Abstract:
A bipolar forceps is provided and includes a housing having one or more shafts that extend therefrom that operatively support an end effector assembly at a distal end thereof. The end effector assembly includes first and second jaw members. A tissue sealing plate disposed on each of the jaw members is provided. The tissue sealing plates is configured to support a plurality of electrodes thereon and arranged in vertically opposing pairs along the length of the jaw members. The plurality of electrodes is adapted to independently connect to an electrosurgical energy source such that each vertically opposing electrode pairs form an independently controllable electrical circuit when tissue is held between the jaw members. A control system having one or more algorithms for independently controlling and/or monitoring the delivery of electrosurgical energy from the electrosurgical energy source to the plurality of electrodes is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority to U.S. Provisional Application Ser. No. 61/041,065 entitled “END EFFECTOR ASSEMBLY FOR ELECTROSURGICAL DEVICES AND SYSTEM FOR USING THE SAME,” filed Mar. 31, 2008 by Nicole McKenna, which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to an electrosurgical forceps and, more particularly, the present disclosure relates to electrosurgical forceps, for use with either an endoscopic or open electrosurgical forceps for sealing, cutting, and/or coagulating tissue, which employ opposing jaw members each having seal plates including selectively independently controllable electrodes. 
         [0004]    2. Description of Related Art 
         [0005]    Electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize and/or seal tissue. 
         [0006]    By utilizing an endoscopic electrosurgical forceps, a surgeon can cauterize, coagulate/desiccate, seal, and/or simply reduce or slow bleeding simply by controlling the intensity, frequency and duration of the electrosurgical energy applied through the jaw members to the tissue. Most small blood vessels, i.e., in the range below two millimeters in diameter, can often be closed using standard electrosurgical instruments and techniques. However, if a larger vessel is ligated, it may be necessary for the surgeon to convert the endoscopic procedure into an open-surgical procedure and thereby abandon the benefits of endoscopic surgery. Alternatively, the surgeon can seal the larger vessel or tissue. 
         [0007]    It is thought that the process of coagulating vessels is fundamentally different than electrosurgical vessel sealing. For the purposes herein, “coagulation” is defined as a process of desiccating tissue wherein the tissue cells are ruptured and dried. “Vessel sealing” or “tissue sealing” is defined as the process of liquefying the collagen in the tissue so that it reforms into a fused mass. Coagulation of small vessels is sufficient to permanently close them, while larger vessels need to be sealed to assure permanent closure. 
         [0008]    As mentioned above, electrosurgical forceps utilize electrosurgical energy to effect hemostasis by heating the tissue and vessels to coagulate, cauterize and/or seal tissue. The source of electrosurgical energy is configured to provide a voltage across tissue, which, in turn, causes current to flow therethrough. The current passing through the tissue, which is acting as a resistor, causes electrical power to be delivered to that portion of tissue (P=I 2 *R), resulting in a transfer of energy to the tissue in the form of heat. 
         [0009]    Typically, the source of electrosurgical energy will be in operative communication with a computer that includes a control algorithm configured to monitor, measure, and/or control the amount of electrosurgical energy that is being delivered to the vessel sealing site. The computer and control algorithm are usually configured to monitor and measure one or more electrical parameters at the tissue sealing site. Common in the art is to have the computer and/or control algorithm configured to measure impedance at the tissue sealing site. When a threshold value of impedance is detected by the computer and/or control algorithm, the electrosurgical energy being transmitted to the tissue sealing site is adjusted accordingly. The measured impedance may be detected, measured, and transmitted to the control algorithm via sensors located on the electrosurgical forceps and in operative communication the computer. 
         [0010]    Electrosurgical forceps also include end effector assemblies that include opposing jaw members pivotally connected to each other and each having a seal plate configured to cause a tissue effect when tissue is grasped therebetween. The seal plates are employed to transmit electrosurgical energy to the tissue sealing site when the jaw members are in a closed configuration. Each seal plate typically extends the length of their respective jaw member, or portion thereof. The seal plates may be in operative communication with the control algorithm via the sensors. 
