Patent Publication Number: US-2016242841-A1

Title: Apparatus for performing an electrosurgical procedure

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an apparatus for performing an electrosurgical procedure. More particularly, the present disclosure relates to an electrosurgical apparatus including an end effector assembly having a pair of jaw members that provide a mechanical advantage at the end effector. 
     2. Description of Related Art 
     Electrosurgical instruments, e.g., electrosurgical forceps (open or closed type), are well known in the medical arts and typically include a housing, a handle assembly, a shaft and an end effector assembly attached to a distal end of the shaft. The end effector includes jaw members configured to manipulate tissue (e.g., grasp and seal tissue). Typically, the electrosurgical forceps utilizes both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize, seal, cut, desiccate, and/or fulgurate tissue. Typically, one or more driving mechanisms, e.g., a drive assembly including a drive element, is utilized to cooperate with one or more components operatively associated with the end effector to impart movement to one or both of the jaw members. 
     To facilitate moving the jaw members from an open position for grasping tissue to a closed position for clamping tissue (or vice versa) such that a consistent, uniform tissue effect (e.g., tissue seal) is achieved, one or more types of suitable devices may be operably associated with the electrosurgical forceps. For example, in some instances, one or more cam members, e.g., a cam pin, may operably couple to the drive element, e.g., a drive rod, wire, cable, etc., and operably couple to a cam slot that is operably associated with one or both of the jaw members. 
     Typically, the cam slots are operably disposed on proximal end of the jaw members. In certain instances, to facilitate movement of the jaw members, the proximal ends of the jaw members are configured to extend outside of the shaft profile. In this extended position, the proximal ends of the jaw members are commonly referred to as “flags.” 
     In certain instances, the shaft may bend or deform during the course of an electrosurgical procedure. For example, under certain circumstances, a clinician may intentionally bend or articulate the shaft to gain a desired mechanical advantage at the surgical site. Or, under certain circumstances, the surgical environment may cause unintentional or unwanted bending or flexing of the shaft, such as, for example, in the instance where the shaft is a component of a catheter-based electrosurgical forceps. More particularly, shafts associated with catheter-based electrosurgical forceps are typically designed to function with relatively small jaw members, e.g., jaw members that are configured to pass through openings that are 3 mm or less in diameter. Accordingly, the shaft and operative components associated therewith, e.g., a drive rod, are proportioned appropriately. That is, the shaft and drive rod are relatively small. 
     As can be appreciated, when the shaft is bent or deformed (either intentionally or unintentionally) the frictional losses associated with “flags” extending through the shaft profile may be transferred to one of the drive rod, drive element, and/or a spring operably associated with the drive assembly, which, in turn, may diminish, impede and/or prevent effective transfer of the desired closure force that is needed at the jaw members. Moreover, the frictional losses may also lessen the operative life of the spring, which, in turn, ultimately lessens the operative life of the electrosurgical instrument. 
     SUMMARY 
     The present disclosure provides an endoscopic forceps. The endoscopic forceps includes a housing having a shaft that extends therefrom and defines a longitudinal axis therethrough. An end effector assembly is operatively connected to a distal end of the shaft and includes a pair of first and second jaw members. The first and second jaw members are pivotably coupled to one another. The first and second jaw members are movable relative to one another from an open position, wherein the first and second jaw members are disposed in spaced relation relative to one another, to a clamping position, wherein the first and second jaw members cooperate to grasp tissue therebetween. A drive mechanism includes a driving structure with a bifurcated distal end having two substantially resilient legs. A driving structure guide is operably associated with the shaft and is operably disposed adjacent the end effector assembly. The driving structure guide includes at least two grooves each configured to receive respective ones of the two legs of the bifurcated distal end. 
