Hemostatic bi-polar electrosurgical cutting apparatus and method

AU9221999f 12^ PATENT ABRIDGMENT (11) Document no. ^AU-^B-²¹⁹_ft⁹₇⁹/₇⁹|₃ |i|aKuan^^ ⁽⁵⁴⁾SoSTAT.C B.-POLAB ELECTROSURGICAL CUTT.NG APPARATUS AND METHOD International Patent Classification(s) (51)* A61B 017/39 _App,ication Date : 05.06.92 (21) Application No.-.21999/92 (87) PCT Publication Number: WO92/21301 (30) Priority Data (31) Number (32) Date (33) Country ^ ^^ ^ _AMER1CA 711920 07.06.91 (43) Publication Date: 08.01.93₍44) Publication Date of Accepted Application : 17.10.96 (71) Applicant(s) HEMOSTATIX CORPORATION (72) Inventor(s) PHILIP E. EGGERS⁽⁷⁴⁾ cSS rCO^GPO BOX 1074, BRISBANE OLD 4001 (56) Prior Art Documents US 4940468 US 4271838 US 3651811 (57) Claim Apparatus for ha.ostatically cutting ,««.. the apparatus comprising a_£ir_St support .ember« a first shearing member, a first shearing surface and a^£",J edge- a second support member having a_£irsccutting edge a_Bhearin_g surface ^s:r: rr-^: ™ - — —:°: and a secondshearing members_pl,ot.lly ^rnrng the frrst ^^ ^^_surfaoes together so that the I_contacts the_£ace one another and the, f«.t -' J_memberpivots second cutting edge as the first shea g_ors__llke native to the second shearing me^«». "^^ _motiorl,_the connection means: comp "^_the£lrst insulative material that •^l«^t"^,a"^y_nemberat the shearing me^er from the second ri*^^_COnnection means wherein the *-_conductlve emprises a oolite ^J_lnsulatlve^^.x r;:: %£u - - ——^ottheEirst./2F (11)AU-B-21999/92-2- (10) 672753 shearing member to electrically isolate the first and second shearing members from one another along their respective lengths when the first and second cutting edges contact each other. 18.Apparatus according to any one of claims 1 to 17, for cutting and coagulating tissue, wherein the first shearing member comprises a first blade member having a portion defining the first shearing surface, the first cutting edge having a length, and a first electrode extending substantially for the length of the first cutting edge; and the second shearing member comprises a second blade member having a portion defining the second shearing surface, the second cutting edge having a length, and a second electrode extending substantially for the length of the second cutting edge; the electrically conductive material of the composite of the first blade member forms the first electrode; and the second blade member comprises an electrically conductive material; and wherein the layer of electrically insulative material of the first blade member electrically isolates the first electrode from the second electrode when the first and second cutting edges contact each other. 19.Apparatus for cutting and coagulating tissue, the apparatus comprising a first blade member having a portion defining a first shearing surface, a first cutting edge having a length, a first exterior surface, and a first electrode extending substantially for the length of the first cutting edge; a second blade member having a portion defining a second shearing surface, a second cutting edge having a length, a second exterior surface J.hd a second electrode extending substantially for the length of the second cutting edge; connection means for pivotally joining the first and second blade members together so that the first and second shearing ../3 -' ........... —--------*-,^~^^.**^^**~_l^ (11)AU-B-21999/92 (10)672753 ' - 3 - faces face one another and the first cutting edge contacts the second cutting edge as the first blade member pivots relative to the second blade member in a scissors-like motion; wherein the first blade member comprises an electrically insulative material and the first electrode comprises first layer of electrically conductive material disposed on the first exterior surface; and the second blade member comprises an electrically insulative material and the second electrode comprises a second layer of electrically conductive material disposed on the second exterior surface; wherein the electrically insulative material of the firsb blade member and the electrically insulative material of the second blade member electrically isolate the first electrode from the second electrode when the first and second cutting edges contact each other.

m. ^~- —- -f¹' "1 OPI DATE08/01/93 APPLN. ID 21999/92 AOJP DATE 25/02/93 PCT NUMBER PCT/US92/04664 AU9221999 ...-ATY(PCD (51) International Patent Classification 5 A61B 17/39 Al (11) International Publication Number:WO 92/21301 (43) International Publication Date: 10 December 1992 (10.12.92) (21)International Application Number:PCT/US92/04664 (22)International Filing Date:June 1992 (05.06.92) (81) Designated States: AT, AU, BB, BF (OAPI patent), BG, BJ (OAPI patent), BR, CA, CF (OAPI patent), CG (OA­PI patent), CH, CI (OAPI patent), CM (OAPI patent), CS, FI, GA (OAPI patent), GN (OAPI patent), HU, JP, KP, KR, LK, MG, ML (OAPI patent), MN, MR (OAPI patent), MW, NO, PL, RO, RU, SD, SE, SN (OAPI pa­tent), TD (OAPI patent), TG (OAPI patent).

(30)Prioritvdata: 711,920 7 June 1991 (07.06.91) US ^/''{H[strike]) [/strike][strike]Appl[/strike]i[strike]cant; HEMOSTATIC SURGERY CORPORATION [/GB]; Box 258) Georgetown, Grand Cayman BWI [/strike]-<GB)r.