         [0011]    During vessel sealing procedures, in some instances, eschar may form and accumulate on the seal plates (e.g., proximal end of one or both of the seal plates). As is known in the art, because eschar is highly resistive it tends to act like a resistor and impedes the flow current. As a result, the impedance measured across tissue, at the vessel sealing site, may be inaccurate for purposes of controlling the amount of electrosurgical energy delivered to the tissue sealing site. That is, because the total impedance measured at the tissue sealing site is now a combination of both the resistance of the tissue and the resistance of the eschar formed on one or both of the seal plates, the measured impedance may not be an entirely accurate representation of the actual impedance of the tissue as the tissue is being cooked. Consequently, and as will be discussed in greater detail below, non-uniform and/or incomplete tissue seals may form when eschar builds on tissue sealing plates. This anomaly becomes of particular concern in instances where the jaw members have been designed to have a longer length to accommodate certain tissue types. 
       SUMMARY 
       [0012]    A bipolar forceps is provided. The bipolar forceps includes a housing having one or more shafts which extends therefrom that operatively supports an end effector assembly at a distal end thereof The end effector assembly includes first and second jaw members pivotably connected to each other and moveable from an open spaced apart position to a closed position to grasp tissue. The bipolar forceps also includes a tissue sealing plate disposed on each of the jaw members, wherein each tissue sealing plate is configured to support a plurality of electrodes thereon arranged in vertically opposing pairs along the length of the jaw members. Each of the plurality of electrodes is adapted to independently connect to an electrosurgical energy source such that each vertically opposing electrode pair forms an independently controllable electrical circuit when tissue is held between the first and second jaw members. A control system having one or more algorithms for independently controlling and/or monitoring the delivery of electrosurgical energy from the electrosurgical energy source to the plurality of electrodes is also provided. 
         [0013]    The one or more algorithms are configured to determine a threshold condition when an electrical parameter is reached. The electrical parameter is selected from the group consisting of impedance, voltage, or current. Moreover, the one or more algorithms are configured to re-route the electrosurgical energy to only those electrode pairs which require additional electrosurgical energy to reach an end seal condition when the threshold condition is reached. In operation, an abnormal electrode pair “end seal” condition causes the one or more algorithms to execute an override command if certain other electrical or physical conditions do not correlate to a safe end seal condition. Alternatively, an abnormal electrode pair “end seal” condition causes the one or more algorithms to execute a re-grasp alarm if certain other electrical or physical conditions do not correlate to a safe end seal condition. 
         [0014]    In embodiments the plurality of electrodes is insulated from each other by a non-conductive material. 
         [0015]    The control system is configured to query the electrode pairs individually and/or in together upon a condition being met prior to adjusting electrical delivery. A bipolar forceps according to claim  1 , wherein the control system 
         [0016]    A method for performing an electrosurgical procedure is also provided including the initial step of providing a bipolar forceps. The bipolar forceps includes a housing having one or more shafts which extends therefrom that operatively supports an end effector assembly at a distal end thereof. The end effector assembly includes first and second jaw members pivotably connected to each other and moveable from an open spaced apart position to a closed position to grasp tissue. The bipolar forceps includes a tissue sealing plate disposed on each of the jaw members, wherein each tissue sealing plate is configured to support a plurality of electrodes thereon arranged in vertically opposing pairs along the length of the jaw members. Each of the plurality of electrodes is adapted to independently connect to an electrosurgical energy source such that each vertically opposing electrode pair forms an independently controllable electrical circuit when tissue is held between the first and second jaw members. The bipolar forceps includes a control system having one or more algorithms for independently controlling and/or monitoring the delivery of electrosurgical energy from the electrosurgical energy source to the plurality of electrodes. The method for performing an electrosurgical procedure also includes the steps of: delivering electrosurgical energy from the source of electrosurgical energy to the plurality of electrodes on each of the seal plates; measuring the impedance levels across tissue at each of the plurality of electrodes; comparing the measured values of impedance levels at each of the plurality of electrodes with known threshold values of impedance; and adjusting the amount of electrosurgical energy being delivered to each of the plurality of electrodes as needed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0017]      FIG. 1  is a perspective view of a bipolar forceps in accordance with the present disclosure; 
           [0018]      FIG. 2  illustrates an electrical wiring diagram for the bipolar forceps depicted in  FIG. 1  in accordance with the present disclosure; 
           [0019]      FIG. 3  is s side cross-sectional view of jaw members in accordance with the present disclosure; 
           [0020]      FIG. 4  is an exploded with of the jaw member depicted in  FIG. 3 ; and 
           [0021]      FIG. 5  is a flow chart illustrating a method for performing an electrosurgical procedure in accordance with the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. 