     The present disclosure provides endoscopic forceps. The endoscopic forceps includes a housing having a shaft that extends therefrom and defines a longitudinal axis therethrough. An end effector assembly is operatively connected to a distal end of the shaft and includes a pair of first and second jaw members. The first and second jaw members are pivotably coupled to one another via a central pivot pin. The first and second jaw members are movable relative to one another from an open position, wherein the first and second jaw members are disposed in spaced relation relative to one another, to a clamping position, wherein the first and second jaw members cooperate to grasp tissue therebetween. A drive mechanism is operably associated with the housing and includes a driving structure. A movable cam operably disposed adjacent the end effector includes two or more cam slots thereon. The two or more cam slots are in operative communication with respective cam followers that are operably coupled to respective ones of the first and second jaw members. The respective cam followers angled offset from the pivot pin such that a closure force in the range from about 3 kg/cm 2  to about 16 kg/cm 2  is present at the first and second jaw members when the first and second jaw members are in the clamping position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Various embodiments of the present disclosure are described hereinbelow with references to the drawings, wherein: 
         FIG. 1  is a side, perspective view of an endoscopic bipolar forceps showing an end effector assembly including jaw members according to an embodiment of the present disclosure; 
         FIG. 2  is a side, perspective view of the endoscopic bipolar forceps depicted in  FIG. 1  illustrating internal components associated with a handle assembly associated with the endoscopic bipolar forceps; 
         FIG. 3  is a schematic view of the jaw members depicted in  FIGS. 1 and 2  illustrating a distal end of a driving structure operably coupled to the jaw members; and 
         FIG. 4  is a schematic view illustrating a distal end of a driving structure operably coupled to the jaw members of the end effector depicted in  FIGS. 1 and 2  according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Detailed embodiments of the present disclosure are disclosed herein; however, the disclosed embodiments are merely examples 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. 
     In the drawings and in the descriptions that follow, the term “proximal,” as is traditional, will refer to an end that is closer to the user, while the term “distal” will refer to an end that is farther from the user. 
     With reference to  FIGS. 1 and 2 , an illustrative embodiment of an electrosurgical apparatus, e.g., a bipolar forceps  10  (forceps  10 ) is shown. Forceps  10  is operatively and selectively coupled to an electrosurgical generator (not shown) for performing an electrosurgical procedure. As noted above, an electrosurgical procedure may include sealing, cutting, cauterizing, coagulating, desiccating, and fulgurating tissue all of which may employ RF energy. The electrosurgical generator may be configured for monopolar and/or bipolar modes of operation and may include or be in operative communication with a system that may include one or more processors in operative communication with one or more control modules (not shown) that are executable on the processor. The control module may be configured to instruct one or more modules to transmit electrosurgical energy, which may be in the form of a wave or signal/pulse, via one or more cables (e.g., an electrosurgical cable  310 ) to the forceps  10 . However, in certain embodiments, the forceps  10  may be battery powered. In this instance, the forceps  10  is not configured to communicate with either an electrosurgical generator and/or a system. 
     Forceps  10  is shown configured for use with various electrosurgical procedures and generally includes a housing  20 , electrosurgical cable  310  that connects the forceps  10  to the electrosurgical generator, a rotating assembly  80  and a trigger assembly  70 . For a more detailed description of the rotating assembly  80 , trigger assembly  70 , and electrosurgical cable  310  (including line-feed configurations and/or connections), reference is made to commonly-owned U.S. patent application Ser. No. 11/595,194 filed on Nov. 9, 2006, now U.S. Patent Publication No. 2007/0173814. 
     With continued reference to  FIGS. 1 and 2 , forceps  10  includes a shaft  12  that has a distal end  14  that is configured to mechanically engage an end effector assembly  100  operably associated with the forceps  10  and a proximal end  16  that mechanically engages the housing  20 . 
     One or more driving structures or guides are operably associated with the shaft  12 . More particularly, as best seen in  FIG. 3 , a drive wire guide  13  (guide  13 ) of suitable proportion is operably disposed adjacent the distal end  14  of the shaft  12 , as best seen in  FIG. 3 . Guide  13  may be made from any suitable material including, but not limited to, plastic, metal, metal alloy, etc. Guide  13  is operably coupled to an internal frame of the shaft  12  by one or more suitable coupling methods. In the illustrated embodiment, guide  13  is monolithically formed, e.g., molding, stamping, machining, etc., with the shaft  12 . 
