Patent Publication Number: US-9839467-B2

Title: Surgical forceps capable of adjusting seal plate width based on vessel size

Description:
This application is a continuation application of U.S. patent application Ser. No. 12/696,592, filed on Jan. 29, 2010, now U.S. Pat. No. 8,556,929, the entire contents of which are hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     The present disclosure relates to a surgical forceps, and more particularly, to a surgical forceps and method for determining and adjusting a seal plate width based upon a diameter of tissue to be sealed. 
     TECHNICAL FIELD 
     As an alternative to open forceps for use with open surgical procedures, modern surgeons use endoscopic or laparoscopic instruments for remotely accessing organs through smaller, puncture-like incisions. More recently, Natural Orifice Translumenal Endoscopic Surgery (NOTES) procedures have been developed, for example, to access the abdominal cavity via the mouth, for scar-less surgery. Much like laparoscopy, NOTES is beneficial to patients in that it reduces scarring and healing time. However, while these minimally invasive surgical procedures are advantageous in many respects, the reduced access area presents new problems for surgical instrument design. For example, achieving a high seal pressure with a surgical forceps becomes increasingly more difficult as the size of the jaw members decrease. 
     Further, it has been found that the seal pressure required to adequately seal a vessel is dependent on both the vessel size and seal plate width. Accurate application of pressure is important to oppose the walls of the vessel, to reduce tissue impedance to a low enough value that allows enough electrosurgical energy through tissue, to overcome the forces of expansion during tissue heating, and to contribute to the end tissue thickness which is an indication of a good seal. If the pressure is not great enough, the vessel may not properly or effectively seal and if the pressure is too great, the seal may shred or tear. 
     Accordingly, instead of attempting to identify and apply a specific pressure to a vessel according to vessel size and seal plate width, a pre-determined pressure may be applied to adequately seal different size vessels if the seal plate widths are adjustable according to the diameter of the vessel to be sealed. Such a feature would also be advantageous in the design of surgical instruments in that a designer need not provide an instrument capable of applying a wide-range of seal pressures, but, rather, can provide an instrument capable of applying a single pre-determined pressure for sealing vessels. 
     SUMMARY 
     In accordance with the present disclosure, a surgical forceps is provided that includes a housing having a shaft attached to the housing. An end effector assembly is attached at a distal end of the shaft. The end effector assembly includes first and second jaw members having opposed seal plates, each of the seal plates having a width. One or both jaw members are moveable from an open position to a closed position for grasping tissue. A sensing component is configured to determine an output relating to a diameter of tissue and/or a composition of tissue disposed between the opposed seal plates. An expanding component is configured to expand the width of one or both seal plates according to the determined output. 
     In one embodiment, the sensing component includes a pair of electrodes operably associated with the jaw members. The electrodes are configured to measure an electrical characteristic of tissue disposed between the jaw members, thereby determining the diameter of tissue or the composition of tissue disposed therebetween. In one embodiment, the electrical characteristic is impedance. 
     In another embodiment, a processing component is included. The processing component is configured to convert the output into a seal plate width according to user-input data. The processing component is in communication with the expanding component such that the expanding component expands the seal plate widths according to the width determined by the processing component. 
     In yet another embodiment, the expanding component includes a shape memory alloy. The shape memory alloy is configured to expand the widths of the seal plates when heated. The shape memory alloy is further configured to allow the seal plates to return to an un-expanded width when cooled. 
     In yet another embodiment, the expanding component includes an expandable substrate disposed within each jaw member. A lumen is defined through each of the expandable substrates. The lumens are configured for receiving a fluid therethrough for expanding the expandable substrates. As the expandable substrates expand, the respective seal plate widths are expanded as well. 
     In still yet another embodiment, the expanding component includes a gear assembly configured to expand the widths of the seal plates. 
     In yet another embodiment, the expanding component includes an expandable scaffold assembly disposed within each jaw member. Each of the expandable scaffold assemblies is configured such that upon expansion, the widths of the seal plates are also expanded. 
     In still yet another embodiment, one or more handles is provided for moving the jaw members between the open and closed positions. Further, the handle may be configured such that pulling the handle applies a pre-determined seal pressure to seal tissue disposed between the jaw members. 
