Abstract:
A high frequency surgical instrument which has at least one treatment electrode ( 11, 11′, 11 ″) which can be or is connected to a high frequency generator ( 12 ), which is at least partly fluid-permeable and to which a fluid, in particular a liquid, which counteracts the sticking of the biological tissue to the treatment electrode ( 11 ) can be or is fed in through at least one liquid infeed passage ( 13 ). At least the region ( 11, 11′, 11 ″) of the treatment electrode which is intended for the interaction with the biological tissue consists totally or partly of a liquid-permeable, porous, biologically compatible sinter material.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a high frequency surgical instrument and in particular to high frequency surgical instruments which are intended for the coagulation of biological tissue with high frequency energy. 
     In the coagulation of biological tissue with high frequency energy the tissue is heated as a result of the current flow and the blood stoppage is achieved through a complex thermally activated biochemical action mechanism. This process rests mainly on the thermal conversion of the proteins in the blood from about 60° C. onwards and from the blood coagulation. Disadvantageous in this is that tissue and blood stick to the coagulation electrodes, through which the vessel in the biological tissue which had just been closed can tear open again and the current flow for the next coagulation can be hindered through the resistance increase. This sticking is influenced by a plurality of factors; the greater the electrode heating is, the stronger is the sticking. 
     From the book “Hochfrequenz-und Lasertechnik in der Medizin” by Reidenbach, Springer Verlag, 1983, pages 148 to 167, a method of hydrothermozation is already known in which distilled water or a saline solution emerges from bores of hollow coagulation electrodes and the sticking effect is reduced through the cooling action and/or the separation of electrode and tissue which thereby sets in. Disadvantageous in this known method is on the one hand the non-uniformity of the liquid output in the region of the treatment electrode and/or the large amount of liquid which is required for a salt jet HF coagulation and which inevitably makes the coagulation itself more difficult through its cooling action. 
     This principle was already used for the flushing of a bipolar coagulation forceps (DE-OS 44 40 158). Disadvantageous in this is that here as well the uniformity of the liquid output is insufficient and the flushing liquid cannot emerge between the tissue and branches of the forceps during the coagulation. 
     From DE-PS 42 12 053 it is known to provide a hard material layer on the electrodes, which however has only an insufficient effectiveness since the electrical impedance of the electrodes is increased and thereby higher electrical voltages are given off by the high frequency generator, which again reinforce the sticking. Anti-adhesion layers on a Teflon basis or silicon coatings (U.S. Pat No. 5,549,604) act similarly disadvantageously. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to create a high frequency surgical instrument of the initially named kind in which the disadvantageous sticking of biological tissue during the coagulation is largely avoided without the coagulation process itself being impaired. 
     In accordance with the invention the liquid infeed for the actual coagulation takes place extremely finely distributedly and uniformly through a fluid-permeable, in particular liquid-permeable, porous sinter material, which preferably consists of a biologically unobjectionable, electrically conducting material, e.g. stainless steel or titanium. 
     The sinter material is advantageously formed as a molded body, which can e.g. be elliptical, spherical or cylindrical. 
     The treatment electrode, which consists at least partly of sinter material, should be formed at a hollow shaft or hose, with it being possible for the conducting in of the high frequency energy to take place either through an electrically conducting execution of the shaft or hose, through leads or through an electrically conducting fluid. 
     For the sake of the simple manufacture the sinter electrodes in accordance with the invention can also extend over regions which do not come into contact with the biological tissue. In this case it is expedient to partly close off the pores of the sinter material. 
     Expedient for the infeed of the fluid. 
     The application of the sinter material can take place in accordance with a particularly preferred exemplary embodiment that it is suitable for the formation of thin-walled sinter bodies at needle electrodes. 
