Abstract:
A surgical simulation system is provided. The system includes at least one simulated body organ placed upon the base of an organ tray and at least one covering layer placed over the simulated body organ. At least one of the simulated body organ and covering layer includes electro-conductive gel that is operably severable under application of electrical current to simulate electrosurgery in a training environment. The training environment comprises a top cover connected to and spaced apart from a base to define an internal cavity that is partially obstructed from direct observation by a practitioner. The tray, simulated body organs and covering layer are placed inside the internal cavity for the practice of laparoscopic surgical procedures.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and benefit of U.S. Provisional Patent Application Ser. No. 61/771,316 filed on Mar. 1, 2013 entitled “Advanced surgical simulation constructions and methods” which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This application is generally related to surgical training tools, and in particular, to anatomical models simulating organs or tissue for teaching and practicing various surgical techniques and procedures. 
       BACKGROUND OF THE INVENTION 
       [0003]    Medical students as well as experienced doctors learning new surgical techniques must undergo extensive training before they are qualified to perform surgery on human patients. The training must teach proper techniques employing various medical devices for cutting, penetrating, clamping, grasping, stapling and suturing a variety of tissue types. The range of possibilities that a trainee may encounter is great. For example, different organs and patient anatomies and diseases are presented. The thickness and consistency of the various tissue layers will also vary from one part of the body to the next and from one patient to another. Accordingly, the skills required of the techniques and instruments will also vary. Furthermore, the trainee must practice techniques in readily accessible open surgical locations and in locations accessed laparoscopically. 
         [0004]    Numerous teaching aids, trainers, simulators and model organs are available for one or more aspects of surgical training. However, there is a need for model organs or simulated tissue elements that are likely to be encountered in endoscopic, laparoscopic, transanal, minimally invasive or other surgical procedures that include the removal of tumors or other tissue structures. For example, there is a need for realistic model organs for the repeatable practice of removing a tumor or other undesired tissue followed by the closure of the target area by suturing or stapling as part of the same surgical procedure. 
         [0005]    In view of the above, it is an object of this invention to provide a surgical training device that realistically simulates such particular circumstances encountered during surgery. The medical training and simulation systems and devices of the present invention provide a user with visual, tactile and technical properties that emulate the situations extant in live surgical procedures. Emulation is an effort to equal or surpass real surgical conditions or effects in a surgical simulation. 
         [0006]    In order to simplify training and minimize the use of cadavers in surgical training and in practice, the present invention contemplates the use of synthetic materials that are compounded, configured and combined to emulate the properties, responses and characteristics of human or animal tissue under surgical conditions and in response to the activities of surgical instruments. Such conditions and activities may include incision, penetration, dissection, occlusion, anastomosis, approximation, ablation, and the like. 
         [0007]    Many surgical procedures involve the use of energy-based surgical instruments such as electrosurgical blades, probes, scissors, graspers, dissectors and the like. Electrosurgery is generally considered the application of high voltage, high frequency electrical energy to tissue for the purpose of cutting or destroying. Electrocautery is a type of electrosurgery in which an electrical current generates resistance heating in the instrument, which is sufficiently high to apply to tissue for the purpose of cutting or destroying tissue. Additionally, many procedures make use of energy devices based on high frequency sound. These instruments provide a surgeon with the convenience of nearly effortless cutting and dissection and nearly instant thermal hemostasis. Such instruments have become a standard within the surgical community and are used regularly. 
         [0008]    It becomes readily apparent that any fake organs or organ simulation modules or training modules must include the ability to train in the use of energy-based surgical instruments. Many of the existing training or simulation modules require the use of harvested animal tissue, synthetic materials that must be wetted or infused with saline solution or materials having embedded metallic particles so that they are electrically conductive and suitable for energy-based surgical technique training. The most preferred synthetic materials such as silicone rubber, latex, vinyl, polyester, polyurethane and the like do not respond to energy-based surgical instruments and devices in a way that satisfies the need to train users to use the instruments in an actual surgical procedure. Therefore, one aspect of the present invention is to provide a combination of synthetic materials, some that have dielectric characteristics, and some that are electrically conductive and yet mimic the physical properties of natural tissue and action of energy-based surgical instruments and devices. In addition, the present invention provides a method for constructing various body parts, conduits, organs, cysts, tumors and the like that provides life-like synthetic samples. 