     Guide  13  is in operative communication with a drive mechanism  130  ( FIG. 2 ). Specifically, guide  13  includes a multi-grooved (or multi-slotted) configuration that is configured to receive a driving structure  133  (or operative component associated therewith) that is operably associated with the drive mechanism  130  ( FIGS. 1 and 2 ). More specifically, guide  13  includes a first groove  13   a  that is configured to receive a leg or branch  135   a  of a bifurcated distal end  135  that is operably coupled driving structure  133 . Likewise, a second groove  13   b  is configured to receive a leg or branch  135   b  of the bifurcated distal end  135 . 
     Each of the first and second grooves  13   a  and  13   b  includes a generally arcuate configuration that extends along a respective length thereof. The arcuate configuration of the grooves  13   a  and  13   b  facilitates movement of the respective legs  135   a  and  135   b  therein. Moreover, the arcuate configuration of the grooves  13   a  and  13   b  allows a greater length of the legs  135   a  and  135   b  to be positioned within the grooves  13   a  and  13   b  for a given area within the shaft  12 . 
     With reference again to  FIGS. 1 and 2 , handle assembly  30  includes a fixed handle  50  and movable handle  40 . In one particular embodiment, fixed handle  50  is integrally associated with housing  20 . Movable handle  40  is movable relative to fixed handle  50  for effecting movement of one or more components, e.g., driving structure  133 , operably associated with drive mechanism  130  ( FIG. 2 ). Handle assembly  30  including movable handle  40  may be configured such that proximal movement of the movable handle  40  “pulls” the driving structure  133 , which, in turn, imparts movement of one or both of a pair of jaw members  110  and  120  from a normally closed or clamping position ( FIGS. 2 and 3 ) to an open position ( FIG. 1 ). Alternatively, handle assembly  30  including movable handle  40  and drive mechanism  130  may be configured such that proximal movement of the movable handle  40  “pushes” the driving structure  133 , which, in turn, imparts movement of the jaw members  110  and  120 . 
     Drive mechanism  130  is in operative communication with movable handle  40  (see  FIGS. 1 and 2 ) for imparting movement of both or, in some instances, one of the jaw members  110 ,  120  of end effector assembly  100 . More particularly, one or more suitable mechanical interfaces, e.g., a linkage interface, gear interface, or combination thereof operably couples the movable handle  40  to the drive mechanism  130 . In the embodiment illustrated in  FIGS. 1-3 , proximal movement of the movable handle  40  moves the jaw members  110  and  120  away from each other from the normally closed position to the clamping position. 
     Driving structure  133  is configured such that proximal movement thereof causes the jaw members  110  and  120  to move from the clamping position ( FIGS. 2 and 3 ) to the open position ( FIG. 1 ) and vice versa. To this end, driving structure  133  may be any suitable driving structure including but not limited to a wire, rod, cable, resilient band, etc. In the illustrated embodiment, driving structure  133  is a drive wire  132  of suitable configuration ( FIGS. 1-4 ). 
     Drive wire  132  includes a proximal end (not explicitly shown) that is in operative communication with the movable handle  40 . 
     The bifurcated distal end  135  operably couples to the drive wire  132  and includes legs  135   a  and  135   b  that are configured to translate within the guide  13  (see  FIG. 3 , for example). Drive wire  132  is configured such that the drive wire  132  including the bifurcated distal end  135  does not tend to “buckle” or “kink” when the drive wire  132  is moved proximally and/or distally within the shaft  12  and through the guide  13 . 
     The bifurcated distal end  135  including the legs  135   a  and  135   b  may be a wire, a band, a cable or the like. In the illustrated embodiment, the distal end  135  including the legs  135   a  and  135   b  is a substantially flexible wire of suitable dimensions. In some embodiments, the bifurcated distal end  135  may be a combination of two or more materials and/or structure. For example, and in one particular embodiment, the bifurcated distal end  135  may include a proximal wire portion that operably couples to a pair of legs  135   a  and  135   b  that are flexible bands. Other configurations are contemplated. 
