Surgical vaporization electrode

Abstract

Surgical vaporization electrode (1) for connection to a surgical RF generator, comprising an electrode head (2) with a first electrode (3) in a first plane (3b), comprising at least one first electrode surface (3a), and with a second electrode (4) in a second plane (4b) parallel to the first plane (3b), complementary to the first plane (3b), comprising at least one second electrode surface (4a), wherein the first electrode (3) and the second electrode (4) are insulated from each other by a first insulating layer (5), wherein the second electrode (4) and the first insulating layer (5) are formed with one or more recesses (6), and wherein, in the operating state, plasma is ignited on at least one of the at least one electrode surface (3a, 4a).

Description

Technical area

[0001] The invention relates to a surgical vaporization electrode. State of the art

[0002] Electrical surgical resection instruments are known from the prior art, whereby high-frequency alternating current (HF current) is passed through the body part to be treated in order to selectively damage or cut the corresponding tissue (high-frequency surgery, HF surgery). The biological tissue is thereby cut, coagulated, and / or vaporized. Such resection instruments are used in various surgical applications, e.g., to remove adenomatous tissue by vaporization. A high-frequency voltage, generated by suitable generators, is applied to the surgical resection instrument, the surgical electrode, and supplied to the working part of the electrode via appropriate leads. Depending on their design, the electrodes can be operated bipolarly or monopolarly.

[0003] In monopolar technique, one pole of the RF voltage source is connected to the patient as the neutral electrode over the largest possible area, while the other pole forms the surgical instrument (active electrode). In contrast to monopolar technique, in bipolar technique the current flows only through a small part of the body, as in this case the current flows from the working surface of the active electrode through the fluid to the neutral electrode located in close proximity. The localized current density of the bipolar electrode causes rapid heating of the tissue surrounding the electrode tip(s), with subsequent vaporization of the tissue fluid or the surrounding irrigation fluid (irrigation solution, saline).

[0004] Electrosurgery is fundamentally based on Joule's law (Q = P*t). A thin gas layer (vapor cushion) forms around the electrode tip due to the power loss P associated with the volume element and the resulting heat. At a sufficiently high voltage (plasma ignition), this layer can be ionized into a constant plasma (surgical plasma vaporization electrode). A disadvantage is that during current activation, some electrical energy is dissipated via the irrigation fluid, meaning that the full RF power is not available at the application site. Another disadvantage is that a significant amount of energy must be expended at the tip of the electrode to maintain the electric field strengths necessary for ignition and the maintenance of a stable plasma.Furthermore, the location of plasma formation on a hemispherical, electrically conductive surface is not precisely predetermined, but rather subject to a stochastic process at the electrode surface. Additionally, vaporization electrodes known from the prior art generally operate according to a quasi-bipolar system, since the active electrode, at which a plasma is ignited in saline, is small compared to the back electrode. A disadvantage is that the current from the active electrode to the back electrode must travel a long distance through the saline, which limits the effectiveness of plasma ignition and causes additional heat generation in the saline.

[0005] German patent application DE 10 2012 016 563 A1 discloses a high-frequency surgical device for treating a tissue surface, comprising an electrode assembly in which a first electrode is formed on a working surface intended for contact with the tissue, and a high-frequency generator to whose pole the first electrode can be connected for operation. The surgical device is characterized in that a second electrode is formed on the working surface, which can be connected to the same pole, and to which a control device is connected, configured to first switch on the first electrode and then switch on the second electrode.

[0006] German patent application DE 10 2015 015 314 A1 discloses a vaporization electrode, wherein a substantially hemispherical working surface of the electrode head is made of a suitable, high-temperature resistant metal. The electrode head is supplied with voltage via an electrical connection cable. The rear surface of the electrode head, forming the cross-sectional area of ​​the sphere, is flat and covered with an insulating ceramic covering. The transition area from the working surface to the rear surface has no edge but is rounded with a minimum radius of curvature that is significantly larger than one-thirtieth of the width corresponding to the hemisphere diameter (= twice the hemisphere radius), which is the dimension of the electrode head in the direction of its maximum extension. The relatively large radius of curvature prevents the main activity of the electrode from being located at its edge due to excessively high local current densities.