Published With international search report.Before the expiration of the time limit for amending theclaims and to be republished in the event of the receip ofamendments.(yi) \cff\o:AaVx Co^po^-^^oA ffS(72)A[/strike]pHww[strike]KHid[/strike] Inventor: EGGERS, Philip, E. [US/US]; 5366 Reserve Drive, Dublin, OH 43017 (US). (74) Agents: P1SANO, Nicola, A. et al.; Fish & Neave, 875 Third Avenue, New York, NY 10022 (US).f ;;; ///^!hr>TcfS7'#7~SX CO#POJ?ft7/&[/strike]*>AfrX-[strike]>' i}$V[/strike]V' ..' J[strike]S[/strike]*-[strike]"? ,*/ ^„ cm eo c/,> yp/op [/strike][strike]W'm[/strike]i[strike]£/s?*ytb[/strike]~-[strike]/ [/strike][strike]£i)4s[/strike]l[strike]/<S.S [/strike][strike]&/ /?srie.S-/[/strike] (54)Title: HEMOSTATIC BI-POLAR ELECTROSURGICAL CUTTING APPARATUS AND METHOD (57) Abstract A surgical instrument (10) is described that incorporates bipolar electrodes on opposing shear­ing members (20, 30) for passing a high frequency current through the tissue for causing hemostasis of the tissue and for cutting the tissue. An electrically insulating material is interposed between the shear­ing members so that the electrodes are spaced apart from 0.002 to 0.050 inches and the current passes between the opposing electrodes through th^ tissue and not between the opposing shearing surfaces (21, 31). The insulating material has a higher hardness than the opposing members to reduce wear of the insulation and provide a self-sharpen­ing feature. Methods of simultaneously causing tis­sue and severing tissue are also provided. The use of a constant voltage high frequency power supply (110) to deliver current to the tissue to cause hemos­tasis is described in conjunction with those meth­ods, I 10 WO 92/21301PCr/US92/04664-1- HEMOSTATIC BI-POLAR ELECTROSURGICAL CUTTING APPARATUS AND METHOD This invention relates to improved hemostatic electrosurgical instruments, and particularly to improved 3pi-polar electrosurgical instruments for severing and causing hemostasis of tissue. ftanVqround of the Invention The control of bleeding during surgery accounts for a major portion of the time involved in an operation. In particular, bleeding that occurs when tissue is incised or severed can obscure the surgeon's vision, prolong the operation, and adversely effect the precision of cutting. Blood loss from surgical cutting may require blood infusion, thereby increasing the risk of harm to the patient. Hemostatic surgical techniques are knovm for reducing the bleeding from incised tissue prior to, during, and subsequent to incision. One such technique uses a heating element to transfer heat to the severed tissue to thermally reform collagen. Heat transferred from the instrument to the issue produces a thin collagenous film which seals over the severed blood vessels and capillaries, thus reducing bleeding. Localized application of heat reduces tissue necrosis or damage that may retard healing. lleetrosurfical techniques that pass a high frequency or radio frequency currant through the L WO 92/21301PCr/US92/04664 - 2 - patient's tissue between two electrodes for both cutting and causing hemostasis tissue also are known. The current passing through the tissue causes joulean (ohmic) heating of the tissue as a function of the current density and the resistance of the tissue through which the current passes. Such heating denatures the tissue proteins to form a coagulum that seals the bleeding sites. Monopolar electrosurgical devices employ a small electrode at the end of a handle in the surgeon's hand and a large electrode plate beneath and in contact with the patient. Only one of the two electrodes required to complete the electrical circuit is manipulated by the surgeon and placed on or near the tissue being operated on. The other electrode is the large plate beneath the patient. The electrosurgery power supply impresses high frequency voltage spikes of thousands of volts between these two electrodes, sufficient to cause an electric arcing from the small 2 0 operating electrode the surgeon holds to the most proximate tissues, then through the patient to the large electrode plate beneath the patient. In the patient, the elisctrical current becomes converted to heat; hottest in the tissues immediately below the small hand-held electrode where the currents are most concentrated. A principal disadvantage of monopolar electrocautery is that current flows completely through the patient. These high voltage electrical currents may arc from the small electrode to nearby non-targeted vital structures, or follow erratic paths as they flow through the patient's body, thus causing damage to tissues both near and at some distance frott the electrode.

WO 92/21301PCr/US92/04664 - 3 - Another drawback of monopolar electrosurgical devices is the excessive tissue damage caused by the high voltage arc, including carbonization of the tissue, which compromises wound healing. Furthermore, monopolar devices typically create vision obscuring smoke, which must be evacuated from the surgical site. In bipolar electrosurgical devices, two electrodes are closely spaced together and have the same surface area in contact with the tissue. The current flow is thus locally confined to the tissue i.

that is disposed between and electrically connects the electrodes. One difficulty encountered with prior art electrosurgical devices is that of controlling the 15 current flow through the patient's tissue to obtain hemostasis in localized areas, ttth^t also heating and causing undesirable trauma to atfa^S* tissue. Although the introduction of hipoUV electrosurgical devices has helped to localize etarrevt flow, previously 20 known bipolar electrosurgical devises present difficulties in selectively applying tM durteht flow. For example, Hildebrandt et »1, U.S. Patent 3,651,811 and Soviet Union Patent Certificate 575,103 describe bipolar electrosurgical spissors having 25 opposing cutting blades forming active electrodes. These devices enable a surgeon to sequentially coagulate the blood vessels contained in the tissue and then mechanically sever the tissue with the scissor blades. However, these devices apparently require the 3 0 surgeon to cycle the powef supplied to the electrodes during separate steps of obtaining hemostasis in the tissue and then cutting the tisstie. In particular, these previously known devices require the surgeon to first energize the electrodes and grasp the tissue to 35 cause hemostasis. once the blood vessels contained mm PCr/US92/04664 WO 92/21301 - 4 - within the tissue are coagulated, the electrodes are deenergized so that the scissor blades Bay be closed completely to sever the tissue mechanically. The scissors are then repositioned for another cut, and the 5 power supply to the scissors cycled on and off agaxn to Lngeal the tissue. Neither of these devxces appear to permit the surgeon to maintain the electrodes continuously energized state, because the power supply would be shorted out or damaged if the blades were permitted to contact each other while energized Accordingly, a major drawback of prevxously known hemostatic bipolar electrosurgical cutting devices is that they have neither recognxzed <** existence of, nor resolved the problem of, selectively delivering a current to obtain hemostasis at one deliveringsixnultaneously allowing location in the tissue, wnne already heBOStatically heated tissue to be severed, would therefore be desirable to provide a bipolar electrosurgioal instrUBent that autoBatioally and₂„ continuously adjusts the current delivery »°«£>~ that it precedes the cutting point, without shortx„_g the electrodes and interrupting the current providing hemostasis of the tissue.,.„„,«, Another drawback of previously known bipolar₂₅electrosurgical devices is the tendency for coagulu. to build up on the electrode surfaces. Such buildup Bay i„pede the cutting ability of the device, cause staking of the tissue to the device, and interfere Tm the surgeon's ability to manipulate the device at the -^^^_drawbaokisthe tendency in previously know* bipolar electrosurgical devices to e^rience some current Lakage near the electrodes rich mat resuit in coagulum buildup on the non-act^₃₅surfaces of the eiectrosurgical instrument as well.

