Medical instrument and electrosurgical system

Abstract

Bipolar medical instrument (10) for cutting tissue under the influence of high-frequency current, wherein the instrument (10) extends along a longitudinal direction (12) from a proximal end (14) to a distal end (16), and wherein an active electrode (30) and a neutral electrode (32) adjacent to the active electrode (30) are arranged at the distal end (16), and the neutral electrode (32) at least partially encloses a first electrical lead (40) leading from the proximal end (14) to the active electrode (30) in a first section of the instrument (10), wherein the neutral electrode (32) has a first curved neutral electrode surface (34) and a second curved neutral electrode surface (36), the first neutral electrode surface (34) being connected to a second lead (42) leading from the proximal end (14) to the first neutral electrode surface (34), and the second neutral electrode surface (36) being connected to a is connected to the third supply line (44),which leads from the proximal end (14) to the second neutral electrode surface (36), wherein the second electrical lead (42) at least partially encloses the first electrical lead (40) in a proximal direction in front of the first section (28), wherein a tubular insulating piece (56) is arranged distally in front of the first neutral electrode surface (34), enclosing the second lead (42), and wherein the insulating piece (56) is partially enclosed by the first neutral electrode surface (34).

Description

[0001] Bipolar medical instrument for cutting tissue under the influence of high-frequency current, wherein the instrument extends along a longitudinal direction from a proximal end to a distal end and wherein an active electrode and a neutral electrode adjacent to the active electrode are arranged at the distal end.

[0002] The invention further relates to an electrosurgical system comprising a high-frequency generator and an instrument of the type mentioned above.

[0003] An instrument and a system of the type mentioned above are known from DE 25 21 719 A1.

[0004] An instrument or system of the type mentioned above is used in open, but preferably in minimally invasive surgery for cutting tissue in the human or animal body.

[0005] The instrument mentioned at the outset can, in accordance with the present invention, be combined with an endoscope to form a so-called resectoscope when used in minimally invasive surgery, or can itself constitute such a resectoscope.

[0006] Electrosurgery, also known as high-frequency surgery, is used therapeutically in various medical specialties, such as urology, gynecology, neurosurgery, and abdominal surgery. Specifically in urology, prostate tissue is removed endoscopically using the aforementioned instrument as part of minimally invasive surgery.

[0007] In electrosurgical resectoscopy procedures, a distinction is made between the monopolar and bipolar application of high-frequency current.

[0008] In monopolar application, only the active electrode, sometimes also called the cutting electrode or treatment electrode, is inserted into the treatment area, while the neutral electrode is positioned externally on the patient. Consequently, the current flows between the active and neutral electrodes through the patient's body, with the disadvantage that the current path through the patient cannot be reliably controlled, potentially leading to organ damage. Furthermore, the neutral electrode attached to the patient's body can cause skin burns.

[0009] In the bipolar technique from which the present invention is based, both the active electrode and the neutral electrode are inserted into the treatment area. The current flow can thus be controlled and limited to the area between the active and neutral electrodes, as it flows spatially only between these two electrodes. Accordingly, medical instruments of the type mentioned above have been developed in which the active and neutral electrodes are arranged on an electrode carrier, allowing the active and neutral electrodes to be inserted adjacent to each other into the treatment area.

[0010] In bipolar medical instruments of the type mentioned above, the active electrode is typically designed with a small effective surface area, resulting in a high current density at the active electrode, while the neutral electrode is typically designed with a relatively large surface area, resulting in only medium or low current densities at the neutral electrode. The active electrode is used for cutting, while the neutral electrode should ideally have no effect on the tissue, but merely serve to limit the current path to the area between the active and neutral electrodes.

[0011] In the instrument known from the aforementioned DE 25 21 719 A1, the neutral electrode is designed as a wide band, while the active electrode is designed as a wire loop. In a further embodiment of DE 25 21 719 A1, the neutral electrode is covered on its side facing away from the active electrode by a plastic extension that is firmly connected to the shaft of the resectoscope.