         [0023]    During electrocautery surgical procedures such as sealing it is common for eschar to form and accumulate on the seal plates, or portions thereof. Typically, eschar develops at or near a proximal end of the seal plate; this area of the seal plate is commonly referred to in the art, and hereinafter referred to as the “heel” of the seal plate. As the amount of eschar forming and accumulating near the heel of the seal plates increases, so too does the impedance at the tissue sealing site; this is because eschar impedes current flow. As described above, this is especially evident if the seal plates are longer than the potential heat transfer. 
         [0024]    As a result of the formation and accumulation of eschar on the seal plates, inaccurate impedance measurements may be communicated to the control algorithm in the generator. Subsequently, these inaccurate impedance measurements are implemented by the control algorithm in calculating and determining whether a threshold level of impedance has been reached which may result in any number of possible errors. For example, if the resultant threshold impedance levels calculated by the control algorithm are in all actuality a false representation of the actual impedance present at the tissue sealing site, the control algorithm is eventually “tricked” into causing the source of electrosurgical energy to be adjusted prematurely, which can ultimately lead to ineffective tissue seals being formed, which may lead to leakage at or near the proximal thrombosis. 
         [0025]    Having end effector assemblies, as described herein, which include seal plates defining multiple electrodes that are independently monitored and controlled greatly reduces the chances of false impedance measurements being transferred to the generator and, as a result reduces the likelihood of a weak or ineffective seal being passed off as “complete”. 
         [0026]    Turning now to  FIG. 1  one embodiment of an electrosurgical forceps  10  in accordance with the present disclosure is shown. For the remainder of the disclosure it will be assumed that the electrosurgical forceps is an endoscopic bipolar forceps, as seen in  FIG. 1 , keeping in mind that any electrosurgical forceps may be employed with the present disclosure. For example, although the majority of the figure drawings depict a bipolar forceps  10  for use in connection with endoscopic surgical procedures, the present disclosure may be used for more traditional open surgical procedures. For the purposes herein, the forceps  10  is described in terms of an endoscopic instrument; however, it is contemplated that an open version of the forceps may also include the same or similar operating components and features as described below. 
         [0027]    Bipolar forceps  10  is shown for use with various electrosurgical procedures and generally includes a shaft  12 , a housing  20 , a handle assembly  30 , a rotating assembly  80 , a trigger assembly  70 , and an end effector assembly  100 , which is operatively connected to a drive assembly. End effector assembly  100  includes opposing jaw members  110  and  140 , which mutually cooperate to grasp, seal and, in some cases, divide large tubular vessels and large vascular tissues. 
         [0028]    Shaft  12  includes a distal end  14  that mechanically engages the end effector assembly  100  and a proximal end  116  that mechanically engages the housing  20 . In the drawings and in the descriptions which follow, the term “proximal,” as is traditional, will refer to the end of the forceps  10  which is closer to the user, while the term “distal” will refer to the end which is farther from the user. 
         [0029]    Handle assembly  30  includes a fixed handle  50  and a movable handle  40 . Fixed handle  50  is integrally associated with housing  20  and handle  40  is movable relative to fixed handle  50 . Fixed handle  50  may include one or more ergonomic enhancing elements to facilitate handling, e.g., scallops, protuberances, elastomeric material, etc. 
