USH2037H1 - Electrosurgical hemostatic device including an anvil - Google Patents

Abstract

An electrosurgical instrument is provided for cauterization and/or welding of tissue of varying impedance, thickness and vascularity especially in the performance of endoscopic procedures. The instrument compresses the tissue between one pole of a bipolar energy source located on one interfacing surface, and a second interfacing surface applying pressure in a predetermined range wherein one of the interfacing surfaces is positioned on an anvil with a specified preload and spring rate. A second pole is located one of the two interfacing surfaces. In a preferred embodiment, the second pole is located on the same interfacing surface 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 formed along a cut line using RF energy.

Description

FIELD OF THE INVENTION

This invention relates to an improved electrosurgical instrument and method for cauterization, coagulation and/or tissue welding in the performance of surgical procedures, especially 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 procedures were quite difficult to perform because of excessive blood loss. Hemostasis is even more crucial in endoscopic or laparoscopic surgery where if the bleeding is not kept under control, the laparoscopy must be abandoned and the patient's body cut to perform open surgery so that inaccessible bleeding may be controlled.

Thus, various techniques have been adapted to control bleeding with varying degrees of success such as, for example, suturing, applying clips to blood vessels, and stapling, as well as electrocautery and other thermogenic 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 vascularized 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.

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 hemostasis in conjunction with tissue cutting. Such devices include, for example, linear and circular cutting and stapling instruments. Typically, a linear cutter has parallel 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 effecting hemostasis. Monopolar devices utilize one electrode associated with a cutting or cauterizing instrument and a remote return electrode, usually adhered externally to the patient. More recently, bipolar instruments have been used because the cauterizing current is generally limited to tissue between two electrodes of the instrument.

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 arc 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 dependent and the forceps are not adapted to simultaneously cauterize a larger area of tissue.

Bipolar scissors have been disclosed where two scissors blades act as two electrodes having insulated shearing surfaces. This device mechanically cuts tissue as coagulating electrical current is delivered to tissue in the current path. Bipolar scissors are also highly technique dependent in their use.

In prior devices, such as the device described in U.S. Pat. No. 5,403,312, electrosurgical energy has been delivered to biologic tissue in order to create a region of coagulation, as, for example, on either side of an incision, thus preventing blood and other bodily fluids from leaking out of the incision. In such a device, if tissue grasped by the jaws is compressed too much by applying excessive pressure to the region of coagulation, the tissue grasped by the end effector may be torn or crushed. If the tissue is not compressed enough because to little pressure is applied to the region of coagulation, the tissue in the region of coagulation may not be not effectively or uniformly cauterized because fluid (e.g. blood) could remain in the region of cauterization. In prior art devices, the surgeon has used tactile feedback and visual clues to determine the amount of pressure to apply to the region in order to obtain optimum coagulation. In instruments wherein the region of coagulation is partially or fully obscured, either by the end effector or by tissue, and is, therefore, not visible to the surgeon, it is particularly difficult for the surgeon to ensure that the appropriate pressure is being applied by the end effectors to ensure proper coagulation. It would, therefore, be advantageous to develop an electrosurgical instrument wherein the surgeon is not required to adjust the pressure applied by the end effector prior to applying electrosurgical energy to tissue in the region of coagulation. It would further be advantageous to design an instrument wherein the pressure applied to the tissue prior to coagulation is within a predetermined range.

One known method of varying the pressure applied to the tissue by the jaws of the end effector involves varying the gap between the jaws depending upon the tissue being grasped. However, such an arrangement would necessitate the use of different instruments, different end effectors or different staple cartridges depending upon the tissue being grasped. It would, therefore, be advantageous to design an instrument wherein the pressure applied by the end effector would vary with the thickness and makeup of the tissue being grasped.

