Abstract:
The invention concerns an electrosurgical instrument comprising two articulated branches, which can be actuated in the manner of a squeezing tool. The instrument further comprises electrode parts at the distal ends of the branches for grasping tissue and for conducting a coagulating current through the tissue in order to cause it to coagulate as well as current-supplying devices for supplying the coagulating current to the electrode parts from an HF generator. At least one device for preventing a short circuit is arranged and configured on the electrode parts in such a way that the electrode parts are unable to touch.

Description:
RELATED U.S. APPLICATIONS  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       REFERENCE TO MICROFICHE APPENDIX  
       [0003]     Not applicable.  
       FIELD OF THE INVENTION  
       [0004]     The invention concerns an electrosurgical instrument.  
       BACKGROUND OF THE INVENTION  
       [0005]     Electrosurgical instruments have been used for many years in high-frequency surgery to coagulate or cut biological tissue. With coagulation, a high-frequency current is passed through the tissue being treated, causing it to alter due to protein coagulation and dehydration. Here, the tissue constricts in such a way that the vessels occlude and bleeding is staunched. A high current density is required for a cutting procedure, the effect being that explosive vaporisation of the tissue fluid and tearing of the cellular membranes completely cut the tissue in two.  
         [0006]     The use of bipolar instruments is gaining in importance more and more, since lower current strengths than with monopolar instruments are required. It is particularly advantageous that the direction of current between the electrode parts of bipolar instruments can be calculated and does not proceed any distance through the body of the patient.  
         [0007]     Bipolar instruments have two articulated squeezing parts and gripping devices are provided at their proximal ends for handling the squeezing parts. At the distal ends of the squeezing parts, there are electrode parts for grasping tissue and for conducting a coagulating current through the tissue. A voltage produced by a HF generator, and the HF current which this provides, is conducted via current-supplying devices to the electrode parts of the bipolar instrument. To prevent a short circuit upon contact of the two electrode parts, the known instruments have a device for preventing a short circuit accommodated on the branches, whereby the electrode parts are always spaced apart when the instrument is closed.  
         [0008]     The problem with the known devices for preventing a short circuit is that they only indirectly define the space between the electrode parts, because they are accommodated away from the electrode parts. Thus, the aspect ratios of the branches, for example, need to be taken into account to determine the appropriate space. This makes the adjustment of space and required HF voltage considerably difficult.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     It is therefore the object of the invention to further construct an electrosurgical instrument of the type specified at the start so that it is possible to adjust the space between the electrode parts to the required HF voltage.  
         [0010]     According to the invention there is provided an electrosurgical instrument comprising consisting of two articulated branches, which are actuated in the manner of a squeezing tool. The instrument further comprises electrode parts at the distal ends of the branches for grasping tissue and for conducting a coagulating current through the tissue to cause it to coagulate as well as current-supplying devices for supplying the coagulating current to the electrode parts from a HF generator. At least one device for preventing a short circuit is arranged and configured on the electrode parts in such a way that the electrode parts are unable to touch.  
         [0011]     Hence, in the present invention the device for preventing a short circuit is now arranged directly at the place where the effective space must be, that is, between the electrode parts. At the same time, coagulation is not prevented, because the tissue is also able to coagulate at a point of contact between tissue and device due to thermal conduction. To this extent, any sparking between the electrode parts can be reliably avoided with a coagulating procedure.  
         [0012]     In one preferred embodiment, the device for preventing a short circuit has a distance element provided as an insulating section on at least one electrode part. Thus the short circuit between the electrode parts is prevented by the distance element, should these touch.  
