_
`Ufllted States Patent
`Yates et al.
`
`[19]
`
`HlllllllllllllllllllllllIllllllllllllllllllllllllllllllllllllllllllllll
`US0054033l2A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,403,312
`Apr. 4, 1995
`
`[75]
`
`[54] ELECTROSURGICAL HEMOSTATIC
`DEVICE
`I'“'°“t°’5‘ Dam C‘ Yam’ Wes‘ Chem’? Jess“
`5- K“'“‘5v C""’*““““i S*°'°"_H~
`M€FS¢11sG81'm3n€0Wn;M8I‘tln
`Madden; Richard P. Nuchols, both of
`Lovehnd, 311 of Ohio
`
`606/S0
`
`3/1994 Parins
`5,290,286
`FOREIGN PATENT DOCUMENTS
`0517244 12/1992 European Pat‘ Off.
`A6lB 17/39
`0513230 12/1992 European Fat. 01?.
`A618 17/39
`wo93/03754 5/1993 WIPO
`A618 17/36
`OTHER PUBLICATIONS
`
`Assignee: Ethicon,Inc., Somerville, NJ_
`‘
`APP“ N°-- 95,797
`Flled
`Jul 22’ 1993
`Int. CL6 ............................................ .. A61B 17/39
`U.S. Cl. ............................. .. 606/50; 606/40;
`606/41; 606/46; 606/49; 606/142; 606/143
`Field of Search .............................. 606/41, 45-52,
`606/39, 40, 142, 143
`References cited
`
`U'S' PATENT DOCUMENTS
`2,031,682 2/1936 W3PPle1‘ 51 a|- «
`45081981
`9/1936 R°‘hl“55 '3‘ 3* ~
`4’633’874 V1987 Chm" at 3]‘
`‘
`4,655,216 4/1937 Tischer .
`4,571,274 9/1987 somchenko _
`4,935,030
`1/1991 Maize, et a1_
`5,057,107 10/ 1991 Parins et al.
`5.035.659
`2/1992 Rygiell
`-
`5’104'025 4/1992 Mam 9‘ 31'
`tal. ...................
`5,151,102 9/1992 K '
`5,190,541
`3/1993 A§$‘ey:?l_°m_
`5.201300 4/1993 Nardella ..
`5,207,691 5/ 1993
`
`.
`
`Automatically Controlled Bipolar Electrocoagula-
`tion~“COA—Comp", Neurosurg. Rev. (1984) 187-190,
`13. Vallfors et al.
`Primary Examiner—Stephen C. Pellegrino
`Assistant Exam1'ner—Michael Peffley
`Attorney, Agent, or Firm-—Susan M. Schmitt
`
`ABSTRACT
`[57]
`An electrosurgical instrument is provided for cauterlza—
`tion and/or welding of tissue of varying impedances,
`thicknesses and vascularity especially in the perfor-
`mance of endoscopic procedures. The instrument com-
`presses the tissue between one pole of a bipolar energy
`source located on one interfacing surface, and a second
`interfacin surface A second
`IE: is located one of the
`_
`3 _
`‘
`9°
`_
`two interfacing surfaces. In a preferred embodiment,
`the second pole is located on the same interfacing sur-
`face as the first pole and an insulator electrically isolates
`the two poles. A preferred application of the invention
`is in a cutting instrument wherein a hemostatic line is
`-
`4
`formed along a cut line using RF energy.
`
`42 Claims, 11 Drawing Sheets
`
`ETHICON ENDO-SURGERY, INC.
`
`EX. 1013
`
`1
`
`

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`11.101LL8e..nS
`
`5,403,312
`
`2
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`U.S. Patent
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`U.S. Patent
`
`Sheet 3 of 11
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`

`
`U.S. Patent
`
`Apr. 4, 1995
`
`Sheet 6 of 11
`
`5,403,312
`
`F/G-/O
`
`APPLY
`
`ELECTRICAL
`
`ENERGY
`
`DETERMINE
`
`SYSTEM CURRENT
`
`AND VOLTAGE
`
`CALCULATE
`
`IMPEDA NCE
`
`VALUE AND
`
`STORE
`
`DETERMINE
`F (2)
`
`IS
`
`IMPEDANCE
`VALUE WI THIN
`NORMAL
`RANGE?