WO 92/21301 PCr/US92/04664 - 5 - It would therefore be desirable to provide an electrosurgical instrument wherein coagulum buildup on the surfaces of the instrument is reduced, thereby improving maneuverability of the instrument at the surgical site and reducing trauma to adjacent tissue. Heretofore, no bipolar electrosurgical instrument for cutting and causing hemostasis of planar tissue areas has recognized or overcome the aforementioned problems. A continuing need for improved hemostatic electrosurgical scissors-like devices for simultaneously causing hemostasis in tissue and severing that tissue therefore exists. smmnarv of th* Tnvention In view of the foregoing, it is an object of the present invention to provide a bipolar electrosurgical scissors-like cutting instrument which simultaneously causes hemostasis of tissue and mechanically severs tissue in a continuous manner at a cutting point that advances along the cutting edges of the scissor members. It is another object of the present invention to provide an electrosurgical scissors-like cutting instrument that eliminates the need for the surgeon to energize and deenergize the electrodes of the scissor members during the steps of causing hemostasis of the tissue and mechanically severing the tissue. The instrument constructed in accordance with the principles of this invention therefore reduces the likelihood that the electrodes may short circuit during 3 0 cutting, thus permitting the instrument to be used for continuously hemostatically cutting tissue. The result is an instrument providing a smoother and more precise surgical cut than previously known devices, which [ \ PCI7US92/04664 WO 92/21301 - 6 - permit hemostasis_and cutting of dxscrete «»• sections in an intermittent, non-continuous, Banner.It is yet another object of the present invention to provide improved hemostatic electrosurgica! scissors that reduce "^¹"^^P and adherence of tissue to the workxnc, and non worK.ng surfaces of the instrument.It is still a further object of the present invention to provide methods for hemostatically severing tissue with an electrosurgical -=~t^ thereby reducing the number of steps requrred of the surgeon to employ the electrosurgical instrument xn a continuous™^ ^ ^ ^ ^^ _{irivention t}„ provide methods of using electrosurgical instruments that reduces coagulum buildup and sticKing of t.ssue to the surfaces of the instrument.These and other objects are accomplxshed xnaccordance with the principles of ^^t^T ,_by providing a bipolar electrosurgical scxssors-lxKe instrument wherein each scissor member oomprxses an electrode for causing hemostasis of tissue and a shearing surface for mechanically severxng the txssue. _Alayer of insulating material is disposed on at least ₅ one shearing surface of the scissors so^th"electrically active portions of the scxsscr members do not contact each other at any point during operation of The instrument. Thus, cu«ent flows through tissue between the scissor members, but short circuits -,0 Which would terminate hemostasis - do not occur «xth this arrangement, hemostasis and cutting occurs xn a continuous manner along tissue disposed between thescissor "^^^^^^_anelectrosur,ical instrument ₃₅ constructed in accordance with the present invention PCI7US92/04664 WO 92/21301 - 7 - comprises a scissors-URe instrument including first and second scissor members. Each scissor member comprises a blade-like portion or shearing member having a shearing surface, a cutting edge and -5 exterior surface. The first and second scxssor members are connected by connecting means so that the respective shearing surfaces move through a range of lotln in a conventional scissors-UKe """^^ That cutting action defines a cutting pout that moves 10 along the cutting edges of the respective shearxng members through the range of motion, as „ *»™-«^ instrument of the present invention further ^""^ electrode on each shearing member »hich rs connected to pol supply that provides a high freguency current.₁₅„, electrically insulating material is interposed¹TetLn the electrodes so that the tetrodes on the respective shearing members do not contact each other in the range of motion. The insulating material is ^sposed so that current passes between the electrodes 20 of toe respective shearing members distal to the cubing point, but not between the shearing sur aces. in a first family of embodiments of the present invention, the first and second =^h-^rin» Lmbers are made of an electrically conducting material „ soCat they comprise, respectively, first and second " electrodes A first layer of eiectrically insulating I tlrial is disposed on at least one of the shearing_Surfaces. thereby forming ^-"^ %££. surface of that shearing member. In tnese the connecting means includes an "1~«™_are insulating material so that the shearing -^"^^a eiectrically isolated at the connecting means The first layer of insulating material, whether disposed on Zl both shearing surfaces, has a total thiefcness in SUBSTITUTE SHEET - 8 - IPEA/US07 0CT1993 PCT/US92/04664 I the range of 0.050 mm to 1.270 mm (0.002 to 0.050 inches), and preferably in the range of 0.076 to 0.178 mm (0.003 to 0.007 inches). T© further achieve the advantages of the present invention, individual instruments of the first family of embodiments may include one or more of the following: a layer of material having a high electrical and thermal conductivity on one or both of the exterior surfaces of the shearing members; a second layer of insulating material disposed on the exterior surfaces of the shearing members, except for regions proximate the cutting edges; and a layer of abherent material disposed on the outermost tissue contacting portions of the instrument. These layers reduce coagulum buildup on the non-working surfaces of scissors, thereby reducing sticking and trauma to adjacent tissue. They also improve maneuverability of the instrument and enhance the surgeon's view of field, thereby enabling more precise surgical cutting. 20A self-sharpening feature can be attained by employing a first layer of a first hardness on one of the shearing surfaces and a second layer of a second different hardness on the other shearing surface. Advantageously, the use of a harder material a ? one of the shearing surfaces provides for obtaining excellently mated cutting edges after a few cycles of operation and keeps the cutting edges sharp during repeated use. In a second family of embodiments of the present invention, the first and second shearing members are mad6 of a non-electrically conducting material, and the electrodes comprise a layer of electrically conducting material disposed on the exterior surfaces of each shearing member. In this arrangement, the electrically insulating material is SUBSTITUTE SHEET.IPEA/US07 0CT1993 9 - PCT/US92/04664 comprised of the shearing members. The electrically conductive layers of the respective shearing members are spaced apart, at the cutting point, a distance in the range of from 0.050 mm to 1.270 mm (0.002 to 0.050 inches), preferably 0.076 to 0.178 mm (0.003 to 0.007 inches), as the cutting point moves through the range of motion. The layer of electrically conducting material on each shearing member may be comprised of an inner layer of a high electrical and thermal conductivity material and an outer layer of an oxidation resistant, high electrical and thermal conductivity material, the outer layer being superimposed in electrical contact over the inner iay^er-....₁₅individual variations on instruments within the second family of embodiments may include an abherent layer covering the electrically conductive layer and a layer of electrically insulating material covering all of the electrically conductive layer except for a region of each shearing member proximate the cutting edge. The present invention also includes methods of using bipolar electrosurgical instruments to simultaneously cause hemostasis in tissue while mechanically severing that tissue in a continuous manner, and without significant coagulum buildup or sticking. The methods include the steps of (A) providing first and second shearing members, each shearing member having a shearing 30 surface, a cutting edge and an electrode, the shearing members connected together so that the shearing surfaces move in opposition through a range Of motion in a scissors-like action that defines a cutting point moving along the .cutting edges through the range of motion? pXSUBSTITUTE SHEETIPEMJS07 0CT1993 - 10 - PCT/US92/04664 (b)connecting the electrodes to a power supply; (c)selecting and maintaining a substantially constant voltage level output across the power supply, the voltage level output independent of the impedance of the load connected across the power supply; (d)providing an electrically insulating material between the first and second electrodes so that the electrodes do not contact each other in the range of motion; (e)placing the electrodes in electrical contact with tissue to be cut so that high frequency current passes between the electrodes and through the tissue distal to the cutting point, but not between the shearing surfaces; and (f)moving the first and second shearing members through the range of motion, thereby passing current through the tissue in a region distal to the cutting point, simultaneously causing hemostasis of the tissue and cutting the tissue at the cutting point. The methods of the present invention include selecting suitable voltage and current ranges for 25 employing the present invention. The methods further include the use of alternating current voltage waveforms having a crest factor — ratio of peak voltage to root-mean-square (RMS) voltage — near unit^. Brief Deserietian of the Drawings The above and other objects and advantages of the invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which Mtfk^MI ISUBSTITUTE SHEET jpy^s_070CT1993- 11 - PCT/US92/04664 like reference numerals refer to like parts throughout, and in which: FIG. 1 is an elevation perspective view of a scissors constructed in accordance with a typical one of a family of embodiments of the present invention; FIG. 2 is a side view of the scissors of FIG. 1, showing tissue disposed between the shearing members; FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2; FIGS. 4-8 are cross-sectional views similar to that of FIG. 2 for various alternative embodiments of the present invention. P^-jr^ nggcriDti™ "? the Invention₁₅Referring to FIGS. 1-3, bipolar electrosurgical scissors 10 for simultaneously causing hemostasis in and shearing a patient's tissue 100 is described. Scissors 10 includes first scissor half 20 and second scissor half 30 pivotally connected by fastener 40. In a first family of embodiments constructed in accordance with present invention, scissor half 20 is made of an electrically conducting material and has at 6ne end a first shearing member 21. Shearing member 21 forms a first electrode comprising shearing surface 22, cutting edge 23 and exterior surface 24. Scissor half 20 has, at the other end, support member 25, preferably configured with a thumb or finger hole for manipulating scissors half 20, and ^leJrical connection 2* which connects the electrode 30 to a conventional constant voltage power supply 10 via eable 21. soissor half 30 is likewise made of an electrically conducting material and has at one end shearing member Si. faring member 31 forms a second electrode comprising shearing surface 32, cutting —_. _ —...a-a^ HmmISUBSTITUTE SHEET' IPEA/US07QCT1993 - 12 - PCT/US92/04664 edge 33 and exterior surface 34. Scissors half 30 also has, at the other end, support member 35, preferably configured with a thumb or finger hole for manipulating scissors half 30, and electrical connection 36 which 5 connects to power supply 110 via cable 37. Power supply 110 may be a high frequency voltage source having a substantially constant voltage at selectable output levels. Such devices are described, for example, in U.S. Patent Nos. 4,092,986 10 and 4,969,885. The power supply used in conjunction with the present invention preferably provides an output voltage level that is substantially constant at the user selected level, and independent of the electrical resistance encountered by the electrodes. 3^5To reduce coagulum buildup on the working surfaces of the scissors, applicant has developed power supplies providing substantially constant voltage output that is independent Of the load impedance, low source impedance and a alternating-current voltage 20 waveform having a crest factor — the ratio of peak voltage to RMS voltage — near unity. The present invention, when powered by such power supplies, has been observed to provide highly satisfactory hemostasis without arcing or charring of the tissue, and little coagulua buildup. Scissor halves 20 and 30 are preferably made of a rigid, structural material capable of sustaining sharp scissors-like cutting edges 23 and 33, such as stainless steel or martensitio stainless steel. 30 Alternatively, materials of high: electrical and thermal , conductivity, and struGturai~lr>strong enough for shearing tissue, such as copper,or copper alloys, may • be used. Halves 20 and 30 are- pivotally connected by fastener 40 in opposition so thafe shearing surfaces M 3S and 32 and cutting edges 23 and 33 of the shearing _mmMimm^_miISUBSTITUTE SHEET' IPEA/US07 0CT1993 - 13 - PCT/US92/04664 members move in scissors-like opposition through a range of motion to sever tissue 100 placed therebetween. Fastener 40 may be, for example, a screw or a rivet that electrically insulates scissor halves 20 and at the pivot point. The fastener may be made of an insulating material, for example, polyamide or nylon. Alternatively, fastener 40 may comprise a combination df non-insulating and insulating materials, such as a stainless steel screw insulated from one or both scissor halves 20 and 30 by nylon bushings. Scissor support members 25 and 35 have insulating coating 11 in regions L₁ to electrically insulate the support members from each other and from the surgeon using scissors 10. Insulating coating 11, which may comprise polyvinyl chloride, nylon, or other plastic insulating material, also may be applied to those areas of scissors 10 not used for cutting tissue. As illustrated in FIG. 3, exterior surfaces 24 and 34 of the shearing members may have a coating 12 of a high electrical and thermal conductivity material, e.g., silver or copper, other than on their respective shearing surfaces 22 and 32. Coating 12 facilitates good electrical contact between exterior surfaces 24 and 34 and the tissue that comes into contact with those surfaces as shearing members 21 and 31 are moved relative to one another. Coating 12 reduces localized heating of the exterior surfaces 24 and 34 of shearing members 21 and 31 fey dissipating the heat thrcughout the thermally conductiftg surface area of the coating, coating 12 also reduces the likelihdodi that joulean heating of shearing members 21 and 31 will occur, because any localized current flow is re-distributed over the efttiire coating 12. Consequently, coating 12 reduces auniiai^aHHISUBSTITUTE SHEET ; IPEA/US070CT1993 14 - PCT/US92/04664 thermal decomposition and sticking of blood and tissue to exterior surfaces 24 and 34 of scissors 10 during use. A thin coating 13 of an electrically insulating material is disposed on each of shearing surfaces 22 and 32 to cover at least as much of those shearing surfaces as could contact each other within the full range of motion of scissor halves 20 and 30. Insulating coating 13 covers cutting edges 2 3 and 3 3 so that the cutting edges are electrically inactive and non-conducting. As shown in FIG. 4, an alternative embodiment provides insulating coating 13 only oh shearing surface 3 2 of shearing member 31. The other shearing surface 21 and cutting edge 23 remain electrically active, i.e., conductive. In this embodiment, electrical isolation between scissor halves 20 and 3 0 is achieved by the single layer of insulating material. Insulating coating 13 allows the scissor halves forming the bipolar electrodes to move relative to each other so that current flows between exterior surface 24 of shearing member 21 and exterior surface 34 of shearing member 31, while ensuring that scissor halves 20 and 30 do not electrically contact each other. This configuration enables the cutting edges to contact each other to sever tissue while preventing short circuiting, which would impede simultaneous coagulation of the blood vessels extending through the tissue. Coating 13 substantially prevents current flow directly between opposing shearing surfaces 22 and 32 when the scissor halves are closed together. Rather, the current flows through the path of least resistance between the electrodes, i.e., through the tissue in direct contact with regions 28 and '38, respectively, ©f 3S exterior surfaoes 24 and 34 of the shearing members.