         [0013]     In another preferred embodiment, adjoining the insulating section, at least one initial cutting section is arranged on at least one of the electrode parts, in particular configured with a reduced space from the opposite electrode relative to the coagulating electrodes, in such a way that an arc for cutting through the tissue is produced from the initial cutting section with any increase in the voltage of the coagulating current. The cutting section is preferably arranged on the electrode part as an area that tapers in relation to the electrode part and protrudes from this. The electrode part will then have an explicit coagulating section beside the cutting section. The electrode part forming the coagulating section and the cutting section may, during a coagulating procedure, operate as a coagulating electrode over its entire surface area, i.e. both over the surface area of the coagulating section and over the surface area of the cutting section, whereas the tapered cutting section is available solely for a subsequent cutting procedure.  
         [0014]     The cutting section guarantees that the arc is only produced here, whereas a disruptive discharge to the opposite electrode cannot occur on the rest of the electrode section as a result of too great a space between the electrode parts. Thus one and the same instrument can be used to both coagulate and cut, and a change of instrument can be avoided to the benefit of an uninterrupted operation.  
         [0015]     The distance element may be configured as both linear in shape and punctiform. The distance element that is linear in shape will then extend, for example, in the direction of the branch progression, concentrically arranged on the electrode part, over the entire electrode part and accordingly form an edge. Advantageously, in this way the steady formation of an arc is made possible and an even cut is guaranteed. A punctiform distance element is easy to manufacture, reliably prevents a short circuit occurring between the electrode parts and, as a result of thermal conduction, also guarantees safe coagulation at the point of contact between tissue and distance element. Several punctiform distance elements arranged on the corresponding electrode part, e.g. at the respective ends of the electrode part, reliably prevent a short circuit and affect neither the coagulating nor the cutting procedure.  
         [0016]     Preferably, a second cutting section will be configured on the electrode part facing the electrode part with the insulating section. This is particularly advantageous if the insulating section facing the second cutting section is arranged directly on the electrode part so that the electrode part does not have an explicit initial cutting section. In this embodiment, the insulating section is preferably smaller than the opposite cutting section, with the result that an arc can be formed around peripheral areas of the insulating section toward the opposite cutting section. This enables a precise cut to be achieved.  
         [0017]     Alternatively, it is possible to configure the cutting section on both opposing electrode parts. Thus the area for the arc formation and the cutting progression are extremely precisely defined.  
         [0018]     Preferably, the device for preventing a short circuit has at least one insulating section which is formed within an electrode part. A distance element provided as a cutting section is then configured on the electrode part facing the insulating section. The cutting section is arranged in such a way that it only comes into contact with the insulating section when the branches are brought together. Advantageously, a precise cut is also provided for here since the arc is formed between the incorporated section and the cutting section. The insulating section with this embodiment is protected from jolts or similar mechanical strains and essentially from the arc also.  
         [0019]     The insulating section in this embodiment may be configured so as to be flush with an electrode surface of the electrode part that has the insulating section. This allows the electrode part to be cleaned simply and safely after treatment.  
         [0020]     Alternatively, it is possible to arrange the insulating section so that it is sunk in the corresponding electrode part, with the result that the electrode part has a recess. The cutting section configured on the opposite electrode part can thus be at least partially lowered into the recess so that an arc can form inside the recess toward the cutting section during the cutting procedure. Surrounding tissue is thus protected from burning, while at the same time a precise cutting line can be defined.  
         [0021]     In one preferred embodiment, the insulating section is symmetrically arranged toward the initial cutting section and/or second cutting section on the respective electrode parts. A symmetrical arrangement of the cooperating sections guarantees a uniformly developing arc on peripheral areas of the distance element, making for an even cutting progression.  
         [0022]     One possible embodiment provides for the distance element being configured in such a way that mechanical cutting can be carried out. Preferably, the distance element will then have a cutting edge which lends itself to mechanical cutting. With appropriate exertion on the part of the surgeon, the tissue can then be cut through completely following a coagulating procedure and without having to change instrument. This allows an especially soft treatment of the tissue to be achieved.  
         [0023]     In one preferred embodiment the cutting section is configured as an edge with an essentially triangular cross-section on at least one electrode part. A triangular cross-section allows for the successive transition from one large surface area of the electrode part to its edge-shaped tapering. The smooth transition is especially suited to using the entire electrode part as a coagulating electrode where there is sufficient tissue thickness, because the entire surface area and the tissue can be brought into contact with each other.  