`
`»
`
`DOES
`F(ZI
`INDICATE THAT
`COAGULATION LEVEL
`HAS BEEN
`REAgHED
`
`TURN OFFENERGY
`AND
`,ND,CA-I-E
`ERROR
`
`INDICATE
`COAGULATION
`COMPLETE
`
`7
`
`

`
`5,403,312
`
`8
`
`

`
`5,403,312
`
`9
`
`

`
`U.S. Patent
`
`Sheet 9 of 11
`
`5,403,312
`
`10
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`

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`5,403,312
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`11
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`

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`6|-6C..nS
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`12
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`

`
`1
`
`5,403,312
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`ELECFROSURGICAI. HEMOSTATIC DEVICE
`
`FIELD OF THE INVENTION
`
`instru-
`This invention relates to an electrosurgical
`ment for cauterization, coagulation and/or tissue weld-
`ing in the performance of surgical procedures, espe-
`cially endoscopic procedures.
`
`BACKGROUND OF THE INVENTION
`
`Surgical procedures requiring cutting of tissue can
`cause bleeding at the site of the cutting. Before surgeons
`had the means to control bleeding many surgical proce-
`dures were quite difficult to perform because of exces-
`sive blood loss. Hemostasis is even more crucial in en-
`doscopic or laparoscopic surgery where if the bleeding
`is not kept under control, the laparoscopy must be aban-
`doned and the patient’s body cut to perform open sur-
`gery so that inaccessible bleeding may be controlled.
`Thus, various techniques have been adapted to con-
`trol bleeding with varying degrees of success such as,
`for example, suturing, applying clips to blood vessels,
`and stapling, as well as electrocautery and other ther-
`mogenic techniques. Advances in tissue joining, tissue
`repair and wound closure also have permitted surgical
`procedures previously not possible or too risky.
`Initially, suturing was one of the primary means for
`providing hemostasis and joining tissue. Before other
`hemostatic and tissue repair means were introduced,
`surgeons had to spend a great deal of time sewing the
`tissue of patients back together.
`Surgical clips were introduced as a means to close off
`blood vessels, particularly when cutting highly vascula-
`rized tissue. Application of surgical clips, however, can
`be cumbersome in certain procedures. The vessels must
`be identified. Then a clip must be individually applied
`on both sides of the intended cut of each identified
`vessel. Also, it may be difficult to find some vessels,
`particularly where the vessel is surrounded by fatty
`tissue.
`
`50
`
`Surgical staplers have been effective in decreasing
`the amount of time it takes to fasten tissue together.
`There are various types of surgical staplers. Staplers
`have been used for tissue joining, and to provide hemo-
`stasis in conjunction with tissue cutting. Such devices
`include, for example, linear and circular cutting and
`stapling instruments. Typically, a linear cutter has par-
`allel rows of staples with a slot for a cutting means to
`travel between the rows of staples. This type of surgical
`stapler secures tissue for improved cutting, joins layers
`of tissue, and provides hemostasis by applying parallel
`rows of staples to layers of surrounding tissue as the
`cutting means cuts between the parallel rows. These
`types of cutting and stapling devices have been used
`successfully in procedures involving fleshy tissue such
`as muscle or bowel, particularly in bowel resection
`procedures. Circular cutting and stapling devices have
`successfully been used, for example,
`in anastomotic
`procedures where a lumen is rejoined. However, the
`results with cutting and stapling devices have been less
`than optimum where the procedure involves cutting
`highly vascularized tissue, such as mesentery or adnexa,
`which are prone to having hemostasis problems.