         [0030]    Movable handle  40  of handle assembly  30  is ultimately connected to the drive assembly which together mechanically cooperate to impart movement to the jaw members  110  and  140  to move from an open position, wherein the jaw members  110  and  140  are disposed in spaced relation relative to one another, to a clamping or closed position, wherein the jaw members  110  and  140  cooperate to grasp tissue therebetween. 
         [0031]    Rotating assembly  80  is operatively associated with the housing  20  and is rotatable approximately 180 degrees about a longitudinal axis “A-A” defined through shaft  12  (see  FIG. 1 ). 
         [0032]    Forceps  10  also includes an electrosurgical cable  310  which connects the forceps  10  to a source of electrosurgical energy, e.g., a generator  500  (shown schematically). It is contemplated that generators such as those sold by Valleylab—a division of Tyco Healthcare LP, located in Boulder Colorado may be used as a source of electrosurgical energy, e.g., Ligasure™ Generator, FORCE EZ™ Electrosurgical Generator, FORCE FX™ Electrosurgical Generator, FORCE 1C™, FORCE 2™ Generator, SurgiStat™ II or other envisioned generators which may perform different or enhanced functions. 
         [0033]    Cable  310  is internally divided into cable leads  310   a,    310   b  and  325   b  which are designed to transmit electrical potentials through their respective feed paths through the forceps  10  to the end effector assembly  100 . More particularly, cable feed  325   b  connects through the forceps housing  20  and through the rotating assembly to jaw member  120 . Lead  310   a  connects to one side of the switch  60  and lead  310   c  connects to the opposite side of the switch  60  such that upon activation of the switch energy is transmitted from lead  310   a  to  310   c.  Lead  310   c  is spliced with lead  310   b  which connects through the rotating assembly to jaw member  110 . 
         [0034]    For a more detailed description of shaft  12 , handle assembly  30 , movable handle  40 , rotating assembly  80 , electrosurgical cable  310  (including line-feed configurations and/or connections), and the drive assembly reference is made to commonly owned patent application Ser. No. 10/369,894, filed on Feb. 20, 2003, entitled VESSEL SEALER AND DIVIDER AND METHOD OF MANUFACTURING THE SAME. 
         [0035]    As shown in  FIGS. 3 and 4 , end effector assembly  100  includes opposing jaw members  110  and  140 . Jaw members  110  and  140  are generally symmetrical and include similar component features which cooperate to effectively sealing and divide tissue. As a result and unless otherwise noted, only jaw member  110  and the operative features associated therewith are described in detail herein but as can be appreciated, many of these features apply to jaw member  140  as well. 
         [0036]    Jaw member  110  includes an insulative structural substrate or support member  116  and an electrically conductive tissue sealing plate  118  (hereinafter seal plate  118 ). The insulator  116  may be dimensioned to securely engage the seal plate  118  by stamping, by overmolding, by metal injection or other known manufacturing techniques. All of these manufacturing techniques produce an electrode having a seal plate  118  which is substantially surrounded by insulating substrate  116 . Jaw member  140  includes a structural support member  146  and an electrically conducive seal plate  148 . 
         [0037]    With continued reference to  FIGS. 3 and 4 , seal plates  118  and  148  are configured in such a manner that electrical current travels from one seal plate (e.g.,  118 ) through tissue to the opposing seal plate (e.g.,  148 ). More particularly, end effector assembly  100  is configured to include a series of opposing electrode pairs disposed within the tissue sealing surfaces of each jaw member  110  and  140 , respectively. More particularly, each jaw member, e.g.,  110 , includes series of electrode  120   a - 120   e  spaced along the tissue sealing surface  118  thereof from the proximal end  116  to a distal end  117  thereof and across the tissue sealing surface  118 . The electrodes  120   a - 120   e  are spaced relative to one another and are either separated by a knife channel  170   a  defined in the jaw member  110  (from the proximal end to the distal end of the jaw member  110 ) or an insulative material  132   a  disposed therebetween. The electrodes  120   a - 120   e  may be arranged in pairs, e.g.,  120   a  and  120   b,    120   c  and  120   d  or may be randomly arranged along the tissue surface depending upon a particular purpose. 