[0007] German patent application DE 195 26 243 C1 describes an electrode for vaporizing tissue, comprising an active electrode part in the form of a plate and electrically conductive, externally insulated branches that support the plate. The plate has at least one recess, arranged transversely to the branches, and forms an angle with the branches of approximately 60° to 120°.

[0008] The publication DE 295 21 028 U1 describes an electrode for vaporizing tissue with a head that is provided with projections and recesses and is supported by at least one externally insulated, electrically conductive branch, wherein the head, which is rigidly attached to the branch, essentially consists of a part of a rotationally symmetric body. Description of the invention

[0009] Starting from the aforementioned electrodes of the prior art, the present invention is based on the objective of providing a device which does not have the aforementioned disadvantages or at least has them to a lesser extent.

[0010] In a first aspect, the invention relates to a surgical vaporization electrode for connection to a surgical RF generator. The electrode has an electrode head with a first electrode in a first plane, comprising at least one first electrode surface, and a second electrode in a second plane parallel to the first plane and complementary to the first plane, comprising at least one second electrode surface, wherein the first electrode and the second electrode are insulated from each other by a first insulating layer, and wherein the second electrode and the first insulating layer are formed with one or more recesses. The first and second electrodes, as well as the intermediate insulating layer, can, for example, be applied to a non-conductive base body of the electrode head; alternatively, the first electrode can be formed as part of an electrically conductive base body.According to the invention, an electrode surface is understood to be that area of ​​the electrode which is exposed to the environment, e.g., a salt solution, during operation. An insulating layer is understood to be a layer consisting of a solid, wherein the solid is a non-conductor with the highest possible specific resistance. According to the invention, the recesses extend through the second electrode and the insulating layer, each forming part of the recess wall. The recesses thus extend from the side of the first electrode facing the insulating layer, across the insulating layer, to the side of the second electrode facing away from the insulating layer. They are not subject to any particular restrictions regarding their shape; they can be any shape, e.g., circular, oval, rectangular, polygonal, etc.or a combination of such shapes, and can be produced by appropriate casting of the insulating layer, by drilling, milling, etching, by laser action, and other methods known from the art. In the operating state of the surgical vaporization electrode according to the invention, plasma is ignited on at least one of the at least one electrode surface. Within the recesses, a current flow is generated between the at least one first and the at least one second electrode surface in the operating state, limited to a very small area, the magnitude of which is determined by the distance between the conductive electrode surfaces.In particular, the offset of the at least one first electrode surface relative to the at least one second electrode surface in the recess during operation can exert a directional effect such that, due to the smaller surface areas, a higher electric field strength is generated locally (peak discharge effect). This allows the gas pocket necessary for plasma ignition to form and ignite more quickly, stably, and with lower energy expenditure in the respective recess. The vaporization electrode according to the invention can thus be ignited even under unfavorable conditions, e.g., in free purge fluid. The targeted use of the input energy results in an increase in efficiency and, consequently, a lower temperature rise in the purge fluid.

[0011] In a preferred embodiment of the surgical vaporization electrode, the first and second planes can be convexly curved. The electrode head can thus be configured with a first electrode in a first, convexly curved plane, comprising at least one first electrode surface, wherein the second electrode is arranged in a second, convexly curved plane parallel to the first plane and comprises at least one second electrode surface. If the first electrode is formed as part of an electrically conductive base body, the at least one first electrode surface lies in the first, convexly curved plane. Advantageously, the electrode head with convexly curved electrode surfaces can have a compact shape.