     Leg  135   a  is movable within the first groove  13   a  Likewise, leg  135   b  is movable within the second groove  13   b.  To facilitate independent movement of the legs  135   a  and  135   b  within the respective first and second grooves  13   a  and  13   b  of the guide  13 , the legs  135   a  and  135   b  are positioned therein in a criss-crossed manner and/or pattern, as best seen in  FIG. 3 . More particularly, the legs  135   a  and  135   b  “cross-over” one another at a medial point within the guide  13 . Positioning the legs  135   a  and  135   b  in this manner within the guide  13  allows that legs  135   a  and  135   b  to move in concert with and independent of one another within the respective first and second grooves  13   a  and  13   b  while allowing the legs  135   a  and  135   b  to concomitantly move the jaw members  110  and  120  from the clamping to open position and vice versa. 
     A distal end of leg  135   a  is operably coupled (by one or more suitable coupling methods, e.g., intent/detent configuration) to a proximal end  117   a  of a jaw housing  117 . Similarly, a distal end of leg  135   b  is operably coupled (by one or more suitable coupling methods, e.g., intent/detent configuration) to a proximal end  127   a  of a jaw housing  127 . 
     To facilitate movement of the legs  135   a  and  135   b  within the respective first and second grooves  13   a  and  13   b,  the bifurcated distal end  135  including legs  135   a  and  135   b  and/or guide  13  including first and second grooves  13   a  and  13   b  may be coated with one or more types of lubricious materials, e.g., PTFE. 
     One or more suitable coupling devices operably couples the bifurcated distal end  135  to the drive wire  132 . In embodiment illustrated in  FIG. 3 , a coupler  131  is utilized to couple the distal end  135  to the drive wire  132 . The coupler  131  includes proximal and distal threaded ends (not explicitly shown) that threadably couple to corresponding threaded ends associated with the distal end  135  and drive wire  132 . As can be appreciated, other coupling methods are contemplated, e.g., the drive wire  132  may have the bifurcated distal end  135  monolithically formed therewith. 
     End effector assembly  100  is illustrated operably disposed at the distal end  14  of the shaft  12  ( FIGS. 1-3 ). End effector assembly  100  includes opposing jaw members  110  and  120  that mutually cooperate to grasp, seal and, in some cases, divide large tubular vessels and large vascular tissues. As noted above, in the illustrated embodiment, jaw members  110  and  120  are movable relative to each other. Jaw members  110 ,  120  are operatively and pivotably coupled via a central pivot pin  111  to each other and located adjacent the distal end  14  of shaft  12 . Respective electrically conductive seal plates  118  and  128  are operably supported on and secured to respective distal ends  117   b  and  127   b  of jaw housings  117  and  127  of the jaw members  110  and  120 , respectively. Jaw members  110  and  120  including respective jaw housings  117  and  127 , and operative components associated therewith, may be formed from any suitable material, including but not limited to metal, metal alloys, plastic, plastic composites, and so forth. 
     Jaw housing  127  and  117  of the respective jaw members  120  and  110  are substantially identical to each other. In view thereof, the operative features of jaw housing  127  are described in detail, and only those features that are unique to jaw housing  117  are described hereinafter. 
     With reference to  FIG. 3 , an embodiment of jaw housing  127  is illustrated. Jaw housing  127  includes a distal end  127   b  that is configured to operably support seal plate  128  and a proximal end  127   a  that operably couples to the distal end  14  of shaft  12 . Proximal end  127   a  includes a generally angled configuration ( FIG. 3 ) and is configured to move, e.g., pivot, within the shaft  12  from the closed or clamping position to the open position (see also  FIG. 1  in combination with  FIG. 2 ). Pivot pin  111  couples the first and second jaw members  110  and  120 , respectively ( FIGS. 1-3 ) for pivotal movement relative to one another. 
     The jaw members  110  and  120  may be coupled to each other via any suitable coupling methods. In the illustrated embodiment, an opening  108  is defined in and extends through the each of the jaw housings  117  and  127  and is configured to receive pivot pin  111 . Opening  108  is shown engaged with pivot pin  111  and, as such, is not explicitly shown. 
     In an assembled configuration, pivot pin  111  is positioned within the opening  108  associated with each of the jaw members  110  and  120 , respectively. Once assembled, the jaw members  120  and/or jaw member  110  may be pivotably supported at the distal end  14  of the shaft  12  by known methods, such as, for example, by the method described in commonly-owned U.S. Pat. No. 7,597,693 to Garrison. 