       SUMMARY OF THE INVENTION 
       [0009]    According to one aspect of the invention a surgical simulation system is provided. The surgical simulation system includes a tray having a base with a perimeter and one or more anatomical receptacle portion formed by at least one upstanding wall configured to substantially cooperate and conform in size and shape with one or more simulated body organ located within the one or more receptacle portion. The system includes one or more simulated body organ placed upon the base within the one or more receptacle portion. At least one covering layer is placed over the one or more simulated body organ. The covering layer is attached to the one or more simulated body organ in at least one location. The least one of the one or more simulated body organ and covering layer includes electro-conductive gel operably severable under application of electrical current to simulate electrosurgery in a training environment. 
         [0010]    According to another aspect of the invention, a surgical simulation system for the practice of electrosurgical activity is provided. The surgical simulation system includes a simulated tissue structure that includes an inner layer that is adjacent to and in contact with an outer layer. The inner layer comprises a foam material and the outer layer comprises an elastomeric hydrogel. The inner layer defines an interior cavity and both the inner layer and the outer layer define a shape of at least a portion of a uterus. The surgical simulation system also includes a simulated pathology located adjacent to or embedded in the inner layer. The simulated pathology is removable from the simulated tissue structure. The elastomeric hydrogel is electro-conductive such that it is operably severable under application of electrical current to simulate electrosurgery in a training environment. 
         [0011]    According to another aspect of the invention, a method for surgical simulation is provided. The method includes the step of providing an organ tray having a base with one or more simulated body organ on it. A covering layer is placed over the one or more simulated body organ. The covering layer includes a first planar layer of non-conductive material and a second planar layer of electro-conductive gel. The covering layer is placed over the one or more simulated body organ such that the second layer is adjacent to the one or more simulated body organ. The organ tray is placed into an internal cavity of a surgical training device such that the organ tray is at least partially obstructed from direct visual observation by a practitioner. The surgical training device includes a top cover spaced apart from the base. The internal cavity is defined between the top cover and base. The surgical training device includes an aperture or penetrable simulated tissue region in the top cover. The method further includes the step of inserting a scope configured to capture video of the internal cavity through the aperture or penetrable simulated tissue region and into the internal cavity of the training device. At least one instrument is inserted through the aperture or penetrable simulated tissue region into the internal cavity of the training device. The method includes the step of separating the first layer from the second layer with the at least one instrument. 
         [0012]    According to one aspect of the invention, a method of making a simulated tumor is provided. The tumor is made by mixing uncured silicone rubber with untreated fumed silicon dioxide. The mixture is then shaped and cured to form a simulated tumor. 
         [0013]    According to one aspect of the invention, a simulated tissue structure for surgical training is provided. The structure includes an organ tray, simulated organs placed on the tray and a covering layer. The covering layer includes a semi-transparent sheet of silicone rubber. 
         [0014]    According to one aspect of the invention, a simulated tissue structure for surgical training is provided. The structure includes an organ tray, simulated organs placed on the tray and a covering layer. The covering layer includes a semi-transparent sheet of silicone rubber and a semi-transparent sheet of hydrogel material. 
         [0015]    According to one aspect of the invention, a method for forming a covering layer for a tray containing simulated tissue includes the step of mixing electro-conductive material such as platinum or tin into liquid silicone. The mixture is spread onto a first layer of polyethylene foam. A second layer of polyethylene foam is placed over the silicone layer. A textured roller or stamping device is moved over the surface of the second layer of foam to calendar the silicone material between the foam layers of foam. The silicone layer is removed from between the foam layers. 
         [0016]    According to another aspect of the invention, a simulated organ model of a uterus is provided. The model includes an outer shell of soft silicone and an inner layer of foam with simulated tumors located between the outer shell and inner layer. 
         [0017]    According to another aspect of the invention, a simulated organ model of a uterus is provided. The model includes an outer shell of soft silicone and an inner layer of foam with simulated tumors located inside the inner foam layer. 