[0012] WO 99 / 16371 A1 also discloses a bipolar medical instrument of the type mentioned above. Similar to the previously described known instrument, the active electrode is positioned relative to the neutral electrode in a direction transverse to the longitudinal axis such that they are not spaced apart from each other.

[0013] From EP 1 163 886 A2, a resectoscopic instrument is known in which the active electrode and the neutral electrode are electrically separated on their facing sides by an insulator body, so that any straight line of connection between the electrodes passes through the insulator body. This is intended to make the direct current flow between the two electrodes more difficult or to reduce it.

[0014] US 9,474,438 B2 shows a medical instrument in which an active electrode and a neutral electrode can be used. Tubular elements of the neutral electrode can be arranged coaxially to conductors of the active electrode.

[0015] EP 2 767 250 B1 discloses an electrode arrangement with a proximal end that can be connected to an electrosurgical instrument comprising a housing with a continuous longitudinal axis and an electrosurgical power source. The distal end includes a cutting electrode with a loop configuration configured for cutting tissue. The distal end also includes a return electrode that is functionally positioned adjacent to the cutting electrode. A dielectric shield is functionally positioned between the cutting electrode and the return electrode. The dielectric shield extends distally beyond the cutting electrode to prevent current flow to the return electrode when the dielectric shield, the cutting electrode, and the return electrode are immersed in a conductive solution and the cutting electrode is energized, thereby concentrating the current density at the cutting electrode.

[0016] JP H06-191 A discloses a catheter device consisting of a coaxial structure. An inner conductor is connected to a front electrode and an outer conductor (ground) to a near electrode. A coaxial connector is used for the catheter's connection points and is connected to the radio frequency generator via the connecting coaxial cable.

[0017] DE 10 2013 109 505 A1 discloses a bipolar medical instrument for cutting tissue under the influence of high-frequency current, wherein the instrument extends along a longitudinal direction from a proximal end to a distal end, with an active electrode and a neutral electrode adjacent to the active electrode arranged at the distal end, and wherein the neutral electrode has a curved path with a first and a second curvature, the respective directions of the curvatures being different. Furthermore, an electrosurgical system comprising a high-frequency generator and such a bipolar medical instrument, which can be connected to the high-frequency generator, is disclosed.

[0018] The invention is based on the objective of providing an improved instrument and an improved system of the type mentioned above.

[0019] The problem is solved by a bipolar medical instrument according to claim 1.

[0020] One of the advantages of such an instrument is its design as separate rods, referred to later in the figures as electrode carrier sections. The rods can be easily connected with clamps, referred to later in the figures as retaining elements. Each rod contains a supply and return path for the energy, which is provided during operation by a high-frequency generator. This design allows for particularly increased mechanical stability.

[0021] In the distal direction, a tubular insulating piece is arranged in front of the first neutral electrode surface, enclosing the second lead, with the insulating piece being partially enclosed by the first neutral electrode surface. This reduces the risk of unintentional ignition of the neutral electrode.

[0022] In a preferred embodiment, the first neutral electrode surface and the second neutral electrode surface are not electrically connected at the distal end and / or are only electrically connected at the proximal end.

[0023] This design eliminates the need for an electrical bridge between the linkages. The neutral electrodes are connected separately, without a direct connection to each other.

[0024] In a further preferred embodiment, the second supply line and / or the third supply line are tubular in shape.

[0025] This results in a stable structure that is well suited for efficient manufacturing.

[0026] In a further preferred embodiment, the first neutral electrode surface or the second electrical lead tapers conically in a second section in a proximal direction.

[0027] This design makes it possible to achieve at least a substantially constant diameter of the rods in the various sections of the instrument along its longitudinal extent.

[0028] In a further preferred embodiment, the first neutral electrode surface encloses the first electrical lead to at least 120°, preferably at least 180°, particularly preferably at least 270° and in particular completely.