         [0024]     Advantageously, the cutting section is configured as an edge with an essentially rounded or circular cross-section on at least one electrode part. On one transition between the explicit coagulating section and the cutting section, the preference is to configure the cutting section in a truncated manner so that a secure anchorage of the cutting section to the corresponding electrode part is guaranteed. With this embodiment there is a relatively large electrode surface available for the coagulating procedure, whereas the cutting section configured as an edge is hardly of any consequence where there is sufficient tissue thickness. At an advanced stage of an operation, on the other hand, and with sufficient proximity of the opposite electrode parts of the electrosurgical instrument, the edge-shaped configuration of the cutting section allows the current density to be increased in such a way that a cutting procedure is possible.  
         [0025]     Preferably, the insulating section is constructed from material that is resistant to arc erosion. Thus, reliable resistance to abrasion from the arc is provided.  
         [0026]     In one preferred embodiment the insulating section consists of a ceramic material. Advantageously, ceramics have a high degree of resistance to corrosion and a high degree of resistance to abrasion from the arc and also to mechanical strain.  
         [0027]     Embodiments of the invention will now be described by way of examples with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1   a  is a cross-section of a schematically represented electrode arrangement in a first embodiment during a coagulation phase;  
         [0029]      FIG. 1   b  shows the electrode arrangement shown in  FIG. 1   a  at the end of the coagulation phase;  
         [0030]      FIG. 1   c  shows the electrode arrangement shown in  FIG. 1   a  during a cutting phase;  
         [0031]      FIG. 2  is a cross-section of a schematically represented electrode arrangement in a second embodiment;  
         [0032]      FIG. 3  is a cross-section of a schematically represented electrode arrangement in a third embodiment;  
         [0033]      FIG. 4  is a cross-section of a schematically represented electrode arrangement in a fourth embodiment;  
         [0034]      FIG. 5  is a cross-section of a schematically represented electrode arrangement in a fifth embodiment;  
         [0035]      FIG. 6  is a cross-section of a schematically represented electrode arrangement in a sixth embodiment;  
         [0036]      FIG. 7  is a side elevation of a schematically represented electrosurgical instrument with an electrode arrangement according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0037]     In the following description, the same reference numerals are used for the same and similarly working parts.  
         [0038]      FIG. 1   a  depicts a front elevation as a cross-section of an electrode arrangement during a coagulation phase in a first embodiment. Represented here are two opposite electrode parts  18 ,  19 , wherein one electrode part  18  has a cutting section or a cutting portion  18   a  and an insulating section or an insulating portion  21  configured as a distance element. In this embodiment, the distance element forms a device  20  for preventing a short circuit. Treated tissue  30  is clamped between the electrodes.  
         [0039]     The insulating section  21  prevents an unwanted short circuit between the electrode parts  18 ,  19  when the branches  11 ,  12  are brought together and may be configured as both linear in shape and punctiform. The distance element that is linear in shape will then extend, for example, in the direction of the branch progression, concentrically arranged on the electrode part, over the entire electrode part and accordingly form an edge. Advantageously, the steady formation of an arc is thus made possible and an even cut is guaranteed. A punctiform distance element is easy to manufacture, reliably prevents a short circuit occurring between the electrode parts and, as a result of thermal conduction, also guarantees safe coagulation at the point of contact between tissue and distance element. Several punctiform distance elements arranged on the corresponding electrode part, e.g. at the respective ends of the electrode part, reliably prevent a short circuit and affect neither the coagulating nor the cutting procedure. The cutting section  18   a  is in any event configured as linear in shape.  
         [0040]     Besides preventing a short circuit, the section  21  defines a thickness of the tissue  30  that remains after the coagulation phase, because it prevents an arc forming prematurely with any pre-set coagulating voltage due to too small a space between the electrode parts  18 ,  19 .  