[0012] In an advantageous embodiment, the at least one second electrode surface can be larger or largely the same size as the at least one first electrode surface, wherein, in bipolar operation, the first and second electrodes can function as alternating poles. This means that, unlike conventional vaporization electrodes, there is no clear assignment of active and return electrodes: the first and second electrodes according to the invention alternate at the frequency of the current. When the surgical vaporization electrode is connected to a suitably designed surgical RF generator, a plasma is ignited, for example, on both the first and second electrode surfaces.The invention is not limited to the presence of a first and a second electrode in the electrode head of the surgical vaporization electrode; embodiments with further electrodes are possible, for example, a third electrode, e.g., for triggering plasma ignition. Since conventional vaporization electrodes operate using only a quasi-bipolar technique, namely with an active (RF-voltage-energized) electrode and a return electrode, the return electrode is significantly larger than the active electrode, so that the plasma only ignites at the active electrode.In the inventive embodiment of the vaporization electrode, the two electrodes with their corresponding electrode surfaces can be connected to a surgical RF generator in such a way that they function as alternating poles in bipolar operation, wherein the electrode surfaces are dimensioned such that the second electrode surface is larger or largely the same size as the first electrode surface. If the working areas of both electrode surfaces exposed to the saline are largely the same size, the vaporization electrode operates in a truly bipolar manner with alternating plasma ignition at both electrodes. Since the first insulating layer keeps the first and second electrodes at a defined distance from each other, the current flow is limited to the small electrode surfaces.

[0013] This minimizes the heat input into the saline surrounding the electrode head and the tissue compared to conventional vaporization electrodes, while simultaneously allowing a stable plasma to be ignited across the entire RF-exposed electrode surface.

[0014] In an additional embodiment of the surgical vaporization electrode, the second electrode can be at least partially recessed relative to the first insulating layer; for example, the second electrode can be recessed relative to the first insulating layer in the area of ​​at least one recess. Recessing the at least one second electrode ensures that a short circuit is avoided between the first and second electrodes, separated by the first insulating layer, with their respective at least one first and at least one second electrode surfaces.

[0015] In an advantageous implementation of the vaporization electrode, the second electrode can be arranged on the side facing away from the first insulating layer with a second insulating layer that includes one or more recesses. This second insulating layer limits the surface area of ​​the second electrode from the tissue on the side facing away from the first insulating layer. Advantageously, the dimensions of the second electrode surface, which is exposed to the saline during operation, can be adjusted using this second insulating layer, such that a stable plasma can be ignited while simultaneously minimizing heat input into the surrounding saline. In particular, the size ratio between the first and second electrode surfaces can be finely adjusted.In a particularly advantageous further development of the surgical vaporization electrode, the second insulating layer can be at least partially recessed relative to the second electrode. This additional insulating layer limits the surface area of ​​the second electrode from the tissue, but can create sufficiently free edges or corners on the second electrode surface in the area of ​​the recesses, ensuring sufficiently high electric field strengths to reach the threshold conditions for vapor layer formation. By selecting a suitable ratio of insulation to edge coverage, uniform plasma ignition at the respective electrode surfaces can be achieved and its stability guaranteed.The recess / total electrode area ratio and the edge / surface ratio of the electrode surface of the second electrode can thus be adjusted so that a truly bipolar mode of action with stable, alternately igniting plasma on both electrode surfaces is achieved.

[0016] In an advantageous further development of the surgical vaporization electrode, the first insulating layer can have a free edge length of 0.1 to 4.5 mm relative to one or more recesses; preferably, it can have a free edge length between 0.1 and 4 mm, and particularly preferably between 0.1 and 3 mm. The insulating layer can be of varying thickness in separate sections of the vaporization electrode. This allows the electric field strength to be adjusted according to the application and increases the effectiveness of the plasma ignition as well as the stability of the generated plasma, especially at the apex of the electrode head facing the working area.

[0017] In a further implementation of the vaporization electrode according to the invention, different electrode areas of the at least one, first electrode can be activated and deactivated separately. The first electrode can be divided into different electrode areas so that the corresponding electrode surfaces exposed to the saline via the recesses in the operating state can also be activated and deactivated separately. The term "area" here refers to a defined unit, a defined area, or a defined surface.

[0018] In a further implementation of the surgical vaporization electrode, the first insulating layer and / or the second insulating layer can be made of a material selected from the group consisting of anodized aluminum, silicone rubber, ceramic, glass, glass-ceramic, and plastic. Particularly preferably, the first insulating layer and / or the second insulating layer can be made of ceramic. Ceramic insulating materials already known from the prior art are especially suitable for this purpose.