         [0018]    According to another aspect of the invention, a simulated organ model of a uterus is provided. The model includes fallopian tubes of silicone containing electro-conductive material. The fallopian tube includes a lumen extending between a first end and a second end and a bulbous portion near the second end that transitions to a funnel shape at the second end having a plurality of axial cuts in the funnel portion. At least a portion of the lumen includes a soft fibrous material. 
         [0019]    According to another aspect of the invention, a simulated organ model of a uterus is provided. The model includes fallopian tubes of silicone containing electro-conductive material. The fallopian tube includes a lumen extending between a first end and a second end and a bulbous portion near the second end that transitions to a funnel shaped at the second end having a plurality of axial cuts in the funnel portion. At least a portion of the lumen includes a soft fibrous material and a simulated ectopic pregnancy is placed inside the bulbous portion. The simulated ectopic pregnancy is made of silicone rubber and untreated fumed silicon dioxide. 
         [0020]    According to another aspect of the invention, a simulated organ model of a stomach is provided. The model includes a hollow stomach-shaped bladder having a proximal opening and a distal opening. The model includes a predetermined pathway for practicing resection of at least a portion of the stomach along the predetermined pathway. The predetermined pathway is defined by a portion of two opposing inner surfaces of the stomach model being joined together. 
         [0021]    According to another aspect of the invention, a tray for receiving model organs is provided. The tray includes a bottom surface and at least one receptacle portion for receiving at least one organ. The at least one receptacle portion is formed by upstanding walls having a height and shape that substantially conforms to the height, shape and size of the organ to be placed into the receptacle portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  illustrates a side view of a surgical training device with a model organ according to the present invention. 
           [0023]      FIG. 2A  illustrates a side cross-sectional view of a simulated tissue structure according to the present invention. 
           [0024]      FIG. 2B  illustrates a side cross-sectional view of a simulated tissue structure with tumor excised according to the present invention. 
           [0025]      FIG. 2C  illustrates a side cross-sectional view of a simulated tissue structure with an open suture according to the present invention. 
           [0026]      FIG. 2D  illustrates a side cross-sectional view of a simulated tissue structure with a closed suture according to the present invention. 
           [0027]      FIG. 3A  illustrates a top view of a defect layer having a circular shaped defect according to the present invention. 
           [0028]      FIG. 3B  illustrates a top view of a defect layer having an elongated defect according to the present invention. 
           [0029]      FIG. 3C  illustrates a top view of a defect layer having an amorphous defect according to the present invention. 
           [0030]      FIG. 3D  illustrates a top view of a defect layer having a two-piece defect according to the present invention. 
           [0031]      FIG. 3E  illustrates a top view of a multi-part defect layer according to the present invention. 
           [0032]      FIG. 3F  illustrates a top view of a defect layer having multiple defects according to the present invention. 
           [0033]      FIG. 4  illustrates a top view of a simulated tissue structure according to the present invention. 
           [0034]      FIG. 5  illustrates a side cross-sectional view of a simulated tissue structure according to the present invention. 
           [0035]      FIG. 6A  illustrates a perspective view of a modular tissue structure and support according to the present invention. 
           [0036]      FIG. 6B  illustrates a perspective view of a modular tissue structure and support according to the present invention. 
           [0037]      FIG. 7  illustrates a cross-sectional view of a simulated tissue structure configured to mimic a human uterus according to the present invention. 
           [0038]      FIG. 8  illustrates a top view of a modular tissue structure according to the present invention. 
           [0039]      FIG. 9  illustrates a side view of a modular tissue structure according to the present invention. 
           [0040]      FIG. 10A  illustrates a perspective view of a simulated tissue structure according to the present invention. 
           [0041]      FIG. 10B  illustrates a perspective view of a simulated tissue structure according to the present invention. 
           [0042]      FIG. 11A  illustrates a perspective view of a simulated tissue structure according to the present invention. 
           [0043]      FIG. 11B  illustrates a perspective view of a simulated tissue structure according to the present invention. 
           [0044]      FIG. 12  illustrates a perspective view of a suture needle and a simulated tissue structure according to the present invention. 