     A method of sealing tissue is also provided in accordance with the present disclosure. The method includes providing a forceps having a pair of jaw members. The jaw members have opposed seal plates and one or both jaw members is moveable relative to the other from an open to a closed position for grasping tissue. The method also includes the steps of determining an output relating to a diameter of tissue and/or a composition of tissue disposed between the jaw members, adjusting a width of the opposed seal plates according to the output, and moving jaw members from the open to the closed position. Moving the jaw members from the open to the closed position applies a seal pressure to seal tissue disposed between the jaw members. 
     In one embodiment, the widths of the seal plates are adjusted according to the output and user-input data. 
     In another embodiment, moving the jaw members from the open to the closed position applies a pre-determined seal pressure to seal tissue disposed between the jaw members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the subject instrument are described herein with reference to the drawings wherein: 
         FIG. 1  is a top, perspective view of a surgical forceps including a housing, a handle assembly, a shaft, and an end effector assembly, for use with the present disclosure; 
         FIG. 2  is a enlarged, side, perspective view of the end effector assembly of  FIG. 1  having first and second jaw members, wherein the first jaw is shown with parts separated; 
         FIG. 3  is a side, perspective view of the housing of the forceps of  FIG. 1 , with a half of the housing removed; 
         FIG. 4  is a top view of the second jaw member of  FIG. 2 ; 
         FIGS. 5A-5B  show a top view of one embodiment of the second jaw member of  FIG. 2  in which a seal plate is removed to show the features thereinbelow; 
         FIGS. 6A-6B  show a top view of another embodiment of the second jaw member of  FIG. 2  in which the seal plate is removed to show the features thereinbelow; 
         FIGS. 7A-7B  show a top view of yet another embodiment of the second jaw member of  FIG. 2  in which the seal plate is removed to show the features thereinbelow; 
         FIGS. 8A-8B  show a top view of still yet another embodiment of the second jaw member of  FIG. 2  in which the seal plate is removed to show the features thereinbelow; and 
         FIG. 9  is a contour plot of the mean burst pressure as a result of seal plate width and vessel size, with a seal pressure of 120 psi. 
     
    
    
     DETAILED DESCRIPTION 
     Turning now to  FIG. 1 , an endoscopic forceps  10  is shown that includes a housing  20 , a handle assembly  30 , a rotating assembly  80 , a trigger assembly  70  and an end effector assembly  100 . Forceps  10  further includes a shaft  12  having a proximal end  14  that mechanically engages housing  20  and a distal end  16  configured to mechanically engage end effector assembly  100 . Forceps  10  also includes electrosurgical cable  310  that connects forceps  10  to a generator (not shown). Cable  310  has sufficient length to extend through shaft  12  in order to provide electrical energy to at least one of jaw members  110  and  120  of end effector assembly  100 . 
     With continued reference to  FIG. 1 , rotating assembly  80  is operably coupled to housing  20  and is rotatable approximately 180 degrees in either direction about a longitudinal axis “A” defined through forceps  10 . The housing  20  includes two halves that house the internal working components of the forceps  10 . Handle assembly  30  includes a moveable handle  40  and a fixed handle  50 . Fixed handle  50  is integrally associated with housing  20  and handle  40  is moveable relative to fixed handle  50 . 
     Referring now to  FIG. 2 , end effector assembly  100  is configured for mechanical attachment at the distal end  16  of shaft  12  of forceps  10 . End effector assembly  100  includes opposing jaw members  110  and  120 . Handle  40  of forceps  10  (see  FIG. 1 ) ultimately connects to a drive assembly (not shown) which, together, mechanically cooperate to impart movement of the jaw members  110  and  120  from a first, open position wherein the jaw members  110  and  120  are disposed in spaced relation relative to one another, to a second, clamping or closed position wherein the jaw members  110  and  120  cooperate to grasp tissue therebetween. Jaw members  110  and  120  also include longitudinal knife channels  115  defined therein for reciprocation of a knife blade (not shown) therethrough for cutting tissue. 
     With continued reference to  FIG. 2 , opposing jaw members  110  and  120  are pivotably connected about pivot  103  via pivot pin  105 . Jaw members  110  and  120  include electrically conductive sealing plates  112  and  122 , respectively, that are dimensioned to securely engage tissue clamped therebetween. As shown in  FIG. 2 , seal plate  112  of jaw member  110  includes a number of flanges  113  disposed around a perimeter thereof to engage seal plate  112  with expanding component  114 . During assembly, flanges  113  of seal plate  112  are engaged, e.g., slip-fit, with notches  117  of expanding component  114 , retaining seal plate  112  thereon. Alternatively, seal plates  112  and  122  may be secured to jaw members  110  and  120 , respectively, via any other suitable means. Jaw member  110  further includes a jaw cover  116  for housing the components, e.g., sensing component  118 , insulator  119  and expanding component  114 , of jaw member  110 . Jaw member  120  is constructed similarly to jaw member  110 , described above. 
