spiral. This may slightly reduce the flexibility of the conductor, but this supports electrical insulation. However, the flexibility of the conductor is still sufficient to allow the instrument to bend inside the endoscope.

[0025] The conductor is preferably supported within the lumen so that it can move radially, i.e., preferably along its entire length, including its distal end. It has been shown that precise centering of the conductor inside the lumen can be omitted. However, the omission of centering also omits heat-conducting contact between the conductor and the hose, which helps with thermal relaxation of the hose. Therefore, the hose can be made of an environmentally friendly plastic, such as a plastic from the group of polylactides or, if applicable, a plastic from the group of silicone plastics.

[0026] The elimination of centering devices, particularly at the distal end of the instrument, also means that the instrument can be shortened if necessary, i.e., simply cut, and the cut surfaces of the cut conductors form the electrodes.

[0027] The hose can also consist of plastics from the group of polylactides or silicones. Preferably, the polymers for the manufacture of the hose are obtained from renewable raw materials with a neutral CO2 footprint.

[0028] Further details of advantageous embodiments of the invention emerge from the dependent claims, the figures and the associated description. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic view of an appliance according to the invention connected to a delivery device; [Figure 2] 2 is a longitudinal cut-away view through the distal end of the device according to FIG. 1, not drawn to scale. [Figure 3] 2 is a front view of the device according to FIG. 1, not drawn to scale; [Figure 4] 1 is a longitudinal cutaway view, not drawn to scale, of a modified embodiment of an instrument according to the invention; FIG. [Figure 5] 10 is another longitudinal cutaway view, not drawn to scale, of a modified embodiment of the device according to the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0030] FIG. 1 shows an instrument 10 configured as a flexible probe having a distal end 11 that can be inserted into a patient through a working channel of an endoscope (not shown) and thus moved to a surgical site. Additionally, the instrument includes a proximal end 13 provided with a connecting means, e.g., a connector 12. However, unlike the illustration, the instrument 10 can also be configured as a laparoscopic instrument or as an instrument for open surgical use. When the instrument is configured as a flexible probe as shown in FIG. 1, the instrument includes a hose 15 extending from the proximal end 13 to the distal end 11. When the instrument is a laparoscopic instrument, the hose can be configured as a tube shank, i.e., a rigid tube, particularly in its distal portion. This also applies to instruments provided for open surgical use.

[0031] Preferably, hose 15 is made of a plastic from the polylactide group or the silicone group. A lumen 16 extends through hose 15 from proximal end 13 to distal end 11, and has an electrical conductor 17 disposed therein. Conductor 17 extends the entire length of lumen 16.

[0032] A connector 12 connected to the proximal end 13 serves to connect to a supply device 18 including a source 19 of gas for supplying the lumen 16. The source 19 may comprise, for example, an argon reservoir and a pressure control armature and valve for supplying the desired volumetric flow rate of the respective gas, e.g., argon, to the lumen 16 in a controlled manner.

[0033] Additionally, the device 18 includes a generator 20 having an output pole connected to the conductor 17 by a connector 12. Another output pole of the generator 20 is connected by another connector 21 and a wire having a neutral electrode 22 which is generally connected to the patient being treated.

[0034] The generator 20 is configured to generate a high-frequency high voltage suitable for plasma generation, which can have a magnitude of several hundred volts peak-to-peak. The frequency of the high voltage is preferably between 100 kHz and 5 MHz, typically about 350 kHz. Other frequencies are possible within this range. The voltage can be provided unmodulated and pulseless (CW). The generator can also be configured to provide the high voltage in a modulated form, meaning modulated with a square wave having a constant or variable pulse-to-pause ratio, e.g., in an on-off switched fashion. The modulation frequency can be less than 100 kHz.

[0035] In this embodiment, the conductor 17 is a thread made of carbon fibers 23. The carbon fibers 23 may be twisted, twisted, braided, or otherwise connected and held together, thereby configuring the carbon fibers 23 as monofilaments. The carbon fibers then extend the entire length of the device 10, from the connector 12 to the distal end 11 and the exit opening 24 therein. However, the carbon fibers 23 may also be shorter than the entire length of the hose 15, so that the thread formed therefrom is a staple fiber thread. Individual fibers may be spun together to form the thread.

[0036] In a preferred embodiment, the conductors made of carbon fiber 23 are electrically insulated. The insulating material 25 provided for this purpose can consist of a plastic with high electrical insulating capacity and a low electrical loss angle. For example, the insulating material can be selected from the group of plastics of polyimides.