         [0041]      FIG. 1   b  depicts the electrode arrangement according to  FIG. 1   a , although here the end of the coagulation is represented. According to  FIGS. 1   a  and  1   b  a coagulating current flows over an entire surface of the electrode parts  18 ,  18   a ,  19 , with the effect that the interposed tissue  30  is coagulated. As a result of thermal conduction the tissue  30  is coagulated under the insulating section  21 .  
         [0042]      FIG. 1   c  depicts the electrode arrangement described above during a cutting phase. At the end of the coagulation phase, a HF voltage required for the electrosurgical treatment is slightly increased, with the result that between the cutting section  18   a  and the opposite electrode part  19  the arc  23  is formed, which now cuts through the already coagulated tissue  30 .  
         [0043]     The cutting section  18   a  is preferably arranged on the electrode part  18  as an area that tapers in relation to the electrode part  18  and protrudes from this. The electrode part  18  will then consist of an explicit coagulating section beside the cutting section  18   a . The electrode part  18  forming the coagulating section and the cutting section  18   a  may, during a coagulating procedure, operate as a coagulating electrode over its entire surface area, i.e. both over the surface area of the coagulating section and over the surface area of the cutting section  18   a , whereas the tapered cutting section  18   a  is available solely for a subsequent cutting procedure.  
         [0044]     The height of the insulating section  21  and thus the space from the cutting section  18   a  and opposite electrode part  19  and the HF voltage required for cutting are adjusted to each other. The formation of the arc  23  outside the cutting section  18   a , that is, on the remaining areas of the electrode part  18 , is thus avoided.  
         [0045]     Because of the electrode arrangement just described, one and the same instrument can be used to both coagulate and cut, and a change of instrument can be avoided to the benefit of an uninterrupted operation.  
         [0046]     In  FIG. 2 a  front elevation as a cross-section of an electrode arrangement is represented in a second embodiment. Tissue clamped between the electrode parts during a treatment is not represented in this embodiment for the benefit of better clarity. The same applies, moreover, to  FIG. 3  to  6 . The arrangement differs from the one represented in  FIG. 1   a  to  1   c  in that a cutting section  18   a  is configured as an edge with a triangular cross-section. Because of the successive transition from one large surface area of the electrode part  18  to its edge-shaped tapering, this embodiment is especially suited to using the entire electrode part  18  as a coagulating electrode where there is sufficient tissue thickness, because the entire surface area and the tissue can be brought into contact with each other. With a suitable HF voltage, an arc  23  is formed between the cutting section  18   a  and an opposed electrode part  19 .  
         [0047]     The insulating section  21  has in this instance a tapered shape to also facilitate mechanical cutting where necessary, that is, the distance element has an explicit cutting edge  22 . With appropriate exertion on the part of the surgeon, the tissue can then be cut through completely following a coagulating procedure and without having to change instrument. This makes for an especially gentle treatment of the tissue without the use of an arc.  
         [0048]      FIG. 3  depicts a front elevation as a cross-section of an electrode arrangement in a third embodiment. Here both a cutting section  18   a  is configured on an electrode part  18  and a cutting section  19   a  is configured on an electrode part  19 . An insulating section  21  is arranged directly below the cutting section  18   a  and symmetrically to the cutting sections  18   a ,  19   a . A symmetric arrangement of the cooperating sections  18   a ,  21 ,  19   a  guarantees a uniformly developing arc  23  on peripheral areas of the insulating section  21 , making for an even cutting progression. The insulating section  21  functioning as a distance element is smaller than the cutting sections  18   a ,  19   a , so as not to prevent the arc  23  from forming. Because of the narrow cutting sections  18   a ,  19   a  accommodated on the electrode parts  18 ,  19 , the cutting progression can be extremely precisely defined.  