Non electrosurgical endocutters such as those described in U.S. Pat. No. 5,597,107, employ a relatively stiff lower jaw member which includes a staple cartridge in conjunction with a more flexible upper member which acts as an anvil against which the staples are formed. In such instruments, the anvil is generally manufactured to be as stiff as possible, within the limits of size, materials and other design considerations and the spring rate of such an anvil may be, for example, in the range of 350-450 pounds per inch. A stiff anvil helps to ensure that the staples form properly when the instrument is fired. Spring rate, in terms of tissue compression forces in conventional staplers with gap spacing pins, is used in conjunction with the gap pin to create and maintain a minimum gap between the staple cartridge and the anvil, setting the height of the formed staple. Therefore, the designers of conventional stapling instruments with gap spacing pins are primarily interested in the formation of a simple beam with consistent gap to form consistent staples. In other designs, the gap pin is not used and the anvil is designed with sufficient stiffness to facilitate the formation of tissue. It would, therefore, be advantageous to design an electrosurgical instrument where the spring rate of the anvil is sufficiently stiff for the formation of staples while exerting a pressure in a range which facilitates the proper cauterization of tissue.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a hemostatic electrosurgical instrument which can exert pressure in a range to efficiently provide improved hemostasis in multiple tissue types and thickness, e.g., in fleshy or vascular tissue areas, and high, low or combination impedance tissues. Hemostasis is used herein to mean generally the arresting of bleeding including by coagulation, cauterization and/or tissue joining or welding.

Another object of the invention is to provide an improved cutting and stapling device with an electrocautery means for tissue welding or cauterization along a cutting path wherein the device is adapted to grasp tissue and exert a pressure within a predetermined range in order to provide improved hemostasis prior to cutting the tissue.

These and other objects of the invention are described in an electrosurgical device having an end effector with opposing interfacing surfaces associated with jaws for engaging tissue therebetween, and two electrically opposite poles located on one or both of the opposing surfaces. The poles are isolated from each other with an insulating material, or, where the poles are on opposite interfacing surfaces, they may be offset from each other so that they do not directly oppose each other on interfacing surfaces. In particular, an electrosurgical device according to the present invention includes a substantially fixed lower jaw. Further, an electrosurgical device according to the present invention includes a substantially flexible upper jaw having a spring rate in the range of between approximately 200 pounds per inch and approximately 600 pounds per inch. More particularly, the spring rate of the upper jaw is approximately 275 pounds per inch.

An electrosurgical instrument of a preferred embodiment compresses tissue to a pressure within a predetermined range in a compression zone between a first interfacing surface and a second interfacing surface and applies electrical energy through the compression 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 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 compression ridge on both interfacing surfaces. A coagulation 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 isolates the two poles and enables the current path between 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. Compression also stops significant blood flow and squeezes out blood which acts as a heat sink, particularly when flowing through blood vessels. Thus, compression optimizes 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 instrument poles or electrical arcing common in bipolar instruments.

In one embodiment of the present invention, the pressure initially applied to tissue in the compression zone is between approximately 30 pounds per square inch (psi) and approximately 250 psi. In a further embodiment of the present invention, the pressure initially applied to tissue in the compression zone is between approximately 75 psi and 250 psi. In a further embodiment of the present invention, the pressure initially applied to tissue in the compression zone is between approximately 115 psi and 185 psi.

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.

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 cut line or a cutting path. In one embodiment, the first pole comprises an elongated electrode. The elongated electrode along with the adjacent insulator form a ridge to compress the tissue to be cauterized. The second pole is adjacent the insulator on an opposite side of the insulator 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 communicates 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 between the parallel bars while the rows of staples are applied to the tissue.

In another embodiment, the hemostatic device is incorporated into a linear cutter similar to a linear cutting mechanical stapler. In this embodiment the hemostatic device comprises two parallel and joined elongated 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 hemostasis. 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 impedance 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 impedance out of range for anticipated good coagulation. It may also be used for detecting other instrument abnormalities. It is possible to detect the abnormal condition, for example, by using comparisons of normal ranges of initial tissue impedance in the interface electronics. This could be sensed in the first few milliseconds 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 continue 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 insulator. The electrodes which make up the poles may be located on either the stapler cartridge or the anvil.