     As shown in  FIG. 2 , jaw member  110  includes a sensing component  118 , e.g., an electrode pair disposed therethrough. Although not shown in the drawings, jaw member  120  is constructed similarly to jaw member  110  and includes a sensing component, e.g., an electrode pair, that cooperates with the electrode pair of jaw member  110  to measure the impedance across tissue disposed between the jaw members  110  and  120 . The electrode pair of jaw member  110 , for example, may be configured to transmit a low-voltage alternating-current through tissue disposed between the jaw members  110  and  120 , while the electrode pair disposed through jaw member  120  may be configured to receive the resulting voltage after the voltage has passed through tissue. It is also envisioned that this configuration be reversed, e.g., where the transmitting electrodes are disposed through jaw member  120  and the receiving electrodes are disposed through jaw member  110 . In either configuration, the impedance across tissue can be measured and used to determine the diameter of tissue between jaw members  110  and  120 . 
     Alternatively, the impedance across tissue measured by the pairs of electrodes can be used to determine the resistivity of tissue. Since different components of tissue, e.g., muscle cells, fat cells and fluid, have different resistivities, determining the overall resistivity of tissue can help determine the relative composition of tissue. Further, a second pair of electrodes (not shown) or sensors may be disposed through each of the jaw members  110  and  120  such that the first set of electrode pairs may be configured to measure the cross-sectional diameter of tissue while the second set of electrode pairs is configured to measure the resistivity of tissue. 
     It is also envisioned that any other suitable sensing component may be provided in cooperation with jaw members  110  and  120  to measure the cross-sectional diameter and/or to determine the composition of tissue disposed between jaw members  110  and  120 . Further, it is envisioned that the sensing component could include sensors disposed along the sealing plates  112  and  122  of jaw members  110  and  120 , respectively, for sensing the gap distance between the respective sealing plates  112  and  122 . By determining the gap distance between the sealing plates  112  and  122  at different positions along the plates, the size of the vessel grasped therebetween can be estimated. 
     Ultimately, the sensing component may be configured to measure any electrical or physical characteristic of tissue that may be used to determine a diameter of tissue or tissue composition. Accordingly, any sensor that may be used to measure an electrical or physical characteristic of tissue may be provided for use with end effector assembly  100  of forceps  10 . Suitable sensors include, but are not limited to, impedance sensors, proximity sensors, optical sensors, ultrasonic sensors, chemical sensors, and the like. 
     Referring now to  FIG. 3 , housing  20  of forceps  10  is shown having a half of housing  20  removed. A processing component  21 , disposed within housing  20 , is configured to receive the output, e.g., diameter of tissue and/or composition of tissue, from the sensing component  118 . One or more leads  33 ,  37  are disposed through the housing  20  and shaft  12  to the jaw members  110  and  120  to provide feedback to the processing component  21 . The processing component  21  converts the output into a seal plate width according to specific characteristics, as determined by the output, of tissue to be sealed. 
     The processing component  21  may include electrical circuitry  22  configured to convert the output into a seal plate width for adequately sealing tissue disposed between the jaw members  110  and  120 . Electrical circuitry  22  may be configured to convert the output to a seal plate width according to specific parameters and/or data. Alternatively, electrical circuitry  22  may communicate with an external source, e.g., a generator (not shown), for determining the seal plate width corresponding to the output. Further, a computer chip (not shown) may be provided for storing data and communicating with the electrical circuitry  22  in order to determine the appropriate seal plate width, based upon the output determined by the sensing component  118 . Specific data sets, e.g., the set of seal plate widths required for adequate sealing of vessels having varying diameters, may be used to convert the output into a seal plate width. Algorithms can also be used to determine the seal plate width based upon the specific output determined. Exemplary data, determined by a study of seal plate width as a function of vessel size, for configuring the processing component  21 , will be discussed in detail below. 