`Electrocautery devices have also been used for ef-
`fecting hemostasis. Monopolar devices utilize one elec-
`trode associated with a cutting or cauterizing instru-
`ment and a remote return electrode, usually adhered
`externally to the patient. More recently, bipolar instru-
`
`2
`ments have been used because the cauterizing current is
`generally limited to tissue between two electrodes of
`the instrument.
`
`5
`
`Bipolar forceps have been used for cutting and/or
`coagulation in various procedures. For example, bipolar
`forceps have been used in sterilization procedures
`where the fallopian tubes are sealed off. Generally,
`bipolar forceps grasp tissue between two poles and
`apply electrical current
`through the grasped tissue.
`Bipolar forceps, however, have certain drawbacks,
`some of which include the tendency of the current to
`are between poles when tissue is thin or the forceps to
`short when the poles of the forceps touch. The use of
`forceps for coagulation is also very technique depen-
`dent and the forceps are not adapted to simultaneously
`cauterize a larger area of tissue.
`Bipolar scissors have been disclosed where two scis-
`sors blades act as two electrodes having insulated shear-
`ing surfaces. This device mechanically cuts tissue as
`coagulating electrical current is delivered to tissue in
`the current path. Bipolar scissors are also highly tech-
`nique dependent in their use.
`SUMMARY OF THE INVENTION
`
`It is therefore an object of the present invention to
`provide a hemostatic electrosurgical instrument which
`can efficiently provide hemostasis in multiple tissue
`types and thicknesses, e.g., in fleshy or vascular tissue
`areas, and high, low or combination impedance tissues.
`Hemostasis is used herein to mean generally the arrest-
`ing of bleeding including by coagulation, cauterization
`and/or tissue joining or welding.
`It is another object of the invention to provide a
`bipolar hemostatic device which is capable of being
`used to simultaneously cauterize or weld a relatively
`larger area or length of tissue than in previously known
`devices.
`
`is another object of the invention to provide a
`It
`bipolar electrocautery device having elongated or bar
`electrodes.
`
`Another object of the invention to is provide a hemo-
`static means for providing a line of coagulation adjacent
`to a cutting path of a cutting means for dividing tissue.
`Another object of the invention is to provide a cut-
`ting and stapling device with an electrocautery means
`for tissue welding or cauterization along a cutting path.
`These and other objects of the invention are de-
`scribed in an electrosurgical device having an end effec-
`tor with opposing interfacing surfaces associated with
`jaws for engaging tissue therebetween, and two electri-
`cally opposite poles located on one or both of the op-
`posing surfaces. The poles are isolated from each other
`with an insulating material, or, where the poles are on
`opposite interfacing surfaces, they are offset from each
`other so that they are not diametrically opposed from
`each other on interfacing surfaces.
`An electrosurgical instrument of a preferred embodi-
`ment compresses tissue in a compression zone between
`a first interfacing surface and a second interfacing sur-
`face and applies electrical energy through the compres-
`sion zone. The first interfacing surface is comprised of:
`a first pole of a bipolar energy source, which interfaces
`with the compressed tissue in the compression zone; and
`a second pole electrically isolated from the first pole
`and located on the same or opposite interfacing surface.
`Electrically isolated poles are defined herein to mean
`electrodes isolated from each other by an insulating
`
`13
`
`

`
`5,403,312
`
`3
`material in the end effector and/or offset from each
`other on opposing surfaces.
`In a preferred embodiment, the compression zone is
`an area defined by a compression ridge on one of the
`interfacing surfaces which compresses the tissue against
`the other interfacing surface. Also, there may be a com-
`pression ridge on both interfacing surfaces. A coagula-
`tion zone is defined by the first pole, the second pole,
`and an insulator insulating the first pole from the second
`pole. The second pole, located on one of the interfacing
`surfaces, is generally adjacent to the insulator on the
`same interfacing surface or across from the insulator on
`an opposing surface. This arrangement electrically iso-
`lates the two poles and enables the current path be-
`tween the first and second poles to cross through a
`desired area of tissue.