In one embodiment of the present invention, the pressure exerted by the anvil is a function of the spring rate of the anvil. By providing a “pre-bend” angle on the anvil it is possible to obtain a pre-load (at a zero gap.) A preferred value of preload is in the range of between 12 and 18 pounds with a preferred value of approximately 15 pounds. In one embodiment of the present invention, the spring rate ofjaw32 is between approximately 225 pounds per inch and approximately 350 pounds per inch. More particularly , the spring rate ofanvil18 onjaw32 is preferably in the range of approximately 275 pounds per inch.

These and other objects of the invention will be better understood from the following attached Detailed Description of the Drawings, when taken in conjunction with the Detailed Description of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 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 position;

FIG. 6 is a front cross sectional view of the distal end of the instrument of FIG. 3 taken along theline 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 theline 9—9;

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 present invention;

FIG. 12 is a front cross sectional view of the end effector of another embodiment of the present invention;

FIG. 13 is a front cross sectional view of the end effector of another embodiment of the present invention;

FIG. 14 is a front cross sectional view of the end effector of another embodiment of the present invention;

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;

FIG17 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 effector of FIG. 17;

FIG. 19 is a front cross sectional view of the end effector of another embodiment of the present invention;

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.

FIG. 22 is a cross sectional view of the end effector according to a further embodiment 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 staplinginstrument10 is shown having abody16 coupled to ashaft30 with a lumen extending therethrough and anend effector50 extending from thedistal end21 of theshaft30. Theshaft30 is formed of an insulative material and has an electricallyconductive sheath38 extending through its lumen. Achannel39 extending through thesheath38 guides co-axial movement of a driver means44 within thechannel39. In this particular embodiment, the driver means44 includes a firingtrigger14 associated with thebody16, coupled to aflexible firing rod40 coupled to a drivingrod41, coupled to ablock43. Theblock43 is coupled to a cutting means11 and astaple driving wedge13, which the driving means44 advances by way of theblock43 into theend effector50.

Theend effector50 comprises two interfacingjaw members32,34. Theend effector50 is secured by way ofjaw member34 to thechannel39. Thejaw member32 is movably secured tojaw member34. Thebody16 has a clampingtrigger12 for closing thejaws32,34 which longitudinally advances aclose rack45 coupled to the proximal end of thesheath38. Theclose rack45 advances thesheath38 co-axially through theshaft30. Thesheath38 advances over acamming surface27 ofjaw32 to close thejaws32 and34 onto tissue situated between the jaws. As described in more detail below, theclose rack45 also acts as a switch to close the circuit which communicates electrical energy to theend effector50.

Referring now to FIGS. 3-9 and22 an enlargement of theend effector50 of theinstrument10 is illustrated. Thejaw members32 and34 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 member32 comprises ananvil18, a U-shapedfirst pole52 extending longitudinally with respect to thejaw32, and a U-shaped insulatingmaterial55 surrounding the outside of thefirst pole52.Jaw member32 has aninner surface33 which faces aninner surface35 ofjaw34. Theinner surface33 includesfirst pole52 which comprises two electrically communicating electrode bars53,54 comprised of stainless steel or aluminum, extending substantially along the length of theinner surface33. Thebars53,54 are separated by aknife channel42 extending longitudinally through the first pole's center to form its U-shape. The surface of the bars are formed in flat strips to provide more surface area contact with tissue. Two series ofpockets36,37 located onanvil18, for receiving staple ends, extend along theinner surface33, lateral to and outside ofbars53,54 respectively. The electrode bars53,54 and the insulatingmaterial55 form aridge56 extending out relative to theanvil portion33aof the inner surface33 (FIG.6). Theanvil18 is formed of an electrically conductive material and acts as a second pole electrically opposite to the first pole. Theanvil18 is isolated from thefirst pole52 by theU-shaped insulating material55.

Jaw member34 comprises acartridge channel22 and acartridge23. Thecartridge23 includes atrack25 for thewedge13,knife channel26 extending longitudinally through the center of thecartridge23, a series ofdrivers24 extending intotrack25 andstaples100 arranged in two sets of parallel double rows. When tissue is engaged between thejaws32,34, the driver means44 may be actuated or fired usingtrigger14 to advance the cutting means11 andwedge13 through the engaged tissue to staple and cut the tissue. When thefiring mechanism14 is actuated, thewedge13 is advanced through thetrack25 causing thedrivers24 to displace towards thestaples100, thereby driving thestaples100 through tissue and into anvil pockets36,37.