[0029] With this design, the degree of enclosure can be determined depending on the application. Complete enclosure is considered advantageous with regard to manufacturing. These considerations also apply to the second neutral electrode surface.

[0030] In a further preferred embodiment, the second electrical supply line surrounds the first electrical supply line to at least 120°, preferably at least 180°, particularly preferably at least 270° and in particular completely.

[0031] With this design, the degree of enclosure can be determined depending on the application. Complete enclosure is considered advantageous for manufacturing. These considerations also apply to the third supply line.

[0032] In another preferred embodiment, the second electrical supply line is guided in a tubular insulation, which is optionally enclosed by a metallic tube.

[0033] This design provides good insulation. The optional metal tube allows for thorough cleaning of the instrument.

[0034] In a further preferred embodiment, the diameter of the tubular insulation or, if present, the diameter of the metallic tube corresponds at least approximately to the diameter of the first neutral electrode surface.

[0035] With this design, a constant diameter of the linkages or electrode carrier parts can be achieved.

[0036] In a further preferred embodiment, the first neutral electrode surface is radially widened at its distal end.

[0037] This design can improve the ignition behavior and can be implemented in particular as a crimp or flange.

[0038] In a further preferred embodiment, the first neutral electrode surface and the second neutral electrode surface are separated from each other in a distal direction.

[0039] This design allows for a sufficiently large active electrode even in a compact construction. The angle between the two neutral electrode surfaces, more precisely, between the two longitudinal extensions of the neutral electrode surfaces, is preferably 0.1° - 20°, particularly preferably 2° - 10°, and especially 5° - 7°.

[0040] In a further preferred embodiment, the active electrode emerges from the neutral electrode, in particular through an insulating piece, and extends transversely to the longitudinal extent from the first neutral electrode surface to the second neutral electrode surface.

[0041] This design offers a configuration of the active electrode that allows the physician to work in a familiar manner.

[0042] In a further preferred embodiment, a first contacting area of ​​the first supply line and a second contacting area of ​​the second supply line are formed at the proximal end, which are arranged offset from each other along the longitudinal direction, and the contacting areas in particular each have a cylindrical surface.

[0043] This design allows for multiple contacts, particularly with four contact points. In particular, large-area contacting can be achieved if the longitudinal extent of the contact areas is greater than their respective radii, preferably more than twice as large, and especially preferably more than three times as large. This results in reduced contact resistance. Furthermore, heat loss at the contact points can be reduced. As will be shown later, the first lead wire is routed through the contact area within the second contact area. This design applies accordingly to both rods of the instrument.

[0044] In another preferred embodiment, an edge is formed on the active electrode.

[0045] This design can improve the ignition behavior. It should be noted that this is an independent further development of an active electrode from the prior art, which constitutes an inventive step even without the claimed leads and neutral electrode surfaces.

[0046] In a further preferred embodiment, the area ratio between the neutral electrode and the active electrode is 1 to 10, preferably 2 to 8, particularly preferably 3 to 6 and in particular at least approximately 4.

[0047] In a further preferred embodiment, the distance between the active electrode and the neutral electrode is 0.1 mm to 5 mm, preferably 0.5 mm to 3 mm, particularly preferably 0.75 mm to 2 mm and in particular at least approximately 1 mm.

[0048] In a further preferred embodiment, the neutral electrode is made of steel or contains steel.

[0049] In a further preferred embodiment, the active electrode is made of tungsten or contains tungsten.

[0050] The task is further solved by an electrosurgical system with a high-frequency generator and with a previously described instrument that can be connected to the high-frequency generator.

[0051] Further advantages and features will become apparent from the following description and the attached drawing.