     It is also possible to execute the sinter material as a ceramic body, which makes it necessary to feed in a conducting liquid to the treatment electrode, through which the high frequency energy is conducted in. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a schematic view of a monopolar high frequency surgical instrument made in accordance with the invention with rectilinear fluid infeed passage, 
     FIG. 2 is a corresponding view of a further embodiment with curved fluid infeed passage and a modified coagulation attachment, 
     FIG. 3 is a schematic sectional view of a high frequency surgical instrument in accordance with the invention which is designed as a monopolar puncture needle electrode with cylindrical coagulation attachment, 
     FIG. 4 is an enlarged partial view of the region IV in FIG. 3, 
     FIG. 5 shows the electrode region of a further embodiment of a high frequency surgical instrument in accordance with the invention, with form-locked securing of a sinter body representing the treatment electrode, 
     FIG. 6 is a side view of a high frequency surgical instrument in accordance with the invention which is designed as a bipolar forceps, 
     FIG. 7 is a view which is rotated by 90° about the longitudinal axis  25  of the forceps in accordance with FIG. 6, 
     FIG. 8 is an enlarged side view of the electrode region of the branches of the forceps in accordance with FIGS. 6,  7 , 
     FIG. 9 is a plan view of the object in FIG. 8 with the sinter platelet removed, 
     FIG. 10 is an enlarged sectional view of a further embodiment of the electrode region of the branches of the forceps in accordance with FIGS. 6,  7 , 
     FIG. 11 is a plan view of the object in FIG. 10 with the sinter platelet removed, 
     FIG. 12 is a plan view of a further embodiment of the electrode region of the branches of the forceps in accordance with FIGS. 6,  7  with the sinter platelet removed, 
     FIG. 13 is a sectional view in accordance with line XIII—XIII in FIG. 12, with the sinter platelet left out of FIG. 12 being shown in addition, and 
     FIG. 14 is an enlarged sectional view of the electrode region of the branches of the forceps in accordance with FIGS. 6,  7 , with the releasable connection of the electrode region to the branches of the forceps in accordance with FIGS. 6,  7  being reproduced in addition. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In accordance with FIG. 1 a rectilinear fluid infeed passage  13  is provided in a hollow metal shaft  14  with a longitudinal axis  15  and is provided with a hose connection  23  at the end remote from the patient which is connected to a liquid source  27  which stands under pressure via a hose  26  which is only indicated by broken lines. 
     A metallic connector  16  for the electrical connection of the hollow shaft  14  to a high frequency generator  12  branches off from the hollow shaft  14  at an angle of 45°. The connection piece  16  is preferably secured in a non-illustrated electrode hand grip. 
     A spherical treatment electrode  11  which consists of a fluid-permeable sinter material, in particular sinter metal, is secured at the end of the hollow shaft  14  near the patient. The pores of the sinter body  11  are open forwardly and to the side, but however closed off rearwardly by a closure layer  28  in such a manner that the liquid which is fed in through the fluid infeed passage  13  can emerge only from the forward and lateral region of the treatment electrode  11 . 
     The hollow shaft  14  protrudes into the sinter body  11  and is welded to the latter. The closure layer  28  can be formed through the application of a suitable substance or else through mechanical processing of the rear side of the sinter body  11 . 
     In particular when the spherical treatment electrode-sinter body  11  consists of non-conducting ceramic material, a physiological, 0.9% saline solution should be used as the flushing liquid. 
     The treatment electrode  11  in accordance with FIG. 1 is a monopolar electrode. For this reason a neutral electrode  30  which is to be attached to the body of the patient is connected to the high frequency generator  12  via a conductor  29  which is illustrated with a broken line. 
     In the following figures the same reference symbols designate components corresponding to those in the exemplary embodiment in accordance with FIG.  1 . 
     In the exemplary embodiment in accordance with FIG. 2 the hollow shaft  14  with the fluid infeed passage  13  is bent away, whereas the connection piece  16  lies in a straight line with the treatment electrode, which is formed here as a cylindrical coagulation attachment  11  with rounded-off front end. 
     FIG. 3 shows a monopolar puncture needle electrode, such as is e.g. used for denaturation of tumors. Behind the metallic tip  31  a thin tubular molded body  11 ″ of sinter material is arranged on a region  14 ′ of reduced diameter of the hollow shaft, while the part of the hollow shaft  14  lying behind it is provided with an insulation coating  32 . At the end remote from the patient a plastic molded part  33  is provided in which a Luer lock connector  34  is accommodated. A high frequency connector socket  35  into which a non-illustrated high frequency connection plug can be plugged in opens laterally at the plastic molded part  33  and permits an electrical connection to be established between the non-illustrated high frequency generator and the hollow metal shaft  14 . The fluid infeed passage  13  is again located centrally in the interior of the puncture needle electrode in accordance with FIG.  3 . 
     The region  14 ′ of reduced outer diameter has a number of radial bores  37 , as one can particularly well recognize in FIG.  4 . Through the latter the liquid which is fed in at  34  can enter from the inside into the sinter-molded body  11 , which is expediently applied as a coating onto the region  14 ′ through plasma flame injections. Through the application of the porous material as a coating onto the contracted end part of the hollow metal shaft  14  which is provided with bores  37 , the sinter material, which is fragile per se, is supported over a large area so well that a damage to the sinter coating during use is effectively avoided. The coating  11 ″ preferably consists of porous stainless steel. 