In the embodiment of the invention illustrated in FIG. 22, dimension B, which is measured frominner surface33 ofjaw member32 totissue surface80 of U-shaped insulatingmaterial55, is preferably in the range of from approximately0.0 inches to approximately0.045 inches and preferably approximately 0.0 inches. Dimension C, which is measured frominner edge82 toouter edge84 ofU-shaped insulator55 alongtissue surface80, is preferably in the range of from approximately 0.01 inches to approximately 0.04 inches and preferably approximately0.02 inches. Dimension E, which is measured frominner edge86 toouter edge88 offirst pole52 as measured along tissue surface90, is preferably in the range of from approximately .002 inches to 0.04 inches and preferably approximately 0.020 inches. Dimension G, which is measured from tissue surface90 totissue surface92 withjaws32 and34 closed, is preferably in the range from approximately 0.0 inches to approximately 0.020 inches and preferably approximately 0.001 inches. Dimension G is measured without tissue engaged.

Aknob15 located on the distal end of thebody16 rotates theshaft30,sheath38,channel39 andend effector50 which are directly or indirectly coupled to theknob15 so that theknob15 may be used for rotational placement of theend effector jaws32,34.

Bipolar energy is supplied to theend effector50 from anelectrosurgical generator60 throughwires19,20 extending into thebody16 of the instrument. Thegenerator60 is user controlled by way of afootswitch65.

Wire19 which provides electrical current to the first pole, is coupled through a wire or other electrical contact means61 toelectrical contact62, associated with the first pole, located on the distal end ofclose rack45.Wire20 which carries the current of the opposite pole, is coupled through a wire or other electrical contact means66 to adisc contact67 located at the distal end of theclose rack45 and electrically isolated fromcontact62.

Adisc contact63, associated with the first pole, located at the distal end of thebody16 is in electrical communication with a wire or other contact means64. Contact means64 extends throughchannel39 to endeffector jaw32 where it contactsfirst pole52. Thedisc contact63 permits theknob15 to rotate while contact is maintained between thedisc contact63 and the contact means64. The contact means64 is electrically insulated from thesheath38.

When the clampingtrigger12 is actuated, theclose rack45 moves distally so that thecontact62 comes in electrical communication with thedisc contact63 and thedisc contact67, associated with thesecond pole51, comes in electrical contact with the electricallyconductive sheath38. Thesheath38 moves over thecamming surface27 of the electricallyconductive anvil18 which acts as the return electrode. Thus the electrical circuit is closed when and only when the clampingtrigger12 is closed.

In operation, theend effector50 of the instrument is located at a tissue site where tissue is to be cut. Thejaw members32,34 are opened by pressing arelease button70 which releases abutton spring71 and permits theclose rack45 to move proximally. Tissue is then placed between the interfacinginner surfaces33,35 respectively of thejaw members32,34. The clampingtrigger12 is squeezed to cause thesheath38 to move over thecamming surface27 and thereby close thejaws32,34 and simultaneously close the electrical circuit as described above. The electrode bars53,54 and the insulatingmaterial55, which together form theridge56, compress the tissue against theinner surface35 ofjaw member34. A user then applies RF energy from thegenerator60 using thefootswitch65 or other switch. Current flows through the compressed tissue between thefirst pole52, i.e. thebars53,54, and thesecond pole51, i.e., theanvil18.

In one embodiment of the present invention the initial pressure applied to compress the tissue in the compression zone is between approximately 30 pounds per square inch (psi) and 250 psi. More particularly, in a further embodiment of the present invention the initial pressure applied to compress the tissue in the compression zone is between approximately 75 psi and 250 psi. More particularly in a further embodiment of the present invention the initial pressure applied to compress the tissue in the compression zone is between approximately 75 psi and 175 psi. In one embodiment of the present invention, the initial pressure applied to compress tissue positioned between the jaws is approximately 125 psi. With sufficient pressure applied fluid, including blood, is forced out of the tissue in the compression zone, facilitating coagulation. In addition, pressure applied to tissue within the compression zone facilitates coupling of electrosurgical energy to the tissue by forcing the tissue against the electrode.