     To facilitate pivotable movement of the jaw members  110  and  120 , in the assembled configuration, the guide  13  is offset (or otherwise spaced) from the proximal ends  117   a  and  127   a  of respective jaw members  110  and  120 . Accordingly, the guide  13  does not contact the proximal ends  117   a  and  127   a  and, thus, does not interfere or impede movement of the jaw members  110  and  120  when the jaw members are moved from the clamping to the open position. 
     In use, jaw members  110  and  120  are, initially, in the clamping position (see  FIGS. 2 and 3 ). Movable handle  40  is moved proximally ( FIG. 1 ), which, in turn, causes the drive wire  132  to move proximally. Proximal movement of the drive wire  132  moves the bifurcated distal end  135  including the legs  135   a  and  135   b  proximally within the respective first and second grooves  13   a  and  13   b.  Proximal movement of the legs  135   a  and  135   b  causes the respective jaw members  110  and  120  to move away from one another to the open position, see  FIG. 1 , for example. Subsequently, tissue is positioned between the jaw members  110  and  120 . Once tissue is positioned between the jaw members  110  and  120 , movable handle is released and the jaw members  110  and  120  move toward one another and back to the clamping position with tissue disposed therebetween. In the clamping position closure force in the range from about 3 kg/cm 2  to about 16 kg/cm 2  may be present at the jaw members  110  and  120 . Thereafter, tissue is electrosurgically treated, e.g., tissue is sealed. In one embodiment, a closure force in the range of 3 kg/cm 2  to about 16 kg/cm 2  is used to obtain desired tissue seal characteristics, i.e., is used to provide a uniform and consistent seal across the tissue. 
     The unique configuration of the bifurcated distal end  135  and guide  13  improves the opening and closing angles typically associated with known forceps jaw designs. More particularly, the unique configuration of the guide  13  facilitates turning and routing the drive wire  132  therethrough. Moreover, the unique configuration of the guide  13  including the bifurcated distal end  135  having the non-coupled criss-crossed configuration of the legs  135   a  and  135   b  eliminates the need of having the proximal ends  117   a  and  127   a  (“flags”) extend past the profile of the shaft  12 . 
     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. For example, it is contemplated that in certain instances one or more resilient members, e.g., compression spring (not shown), may be operably associated with or coupled to either bifurcated distal end  135  and/or one or both of the jaw members  110  and  120 . In this instance, the spring may be configured to provide a clamping force or seal force between the jaw members  110  and  120  when the jaw members  110  and  120  are in the clamping position. 
     It is contemplated that in certain embodiments, the legs  135   a  and  135   b  and the respective first and second grooves  13   a  and  13   b  may function as or include a ratchet and pawl system. In this instance, each of the legs  135   a  and  135   b  and the respective first and second grooves  13   a  and  13   b  may be configured to lock the jaw members  110  and  120  in one or more positions, e.g., the clamping position. 
     With reference to  FIG. 4 , an end effector  200  that is suitable for use with the forceps  10  is shown. It should be noted that end effector  200  is substantially identical to end effector  100  described above. In view thereof, and so as not to obscure the present disclosure with redundant information, only the operative components associated with end effector  200  will be described hereinafter. 
     A drive mechanism  230  includes a drive structure  233 . Drive structure  233  may be any suitable drive structure  233  including but not limited to a substantially flexible rod, cable, band or the like. In the illustrated embodiment, drive structure  233  is a substantially flexible drive rod  232 . Drive mechanism  150  including drive rod  232  is configured such that proximal movement of the movable handle  40  causes distal movement of the drive rod  232 , which, in turn, imparts movement of the jaw member  110  and  120  from the clamping position ( FIG. 4 ) to the open position, see  FIG. 1 , for example. 
     Unlike end effector  100  that is operably associated with a guide  13 , end effector  200  is operably associated with a movable cam  19  (cam  19 ), see  FIG. 4 . Cam  19  may be made from any suitable material including but not limited to the materials previously described above with respect to guide  13 , e.g., plastic. Cam  19  may include any suitable shape. In the embodiment illustrated in  FIG. 4 , cam  19  includes a generally rectangular configuration. A proximal end  21  of the cam  19  is operably coupled to a distal end of a drive rod  232  by one or more suitable coupling methods, e.g., soldering, brazing, welding, adhesive, rivet, pin, etc. In the illustrated embodiment, proximal end  21  operably couples to the distal end of a drive rod  232  by way of a rivet  231 . 