`It is believed that the tissue compression normalizes
`tissue impedance by reducing structural differences in
`tissue which can cause impedance differences. Com-
`pression also stops significant blood flow and squeezes
`out blood which acts as a heat sink, particularly when
`flowing through blood vessels. Thus, compression opti-
`mizes delivery of energy to tissue in part by enabling the
`rate of energy delivery to exceed the rate of dissipation
`due to blood flow. The arrangement of the electrodes,
`which make up the poles, is important to ensure that the
`current passing between the two poles passes though
`the compression zone. Also, insulation or isolation of
`the opposite poles from each other on the instrument
`permits tissue compression without shorting of the in- 30
`strument poles or electrical arcing common in bipolar
`instruments.
`Thus, the tissue compression and the arrangement of
`the electrodes permit more efficient cauterization and
`offer the advantage of achieving hemostasis in a wide
`range of tissue impedance, thickness and vascularity.
`Compression is preferably balanced against causing
`unacceptable tissue damage from excessive compres-
`sion. A gap between jaws can be varied depending on
`the intended application of instrument or the thick-
`nesses of tissue on which the instrument is used.
`In an alternative embodiment of the invention, the
`first pole is located on a first interfacing surface of a first
`jaw and the second pole is located on the same jaw as
`the first pole, but not on the interfacing surface.
`The present invention also provides a device capable
`of coagulating a line or path of tissue along or lateral to
`a out line or a cutting path. In one embodiment, the first
`pole comprises an elongated electrode. The elongated
`electrode along with the adjacent insulator fonn a ridge
`to compress the tissue to be cauterized. The second pole
`is adjacent the insulator on an opposite side of the insu-
`lator from the first pole.
`In one preferred embodiment, a cutting means for
`cutting tissue is incorporated into the device and the
`device provides hemostatic lines adjacent to the path of
`the cutting means. Of course, cutting may occur at
`anytime either before, during or after cauterization or
`welding. In one variation of this preferred embodiment,
`stapling means is provided on one or both sides of the
`cutting path.
`In one embodiment, an indicator means communi-
`cates to the user that the tissue has been cauterized to a
`desired or predetermined degree.
`In another embodiment, the coagulation is completed
`prior to any mechanical cutting, i.e., actuation of the
`cutting means. If an indicator means is used, once tissue
`is cauterized, the cutting means may be actuated to cut
`
`4
`between the parallel bars while the rows of staples are
`applied to the tissue.
`the hemostatic device is
`In another embodiment,
`incorporated into a linear cutter similar to a linear cut-
`ting mechanical stapler. In this embodiment the hemo-
`static device comprises two parallel and joined elon-
`gated electrode bars which form one pole, and a slot for
`a cutting means to travel between the bars. Optionally,
`one or more rows of staples may be provided on each
`side of the slot and bars to provide additional hemosta-
`sis. In operation, tissue is clamped between two jaws.
`Electrical energy in the form of radio frequency current
`is applied to the compressed tissue to cauterize the
`blood vessels along the two parallel bars.
`Another embodiment provides a means for detecting
`abnormal
`impedances or other electrical parameters
`which are out of a predetermined range. For example,
`the means for detecting may be used to indicate when
`the instrument has been applied to tissue exhibiting
`impedances out of range for anticipated good coagula-
`tion. It may also be used for detecting other instrument
`abnormalities. It is possible to detect the abnormal con-
`dition, for example, by using comparisons of normal
`ranges of initial tissue impedances in the interface elec-
`tronics. This could be sensed in the first few millisec-
`onds of the application of RF energy and would not
`present a significant
`therapeutic dose of energy. A
`warning mechanism may be used to warn the user when
`the impedance is out of range. Upon repositioning of the
`instrument, the same measurement criteria would apply
`and if the tissue impedance was again out of range, the
`user would again be warned. This process would con-
`tinue until the normal impedance range was satisfied
`and good coagulation could be anticipated.
`Similarly another embodiment provides a tissue
`welding and cauterizing cutting device similar to an
`intraluminal stapler. Preferably, the poles are formed in
`two concentric circle electrodes separated by an insula-
`tor. The electrodes which make up the poles may be
`located on either the stapler cartridge or the anvil.