     In the use of the treatment electrode  11  in accordance with the invention, in addition to the conducting in of voltage through the high frequency generator  12 , liquid, preferably water, is also fed in through the fluid passage  13  and emerges over a large area from the pores of the sinter material  11 ,  11 ″ and thus prevents a sticking of the treated biological tissue to the treatment electrode. 
     In accordance with FIG. 5 the treatment electrode  11 , which is designed as a sinter body, consists, just as in the exemplary embodiment in accordance with FIG. 2, of a cylindrical molded body, which is rounded off at the front but which is however provided at the rear side with a circumferential groove  38 , through which the rear end of the treatment electrode  11 , which is introduced into the forwardly open hollow metal shaft  14 , can be firmly secured to the end of the metal shaft  14  near the patient through a furrow  39  which is provided all around in the region of the circumferential groove  38 . 
     In accordance with FIGS. 6 and 7 the two branches  17 ,  18  of a coagulation forceps  19  are connected mechanically to one another and electrically insulated from one another at their end which is remote from the patient through an insulating body  40 . The contacts  41  which are provided for the conducting in of high frequency energy protrude out of the insulating body  40  at the rear. In or at the branches  17 ,  18  is located in each case a fluid infeed passage  13  which opens in the rear region into a hose connection  23  in each case. 
     In the rear and middle region the branches  17 ,  18  are provided with an insulation coating  32 . 
     As can be particularly well seen in FIGS. 8 and 9, the two branches  17 ,  18  are beveled in the electrode region  25  near the patient so that a planar end surface  20  which is slightly inclined outwardly arises, with the fluid infeed passage  13  opening in a fluid emergence opening  21  in the beveled end surface  20 . 
     The beveled end surface  20  is covered in accordance with the FIGS. 6,  7  and  8  with a planar parallel platelet  11 ′ of sinter material which is preferably welded on. In this way the liquid which is fed in through the fluid infeed passage  13  is pressed from the direction of the beveled surface  20  through the fluid emergence opening  21  into the sinter platelet  11 ′, where it emerges uniformly distributed and uniformly from the outer actual treatment surface  42  as a result of the numerous fine pores. 
     In accordance with FIG. 6 the branches  17 ,  18  are slightly bent off inwardly near the electrode region  25  at  43  in such a manner that the planar parallel sinter platelets  11 ′ which are placed onto the inclined end surfaces  20  have at least substantially mutually parallel treatment surfaces  42 . 
     FIGS. 10 and 11 show with respect to FIGS. 8 and 9 a somewhat different execution of the fluid emergence opening  21 , which is formed here as a slit  21  which extends over approximately the entire length of the sinter platelet  11 ′ so that the sinter platelet  11 ′ is charged from the inside over a greater length with liquid than in the embodiment in accordance with FIGS. 8,  9 . The slit  21  extends at least substantially parallel to the axis  22  of the electrode region  25 . 
     In the embodiment in accordance with FIGS. 12 and 13 the beveled end surface  20  of the electrode region  25  is formed as the base of a groove, the lateral webs  44  of which also support the attached sinter platelet  11 ′ laterally so that it is particularly well protected against damage during use. 
     The sinter platelet  11 ′ in accordance with FIG. 13 can be pressed into the groove, welded at the edges or otherwise secured, e.g. through adhesive bonding. 
     The electrode region  25  in accordance with FIG. 14, which is correspondingly also present in the embodiments in accordance with FIGS. 8 to  12 , is releasably connected to the branches  17 ,  18  of the coagulation forceps  19 . For this the electrode region  25 , which contains the end of the fluid infeed passage  13 , has a coaxial connector stub  24  of reduced diameter at its rearward end which has an outer diameter corresponding to the diameter of the fluid infeed passage  13  contained in the branches  17 ,  18 . Circumferential grooves into which an O-ring  46  is laid in as sealing and snap element are located at the periphery of the connector stub  14  and in the radially oppositely lying wall of the hollow branches  17 ,  18 . In this way the electrode region  25  can be drawn off axially from the branches  17 ,  18  against a latching force and latched in in the opposite direction. Thus both for cleaning and sterilization purposes as well as for repair or for the replacement of damaged sinter platelets  11 ′ the electrode region  25  can be taken off from the branches  17 ,  18  of the coagulation forceps  19 . The pore size of the sinter material lies between 0.5 and 150 μm.