         [0049]     An extremely simple embodiment of an electrode arrangement is depicted in  FIG. 4 . Here an electrode part  19  only has one cutting section  19   a , whereas on an electrode part  18  facing the electrode part  19  there is only an insulating section  21  configured. Because the arc  23  forms in the direction of the cutting section  19   a , this embodiment allows an exact cutting line to be defined in an especially easy way.  
         [0050]      FIG. 5  depicts a front elevation as a cross-section of an electrode arrangement where an electrode part  18  has an insulating section  21  configured within the electrode part  18 , wherein the insulating section  21  terminates flush with an electrode surface  18   b . A second cutting section  19   a  is provided as a distance element on an opposing electrode part  19 . The insulating section  21  and the cutting section  19   a  operate in this embodiment as a device  20  for preventing a short circuit. Advantageously, a precise cut is also provided for here since the arc  23  is formed between the incorporated section  21  and the cutting section  19   a . The insulating section  21  with this embodiment is protected from jolts or similar mechanical strains and essentially from the arc  23  also.  
         [0051]      FIG. 6  depicts a similar configuration of an electrode arrangement as represented in  FIG. 5 . An insulating section  21  is configured here, however, to be sunk in a corresponding electrode part  18 , so that a recess  18   c  is formed on the electrode part  18 . A cutting section  19   a  configured on an opposing electrode part  19  can be at least partially lowered into the recess  18   c , so that an arc  23  can form inside the recess  18   c  toward the cutting section  19   a  during the cutting procedure. Surrounding tissue is thus protected from burning, while at the same time a precise cutting line can be defined.  
         [0052]     In this embodiment, too, the cutting section  19   a  may be configured with an explicit cutting edge, allowing the tissue to be cut through mechanically.  
         [0053]      FIG. 7  depicts a fully illustrated electrosurgical instrument  10  with an electrode arrangement according to the invention. In the illustration the reference numerals  11  and  12  identify two branches of the electrosurgical instrument  10 . These branches  11 ,  12  have ends  13 ,  14  fitted with electrode parts  18 ,  19 , wherein the electrode parts  18 ,  19  face each other. With the aid of the electrode parts  18 ,  19 , it is possible to grasp a vessel, for example, and to coagulate or cut this by supplying a high-frequency current. In addition, gripping parts  11   a ,  12   a  are provided which are attached to respective proximal ends  15 ,  16  of the branches  11 ,  12 . The proximal ends  15 ,  16  of the squeezing parts  11 ,  12  end in a connecting element  17   a  of current-supplying devices  17 . The current-supplying devices  17  serve to connect the electrosurgical instrument  10  to a HF generator (not represented), which produces a HF voltage, so that a HF current may be supplied to the electrode parts  18 ,  19  by, for example, electrical leads (not depicted) running through the instrument  10 .  
         [0054]     An edge-shaped cutting section  18   a  is configured on the electrode part  18 . This has two insulating sections  21 ,  21 ′ configured as two punctiform distance elements. The distance elements arranged at the respective ends of the electrode part  18  or on the cutting section  18   a  reliably prevent a short circuit and affect neither the coagulating nor the cutting procedure.  
         [0055]     To achieve a high degree of resistance of the insulating section to an arc, the section is preferably constructed from material that is resistant to arc erosion. A high degree of resistance to abrasion is provided in particular by the use of ceramic materials.  
       LIST OF REFERENCE NUMERALS  
       [0000]    
       
           10  Electrosurgical instrument  
           11  Squeezing part, branch  
           11   a  Gripping part  
           12  Squeezing part, branch  
           12   a  Gripping part  
           13  Distal end  
           14  Distal end  
           15  Proximal end  
           16  Proximal end  
           17  Current-supplying devices  
           17   a  Connecting element  
           18  Electrode part  
           18   a  Cutting section  
           18   b  Electrode surface  
           18   c  Recess  
           19  Electrode part  
           19   a  Cutting section  
           20  Device for preventing a short circuit  
           21 ,  21 ′ Insulating section  
           22  Cutting edge  
           23  Arc  
           30  Tissue