WO 92/21301PCr/US92/04664 - 15 - This current flow is represented schematically by flux lines 99 shown in FIGS. 3 and 4. The arrangement of the present invention confines current flow between regions 28 and 38 of exterior surfaces 24 and 34 to region 101 (see FIG. 2), from where cutting edges 23 and 33 contact each other to a point distal to the cutting point. That distal point is where either the tissue no longer forms an electrical connection between the electrode surfaces (region 102 of FIG. 2) or the spacing between halves 20 and 30 is sufficiently large that the current density is too low to cause significant joulean heating of the tissue (region 103 of FIG. 2). It is therefore apparent that as scissors 10 is gradually closed, the cutting point moves along cutting edges 23 and 33 of shearing members 21 and 31 distally of fastener 40 and is preceded by region 101 in which a current flows from one scissor halve to the other to achieve hemostasis of the tissue. Thus, 20 hemostasis occurs at a location just in advance of the cutting point while cutting edges 23 and 33 simultaneously sever the hemostatically heated tissue. The embodiment of FIG. 4 permits an asymmetrical current flow between scissor halves 20 and 30 compared to the embodiment of FIG. 3. Specifically, proximal to the cutting point, some current may flow from the uninsulated shearing surface to tissue in contact with that surface, through the tissue, and to an uninsulated portion of the other shearing member. The applicant has determined that this asymmetry has no significant effect on the hemostatic evitting operation or the ability of the device to deliver current to the tissue relative to the exiibodiment of FIG. 3* Electrically insulating layer 13 is preferably ffiad«i of a material having a hardness that is rife pt WO 92/21301PCr/US92/04664 - 16 - greater or substantially greater than the steel or other electrically conducting material used to manufacture conventional scissors-like devices. For example, referring to the embodiment illustrated in FIG. 4, shearing members 21 and 31 may be made of a martensitic stainless steel, e.g., AISI 420. Insulating layer 13 comprises an inorganic electrically insulating material such as a glass, ceramic, nitride, boride or synthetic diamond. Depending upon the material selected, insulating layer 13 may be deposited on shearing surface 32 by conventional techniques, for example, plasma or flame-sprayed deposition. Applicant has obtained good results using ceramic materials such as alumina or zirconia. 15The applied coating forms a non-conductive cutting edge for that shearing member and has a greater hardness than the steel substrate and the steel of opposing shearing member 21. Consequently, as coating 13 rubs against the cutting edge 23 or shearing surface 22 of shearing member 21, steel shearing surface 22 and cutting edge 23 are mechanically ground or polished by the harder insulating material 13. Scissors 10 are therefore self-sharpening and remain sharp during continued use. Furthermore, the relatively lower hardness of steel cutting edge 23 will not wear or degrade the insulating characteristics or structure of the harder electrically insulating coating 13, thus providing a durable instrument. The self-sharpening feature provided by the relatively greater hardness of insulating coating 13 also permits the use of less expensive materials for shearing members 21 and 31* For example_rscissors 10 may be made of a material that may not retain a sharp cutting edge during repeated use absent the self-sharpening characteristie of the applied harder _mmaumiimmim^_jmMmatt^SUBSTITUTE SHEET IPEMJS07 0CT1993 PCT/US92/04664 - 17 - coating. This feature is particularly advantageous for constructing scissors 10 to be disposable, or in havxng disposable shearing meters 21 and 31 that detach fro. their respective support members 25 and 35 (not shown), insulating coating 13 is deposited in a layer having a thickness in the range of 0.050 mm to about 1.270 mm (0.002 inches to about 0.050 inches), more preferably 0.076 to 0.178 mm (0.003 to .007 xnches) The applicant has determined that at thicknesses of 0.025 mm (0.001 inch) or less, the thickness of the insulating layer 13 is insufficient to prevent shortxng of the electrodes. Insulating layer thicknesses above 0.050 mm (0.002 inches) and below 1.270 mm (0.050 inches) provide adequate hemostasis. It has been » observed, however, that the greater the minimum distance between the proximate current conducing portions of the opposing electrodes in the region of Lrent flow through the tissue, the longer the current path through the tissue and the more difficult it becomes to obtain the desired degree of hemostasis.