     With reference now to  FIGS. 2 and 4 , once the output has been determined and converted into a seal plate width, e.g., via processing component  21 , the specific seal plate width is communicated to the jaw members  110  and  120  such that the expanding component  124  may expand the width of the seal plates  112  and  122  accordingly. In the following, reference will be made to jaw member  120  alone but it is understood that the following relates to both jaw members  110  and  120 . 
     Generally, as shown in  FIG. 4 , jaw member  120  includes an electrically conductive seal plate  122  and defines longitudinal knife channel  115  therein. As described above, seal plate  122  is engaged with expandable component  124 , e.g., with the flanges (not shown, similar to flanges  113  of seal plate  112  (see  FIG. 2 )) of seal plate  122  slip-fit into notches  127  of expandable component  124 , which is contained within jaw cover  126 . Expandable component  124  is in communication with processing component  21  of housing  20  (see  FIG. 3 ) such that upon receiving a seal plate width determined by the processing component  21  (as described above), expandable component  124  is expanded to thereby expand seal plate  122  in the direction of arrows “B” and “C,” such that the determined width of seal plate  122  is achieved. Accordingly, it is envisioned that seal plate  122  may be configured to have an at-rest width which is a minimum width required to adequately seal tissue. Thus, seal plate  122  need only expand from the seal plate  122  at-rest position to reach the seal plate width required to seal tissue disposed between jaw members  110  and  120 . 
     Various embodiments of the expandable component  124  in conjunction with jaw member  120  will now be described in detail with reference to  FIGS. 5A-8B . Jaw member  110  is constructed similarly to jaw member  120  and therefore, to avoid duplication, will not be described herein. 
       FIGS. 5A-5B  show jaw member  120  wherein sealing plate  122  has been removed. As described above, when seal plate  122  is replaced, the flanges (not shown) disposed around the perimeter of seal plate  122  engage notches  127  of expandable component  124 , thereby securing seal plate  122  thereon. In the embodiment shown in  FIGS. 5A-5B , expandable component  124  is formed at least partially from a shape memory alloy (SMA). The SMA is surrounded by an insulator  124  to prevent heat from passing through to the SMA  124  and to prevent heat from escaping from the SMA. SMAs suitable for forming expandable member  124  include, but are not limited to, copper-zinc-aluminum-nickel, copper-aluminum-nickel, and nickel-titanium, commonly referred to in the art as Nitinol alloys. The SMA is configured for two-way shape memory effect. Thus, the SMA associated with sealing plate  122  of jaw member  120  remembers two different shapes, a “cold” shape (e.g., an at-rest position) and a “hot” shape (e.g., an expanded position). For purposes herein, M f  is the temperature at which the transition to a martensite phase or stage is finished during cooling, and A s  and A f  are the temperatures at which the transition from the martensite phase to austenite phase starts and finishes, during heating. A s  may be determined by the SMA material and composition and, typically, ranges from about 150° C. to about 200° C. A f  may also be determined by the SMA material and composition and/or the loading conditions and, typically, ranges from about 2° C. to about 20° C. or hotter. 
     Expandable member  124  initially may be in an unexpanded position, as shown in  FIG. 5A . This unexpanded, or at-rest, position corresponds to the SMA being in a cold state, that is, the SMA is in a martensite state (e.g., M f , a point below A s ). When the processing component  21  determines the appropriate seal plate width, a generator (not shown) may be activated to transmit electrosurgical energy through cable  310  into jaw member  120  to heat the SMA. As the SMA “heats up,” it eventually reaches an austenite state (e.g., A s ) and begins to transition from the “cold” shape to the “hot” shape, which, in turn, causes expandable member  124  to expand. During the austenite phase transition (e.g., A s →A f ), the expandable member  124  continues to expand until it reaches a threshold or final austenite stage (A f ), shown in  FIG. 5B . Since sealing plate  122  is engaged with expanding component  124  via the flanges (not shown) and notches  127 , respectively, as the SMA is transitioned (expanded) from the “cold” to the “hot” shape, the width of sealing plate  122  is correspondingly expanded from the unexpanded position of  FIG. 5A  (corresponding to the “cold” shape of the SMA) to the expanded position of  FIG. 5B  (corresponding to the “hot” shape of the SMA). If the SMA is allowed to cool, the SMA, as its temperature decreases, will transition from the austenite stage back to the martensite stage such that the SMA, and thus the seal plate width, will return to the unexpanded, or at-rest position. 