[0037] Regardless of the material selected, the insulation 25 can take the form of a strip of material and can be wound around the conductor 17, which can be made of parallel carbon fibers 23, twisted fibers, braided fibers, or other connected fibers. The insulation 25 can be wound around the conductor 17 along a helical line. In a preferred embodiment, the winding of the insulation 25 follows a right-handed spiral, with a second layer following a left-handed spiral placed above or below. While the double winding provides the insulation 25 with slightly increased stiffness, it does not significantly increase the overall stiffness of the device 10. The windings forming the bandage of the conductor 17, which is made of carbon fibers 23, particularly the double counter-winding of the bandage, provide reliable electrical insulation of the conductor 17 in either case. As a result, the hose 15 can be constructed with a thin wall, since the primary insulation of the conductor 17 is already provided by the insulation 25.

[0038] 2 and 3, the carbon fibers 23 are not covered at the distal end of the conductor 17, for example in the form of a cut surface 30. The cut surface 30 and the respective end or cut surface 31 of the hose 15 can be arranged in a common plane or can be axially offset relative to one another. The ends can be regenerated at any time by shortening the device 10.

[0039] At their ends, the carbon fibers 23 form the electrodes 26 necessary for plasma generation. It is also clear that the lumen 16 is completely free. There is no centering element supporting the conductor 17 in the center of the lumen. Elements connected to the conductor 17 do not abut with pretension on the surface of the hose 15 surrounding the lumen 16. At most, the ends of the carbon fibers 23 protruding from the end of the conductor 17 can branch out in a brush-like fashion and come into contact with the wall. However, due to the electrical resistance provided, each carbon fiber only transmits a proportionate portion of the total current depending on the electrical resistance of the carbon fiber, so the few individual fibers with wall contact only provide a low thermal contribution.

[0040] The device described so far operates as follows.

[0041] To activate, connector 12 is connected to device 18, and instrument 10 is inserted into the patient, either directly or through the working channel of an endoscope. For treatment, source 19 is activated, causing a flow of argon to flow distally through channel 16. Simultaneously, or shortly thereafter, generator 20 is activated, resulting in a high voltage being applied to carbon fiber 23. A spark discharge is formed through the argon flow, thus creating a plasma flow toward the tissue to be treated. Current then flows from generator 17 through conductor 17, through the plasma and the patient's body, and back to generator 20 via neutral electrode 22.

[0042] If the tool 10 is thermally damaged in the area of ​​the outlet opening 24 despite its robustness, the tool 10 can be reset to a ready-to-use state again by shortening its distal end 11 by approximately a few millimeters or centimeters. This causes the hose 15 and the conductors 17 disposed therein to be cut in common to create new cutting surfaces 30, 31. As soon as the tool 10 is then operated again, the insulation 25 melts slightly backward, thereby exposing the carbon fibers 23, and the tool 10 can be operated again without restriction.

[0043] The same procedure can be performed if the instrument 10, which is supplied in a standard length, is too long and must be shortened, for example, by about one or several decimeters. The instrument can then be cut to the desired length, in that the excess length is separated from the distal end 11.

[0044] The used instrument 10 can be burned, as is typically done with hospital waste if it is not or cannot be recycled. In the described embodiment, the instrument contains no metallic elements, except possibly in the area of ​​the connector 12, and ultimately consists only of the elements carbon and hydrogen, and possibly additionally nitrogen and oxygen. Thus, the instrument can be burned to a non-hazardous residue. No toxic waste is produced, and no permanently resistant toxins are produced.

[0045] The device basically described so far can also be realized in modified form, as shown for example in Figure 4. The device 10 shown in Figure 4 comprises, over a significant section of its length, but particularly in the region of the outlet opening 24, a conductor 17 corresponding to the device 10 according to Figure 2 described above. Outside its distal section 11, the conductor 17 can also be formed by a metal conductor 26, for example by an aluminum wire, a steel wire, a stainless steel wire, etc. The length of the section of conductor 17 containing carbon fibre 23 is preferably at least as long as the section that must be severed maximally from the distal end of the device 10 in order to shorten it to the desired minimum length or to re-establish its functionality.

[0046] A crimp connection with a crimp ring 27 or another suitable connection means serves to connect to a conductor containing carbon fibers 23. The crimp ring 27 and the conductor 17 are preferably provided with an electrical insulation, not shown, which may be constructed similarly to the insulation 25 and may in particular consist of polyimide. For example, the insulation may be a polyimide hose, a polyimide coating, or a winding with one or more polyimide bands, according to the model of the insulation 25.