to For the ceramic insulating materials described, insulating layer thicknesses above 1.270 n (⁰-⁰⁵⁰ inches) are believed to be too large for most practical applications.^^ ^ ^ ^ ^ ^^_embodiment of the scissors of FIG, 1 is described. The seizor* constructed as described hereinbefore with respect to PIO. 3, have a coating 14 of an abherent material __*«„,, 13 The abherent material disposed on coating 12. me a«« „ ccnstWn, coating 1* is capable of -""^f frequency current through its thicRneee end further rea^ee the sticKin, and accumuletion of •**-«-tiesue to exterior surfaces H and 34 of the shear „_g »e*ber_S. suitahie abherent materials.for coating u35 include fluorocarbon material, conductor-fUledMliiliiMMaiMIm^hSUBSTITUTE SHEET IPEA/US070CT1993 - 18 - PCT/US92/04664 fluorocarbon coatings or thin fluorocarbon coatings less than about 0.0051 mm (0.0002 inches) thick (which may otherwise be electrically insulating), e.g., Vyolex 10002, available from Du Pont. 5FIG. 6 shows yet another embodiment of the bipolar electrosurgical instrument of the present invention. This embodiment is similar to that of FIG. 4, except that exterior surfaces 24 and 34 of shearing members 21 and 31 are provided only with 10 coating 14 of an abherent material and electrically conducting coating 12 is not applied. Referring now to FIG. 7, another alternative embodiment of the present invention is described. This embodiment is substantially the same as that described hereinbefore with respect to FIG. 4. This embodiments differs, however, in that instead of the electrically conductive coating 12 of the embodiment of FIG. 4, an electrically insulating layer 15 is disposed on exterior surfaces 24 and 34 of shearing members 21 and 31. I-ayer 15 is omitted from regions 28 and 38 immediately adjacent to cutting edges 23 and 33, respectively. Insulating layer 15 inhibits current flow to the tissue other than through regions 28 and 38 adjacent to cutting edges 23 and 33. Accordingly, heating of the tissue is localized to the region in and preceding the shearing region, thereby reducing joulean heating of tissue proximate to the portions of the exterior surfaces of shearing members 21 and 31 covered by insulating layer 15, Materials suitable for use in insulating layer 15 include aluminum oxide, fluor©carbons, polyamide and silicone based coatings. Referring to FIG. 8, an embodiment representative of a second family of embodimettts constructed in accordanee with the present invention is described, with similar components indicated by like- SUBSTITUTE SHEET IPEAAJS07 0CT1993 - 19 - PCT/US92/04664 primed members. In this embodiment, which outwardly resembles the scissors of FIG. 1, opposing shearing members 21' and 31• are made of an electrically insulating material, e.g., a ceramic material such as zirconium oxide or aluminum oxide-based ceramics. The exterior surfaces of members 21' and 31', i.e., those portions other than the shearing surfaces 22' and 32• and cutting edges 23' and 33', have a coating 16 comprising a material of high electrical and thermal conductivity, e.g., copper, silver or nickel. Coating 16 thereby provides opposing electrodes for conduction of high frequency current through tissue between coatings 16 on exterior surfaces 24' and 34' of shearing members 21• and 31'. In this embodiment, coating 16 covers most of the exterior surface of shearing members 21' and 31' such that the current carrying sections closest to cutting edges 23' and 33' are no closer than 0.050 mm to 1.270 mm (0.002 to 0.050 inches), and more preferably 0.076 to 0.178 mm (0.003 to 0.007 inches). With the configuration of the embodiment of FIG. 8, shearing members 21• and 31' provide the desired insulating material between the electrodes.