[0052] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0053] Exemplary embodiments of the invention are shown in more detail in the drawing and are explained in more detail in the following description. They show: Fig. 1 a bipolar medical instrument according to the present invention in side view, here a resectoscope; Fig. 2 elements within the instrument according to Fig. 1 in side view; Fig. 3 elements within the instrument according to Fig. 1 in the top view; Fig. 4 the elements according to Fig. 2 in perspective view; Fig. 5 the enlarged section A from Fig. 4; Fig. 6 a cross-section in the longitudinal direction of the elements according to Fig. 2 in the distal section of the instrument; Fig. 7 a cross-section in the longitudinal direction of the elements according to Fig. 2 in the proximal section of the instrument; Fig. 8 a sectional view of section B from the Fig. 5; Fig. 9 a first alternative design of the neutral electrode of the bipolar medical instrument; Fig. 10 a second alternative design of the neutral electrode of the bipolar medical instrument; Fig. 11 a first alternative design of the active electrode of the bipolar medical instrument; and Fig. 12 a second alternative design of the active electrode of the bipolar medical instrument.

[0054] Fig. Figure 1 shows a bipolar medical instrument 10 for cutting tissue under the influence of high-frequency current in a side view; here, a resectoscope. The basic operating principle of the instrument 10 is known from the prior art; see in particular patent specification EP 1 567 079 B1. Fig. 1-4, 6a and 6b, as well as paragraphs 47 to 72.

[0055] The instrument 10 extends along a longitudinal direction 12 from a proximal end 14 to a distal end 16. The instrument 10 is shown here in its retracted state. It can be seen that both an active electrode 30 (see Fig. 2) as well as a neutral electrode 32 (see Fig. 2) are located within a distal end of a shaft 18 of the instrument 10. The neutral electrode 32 has a first curved neutral electrode surface 34 and a second curved neutral electrode surface 36.

[0056] Fig. Figure 2 shows a side view of an electrode carrier 20, which is arranged to be displaceable within the shaft 18 in the longitudinal direction 12 and is guided by retaining elements 22. The electrode carrier 20 has a first electrode carrier part 21 and a second electrode carrier part 21'.

[0057] Fig. Figure 3 shows the electrode carrier 20 and the retaining elements 22 in a top view. A transverse direction 24 is also shown, which is transverse to the longitudinal direction 12, in particular perpendicular to the longitudinal direction 12. It is indicated that the first neutral electrode surface 34 and the second neutral electrode surface 36 diverge from each other distally. In other embodiments, however, the first neutral electrode surface 34 and the second neutral electrode surface 36 can also run parallel to each other.

[0058] At the proximal end 14 of the first electrode carrier part 21, a first contact area 60 for the first supply line 40 and a second contact area 62 for the second supply line 42 are formed, which are arranged offset from each other along the longitudinal direction 12. In this configuration, the contact areas 60 and 62 each have a cylindrical surface. The same applies to a third contact area 64 and a fourth contact area 66 of the second electrode carrier part 21'.

[0059] Furthermore, the diagram symbolically illustrates how the electrically active elements of the instrument 10 can be connected to a high-frequency generator 26, wherein the high-frequency generator 26 can deliver a first output power of at least 200 W. The first electrode carrier part 21 is connected to a first port 27 of the high-frequency generator 26, and the second electrode carrier part 21' is connected to a second port 27' of the high-frequency generator 26.

[0060] Furthermore, an angle α between the two neutral electrode surfaces 34, 36, or more precisely, between the two longitudinal extensions of the neutral electrode surfaces 34, 36, is also shown. However, the neutral electrode surfaces 34, 36 can also be parallel to each other, in which case α = 0°.

[0061] Fig. 4 shows the elements according to Fig. 2 in perspective view. At the distal end 16, a part of the figure is marked with a circle and the letter A, which is shown enlarged below.

[0062] Fig. Figure 5 shows an enlarged section A from Fig. 4. It can be seen that the active electrode 30 and the neutral electrode 32 adjacent to the active electrode 30 are arranged at the distal end 16. The active electrode 30 is designed as a wire loop. It is shown that the active electrode 30 emerges from the neutral electrode 32, here from the first neutral electrode surface 34 and the second neutral electrode surface 36 respectively, in particular through an insulating piece, and extends transversely to the longitudinal extent 12, i.e., along the transverse direction 24, between the first neutral electrode surface 34 and the second neutral electrode surface 36.