`These and other objects of the invention will be bet-
`ter understood from the following attached Detailed
`Description of the Drawings, when taken in conjunc-
`tion with the Detailed Description of the invention.
`DETAILED DESCRIPTION OF THE
`DRAWINGS
`
`FIG. I is a side elevational view of an endoscopic
`electrocautery linear stapling and cutting instrument of
`one embodiment of the present invention;
`FIG. 2 is a side cross sectional view of the instrument
`of FIG. 1;
`FIG. 3 is a partial cross sectional View of the distal
`end of the instrument of FIG. 1 in an open position;
`FIG. 4 is a partial cross sectional view of the distal
`end of the instrument of FIG. 1 in a closed, unfired
`position;
`FIG. 5 is a partial cross sectional view of the distal
`end of the instrument of FIG. 1 in a closed, fired posi-
`tion;
`FIG. 6 is a front cross sectional view of the distal end
`of the instrument of FIG. 4 taken along the line 6-6;
`FIG. 7 is a bottom isolated View of the anvil jaw of
`the instrument of FIG. 1;
`FIG. 8 is a top isolated view of a cartridge of the
`instrument of FIG. 1;
`FIG. 9 is a side cross sectional view of the jaw of
`FIG. 7 along the line 9-9;
`
`14
`
`

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`5,403,312
`
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`15
`
`FIG. 10 is a flow chart illustrating a feedback system
`of the present invention;
`FIG. 11 is a front cross sectional view of the end
`effector of another embodiment of the prsent inven-
`tlon;
`FIG. 12 is a front cross sectional view of the end
`effector of another embodiment of the present inven-
`tlon;
`FIG. 13 is a front cross sectional view of the end
`effector of another embodiment of the present inven-
`tion;
`FIG. 14 is a front cross sectional view of the end
`effector of another embodiment of the present inven-
`tlon;
`FIG. 15 is a bottom isolated View of the anvil of
`another embodiment of the present invention;
`FIG. 16 is a bottom isolated view of the anvil of
`another embodiment of the present invention;
`FIG. 17 illustrates a cross sectional view of the distal
`end of another embodiment of the present invention;
`FIG. 18 is front cross sectional view of the end effec-
`tor of FIG. 17;
`FIG. 19 is a front cross sectional view of the end
`effector of another embodiment of the present inven-
`tron;
`FIG. 20 is a top view of a cartridge of a circular
`cutter of the present invention;
`FIG. 21 is a bottom view of the anvil of a circular
`cutter of the present invention.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`Referring now to FIGS. 1-9, there is illustrated a
`preferred embodiment of the present
`invention. An
`endoscopic electrocautery linear cutting and stapling
`instrument 10 is shown having a body 16 coupled to a
`shaft 30 with a lumen extending therethrough and an
`end effector 50 extending from the distal end 21 of the
`shaft 30. The shaft 30 is formed of an insulative material
`and has an electrically conductive sheath 38 extending 40
`through its lumen. A channel 39 extending through the
`sheath 38 guides co-axial movement of a driver means
`44 within the channel 39. In this particular embodiment,
`the driver means 44 includes a firing trigger 14 associ-
`ated with the body I6, coupled to a flexible firing rod 40
`coupled to a driving rod 41, coupled to a block 43. The
`block 43 is coupled to a cutting means 11 and a staple
`driving wedge 13, which the driving means 44 advances
`by way of the block 43 into the end effector 50.
`The end effector 50 comprises two interfacing jaw
`members 32, 34. The end effector 50 is secured by way
`of jaw member 34 to the channel 39. The jaw member
`32 is movably secured to jaw member 34. The body 16
`has a clamping trigger 12 for closing the jaws 32, 34
`which longitudinally advances a close rack 45 coupled
`to the proximal end of the sheath 38. The close rack 45
`advances the sheath 38 co-axially through the shaft 30.