The pressure exerted by the anvil is a function of the spring rate of the anvil. By providing a “pre-bend” angle on the anvil it is possible to obtain a pre-load (at a zero gap.) Thus, where a pre-bend angle is applied, the anvil may be viewed as a prestressed beam. A Preferred value of preload is in the range of between 12 and 18 pounds with a preferred value of approximately 15 pounds. The spring rate of the anvil is more accurately a function of the stiffness of the “system”, where the system includes the anvil, channel, cartridge, tube, etc. Each of the elements of the system has a particular spring rate and each may be suitably modified to increase the stiffness of the system.

In one embodiment of the present invention, that the spring rate ofanvil jaw32 is between approximately 225 pounds per inch and approximately 350 pounds per inch. More particularly, the spring rate ofanvil18 onjaw32 is preferably in the range of approximately 275 pounds per inch.

Preferably the bipolar energy source is a low impedance source providing radio frequency energy from about 300 kkHz to 3 MHZ. Preferably, the current delivered 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 means11 is advanced and thestaples100 are fired using the firingtrigger14. Firing is accomplished by rotating the firingtrigger14 acting as a lever arm aboutpivot14a. The driver means44 advances the cutting means11 andwedge13. The cutting means11 cuts the tissue in between thebars53,54 where the tissue has been cauterized. Thus, the cut line is lateral to the coagulation lines formed by the bar electrodes. Thewedge13 simultaneously advances thedrivers24 into thestaples100 causing thestaples100 to fire through tissue and into thepockets36,37 of theanvil18.Staples100 are applied in two longitudinal double rows on each side of the cutting means11 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 U.S. 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 replaceable 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 of the size of the space necessary to contain the double row of staples, a refireable cartridge with stacked staples has not been preferred because of the additional space required for stacking staples. In the multifire stapling 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 embodiment, 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 coagulation zone is not visible to the user. In a particular embodiment, the feedback system measures electrical parameters of the system which include coagulation level.

The feedback system may also determine tissue characteristics 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 decrease 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, Bjoern “Automatically controlled Bipolar Electrocoagulation,” Neurosurg. Rev. p. 187-190 (1984) incorporated herein by reference. Also as desiccation occurs, impedance increases. Tissue carbonization 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 feedback system which is implemented in a preferred embodiment of the present invention. First, energy is applied 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 embodiment provides a continuous audible sound in which the tone varies depending on the impedance level. An additional 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 thefirst pole152 and thesecond pole151 are both located on thesame jaw132 having theanvil118. The U-shapedfirst pole152 forms theknife channel142. AU-shaped insulator155 surrounds thefirst pole152 except on thesurface133 so that it is electrically isolated from thesecond pole151. The compression ridge156 is formed on the cartridge which is made from an electrically non-conductive material. The ridge156 compresses tissue against thefirst pole152 andinsulator155 to form a tissue compression zone.

In FIG. 12, thefirst pole252 and thesecond pole251 are both located on thesame jaw232 having theanvil218. Thefirst pole252 and thesecond pole251 each are located on opposing sides of theknife channel242. Aninsulator255 surrounds thepoles251,252 except on thesurface233 so that thepoles251,252 are electrically isolated from each other. Thecompression ridge256 is formed on the cartridge which is made from an electrically non-conductive material. Theridge256 compresses tissue against thepoles251,252 andinsulator255 to form a tissue compression zone.

In FIG. 13, second pole351 is located on thejaw332 having theanvil318 while thefirst pole352 is located on thecartridge323. The U-shapedfirst pole352 forms theknife channel326 and is surrounded byinsulator355a.AU-shaped insulator355bforms theknife channel342 injaw332. Except for theinsulator355b,the jaw is formed of an electrically conductive material which makes up the second pole351. Thefirst pole352 and theinsulator355a form thecompression ridge356 which compresses tissue against thesurface333 ofjaw332 to form a compression zone. Theinsulator355bis of sufficient width that it preventspoles351,352 form contacting when thejaws332,334 are closed.