[0019] In a second aspect, the present invention relates to a surgical instrument comprising a surgical vaporization electrode as described above and an RF generator, wherein the RF generator is designed and connected to the surgical vaporization electrode in such a way that, in the operating state, plasma is ignited on at least one of the at least one electrode surface.

[0020] In a preferred embodiment, the surgical instrument can have electronic control for activating and deactivating the electrode surfaces. In principle, electronic control devices known per se from the prior art are suitable for this purpose, which are capable of controlling electronic switching modules or high-frequency alternating voltage sources assigned to the respective working surfaces.

[0021] In an advantageous further development, the surgical instrument can include impedance measuring devices, wherein the electronic control is designed to activate and / or deactivate at least one of the electrode surfaces depending on impedance measurements. Using sensors known per se from the prior art, the impedance measurements are used to determine which of the electrode surfaces is in contact with or near tissue; electrode surfaces not in contact with or near tissue can be deactivated accordingly.

[0022] As used here, the singular form of the articles “ein”, “der”, “die” and “das” includes the corresponding plural forms unless otherwise stated.

[0023] A preferred embodiment is described, to which, however, the invention is not limited. In principle, any variant of the invention described or indicated within the scope of this application may be particularly advantageous, depending on the economic, technical, and, where applicable, medical conditions in the individual case. Unless otherwise stated, or insofar as it is technically feasible, individual features of the described embodiment are interchangeable or combinable with each other and with features known per se from the prior art. Detailed description of the figure

[0024] In Fig.Figure 1 shows a section of the electrode head (2) of a surgical vaporization electrode (1) connected to a surgical RF generator (8). For simplification, the individual, convexly curved layers of the hemispherical electrode head are shown in a linear representation without curvature. The electrode head (2) has a first electrode (3) in a first plane (3b, dashed line), which has at least one first electrode surface (3a). In a second plane (4b) parallel to the first plane (3b), the electrode head (2) has a second electrode (4) which has a second electrode surface (4a). The first electrode (3) and the second electrode (4), or the at least one first electrode surface (3a) and the at least one second electrode surface (4a), are insulated from each other by a first insulating layer (5).The second electrode (4) and the first insulating layer (5) are each formed with three largely cylindrical recesses (6.1, 6.2, 6.3). The second electrode (4) has a second insulating layer (7) on the side facing away from the first insulating layer (5). An electrode surface is defined as the area of ​​the electrode that is exposed to the environment, e.g., a salt solution, during operation. The present illustration shows three electrode surfaces (3a) of the first electrode (3) and three electrode surfaces (4a) of the second electrode (4), with the respective electrode surfaces (3a, 4a) of the first and second electrodes (3, 4) adjacent to the corresponding recesses (6.1, 6.2, 6.3).In the operating state, high electric field strengths can be generated within the recesses between the electrode surfaces (3a, 4a) of the first and second electrodes (3, 4), so that the gas pocket necessary for plasma ignition can be created quickly and locally with low energy expenditure. In the illustrated example, the second electrode surface (4a) is larger than the first electrode surface (3a). When the surgical vaporization electrode (1) according to the invention is connected to a suitably designed surgical RF generator (8) connected to the surgical vaporization electrode (1), the first electrode (3) and the second electrode (4) function as alternating poles in bipolar operation, so that an alternating plasma is ignited at both the first electrode (3) and the second electrode (4), which is stable overall.The current flow between the electrodes (3, 4) is restricted to the electrode surfaces (3a, 4a) exposed to the saline in the corresponding recesses (6), since the insulating layer (5) brings the corresponding electrode surfaces of the first and second electrodes (3, 4) close together. This also minimizes the heat input into the saline surrounding the electrode head (2) and into the tissue. In the illustrated embodiment, as shown, in the region of one of the several recesses (recess 6.2), the second electrode (4) is set back relative to the first insulating layer (5), so that the first insulating layer (5) in recess (6.2) has an edge length that is longer by the length b than, for example, the first insulating layer (5) in the region of recess 6.3.The distance between the conductive electrode surfaces (3a, 4a) is thus increased, and simultaneously the second electrode surface (4a) also increases relative to the first electrode surface (3a) in the area of ​​this recess 6.2. By fine-tuning the distance between the conductive electrode surfaces (3a, 4a) (across the edge length of the first insulation) and the size ratio of electrode surface (3a) / electrode surface (4a) in the area of ​​the respective recess, optimal operation of the vaporization electrode according to the invention can be ensured. In addition, the conductive electrode surface (4a) of the second electrode (4) can also be equipped with special properties, e.g., edges, as shown in the area of ​​recess 6.1, the second insulating layer (7) is set back from the second electrode (4); corresponding edges or corners of the second electrode (4) are left free in such a way that sufficiently high electric field strengths are obtained to reach the threshold conditions for vapor layer formation, thereby achieving uniform ignition of a plasma on both electrode working surfaces (3a, 4b) and ensuring its stability. Reference symbol list 1 surgical vaporization electrode 2 electrode heads 3 first electrode 3a first electrode surface 3b first level 4 second electrode 4a second electrode surface 4b second level 5 first insulation layer 6 Recess 7 second insulation layer 8 connections to the RF generator