EXAMPLES Scissors in accordance with the embodiments illustrated in FIGS. 1-3 and 4 have been constructed of a martensitic stainless steel material (Grade AISI 420)^ Scissor halves 20 and 30 were nominally 177.8 mm (seven inches) in length with shearing members 21 and 31 extending 38.1 ma (one and one-half inches) beyond fastener 40. Shearing wembers 21 and 31 were 2.5 to 7.6 mm (0.1 to 0.3 inches) wide and 1.78 to 2.54 mm (0.07 to 0.10 inches) thick, the smaller dimensions being distal to the pivot. An insulating coating 13 w\ISUBSTITUTE SHE . 'PEA/US 07 OCT 1993 - 20 - PCT/US92/04664 f was deposited on shearing surface 32 of shearing member 31 by plasma spraying alumina to a thickness in the range of 0.076 to 0.178 mm (0.003 to 0.007 inches). Coating 13 was applied along the length of member 31 that contacts opposing member 21 in the full range of motion. Using conventional electroplating techniques, exterior surfaces 24 and 34 were provided with a coating 12 of a material having a high electrical and thermal conductivity comprising three layers: 10a first layer of copper, 0.050 to 0.076 mm (0.002 to 0.003 inches) thick, was deposited on all surfaces except the shearing surfaces; a second layer of nickel, 0.254 to 1.016 mm (0.010 to 0.040 inches) thick, was then deposited on the copper layer and; a third layer of gold, 0.508 to 1.016 mm (0.020 to .040 inches) thick, was deposited on the nickel layer. The nickel and gold layers provide an oxidation resistant protective outer layer for the thermally and electrically conductive sublayer of copper. Support members 25 and 35 included a coating 11 of an insulating material about 0.127 mm (0.005 inches) thick. 25Experiments were performed on biological tissue and raw beefsteak using the above-described scissors in conjunction with an experimental power supply. The experimental power supply was operated at various selected constant frequencies in the range of 400 to 800 kHz and at selected levels providing a substantially constant voltage output level at the electrodes of the scissors in the range of 10 to volts (RMS)* This power supply had a low source impedance, and provided an alternating-current vdltage wavelotm having a crest factor near one. The voltage ii4Bda«MiitalliMHMilMBMULSUBSTITUTE SHEET. ; IPEA/US070CT1993- 2X - PCT/US92/04664 waveform was maintained at a substantially constant level in the sense that the output volatage did not droop significantly at high loading. The preferred operating range for the above-described embodiment was found to provide a voltage at the electrodes of the instrument of 10-120 volts, more preferably 30-90 volts (RMS). The instrument operated satisfactorily throughout the above range of operating conditions, causing hemostasis of tissue and cutting tissue with minimal bleeding of that tissue. Accumulation of coagulated blood and tissue on the scissors was slight. Frequencies below 100 kHz are known to affect the neuro-muscular systems of the patients, and may cause undesired stimulation. Applicant observed that frequencies above 800 kHz provided no advantage in operation and added cost to the power supply. While applicant believes that it would be possible to use higher frequencies, up to 2 MHz, the line losses in the cable connecting the electrosurgical instrument to the power supply would make use of such frequencies impractical. Applicant observed that voltages (at the electrodes) below 10 volts (RMS) did not produce adequate joulean heating in the tissue to cause hemostasis. While prior art bipolar electrosurgical hemostatic teachings indicated that voltages above 120 volts (RMS) would be most desirable for achieving hemostasis of tissue, applicant observed that voltages above 120 volts (FMS) caused localized overheating of the electrodes and excessive accumulation of coagulum. Above 120 volts (RMS), rapid coagulum buildup necessitated frequent cleaning of the scissors, for example, every one to three cuts.