In FIG. 14, thefirst pole452 and thesecond pole451 are both located on thejaw434 having thecartridge423. Thefirst pole452 and thesecond pole451 each are located on opposing sides, forming theknife channel426 through thecartridge423. Aninsulator455asurrounds thepoles451,452 except on :thesurface435, so that thepoles451,452 are electrically isolated from each other. Thecompression ridge456 is formed on thecartridge423 and forms a compression zone by compressing tissue against aninsulator455bdisposed on thesurface433 of thejaw432.

FIG. 15 illustrates an alternative embodiment. The first andsecond poles551,552 andknife channel542 are arranged in a similar configuration as in FIG. 12 except that the first andsecond poles551 and552 each comprise a series of electrically connected electrodes staggered along the length of the knife channel with insulating material in between staggered electrodes.

FIG. 16 illustrates staggered electrodes as in FIG. 15 but withfirst pole electrodes652 andsecond pole electrodes651 alternating along the length of theknife channel642 and on each side of theknife channel642.

FIGS. 17 and 18 illustrate another embodiment in which first andsecond poles751,752 each comprise staggered electrodes. In this embodiment, thefirst pole752 is staggered along each side of the knife channel126 and located on thecompression ridge756 formed on thecartridge723. Thesecond pole751 is staggered along each side of theknife channel742 on thesurface733 ofjaw732. As can be seen from FIG. 18, thepoles751,752 are vertically aligned, but as illustrated in FIG. 17, are staggered so that when thejaws732,734 are closed, the poles are electrically isolated from each other byinsulators755a,755b.

FIG. 19 illustrates an alternative embodiment of the end effector. Thefirst pole852 and thesecond pole851 are both located on thejaw832 having ananvil818. Thefirst pole852 forms theridge856 for compressing tissue in a compression zone and is located on interfacingsurface833. Thesecond pole851 is located on the side of theanvil818 and not on interfacingsurface833.

FIGS. 20 and 21 illustrate a circular cutter of the present invention with stapling means. FIG. 20 illustrates thestapler cartridge900 with aninterfacing surface933. A double row ofstaple apertures901 through which staples are driven into tissue are staggered about the outer circumference of thesurface932. Afirst pole952 encircles the inner circumference of thesurface933. Aninsulator955 electrically isolates thefirst pole952 from theportion933aof thesurface933 surrounding the staple apertures. Thestaple aperture portion933ais formed of an electrically conductive material and acts as a second pole. Acircular cutting knife911 is recessed within thecartridge900 radially inward from the inner circumference of thesurface933.

FIG. 21 illustrates ananvil918 withpockets937 for receiving staples and acompression ridge956 for compressing tissue against thefirst pole952 andinsulator955 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 cutting however, tissue welding electrical current may be delivered between thefirst pole952 and thestaple aperture portion933ato tissue.

In an alternative embodiment, the circular cutter may be used without staples. Electrical current is delivered through the poles to weld and coagulate tissue, then the knife may be advanced to cut tissue in a procedure such as an anastomosis.

In operation, the jaws of the instrument, for example,jaws32 and34 ofend effector50, are closed around the tissue which is to be treated. Tissue trapped between the instrument jaws is compressed as described herein

An electrosurgical instrument according to the present invention is beneficial in that coagulation of tissue is enhanced since the pressures applied force fluid out of the coagulation region without tearing the tissue. The pressure ranges specified herein are also beneficial in that, using an instrument according to the present invention, contact between the tissue and electrodes is improved, coagulation is improved throughout the tissue and charring is reduced.

Several variations of this invention has been described in connection with two specific embodiments involving endoscopic cutting and stapling. Naturally, the invention may be used in numerous applications where hemostasis in desired. Accordingly, will be understood by those skilled in the art that various changes and modifications may be made in the invention without departing from its scope, which is defined by the following claims and their equivalents.