           [0045]      FIG. 13  illustrates a schematic of a model of female uterine anatomy with tumor placement according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0046]    A surgical training device  10  that is configured to mimic the torso of a patient such as the abdominal region is shown in  FIG. 1 . The surgical training device  10  provides a simulated body cavity  18  substantially obscured from the user for receiving model organs or simulated or live tissue  20 . The body cavity  18  is accessed via a tissue simulation region  19  that is penetrated by the user employing devices to practice surgical techniques on the tissue or organ  20  found located in the body cavity  18 . Although the body cavity  18  is shown to be accessible through a tissue simulation region  19 , a hand-assisted access device or single-site port device may be alternatively employed to access the body cavity  18  as described in U.S. patent application Ser. No. 13/248,449 entitled “Portable Laparoscopic Trainer” filed on Sep. 29, 2011 and incorporated herein by reference in its entirety. The surgical training device  10  is particularly well suited for practicing laparoscopic or other minimally invasive surgical procedures. 
         [0047]    The surgical training device  10  includes a base  12  and a top cover  14  connected to and spaced apart from the base  12  to define an internal body cavity  18  between the top cover  14  and the base  12 . At least one leg  16  interconnects and spaces apart the top cover  14  and base  12 . A model organ or simulated tissue  20  is disposed within the body cavity  18 . The model organ  20  shown in  FIG. 1  is a partial colon or intestine that is shown suspended from the top cover  14  by tethers  22  and connected to at least one leg  24 . The at least one leg  24  has an aperture (not shown) facing the internal body cavity  18 . The model colon  20  includes a tube  26  having a proximal end and a distal end. The proximal end of the tube  26  is interconnected with the aperture of the leg  24  such that the aperture provides an access port to the lumen of the tube  26 . The access port and aperture is shown to be closed off in  FIG. 1  with an access device  28  which in combination with a sealed distal end of the tube  26  provides a model organ  20  that is adapted for insufflation with fluid deliverable via an insufflation port  30 . An optional insert  32  made of soft material such as silicone creates a realistic interface for the access port. The distal end of the tube  26  extends into the body cavity  18  and is suspended within the body cavity  18 . The interior of the tube  26  of the simulated organ  20  is accessible via the access port of leg  24  or via the tissue simulation region  19  or instrument insertion ports  34 . An endoscopic camera inserted into the body cavity  18  or into the organ  20  via the access port generates a live image for display on a fold out video screen  36  shown in the closed position in  FIG. 1 . An endoscope is a visualization device that is used to view a hollow structure. Although the simulated organ  20  of  FIG. 1  is ideal for practicing procedures related to transanal minimally invasive surgery, any simulated organ or tissue portion may be employed. One particular aspect of the organ  20  is at least one tumor or defect  38  is provided and connected to the organ. As shown in  FIG. 1 , the tumor  38  is connected to the wall of the organ tube  26 . 
         [0048]    Turning now to  FIG. 2A  there is shown a partial side cross-sectional view of a portion of a simulated organ  20  that includes the tumor  38 . The simulated organ or tissue  20  includes a base layer or organ wall  40 . The organ wall  40  is made from a material configured to mimic real live tissue such as silicone or other polymer and is dyed appropriately. One or more base layers  40  of varying thicknesses and colorations may be employed to comprise the entirety of the wall  40 . In one variation, the organ wall  40  is rigid and made of polymeric material. Above the base layer  40  is a second layer or defect layer  42 . The defect layer  42  is the same size or smaller than the base layer  40  forming a raised platform for the tumor  38 . The defect layer  42  is connected to the base layer  40  by adhesive or other means known to one having ordinary skill in the art including being integrally formed with the base layer  40  as a single unit. The defect layer  42  is made of silicone and in one variation of the same color as the base layer  40  such that the defect layer  42  blends into the background of the base layer  40 . The defect layer  42  includes at least one defect or gap  44 . In one variation, the defect  44  is a pre-fabricated breach in the defect layer  42  that mimics an incision, gap or other void in real tissue resulting from a tear, cut, removal or other surgical procedure that requires surgical attention by way of suturing, stapling or the like to close the defect. Such a situation arises most often in the removal of a tumor  38  where surrounding tissue is also removed together with the tumor  38  to preventatively ensure the entirety of the tumor is excised leaving behind a remnant defect in the tissue. The defect  44  comprises two opposed sides or surfaces defining a gap therebetween. Although the adjacent sides or surfaces are shown to be vertical with respect to the base layer  40 , the invention is not so limited and the juxtaposed surfaces or sides can have any shape and, for example, be curved. The defect  44  can be any shape as will be discussed with respect to  FIGS. 3A-3F . 