[0063] Fig. Figure 6 shows a longitudinal cross-section of the elements 12 according to Fig. 2 in the distal section 16 of the instrument 10. The neutral electrode 32, here the first neutral electrode surface 34, encloses, at least partially, in a first section of the instrument 10 a first electrical lead 40, which leads from the proximal end 14 to the active electrode 30.

[0064] The first neutral electrode surface 34 is connected to a second lead 42, which leads from the proximal end 14 to the first neutral electrode surface 34, and the second neutral electrode surface 36 is connected to a third lead 44 (see Fig. 8) connected, leading from the proximal end 14 to the second neutral electrode surface 36, wherein the second electrical supply line 42 at least partially encloses the first electrical supply line 40 in the proximal direction in front of the first section 28. An insulating sheath 41 is arranged between the second supply line 42 and the first supply line 40. This applies accordingly between the third supply line 44 and the first supply line 40.

[0065] The first neutral electrode surface 34 and the second neutral electrode surface 36 are not electrically connected at their distal end 16. Alternatively, the configuration can be such that the first neutral electrode surface 34 and the second neutral electrode surface 36 are only electrically connected at their proximal end 14, for example, see [reference]. Fig. 3, via common potentials of the high-frequency generator 26. The second supply line 42 and the third supply line 44 are designed here in a tubular form.

[0066] The first neutral electrode surface 34 or the second electrical supply line 42 tapers conically in a second section 50 in the proximal direction, i.e., towards the proximal end 14. Similarly, although not shown, the second neutral electrode surface 36 or the third electrical supply line 42 also tapers conically in the proximal direction in the second section 50. In the embodiment shown, the first neutral electrode surface 34 surrounds the first electrical supply line 40.

[0067] The second electrical lead 42 is guided in a tubular insulation 52, which is optionally enclosed by a metallic tube 54. The diameter of the tubular insulation 52, or, if present, the diameter of the metallic tube 54, is chosen to correspond at least approximately to the diameter of the first neutral electrode surface 34.

[0068] It can also be seen that in a distal direction in front of the first neutral electrode surface 34 a tubular insulating piece 56 is arranged, which encloses the second supply line 42, wherein the insulating piece 56 is also enclosed by the first neutral electrode surface 34.

[0069] Fig. Figure 7 shows a cross-section in the longitudinal direction 12 of the elements according to Fig. 2 in the proximal section 16 of instrument 10. On the left side, the continuation of the elements is shown, which in Fig. Figure 6 is shown on the right-hand side. The first contact area 60, designed as a conductive, cylindrical sleeve 61 on the first supply line 40, and the second contact area 62, designed as a conductive, cylindrical sleeve 63 on the second supply line 42, are again visible. The same applies to the third contact area 64 and the fourth contact area 66.

[0070] Fig. Figure 8 shows a cross-sectional view of section B from the Fig. 5. All previous explanations remain valid.

[0071] Fig. Figure 9 shows a first alternative embodiment of the neutral electrode 32 of the bipolar medical instrument 10. The first neutral electrode surface 34 is radially widened at its distal end. Enlarging the area of ​​the neutral electrode facing the active electrode 30 can improve the ignition behavior. This enlargement can be implemented as a crimp 47, as shown here.

[0072] Fig. Figure 10 shows a second alternative embodiment of the neutral electrode 32 of the bipolar medical instrument 10, in which the area facing the active electrode 30 is again enlarged. This enlargement can be implemented as a flange 49 or a cylindrical shell with a larger radius, as shown here.

[0073] Fig. Figure 11 shows a first alternative embodiment of the active electrode 30 of the bipolar medical instrument 10. An edge 68 is formed on the active electrode. The design of the edge 68 can improve the ignition behavior. The edge 68 can be designed, as shown here, as an attached ring 70 or ring 70'. The ring 70 and the ring 70' are arranged on the sides – with respect to the transverse direction 24 – of the active electrode 30.