Claims (19)

What is claimed is:

1. An end effector for an electrosurgical device, wherein said end effector comprises:

first and second jaw members;

first and second opposing interfacing surfaces, said interfacing surfaces being capable of engaging tissue therebetween, and said end effector capable of receiving bipolar energy therein, said first jaw comprising an anvil having a spring rate of between approximately two hundred twenty five pounds per inch and three hundred fifty pounds per inch;

electrically isolated first and second poles comprising electrically opposite electrodes capable of conducting bipolar energy therethrough; wherein said first pole is comprised of one or more first electrodes of a first electrical potential; wherein said second pole is comprised of one or more second electrodes of a second electrical potential;

wherein at least one of said one or more first electrodes is located on at least one of said first and said second interfacing surfaces and wherein at least one of said one or more second electrodes is located on at least one of said first and second interfacing surfaces, so that bipolar energy may be communicated between said poles through the tissue; and

wherein each said one or more first electrodes is offset from each said one or more second electrodes, at said first and second interfacing surfaces.

2. The end effector ofclaim 1 wherein said spring rate is approximately two hundred and seventy five pounds per inch.

3. The end effectorclaim 1 wherein said anvil is pre-bent such that, when said first and second jaws are closed, with at least a portion of said first and second interfacing surfaces touching to create a zero gap, said anvil has a preload in a range of between approximately twelve pounds and eighteen pounds.

4. The end effector ofclaim 1 wherein a portion of said second interfacing surface comprises a ridge extending from said second interfacing surface to form a tissue compression zone between interfacing surfaces.

5. The end effector ofclaim 4 wherein current flowing between said first and second poles provides coagulation in the compression zone.

6. The end effector ofclaim 1 wherein said end effector includes a cutting element mounted on said end effector to divide tissue engaged by said end effector when said cutting element is actuated to move said cutting element through said tissue.

7. The end effector ofclaim 6 wherein said end effector further comprises at least one staple and at least one driver adapted to apply said at least one staple lateral to said cutting line.

8. The end effector ofclaim 1 wherein said one or more first electrodes comprises an electrode having a relatively circular shape and is located on an outer circumference of said first interfacing surface.

9. The end effector ofclaim 8 wherein said end effector includes a cutting element mounted on said end effector and being adapted to divide tissue engaged by said interfacing surfaces.

10. The end effector ofclaim 9 wherein said end effector further comprises at least one staple and at least one driver adapted to drive said at least one staple through tissue

11. An electrosurgical instrument comprising:

a handle,

an actuating means coupled to said handle,

an end effector coupled to the distal end of said actuating means,

a means for communicating bipolar electrical energy from a biopolar energy source to said end effector,

said end effector including:

first and second jaw members,

a first interfacing surface,

a second interfacing surface,

a first pole comprising one or more first electrodes of a first electrical potential located on at least one of said interfacing surfaces,

a second pole comprising one or more second electrodes of a second electrical potential located on at least one of said interfacing surfaces, and

an insulator arranged to offset each of said one or more first electrodes from each of said one or more second electrodes, at said interfacing surfaces,

wherein said actuating means is capable of causing said end effector to engage tissue between the first interfacing surface and the second interfacing surface,

wherein said first jaw member is an anvil and wherein said anvil has a spring rate of between approximately two hundred twenty five pounds per inch and approximately three hundred fifty pounds per inch,

wherein said first pole and said second pole are comprised of electrically opposite electrodes capable of conducting electrical energy supplied from said means for communicating bipolar electrical energy from a bipolar energy source, through tissue adjaccent to said one or more first electrodes and said one or more second electrodes.

12. The electrosurgical device ofclaim 11 wherein said spring rate is approximately two hundred and seventy five pounds per inch.

13. The electrosurgical device ofclaim 11 wherein said anvil is pre-bent such that, when said first and second jaws are closed, with at least a portion of said first and second interfacing surfaces touching to create a zero gap, said anvil has a preload in a range of between approximately twelve pounds and approximately eighteen pounds.