`The sheath 38 advances over a camming surface 27 of
`jaw 32 to close the jaws 32 and 34 onto tissue situated
`between the jaws. As described in more detail below,
`the close rack 45 also acts as a switch to close the circuit
`which communicates electrical energy to the end effec-
`tor 50.
`
`60
`
`Referring now to FIGS. 3—9 an enlargement of the
`end effector 50 of the instrument 10 is illustrated. The
`jaw members 32 and 34 are shown in an unclamped
`position in FIG. 3, in a clamped, unfired position in
`FIG. 4 and in a clamped, fired position in FIG. 5. Jaw
`
`65
`
`6
`member 32 comprises an anvil 18, a U-shaped first pole
`52 extending longitudinally with respect to the jaw 32,
`and a U-shaped insulating material 55 surrounding the
`outside of the first pole 52. Jaw member 32 has an inner
`surface 33 which faces an inner surface 35 of jaw 34.
`The inner surface 33 includes first pole 52 which com-
`prises two electrically communicating electrode bars
`53, 54 comprised of aluminum, extending substantially
`along the length of the inner surface 33. The bars 53, 54
`are separated by a knife channel 42 extending longitudi-
`nally through the first pole’s center to form its U-shape.
`The surface of the bars are formed in flat strips to pro-
`vide more surface area contact with tissue. Two series
`of pockets 36, 37 located on anvil 18, for receiving
`staple ends, extend along the inner surface 33, lateral to
`and outside of bars 53, 54 respectively. The electrode
`bars 53, 54 and the insulating material 55 form a ridge 56
`extending out relative to the anvil portion 33a of the
`inner surface 33 (FIG. 6). The anvil 18 is formed of an
`electrically conductive material and acts as a second
`pole electrically opposite to the first pole. The anvil 18
`is isolated from the first pole 52 by the U-shaped insulat-
`ing material 55.
`Jaw member 34 comprises a cartridge channel 22 and
`a cartridge 23. The cartridge 23 includes a track 25 for
`the wedge 13, knife channel 26 extending longitudinally
`through the center of the cartridge 23, a series of drivers
`24 extending into track 25 and staples 100 arranged in
`two sets of parallel double rows. When tissue is engaged
`between the jaws 32, 34, the driver means 44 may be
`actuated or fired using trigger 14 to advance the cutting
`means 11 and wedge 13 through the engaged tissue to
`staple and cut the tissue. When the firing mechanism 14
`is actuated, the wedge 13 is advanced through the track
`25 causing the drivers 24 to displace towards the staples
`100, thereby driving the staples 100 through tissue and
`into anvil pockets 36, 37.
`A gap pin 29 located on the inner surface 33 towards
`the tip of the anvil 18 fits into a gap 28 is formed on the
`inner surface 35 of the cartridge 23. The gap 28 and gap
`pin 29 serve to align the staples 100 with the pockets 36,
`37 and the knife channels 42, 26 with each other.
`A knob 15 located on the distal end of the body 16
`rotates the shaft 30, sheath 38, channel 39 and end effec-
`tor 50 which are directly or indirectly coupled to the
`knob 15 so that the knob 15 may be used for rotational
`placement of the end effector jaws 32.34.
`Bipolar energy is supplied to the end effector 50 from
`an electrosurgical generator 60 through wires 19, 20
`extending into the body 16 of the instrument. The gen-
`erator 60 is user controlled by way of a footswitch 65.
`Wire 19 which provides electrical current to the first
`pole,
`is coupled through a wire or other electrical
`contact means 61 to electrical contact 62, associated
`with the first pole, located on the distal end of close
`rack 45. Wire 20 which carries the current of the oppo-
`site pole, is coupled through a wire or other electrical
`contact means 66 to a disc contact 67 located at the
`distal end of the close rack 45 and electrically isolated
`from contact 62.
`
`A disc contact 63, associated with the first pole, lo-
`cated at the distal end of the body 16 is in electrical
`communication with a wire or other contact means 64.