     With reference to  FIGS. 1-2 and 5A-5B , in operation, as can be appreciated, forceps  10  is positioned such that tissue to be sealed is disposed between jaw member  110  and  120 . The sensing components  118  may then be used to determine an output, e.g., the diameter of tissue and/or composition of tissue disposed through jaw members  110  and  120 . The determined output is then communicated to the processing component  21  for determining an appropriate seal plate width corresponding to the specific output. Thereafter, an appropriate amount of electrosurgical energy is supplied to expandable member  124 , e.g. via a generator (not shown), such that the SMA transitions from its “cold” to its “hot” state, thereby expanding seal plate  122  during this transition. Accordingly, the SMA may be heated to a specific point such that seal plate  122  is expanded to the width determined by the processing component  21 . A pre-determined seal pressure may then be applied, e.g., by squeezing handle  40  which, in turn, moves the jaw members  110  and  120  from the open to the closed position, to adequately seal tissue disposed between jaw members  110  and  120 . 
       FIGS. 6A-6B  illustrate another embodiment of the jaw member  220  wherein the seal plate  122  ( FIG. 2 ) has been removed for viewing purposes. Jaw member  220  includes an expandable substrate  224  defining a “U”-shaped lumen  225  therethrough. Inlet tubes  230  connect lumen  225  of the expandable substrate  224  to an source (not shown) for selectively permitting fluid  240  to flow through lumen  225 . A plurality of notches  227  is disposed around the perimeter of expandable substrate  224 . Notches  227  are configured to engage the flanges (not shown) of seal plate  122  ( FIG. 2 ) for securing the seal plate  122  ( FIG. 2 ) in place. Knife channel  215  is defined through a central portion of expandable substrate  224 . 
       FIG. 6A  shows the expandable substrate in a contracted, or fluid-less state. At this position, expandable substrate  224 , and thus seal plate  122  ( FIG. 2 ) have a minimum width. Upon introduction of a fluid  240  through lumen  225  of expandable substrate  224 , expandable substrate  224  is expanded to the position shown in  FIG. 6B , thereby expanding seal plate  122  ( FIG. 2 ) which is engaged to expandable substrate  224  via the flanges (not shown) and notches  227 , respectively. Fluid  240  may be a heated fluid  240 , such that, upon passage through lumen  225 , fluid  240  heats expandable substrate  224 , thereby expanding expandable substrate  224 . In this configuration, an insulator  228  is provided to prevent heat transfer between seal plate  122  ( FIG. 2 ) and expandable substrate  224  and vice versa. As can be appreciated, the removal of fluid  240  from lumen  225  allows expandable substrate  224  to cool. As expandable substrate  224  cools, it contracts, thereby contracting the seal plate  122  ( FIG. 2 ). Thus, in operation, fluid  240  may be supplied in varying amounts and/or temperatures to expand the seal plate width according to the determined output. 
     Turning now to the embodiment of  FIGS. 7A-7B , jaw member  320  includes expanding component  324  having notches  327  disposed around a perimeter thereof for engagement with the flanges (not shown) of seal plate  122  ( FIG. 2 ). Gear assembly  340  mechanically cooperates with forcing members  345   a  and  345   b  to expand and contract expanding component  324 . Forcing members  345   a  and  345   b  are disposed on either side of knife channel  315  defined within expanding component  324 . As shown in  FIG. 7A , forcing members  325  are in a contracted, or close, position. Once the sensing component  118  (see  FIG. 2 ) and processing component  21  (see  FIG. 3 ) cooperate to determine the appropriate seal plate width for the particular vessel disposed between jaw members  110  and  120  ( FIG. 2 ), gear assembly  340  is activated to adjust the seal plate width accordingly. For example, gear assembly  340 , initially disposed in the position shown in  FIG. 7A , may be activated according to the determined diameter of tissue to be sealed such that gear assembly  340  causes forcing members  345   a  and  345   b  to translate outwardly. Accordingly, expanding component  324 , seal plate  122  ( FIG. 2 ), and knife channel  315  are all expanded to the positions shown in  FIG. 7B . The position shown in  FIG. 7B  may correspond to a specific seal plate width according to the specific output determined. 