[0047] FIG. 5 shows another modified embodiment of the device 10 according to the present invention. This embodiment may have a conductor 17 according to the model of the embodiment according to FIG. 2, extending over the entire length of the device 10 and consisting entirely of carbon fiber 23. However, the conductor 17 may also be configured according to the model of the embodiment according to FIG. 4, may include a metal conductor 26 in its proximal section, or both. A feature of the embodiment according to FIG. 5 is that the distal end of the conductor 17 supports a small electrode 28. This small electrode 28 may be a needle, pin, or another body made of metal, conductive ceramic, or carbon, e.g., graphite. The small electrode 28 may further be electrically and mechanically connected to the conductor 17 by a crimp ring 29 or another suitable fastener.

[0048] It applies to all of the above-described embodiments that other suitable attachment means, such as plastic contraction elements or tightly wound wire, or suitable bonding materials, such as plastic threads, ceramic fibers, glass fibers or carbon fibers, can be used instead of the respective crimping rings 27, 29. The metal conductor 26 and the miniature electrodes 28 each extend over part of their length into the carbon fiber conductor 17 and thereby have a rigid mechanical and electrical connection to that conductor.

[0049] The improved instrument 10 for argon plasma surgery comprises a plastic hose 15 and an electrical conductor 17 extending therethrough. The conductor is formed of a carbon fiber 23 thread or a flexible or rigid body containing the carbon fiber 23. The carbon fiber 23 is particularly useful for current conduction and thermal cooling of plasma footpoints formed on the carbon fiber 23 at the end of the electrical conductor 17 or directly within a small body 28 that contacts the conductor. The electrical conductor 17 is positioned inside the lumen 16 of the hose 15 without being centered and thus without forcibly contacting the inner wall of the hose 15. In this way, the high thermal conductivity of the conductor 17 in the longitudinal direction results in low thermal stress in the hose 15 and therefore a long life for the instrument 10. In addition, this structure allows the instrument 10 to be made of a halogen-free plastic, making thermal disposal of the instrument 10 after use a non-issue. This is particularly applicable when the instrument 10 is constructed entirely or predominantly metal-free. [Explanation of symbols]

[0050] 10. Equipment 11 Distal end of instrument 10 12 Connectors 13 Proximal end of instrument 10 15 Hose 16 lumen 17 Conductor 18 Equipment 19 Source 20. Generator 21 Connector 22 Neutral electrode 23 Carbon Fiber 24 Exit opening 25 Insulation 26 Metallic Conductors 27 Crimping ring 28 Small electrode 29 Crimping ring 30,31 Cut surface

Claims

1. An apparatus (10) for medical plasma treatment of living tissue, comprising: a hose (15) having a proximal end (13) and a distal end (11) and at least one lumen (16), said lumen being connected or connectable to a gas source (19) at said proximal end (13), said hose (15) terminating in an outlet opening (24) at said distal end (11) of said hose (15); a conductor (17) extending through the entire length of said lumen (16) and terminating at said exit opening (24); A device characterized in that said conductor (17) consists entirely or partly of or comprises carbon fibres (23).

2. 2. The device according to claim 1, characterized in that the carbon fibers (23) are arranged mainly in the direction of the lumen (16).

3. 3. A device according to claim 1 or 2, characterized in that the conductor (17) is a thread, a twine, a cord or a string.

4. 4. The device of claim 3, wherein the yarn is a multifilament yarn.

5. 4. The device of claim 3, wherein the yarn is a staple fiber yarn.

6. 3. A device according to claim 1 or 2, characterized in that the conductor (17) has a constant cross section over its entire length.

7. 3. The device according to claim 1 or 2, characterized in that the conductor (17) comprises a cutting surface (30) at the outlet opening (24).

8. 2. The device according to claim 1, characterized in that the conductor (17) is provided with an insulating material (25).

9. 9. The device according to claim 8, characterized in that the insulating material (25) is formed so as to extend over the entire length of the conductor (17).

10. 10. Device according to claim 8 or 9, characterized in that the insulating material (25) consists of a plastic from the group of polyimides.

11. 10. An appliance according to claim 8 or 9, characterized in that the conductor (17) is wrapped with an insulating plastic band for electrical insulation.

12. 3. The device according to claim 1 or 2, characterized in that the conductor (17) is supported radially movably inside the lumen (16).

13. 3. A device according to claim 1 or 2, characterized in that the conductor (17) is supported so as to be freely movable in the radial direction within the distal end (11) of the hose.

14. 3. A device according to claim 1 or 2, characterized in that the hose (15) is made of a halogen-free plastic material.

15. 3. The device according to claim 1 or 2, characterized in that the hose (15) consists of a plastic from the group of polylactides or from the group of silicones.

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