tt/nmSUBSTITUTE SHEETIPE/VUS07 0CT1993 - 22 - PCT/US92/04664 Applicant observed that the device according to FIG. 4, which has coating 13 on only one shearing surface, provides the same level of performance as devices having insulating layers on both shearing surfaces /when operated under the same conditions). For both embodiments, the amount of heating and depth of hemostasis on both sides of the cut tissue are substantially uniform. It will of course be understood by one skilled ija the art that use of a voltage level greater than the above specified ranges may be suitable for causing hemostasis in tissue having higher impedance. * * * The scissors of the present invention also can be used for blunt dissection, for example, by spreading the scissors as they are advanced into tissue during the raising of a skin flap. For such an embodiment, the blunt tips of the scissors are configured to cause hemostasis during the blunt dissection procedure. In such a procedure, the scissors are closed when inserted and then gradually opened, causing current flow outward of the cutting point, i.e., so that the dissected tissue hemostatically severed. 25The various embodiments described herein are presented for purposes of illustration and not limitation, as the present invention can be practiced with surgical scissors-like instruments of any type or size having two cutting or shearing members movable with respect to one another. Thus, instruments constructed in accordance with the present invention may be adapted for use in cutting surface tissue, deep tissue and internal tissue, vessels, capillaries or organs, as may be required, for example, in SUBSTITUTE SHEET IPEAAJS07 0CT1993 - 23 - PCT/US92/04664 microsurgery, tnacrosurgery, laparoscopy and other surgical procedures. The present invention includes the method steps of employing an apparatus having shearing members 5 that include electrodes, wherein operation of the apparatus simultaneously causes hemostasts of tissue and severs that tissue. As noted in the EXAMPLES provided above, applicant has observed that use of a scissors-like apparatus employing electrodes isolated by an intervening layer of insulating material at frequencies in the range of 400 to 800 kHz and 10 to 120 volts (RMS) provides satisfactory results. The method of the present invention, suitable for use in a great variety of surgical procedures, comprises the steps of 5 (a)providing first and second shearing members, each shearing member having a shearing surface, a cutting edge and an electrode, the shearing members connected together so that the shearing surfaces move in opposition through a range of motion in a scissors-like action that defines a cutting point moving along the cutting edges through the range of motion; (b)connecting the electrodes to a power supply; (c)selecting and maintaining a substantially constant voltage level output across the power supply, the voltage level output independent of the impedance of the load connected across the power supply; (d)providing an electrically insulating material between the first and second electrodes so that the electrodes do not contact each other in the rahge of motion; SUBSTITUTE SHEET IPEA/US07 0CT1993 - 24 - PCT/US92/04664 (e)placing the electrodes in electrical contact with tissue to be cut so that high frequency current passes between the electrodes and through the tissue distal to the cutting ;nint, but not between the shearing surfaces; and (f)moving the first and second shearing members through the range of motion, thereby passing current through the tissue in a region distal to the cutting point, simultaneously causing hemostasis of the tissue and cutting the tissue at the cutting point. Of course, it will be apparent to one skilled in the art that steps (a) and <d) described above can be combined by simply providing an apparatus as 15 hereinbefore described. Operation of the apparatus in the range 30 to 90 volts (RMS) will be desirable in many cases, depending upon the impedance of the tissue encountered during the surgical procedure. The use of a power supply having a selectable 20 substantially constant voltage level output that is independent of load impedance provides sufficient pomi to cause effective hemostasis. Use of constant voltage output levels lower than those generally used in previously known electrosurgical instruments reduce 25 the power delivered to the electrodes when they are nof in contact with tissue, i.e., open-circuited, and reduces the likelihood of generating a current arc when the electrodes are brought into contact yith the tissue. 3₀ ^ tlse of a constant voltage level output that is independent of the load impedance inhibits excessive current flow through the tissue, as the tissue resistance increases during desiccation. Conseguentiy, the depth of hettostasis obtained in the tissue can be 3S more precisely controlled, and localized overheating of .l._ VSUBSTITUTE SHEET⁰_{lpEA/US070CTigg3} - 25 -PCT/US92/04664 the electrodes better avoided. Reduced localized heating of the electrodes also inhibits coagulum buildup, which can both interfere with efficient hemostasis and impede maneuverability of the instrument. One skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, and that the present invention is limited only by the claims which follow.

26 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: ₁Apparatus for hemostatically cutting_; tissue, • „*„* =. first support member having a the apparatus comprising a first suppo i» =. f-ir^t- shearing surface ana a first shearing member, a first snean y first cutting edge, a second support — havrng . second shearing_me_mber having a second shears and a second cutting edge; and connection rceans for totally fining the first and second shearing ^bers toother so that the first and second shearing surfaces ac one another and the first cutting edge contacts the second cutting edge as the first shearing_me_mber p.vots elative to the second shearing_me_Bber in a «.-££_motion, the connection_means ccpr.srng an •1««"^ insulative material that electrically isolates the frrst shearing member fro* the second shearing member at the connection means wherein the first shearing member X_Ees a composite of an electrically conductive m ILal and a layer of electrically insulative mate disposed substantially for the entire length of the first disposea_electrically isolate the first and shearing member to electrically_second shearing members from one another along their second a a .,.,,- fiv-st and second cutting respective lengths when the first edges contact each other. , The apparatus according to claim 1 wherein the_layer of electrically insulative material of the first shlaring member forms substantially the entire first cutting edge and first shearing surface. 3 The apparatus according to claim : and wherein the layer of electrically insulative material has a Z*J. that is greater than the hardn.ss of the second cutting edge and the second shearing surface.

. The apparatus according to claim 1 or 2 wherein the layer of electricaUy insulate material of the first shearing meter has a thiclmees in a range of 0.050 y' * 27 to 1.270 mm (0.002 to 0.050 inches). 5. The apparatus according to claim 4 wherein the layer of electrically insulative material of the first shearing member has a thickness in a range of 0.076 to 0.178 mm (0.003 to 0.007 inches).

i 6.The apparatus according to any one of claims 1 to 5 wherein the layer of the first shearing member has a first thickness and wherein the second shearing member comprises a layer of electrically insulating material having a second thickness and the sum of the first and second thicknesses is selected in a range of from 0.050 to 1.270 mm (0.002 to 0.050 inches). 7.Apparatus according to claim 1 wherein the first shearing member has a portion defining a first electrode extending substantially for the length of the first cutting edge and wherein the second shearing member 2 0 comprises a composite of an electrically conductive material and a layer of electrically insulative material, the second shearing member having a portion defining a second electrode extending substantially for the length of the second cutting edge; the layer of the first 25 shearing member and the layer of the second shearing member electrically isolating the first electrode from the second electrode when the first and second cutting edges contact each other. 3 0 8. The apparatus according to claim 7 wherein the layer of the first shearing member has a thickness selected in the range of from 0.05d to 1.270 mm (0.002 to 0.050 inches).

9. The apparatus according to claim 7 wherein the layer of the first sheafing member has a first thickness and the layer Of the sedOhd shearing member has a second thickness and the gum of the first ahd second thicknesses is selected in a range of from 0.050 to 1.270mm (0.002 to 0.050 inches). The apparatus according to any one of claims 6 to' 9 and wherein the layer of the first shearing member has a first hardness and the layer of the second shearing member has a second hardness different than the first hardness. 11The apparatus according to any one of claims 1 to 10 and further comprising a layer of material having a high electrical and thermal conductivity disposed on at least one of the first and second shearing members. 12The apparatus according to any one of claims 1 to' 11 and further comprising a layer of electrically conductive abherent material disposed on at least one of the first and second shearing members. 13 The apparatus according to any one of claims 1 to" 12 wherein the first shearing member further comprises a first support member and the second shearing member further comprises a second support member, the first and second support members cooperating with the connection means the first and second support members havmg a layer of electrically insulating material disposed thereon. 14 The apparatus according to any one of claims 1 to" 13 in combination with a power supply that provides a high frequency alternating-current waveform, the power supply having a selectable substantially constant voltage level output that is independent of the load impedance, and means for electrically connecting the power supply to the first and second electrodes.₁₅The apparatus according to claim 14 wherein the substantially constant vdltage level output of the power 29_supplyisselectable to provide a voltage across the first and second electrodes from the range of 10 to volts (RMS). -,+-„=. anrnrdina to claim 14 or 15 i aThe apparatus accoramy wherein the power supply provides a voltage waveform having a crest factor near unity. The apparatus of any of claims 14 to 16 wherein_tIe power supply provides an alternating-current^ voltage waveform having a high freguency selected from the range of 100 kHz to 2 MHz. Apparatus according to any one of claims 1 to₁₇; for cutting and coagulating tissue, wherem the first shearing member comprises a first_bi_ade member having a portion defining the fi»t sh^ surface the first cutting edge havxng a length, and a first electrode extending substantially for the length of ^ first cutting edge; and the second shearing member prises -a second blade member having a ^- £^ the second shearing surface, the second cuttxng edge having a length, and a second electrode extending sLtantially for the length of the second cuttxng edge, the electrically conductive materxal of the ^ of the first blade member forms the first composite or rne j-xj-oo <="|pctrode; and_the second blade member comprises an electrically conductive material; and,_nqnlative wherein the layer of electrically insulative serial of the first blade member electrically isolates Xfir* electrode from the second electrode when the first and second cutting edges contact each other.