`Contact means 64 extends through channel 39 to end
`efiector jaw 32 where it contacts first pole 52. The disc
`contact 63 pennits the knob 15 to rotate while contact is
`maintained between the disc contact 63 and the contact
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`15
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`5,403,312
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`25
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`7
`means 64. The contact means 64 is electrically insulated
`from the sheath 38.
`When the clamping trigger 12 is actuated, the close
`rack 45 moves distally so that the contact 62 comes in
`electrical communication with the disc contact 63 and
`the disc contact 67, associated with the second pole 51,
`comes in electrical contact with the electrically conduc-
`tive sheath 38. The sheath 38 moves over the camming
`surface 27 of the electrically conductive anvil 18 which
`acts as the return electrode. Thus the electrical circuit is
`closed when and only when the clamping trigger 12 is
`closed.
`In operation, the end effector 50 of the instrument is
`located at a tissue site where tissue is to be cut. The jaw
`members 32, 34 are opened by pressing a release button
`70 which releases a button spring 71 and permits the
`close rack 45 to move proximally. Tissue is then placed
`between the interfacing inner surfaces 33, 35 respec-
`tively of the jaw members 32, 34. The clamping trigger
`12 is squeezed to cause the sheath 38 to move over the
`camming surface 27 and thereby close the jaws 32, 34
`and simultaneously close the electrical circuit as de-
`scribed above. The gap spacing pin 29 causes the anvil
`18 to be held roughly parallel to the cartridge 23. The
`electrode bars 53, 54 and the insulating material 55,
`which together form the ridge 56, compress the tissue
`against the inner surface 35 ofjaw member 34. A gap of
`about between 0.012 and 0.022 inches exists between
`jaw members in the compression zone. A user then
`applies RF energy from the generator 60 using the foot-
`switch 65 or other switch. Current flows through the
`compressed tissue between the first pole S2, i.e. the bars
`53, 54, and the second pole 51, i.e., the anvil 18.
`Preferably the bipolar energy source is a low impe-
`dance source providing radio frequency energy from
`about 300 kHz to 3 MHZ. Preferably, the current deliv-
`ered to the tissue is from 0.1 to 1.5 amps and the voltage
`is from 30 to 200 volts RMS.
`An audible, visible, tactile, or other feedback system
`may be used to indicate when sufficient cauterization
`has occurred at which point the RF energy may be
`turned off. An example of such a feedback system is
`described below. After the RF energy is turned off, the
`cutting means 11 is advanced and the staples 100 are
`fired using the firing trigger 14. Firing is accomplished
`by rotating the firing trigger 14 acting as a lever arm
`about pivot 14a. The driver means 44 advances the
`cutting means 11 and wedge 13. The cutting means 11
`cuts the tissue in between the bars 53, 54 where the
`tissue has been cauterized. Thus, the cut line is lateral to
`the coagulation lines formed by the bar electrodes. The
`wedge 13 simultaneously advances the drivers 24 into
`the staples lfltl causing the staples 100 to fire through
`tissue and into the pockets 36, 37 of the anvil 18. Staples
`100 are applied in two longitudinal double rows on each
`side of the cutting means 11 as the cutting means cuts
`the tissue.
`Operation of linear staplers are known in the art and
`are discussed, for example, in U.S. Pat. Nos. 4,608,981,
`4,633,874, and US. application Ser. No. 07/917,636
`incorporated herein by reference.
`In one embodiment the cartridge provides multifire
`stapling capabilities by replacing the double row of
`staples with a single row. In the laparoscopic stapling
`and cutting devices presently in use, a single shot re-
`placeable cartridge is used. In order to provide better
`hemostasis, this type of stapler was designed to provide
`a double row of staples for each parallel row. Because
`
`8
`of the size of the space necessary to contain the double
`row of staples, a refireable cartridge with stacked sta-
`ples has not been preferred because of the additional
`space required for stacking staples. In the multifire sta-
`pling embodiment a single row of staples is used. Using
`a single row of staples permits stacking of staples in the
`space previously occupied by the second row of staples,
`providing multifire capabilities. In a further embodi-
`ment, no staples are required and the electrical current
`lines provide the necessary hemostasis.