14. An electrosurgical instrument having an end effector, wherein said end effector comprises:

first and second opposing interfacing surfaces, said interfacing surfaces capable of engaging tissue therebetween, and said end effector capable of receiving bipolar energy therein;

a cutting element arranged on said instrument to cut tissue engaged by said end effector when said cutting element is actuated, wherein said first interfacing surface includes a first slot extending longitudinally therethrough for receiving said cutting element;

a cartridge containing at least one row of staples and at least one driver adapted to apply said staples to tissue engaged by said end effector, said cartridge having a second slot extending longitudinally therethrough for receiving said cutting element, said first and second slots arranged to permit said cutting element to travel lateral to said at least one row of staples, said cartridge forming at least a portion of said second interfacing surface;

an anvil for receiving and forming said staples, said anvil forming at least a portion of said first interfacing surface which said anvil has a spring rate of between approximately two hundred twenty five pounds per inch and three hundred fifty pounds per inch;

electrically isolated first and second poles positioned on said first interfacing surface and comprising electrically opposite electrodes, wherein said first pole is comprised of first and second elongated substantially parallel electrodes arranged on opposite sides of said first slot and said second pole comprises an electrode positioned on said anvil;

first and second compression ridges extending from said first interfacing surface, wherein said first and second electrodes comprise at least a portion of said first and second compression ridges;

third and fourth electrically insulating compression ridges extending from said second interfacing surface;

a first tissue contacting surface on said first and second compression ridges;

a second tissue contacting surface on said third and fourth compression ridges; and

a recessed insulation region separating said first pole from said second pole wherein said recessed insulation region includes a recessed tissue contacting surface, said recessed tissue contacting surface being approximately level with said portion of !said first interfacing surface comprising said anvil.

15. The electrosurgical device ofclaim 14 wherein spring rate is approximately two hundred seventy five pounds per inch.

16. The electrosurgical device ofclaim 14 wherein said anvil is pre-bent such that, when said end effector is closed, with at least a portion of said first and second interfacing surfaces touching to create a zero gap, said anvil has a preload in a range of between approximately twelve pounds and eighteen pounds.

17. An electrosurgical instrument comprising:

a handle,

an actuating means coupled to said handle,

an end effector coupled to the distal end of said actuating means,

a means for communicating bipolar electrical energy from a bipolar energy source to said end effector,

said end effector comprising:

first and second opposing interfacing surfaces, said interfacing surfaces capable of engaging tissue therebetween, and said end effector capable of receiving bipolar energy therein;

a cutting element arranged on said instrument to cut tissue engaged by said end effector when said cutting element is actuated, wherein said first interfacing surface includes a first slot extending longitudinally therethrough for receiving said cutting element;

a cartridge containing at least one row of staples and at least one driver adapted to apply said staples to tissue engaged by said end effector, said cartridge having a second slot extending longitudinally therethrough for receiving said cutting element, said first and second slots arranged to permit said cutting element to travel lateral to said at least one row of staples, said cartridge forming at least a portion of said second interfacing surface;

an anvil for receiving and forming said staples, said anvil forming at least a portion of said first interfacing surface wherein said anvil has a spring rate of between approximately two hundred twenty five pounds per inch and three hundred fifty pounds per inch;

electrically isolated first and second poles positioned on said first interfacing surface and comprising electrically opposite electrodes, wherein said first pole is comprised of first and second elongated substantially parallel electrodes arranged on opposite sides of said first slot and said second pole comprises an electrode positioned on said anvil;

first and second compression ridges extending from said first interfacing surface, wherein said first and second electrodes comprise at least a portion of said first and second compression ridges;

third and fourth electrically insulating compression ridges extending from said second interfacing surface;

a first tissue contacting surface on said first and second compression ridges;

a second tissue contacting surface on said third and fourth compression ridges;

and

a recessed insulation region separating said first pole from said second pole wherein said recessed insulation region includes a recessed tissue contacting surface, said recessed tissue contacting surface being approximately level with said portion of said first interfacing surface comprising said anvil.

18. The electrosurgical device ofclaim 17 wherein said spring rate is approximately two hundred seventy five pounds per inch.

19. The electrosurgical device ofclaim 17, wherein said anvil is pre-bent such that, when said end effector is closed, with at least a portion of said first and second interfacing surfaces touching to create a zero gap, said anvil has a preload in a range of between approximately twelve pounds and approximately eighteen pounds.

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