         [0038]    Jaw member  140  includes a series of corresponding electrodes  142   a - 142   e  which oppose respective electrodes  120   a - 120   e  disposed on jaw member  110  such that during activation each pair of opposing electrodes, e.g.,  120   a  and  142   a,    120   b  and  142   b,    120   c  and  142   c,    120   d  and  142   d,  and  120   e  and  142   e  treat tissue disposed therebetween to form a tissue seal. Much like electrodes  120   a - 120   e,  electrodes  142   a - 142   e  are spaced relative to one another by a knife channel  170   b  or an insulative material  132   b  disposed therebetween. As explained in more detail below, each electrode pair, e.g.,  120   a  and  142   a,  is controlled and monitored by a computer  504  operatively coupled to generator  500 . 
         [0039]    Seal plates  118  and  148  may be configured in such a manner that when jaw members  110  and  140  are in a closed configuration, a knife blade, not shown, or portion thereof, may translate within channels  170   a  and  170   b  defined by seal plates  118  and  148 . 
         [0040]    Generator  500  is configured to control and/or monitor one or more electrode pairs operatively coupled to or disposed on seal plates  118  and  148  of jaw members  110  and  140 , respectively. Generator  500  includes a control system  502  having one or more computers and/or computer programs  504  which include one or more control algorithms. 
         [0041]    Computer  504  is housed within electrosurgical generator  500  and disposed in operative communication therewith via the community circuitry, not shown, associated with generator  500 . One or more controls  506  may be utilized to set certain parameters of the computer  504 . Within the purview of the present disclosure, computer  504  may be remotely located with respect to generator  500 . Here, generator  500  and computer  504  may be operatively connected to each other via any number of wire or wireless connections known in the art. 
         [0042]    Computer  504  include any number of computer programs, software modules and drivers associated therewith such that electrosurgical generator  500  functions to control or monitor each individual electrode to enhance the sealing procedure. For example, computer  504  captures and receives input data from the electrodes, either individually (or in pairs across the width of the jaw surface), and transmits the captured and received input data to an input algorithm of the computer  504 . The input data is representative of one or more electrical parameters associated with electrosurgical sealing, (e.g., tissue impedance). Based on the input data received, computer  504  controls the amount of electrosurgical energy to each electrode. 
         [0043]    As mentioned above, the internal control algorithm(s) of computer  504  are configured to receive the input data and execute internal code to compare impedance levels measured along the tissue sealing surfaces  118 ,  148  proximate each individual opposing electrode pair, e.g., opposing electrode pair  120   a  and  142   a,    120   b  and  142   b,    120   c  and  142   c,    120   d  and  142   d,  and  120   e  and  142   e,  with known threshold levels of impedance stored in, or accessible to the control algorithm. As impedance levels measured at the tissue sealing site approaches and/or reaches known threshold levels of impedance, the control algorithm of computer  504  independently monitors and controls the amount of electrosurgical energy that is delivered to each electrode pair, e.g., electrode pair  120   a  and  142   a,  which provides a more accurate seal geometry between opposing tissue sealing surfaces  118  and  148  especially with longer jaw lengths. In other words, each individual sealing site respective to each electrode pair  120   a  and  142   a  may be accurately controlled and monitored to deliver the optimum amount of energy to tissue, reduce the chances of eschar buildup and maximize seal quality across the entire tissue sealing surfaces  118  and  148 . 