`A preferred embodiment of the present invention
`includes a feedback system designed to indicate when a
`desired or predetermined degree of coagulation has
`occurred. This is particularly useful where the coagula-
`tion zone is not visible to the user. In a particular em-
`bodiment, the feedback system measures electrical pa-
`rameters of the system which include coagulation level.
`The feedback system may also determine tissue char-
`acteristics at or near a coagulation zone which indicate
`degree of coagulation. The electrical impedance of the
`tissue to which the electrical energy is applied may also
`be used to indicate coagulation. Generally, as energy is
`applied to the tissue, the impedance will initially de-
`crease and then rise as coagulation occurs. An example
`of the relationship between electrical tissue impedance
`over time and coagulation is described in Vaellfors,
`Bertil and Bergdahl, Bjoem “Automatically controlled
`Bipolar Electrocoagulation,” Neurosurg. Rev.
`p.
`187-190 (1984) incorporated herein by reference. Also
`as desiccation occurs, impedance increases. Tissue car-
`bonization and or sticking to instrument as a result of
`over application of high voltage may be prevented
`using a feedback system based on tissue impedance
`characteristics. Other examples of tissue characteristics
`which may indicate coagulation include temperature
`and light reflectance.
`Referring to FIG. 10, a flow chart illustrates a feed-
`back system which is implemented in a preferred em-
`bodiment of the present invention. First, energy is ap-
`plied to the tissue. Then the system current and voltage
`applied to the tissue is determined. The impedance
`value is calculated and stored. Based on a function of
`the impedance, for example, which may include the
`impedance, the change in impedance, and/or the rate of
`change in impedance, it is determined whether desired
`coagulation has occurred. If coagulation has occurred
`to a predetermined or desired degree, an indication
`means indicates that the energy should be turned off.
`Such an indication means may include a visible light, an
`audible sound or a tactile indicator. The feedback means
`may also control the generator and turn the energy off
`at a certain impedance level. An alternative embodi-
`ment provides a continuous audible sound in which the
`tone varies depending on the impedance level. An addi-
`tional feature provides an error indication means for
`indicating an error or instrument malfunction when the
`impedance is below a normal minimum and/or above a
`maximum range.
`FIGS. 11-14 illustrate alternative configurations of
`an end effector. In FIG. 11 the first pole 152 and the
`second pole 151 are both located on the same jaw 132
`having the anvil 118. The U-shaped first pole 152 forms
`the knife channel 142. A U-shaped insulator 155 sur-
`rounds the first pole 152 except on the surface 133 so
`that it is electrically isolated from the second pole 15].
`The compression ridge 156 is formed on the cartridge
`which is made from an electrically non-conductive
`material. The ridge 156 compresses tissue against the
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`65
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`16
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`5,403,312
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`first pole 152 and insulator 155 to form a tissue compres-
`sion zone.
`
`10
`FIGS. 20 and 21 illustrate a circular cutter of the
`present invention with stapling means. FIG. 20 illus-
`trates the stapler cartridge 900 with an interfacing sur-
`face 933. A double row of staple apertures 901 through
`which staples are driven into tissue are staggered about
`the outer circumference of the surface 932. A first pole
`952 encircles the inner circumference of the surface 933.
`An insulator 955 electrically isolates the first pole 952
`from the portion 933a of the surface 933 surrounding
`the staple apertures. The staple aperture portion 933a is
`formed of an electrically conductive material and acts
`as a second pole. A circular cutting knife 911 is recessed
`within the cartridge 900 radially inward from the inner
`circumference of the surface 933.
`FIG. 21 illustrates an anvil 918 with pockets 937 for
`receiving staples and a compression ridge 956 for com-
`pressing tissue against the first pole 952 and insulator
`955 of the cartridge. The circular cutter is operated
`similarly to the circular stapler described in U.S. Pat.
`No. 5,104,025 incorporated herein by reference. Prior
`to stapling and cuttin