     Two or more cam slots  19   a  and  19   b  of suitable proportion are operably disposed on the cam  19  ( FIG. 4 ). To facilitate opening and closing the jaw members  110  and  120 , cam slots  19   a  and  19   b  are disposed in different planes and in a generally criss-crossed manner so that the cam pins  23   a  and  23   b  do not intersect each other during opening ad closing of the jaw members  110  and  120 . 
     Continuing with reference to  FIG. 4 , cam slot  19   a  operably couples to a cam follower, e.g., a cam pin  23   a,  that is operably disposed on jaw member  110  at a proximal end  117   a  thereof. Similarly, Cam slot  19   b  operably couples to a cam follower, e.g., a cam pin  23   b  that is operably disposed on jaw member  120  at a proximal end  127   a  thereof. The cam pins  23   a  and  23   b  are offset from the pivot pin  111  at a predetermined angle such that, in one embodiment, a closure force in the range from about 3 kg/cm 2  to about 16 kg/cm 2  is present at the jaw members  110  and  120  when the first and second jaw members are in the clamping position. In the illustrated embodiment, the cam pins are offset from the pivot pin  111  at an angle (that ranges from about 25° to about 65°) and a distance to provide desired forces and mechanical advantages for a specific application. Offsetting the cam pins  23   a  and  23   b  at desirable angles with respect to the pivot pin  111  facilitates movement of the proximal ends  117   a  and  127   a  within the limited area at the distal end  14  of the shaft  12 . 
     To facilitate movement of the cam pins  23   a  and  23   b  within the respective cam slots  19   a  and  19   b,  the cam pins  23   a  and  23   b  and/or cam slots  19   a  and  19   b  may be coated with one or more types of lubricious materials, e.g., PTFE. 
     In use, jaw members  110  and  120  are, initially, in the clamping position (see  FIGS. 2 and 4 ). Movable handle  40  is moved proximally ( FIG. 1 ), which, in turn, causes the drive rod  232  and the cam  19  including cam slots  19   a  and  19   b  to move distally. Distal movement of the cam  19  including the cam slots  19   a  and  19   b  cams the respective cam pins  23   a  and  23   b  causing the respective jaw members  110  and  120  to move away from one another to the open position, see  FIG. 1 , for example. Subsequently, tissue is positioned between the jaw members  110  and  120 . Once tissue is positioned between the jaw members  110  and  120 , movable handle is released (or moved proximally depending on the specific configuration of the movable handle  40 ) and the jaw members  110  and  120  move toward one another and back to the clamping position with tissue disposed therebetween. In certain instances, the jaw members  110  and  120  may be spring biased in either an open or closed configuration. In the clamping position closure force in the range from about 3 kg/cm 2  to about 16 kg/cm 2  is present at the jaw members  110  and  120 . Thereafter, tissue is electrosurgically treated, e.g., tissue is sealed. In one embodiment, a closure force in the range of 3 kg/cm 2  to about 16 kg/cm 2  is used to obtain desired tissue seal characteristics, i.e., is used to provide a uniform and consistent seal across the tissue. 
     The movable cam  19  including cam slots  19   a  and  19   b  improves the opening and closing angles typically associated with known forceps jaw designs. More particularly, the unique crisscrossed configuration of the cam slots  19   a  and  19   b  facilitates camming the cam pins  23   a  and  23   b  therein. Moreover, the unique configuration of the crisscrossed configuration of the cam slots  19   a  and  19   b  eliminates the need of having the proximal ends  117   a  and  127   a  (“flags”) extend past the profile of the shaft  12 . Further, the unique configuration of the crisscrossed configuration allows the cam slots to be formed as a separate piece, from a separate process or with a separate material. As can be appreciated, this may change cam slot shapes, e.g., curvature and angles, and resulting mechanical advantages. 
     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.