         [0044]    The computer  504  (and algorithms disposed therein) may be configured to monitor and control the end or shut off parameters for each respective pair of electrodes  120   a  and  142   a,    120   b  and  142   b,    120   c  and  142   c,    120   d  and  142   d,  and  120   e  and  142   e  before an “end seal” signal will be reached Energy may be re-routed to only those electrode pairs which require additional energy or longer “cook time” to reach an end seal condition. As mentioned above, an abnormal electrode pair “end seal” condition may be met with some scrutiny by the algorithm and, may be overridden if certain other electrical or physical conditions do not correlate to an end seal condition or a re-grasp alarm may be triggered to avoid an unsafe condition. 
         [0045]    As best shown in  FIGS. 3 and 4 , computer  504  is operatively connected with each electrode pair, e.g.,  120   a  and  142   a,  via one or more of cable connections  340   a - 340   c  and  342   a - 342   c,  respectively. Various types of electrical connections may be utilized which are known in the art and the electrical connections may be routed through the instrument shaft(s) and connected to one or more printed circuit boards (PCBs) disposed within the forces  10 . 
         [0046]    The electrode pairs, e.g., e.g.,  120   a  and  142   a,    120   b  and  142   b,    120   c  and  142   c,    120   d  and  142   d,  and  120   e  and  142   e  are sized, configured and arranged in such a manner that tissue to be sealed contacts a sufficient number of electrodes to optimize seal quality. For example, larger electrodes pairs, e.g.,  120   a  and  142   a  and  120   e  and  142   e  may be positioned at the proximal and distal ends, respectively, of the tissue sealing surfaces  118  and  148  and smaller electrode pairs  120   c  and  142   c  may be more centrally disposed on the tissue sealing surfaces to optimize sealing. The electrodes  120   a - 120   e  and  142   a - 142   e  may be symmetrically or asymmetrically arranged on either side of knife slots  170   a  and  170   b  in opposing pairs depending upon a particular purpose of to optimize sealing a particular tissue type. 
         [0047]    One or more sensors  400  may be utilized to detect one or more other electrical of physical parameters, e.g., temperature, optical clarity, tissue expansion, rate of tissue expansion, pressure, etc. and relay the information back to the generator  500  for utilization by one or more algorithms of computer  504  to regulate energy delivery. Sensors  400  may include thermocouples, photodiodes, transducers, accelerometers, microsensors manufactured using MEMS technology or other types of sensors are contemplated and within the purview of the present disclosure. 
         [0048]    The present disclosure also provides a method for performing an electrosurgical procedure. At step  400 , an electrosurgical forceps is provided. At step  402 , electrosurgical energy is delivered from the source of electrosurgical energy to the plurality of electrodes on each of the seal plates. At step  404 , the impedance level across tissue at each of the plurality of electrodes is measured. At step  406 , the measured values of impedance levels at each of the plurality of electrodes are compared with known threshold values of impedance. At step  408 , the amount of electrosurgical energy being delivered to each of the plurality of electrodes is adjusted as needed. 
         [0049]    From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the same. 
         [0050]    For example, while it is shown in the figures that electrodes  120   a - 120   e  and  142   a - 142   e  of respective seal plates  118  and  148  having the same charge, it is within the purview of the present disclosure that the electrodes or different opposing pairs of electrodes defined by their respective seal plates may have alternating potentials along the seal surfaces. Obviously, in this instance, the electrical connections would have to be slightly altered to accomplish this purpose. 
         [0051]    In one embodiment, the computer  504  measures the impedance (or other electrical parameters) in real time and continually adjusts the electrical output in real time to optimize the tissue seal. In another embodiment, the computer  504  is configured to measure the electrical parameters in real time and make adjustments over a pre-set time period, only upon a threshold condition being met or after a pre-set number of pulses. The computer  504  may also be configured to further query the electrode pairs either individually or in pairs upon a condition being met prior to adjusting electrical delivery. For example, the computer  504  may be configured to query one or more adjacent electrode pairs (or one or more sensors) for further electrical information (or other information relating to temperature, pressure, rate of tissue expansion, optical clarity, etc) before altering electrical delivery if an abnormal electrical condition has occurred prior to adjusting the delivery of electrical energy. 
         [0052]    While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.