Claims

[1] Surgical vaporization electrode (1) for connection to a surgical HF generator, comprising an electrode head (2) with a first electrode (3) in a first plane (3b), having at least one first electrode surface (3a), and with a second electrode (4) in a complementary second plane (4b) running parallel to the first plane (3b), having at least one second electrode surface (4a), wherein the first electrode (3) and the second electrode (4) are insulated from one another by a first insulation layer (5), wherein the second electrode (4) and the first insulation layer (5) are formed with one or more recesses (6), and wherein, in the operating state, plasma is ignited on at least one of the at least one electrode surface (3a, 4a). [2] Surgical vaporization electrode (1) according to claim 1, wherein the first plane (3b) and the second plane (4b) are convexly curved. [3] Surgical vaporization electrode (1) according to one of claims 1 or 2, wherein the at least one second electrode surface (4a) is larger or substantially the same size with respect to the at least one first electrode surface (3a), wherein in bipolar operation the first (3) and the second electrode (4) function as alternating poles. [4] Surgical vaporization electrode (1) according to one of the preceding claims, wherein the second electrode (4) is at least partially set back from the first insulation layer (5). [5] Surgical vaporization electrode (1) according to one of the preceding claims, wherein the second electrode (4) is arranged on the side facing away from the first insulation layer (5) with a second insulation layer (7) which leaves out one or more recesses (6). [6] Surgical vaporization electrode (1) according to claim 5, wherein the second insulation layer (7) is at least partially set back from the second electrode (4). [7] Surgical vaporization electrode (1) according to one of the preceding claims, wherein the first insulation layer (5) has a free edge length of 0.1 to 4.5 mm, preferably between 0.1 to 4 mm and particularly preferably between 0.1 to 3 mm, relative to the one or more recesses (6). [8] Surgical vaporization electrode (1) according to one of the preceding claims, wherein different electrode areas of the at least one first electrode (3) can be activated and deactivated separately from one another. [9] Surgical vaporization electrode (1) according to one of the preceding claims, wherein the first insulation layer (5) and / or the second insulation layer (7) consists of a material selected from the group consisting of anodized metal, silicone rubber, ceramic, glass, glass ceramic, plastic. [10] Surgical vaporization electrode (1) according to claim 9, wherein the first insulation layer (5) and / or the second insulation layer (7) are made of ceramic. [11] Surgical instrument, comprising a surgical vaporization electrode (1) according to one of the preceding claims 1 to 10 and an RF generator, wherein the RF generator is designed and connected to the surgical vaporization electrode (1) such that, in the operating state, plasma is ignited on at least one of the at least one electrode surface (3a, 4a). [12] Surgical instrument according to claim 11, further comprising an electronic control for activating and deactivating the electrode surfaces (3a, 4a). [13] Surgical instrument according to claim 12, further comprising impedance measuring means, wherein the electronic control is adapted to activate or deactivate at least one of the electrode surfaces (3a, 4a) in dependence on impedance measurements.

Images