₁₉Apparatus for cutting and coagulating tissue, - ^r,* a first blade number having a the apparatus comprising a first Dia , j,' • ^ ^ -F-ir-of- shearing surface, a rirsi, portion defining a first sneaj. j-^y portion « ^f4_r«,i- exterior surface, Cutting edge having a length, a first exteri and a first electrode extending substantially for the length of the first cutting edge; a second blade member having a portion defining a second shearing surface, a second cutting edge having a length, a second exterior surface and a second electrode extending substantially for the length of the second cutting edge; connection means for pivotally joining the first and second blade members together so that the first and second shearing faces face one another and the first cutting edge contacts the second cutting edge as the first blade member pivots relative to the second blade member in a scissors-like motion; wherein the first blade member comprises an electrically insulative material and the first electrode comprises first layer of electrically conductive material disposed on the first exterior surface; and the second blade member comprises an electrically insulative material and the second electrode comprises a second layer of electrically conductive material disposed on the second exterior surface; wherein the electrically insulative material of the first blade member and the electrically insulative material of the second blade member electrically isolate the first electrode from the second electrode when the first and second cutting edges contact each other.

V 20. The apparatus according to claim 19 further comprising a layer of an electrically insulative material disposed on each of the first and second layers of electrically conductive material, except for a first region proximate to the first cutting edge and a second region proximate to the second cutting edge.

21. The ar^paratus according to claim 19 or 20 further comprising a layer of an electrically conductive abherent material disposed in superposition on the first and second layers of electrically conductive material.

31₂₂The apparatus according to any one of claims 19 „ the first electrode and the second t-^ on wherein the xxjibL. c^.^-to 21 wherei^^ ^^.^_edge electrode are spaced apart, wneu j 4.nnn pdae a distance in a range contacts the second cutting edge, a_offrom 0.050 to 1.270 imn (0.002 to 0.050 inches). The apparatus according to any one of claims 19 to'22 in combination with a power supply that provides a •.iternating-current waveform, the power_highfreguenc, ^^^^^^_constantvoltage supply having a selectam_impedance, level output that is independent of the loa y and means for electrically connecting the power supply to the first and second electrodes. ~.p r<"la-im23 wherein the₉a The apparatus of claim_SUPP1Yis .execta^e to p^i e a. vo1 . ac^o. ^ first and second electrodes in a range ot volts (RMS). *: oia-im ?3 or 24 wherein the r?:; The apparatus of claim 2 J or_lvProvides an alternating-current voltage power supply provides an Lveform having a frequency selected m a range 100 kHz to 2 MHz. DATED this 15th day of August 1996 HEMOSTATIX CORPORATION By their Patent Attorneys CULLEN & CO.

p WO 92/21301 PCr/US92/04664 1/4 ^l^c/^c7^cl f^I 10V'I_______ WO 92/21301 PCT/US92/04664 2/4TO'FⁱWO 92/21301PCT/US92/046643/4i¹FIG. 3FIG. 5FIG. 4FIG. 3FIG. 5FIG. 4hWO 92/21301PCT/US92/046644/4FIG. 6FIG. 6FIG. 7FIG. 7FIG. 8fINTERNATIONAL SEARCH REPORT Intes/uuional Application No. PCT/US92/04664 A. CLASSIFICATION OF SUBJECT MATTER IPC(S) :A61B 17/39 US CL :606/48 According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symboLs) U.S. : 30/35-36.233,51/246,76/82,82.2. 128/399,402,606/32,34,37,39-40,45,49-52,167,174 Documentation searched other than minimum none documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and. where practicable, search terms used) Automated Patent System Search terms on attachment.

DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No.

US,A. 3,651.811 (HILDEBRANDTET AL), 28 March 1972, see whole document. US.A, 4,271,838 (LASNER ET AL.), 09 JUNE 1981, See column 4 and figures 1 and 4. US,A, 4,940,468 (PETILLO), 10 JULY 1990, See lines 30-36 of column 3. The Cavitron Bipolar Coagulator, 1979, Cavitron Surgical Systems, See front and back of brochure.

31-34 31-34 31-34 31-34 ["] Further documents are listed in the continuatioB of Box C. Q Sefc patent family annex later document publahsi ifter the mtenuupnal filial dele or priority date and not •> cooflict with the application Cut cited to undentaad the principle or theory underiying the mvraooadocument of paitkular rekvance; the ctaimed invraooo cannot be cooeidemt novel or cannot be conaideRd to involve an mveotive Hep what the doctancntia taken alonedocnent of paiticuhr rdevance; the clautol inventioo cannot be cooaidend to involve an inventive Hup when the document combined with one or more other fuch dncumenn. «uch combmeuoo been obvioue to a penoa •killed in the artdeoMnentiBanber of the aame patent ftmilyf>Specal euef ono of cited documenu:A'd(x:iimcBldefiiUBilhe|cw:r»lit«eoflhe«it*hictiiihotcooil»iMHiu> beptrtof p«io<nik»relevmiice E"_e,_rb_etdocuiiieatpubliihe«looor«fte«'ll>einJenl«ioii^min|<UJe•! *doctmait whidnniy threw doubtt oo priority ctahnrt) or which i>ciod to Mttbliih the jmblicMiQO due of UKXher cituioo or otherspecial K**oa-(u •pecifiedii •O'document refefftOf 6> w ortl diifikwu*. me. e«hibitioo or othermean* •p"document pubttaWd prior to the ifitenulioae) filini dele but biertheathe pnonty dele cleimed"T•X'•St' Date of mailing of the intemi«onal search report Date of the acluai completion of the international search 07 SEPTEMBER 1992 Name and mailihg addres* of the ISA^ Comnuwioner of Pitenu and Trademarka Box PCt"_ Washington. 0.6. 20231 Authorized officer PAUL lU^T^KECLi Teleflhonc No. (103) 308-0858, "If aesimile No, NOT APPLICABLE _ „ Pom PCr/tSA/210 (Soeond shett)(July 1992)*