     With reference to  FIGS. 8A-8B , jaw member  420  is shown having a scaffold assembly  424  disposed thereon. A plurality of notches  427 , disposed around the perimeter of scaffold assembly  424 , is configured to engage the flanges (not shown) of seal plate  122  ( FIG. 2 ) for securing the seal plate  122  ( FIG. 2 ) thereon. Knife channel  415  is defined through a central portion of scaffold assembly  424 . Scaffold assembly  424  includes expanding members  430  and longitudinal bars  440 . Longitudinal bars  440  are configured to maintain the integrity of scaffold assembly  424 , while expanding members  430  are configured to expand scaffold assembly  424  from the position shown in  FIG. 8A  to the position shown in  FIG. 8B . 
     In operation, when the determined seal plate width for sealing the particular size tissue disposed between the jaw member requires the current seal plate width to be expanded, expanding members  430  are expanded, thereby forcing longitudinal bars  440  into a spaced-apart configuration with respect to one another. This expansion of scaffold assembly  424  similarly causes the expansion of seal plate  122  ( FIG. 2 ) according to the seal plate width desired. When it is determined that the seal plate width needs to be reduced, expanding members  430  are retracted, bringing longitudinal bars  440  into a closer-together position, thereby retracting scaffold assembly  424  and seal plate  122  ( FIG. 2 ). 
     Referring to  FIGS. 1-3 , the above-described embodiments of the jaw members  110  and  120  allow the seal plate width to be adjusted according to the diameter of tissue and/or composition of tissue to be sealed. Adjusting seal plate width allows a user to apply a pre-determined seal pressure to vessels of varying sizes. Thus, a user will not have to apply an estimated seal pressure, e.g., by selectively squeezing handle  40  to an estimated position according to the estimated seal pressure desired. Instead, a user may apply a single, pre-determined seal pressure for a range of vessel sizes. Similarly, the instrument may be designed for application of a single, pre-determined seal pressure, e.g., where the user squeezes handle  40  through its complete range of motion to achieve the pre-determined seal pressure. In either of the above configurations, adequate and effective seals are ensured because two factors affecting the quality of a seal, i.e., vessel size and seal pressure, are used to determine the appropriate seal plate width for sealing tissue according to the above-mentioned factors. 
     Additionally, seal plates  112  and  122  may be expandable to different widths. As can be appreciated, it may be desirable for seal plates  112  and  122  to be expandable to different widths in order to properly seal tissue according to the specific size, shape, composition, and/or other characteristics of tissue to be sealed. Expanding the opposing seal plates  112 ,  122  to different widths can be achieved, for example, by allowing the processing component  21  to independently expand the seal plates  112 ,  122 . In such an embodiment, the processing component  21 , based upon the determined output, or user input data, would activate the expanding components  114 ,  124  to independently expand each respective seal plate  112 ,  122  to a specific width. Thus, if the determined output indicates that seal plates having different widths would be desirable to seal the particular tissue disposed between jaw members  110  and  120 , seal plate  112  would be expanded to a first width, while seal plate  122  would be expanded to a second, different width. On the other hand, if it is determined that seal plates having the same width would be more desirable, seal plates  112  and  122  would both be expanded to the specific width determined. Alternatively, only one of the seal plates  112 ,  122  may be expandable. For example, seal plate  112  may be fixed in position, while seal plate  122  is expandable. In this configuration, seal plate  122  can be expanded to the width of seal plate  112  such that the seal plates  112  and  122  have equal widths, or seal plate  122  may be expanded such that the seal plates  112  and  122  have different widths. 
     As mentioned above, specific data or formulae may be input into the processing component  21  to determine the appropriate seal plate width corresponding to the diameter of the vessel to be sealed and the seal pressure to be applied. Accordingly, a study was conducted to determine how seal plate width and blood vessel size, under a constant seal pressure, influence the quality of the seal produced, measured through burst pressure. Burst pressure is the pressure required to open, or burst, a previously sealed vessel by forcing a fluid through the sealed vessel. The range of values tested for seal plate width was about 0.03 inches to about 0.08 inches. Vessel diameters ranged from about 2 mm to about 6 mm. In the study discussed above, the vessels were sealed by applying a constant seal pressure of 120 psi.  FIG. 9 , a contour plot of burst pressure vs. vessel size, shows the results of the study. Data extrapolated from  FIG. 9  and/or algorithms corresponding to the results shown in  FIG. 9  can be input into processing component  21  for determining the appropriate seal plate width as a function of vessel size (with a constant seal pressure). 
     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. 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.