[0074] Fig. Figure 12 shows a second alternative embodiment of the active electrode 30 of the bipolar medical instrument 10, in which an edge 68 is again formed. The edge 68 can be configured, as shown here, as a locally limited flattening 72 of the active electrode 30. The flattening 72 is located at least approximately in the middle of the active electrode 30.

Claims

[1] Bipolar medical instrument (10) for cutting tissue under the influence of high-frequency current, wherein the instrument (10) extends along a longitudinal direction (12) from a proximal end (14) to a distal end (16), and wherein an active electrode (30) and a neutral electrode (32) adjacent to the active electrode (30) are arranged at the distal end (16), and the neutral electrode (32) at least partially encloses a first electrical lead (40) leading from the proximal end (14) to the active electrode (30) in a first section of the instrument (10), wherein the neutral electrode (32) has a first curved neutral electrode surface (34) and a second curved neutral electrode surface (36), the first neutral electrode surface (34) being connected to a second lead (42) leading from the proximal end (14) to the first neutral electrode surface (34), and the second neutral electrode surface (36) is connected to a third supply line (44),which leads from the proximal end (14) to the second neutral electrode surface (36), wherein the second electrical lead (42) at least partially encloses the first electrical lead (40) in a proximal direction in front of the first section (28), wherein a tubular insulating piece (56) is arranged distally in front of the first neutral electrode surface (34), enclosing the second lead (42), and wherein the insulating piece (56) is partially enclosed by the first neutral electrode surface (34). [2] Instrument according to claim 1, wherein the first neutral electrode surface (34) and the second neutral electrode surface (36) are not electrically connected at the distal end (16) and / or are electrically connected only at the proximal end (14). [3] Instrument according to one of the preceding claims, wherein the second supply line (42) and / or the third supply line (44) are tubular in shape. [4] Instrument according to one of the preceding claims, wherein the first neutral electrode surface (34) or the second electrical lead (42) tapers conically in a proximal direction in a second section. [5] Instrument according to one of the preceding claims, wherein the first neutral electrode surface (34) surrounds the first electrical lead (40) to at least 120°, preferably at least 180°, particularly preferably at least 270° and in particular completely. [6] Instrument according to one of the preceding claims, wherein the second electrical supply line (42) surrounds the first electrical supply line (40) to at least 120°, preferably at least 180°, particularly preferably at least 270° and in particular completely. [7] Instrument according to one of the preceding claims, wherein the second electrical supply line (42) is guided in a tubular insulation (52) which is optionally enclosed by a metallic tube (54). [8] Instrument according to claim 7, wherein a diameter of the tubular insulation (52) or, if present, a diameter of the metallic tube (54) corresponds at least approximately to the diameter of the first neutral electrode surface (34). [9] Instrument according to one of the preceding claims, wherein the first neutral electrode surface (34) is radially flared at its distal end. [10] Instrument according to one of the preceding claims, wherein the first neutral electrode surface (34) and the second neutral electrode surface (36) are separated from each other in a distal direction. [11] Instrument according to one of the preceding claims wherein the active electrode (30) exits from the neutral electrode (32), in particular through an insulating piece (56), and extends transversely to the longitudinal extent (12) from the first neutral electrode surface (34) to the second neutral electrode surface (36). [12] Instrument according to one of the preceding claims, wherein a first contacting area (60) of the first supply line (40) and a second contacting area (62) of the second supply line (42) are formed at the proximal end, which are arranged offset from each other along the longitudinal direction (12), and the contacting areas (60, 62) in particular each have a cylindrical surface. [13] Instrument according to one of the preceding claims, wherein an edge (68) is formed on the active electrode. [14] Electrosurgical system comprising a high-frequency generator (26) and an instrument (10) according to any one of claims 1 to 13, which can be connected to the high-frequency generator (26).

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