         [0049]    Turning now to  FIG. 3A , there is shown a top view of a defect layer  42  having a circular defect  44 . A defect layer  42  with an elongated, oblong or elliptically shaped defect  44  is shown in the  FIG. 3B . The defect  44  can be amorphic or any shape as shown in  FIG. 3C . The defect layer  42  may be multi-part as shown in  FIG. 3D  wherein the defect layer  42  includes two or more adjacent defect layer pieces  42   a ,  42   b  juxtaposed to create at least one defect  44  therebetween. Another multi-part defect layer  42  is shown in  FIG. 3E  where a plurality of adjacent defect layer pieces  42   a ,  42   b  and  42   c  form one or more defects  44  therebetween. Of course, a defect layer  42  may include multiple defects  44   a ,  44   b  and  44   c  as shown in  FIG. 3F . The defects  44  may all be the same or have different shapes as shown in  FIG. 3F . The shape, thickness and size of the defect allow the surgeon trainee to practice suturing across defects of varying difficulty. In one variation, the defect layer  42  is not of equal thickness. Instead, the thickness of the defect layer  42  varies at the defect  44  location to increase the difficulty of suturing or closing the defect. 
         [0050]    Referring back to  FIG. 2A , a tumor  38  is located above the defect layer  42 . The tumor  38  is preferably a different color from the base layer  40  or defect layer  42  or both such that it is readily identifiable by the trainee. Preferably, the tumor  38  is made of silicone or other polymer material and is red, black, blue or dark brown in color. In general, the tumor  38  is of a darker color than the base or defect layers  40 ,  42  or otherwise in contrast therewith when viewed through a scope. In one variation, the tumor  38  is connected to the defect layer  42  by adhesive or other means known to one of ordinary skill in the art. In another variation, the tumor  38  is not connected or attached to the defect layer  42  but is removably located thereon. 
         [0051]    Still referencing  FIG. 2A , the simulated tissue structure  20  includes a cover layer  46  located above the tumor  38 . In one variation, the cover layer  46  overlays the tumor  38 , defect layer  42  and the base layer  40 . The cover layer  46  is preferably transparent or translucent in color and made of a polymer material such as silicone. In another variation, the cover layer  46  is the same color as the base layer  40  or defect layer  42 . The cover layer  46  is at least as thick as the base layer  40  or defect layer  42  and in one variation is thinner than the defect layer  42  and in another variation is thinner than the base layer  40 . The cover layer  46  is sized to cover the entire tumor  38  and defect layer  42  and is big enough to contact the base layer  40  in one variation. In another variation, the cover layer  46  is sized to cover the entire tumor  38  and contact the defect layer  40 . The cover layer  46  is connected to the base layer  40 , defect layer  42 , tumor  38  or any more than one of the three layers by way of adhesive or other means known to one of ordinary skill in the art. In another variation, the cover layer  46  is smaller and connected to the defect layer  42  alone. In yet another variation, the cover layer  46  is connected to both the defect layer  42  and base layer  42  by adhesive or other means known to one of ordinary skill in the art. The cover layer  46  can be any shape or size and be configured to provide a smooth surface to the surgeon instead of a layered surface to the artificial tumor location. The cover layer  46 , tumor  38 , defect layer  42  or base layer  40  includes surface texturing in one variation. Also, the cover layer  46  assists in keeping the tumor  38  and defect layer  42  sandwiched between the cover layer  46  and base layer  40  which is advantageous in a variation wherein the tumor  38  is not adhered to the defect layer  42 . A top planar view of the base layer  40 , defect layer  42 , cover layer  46  and tumor  38  is shown in  FIG. 4 . In one variation, any one or more of the base layer  40 , defect layer  42  and cover layer  46  is formed of silicone molded over a woven, fabric, or mesh material such as nylon or cheesecloth so that the silicone layer has an integrated mesh structural support or other type of reinforcement. Any one or more of the layers  38 ,  40 ,  42 ,  46  can include a fabric or mesh reinforcement combined with an elastic polymer such silicone. The mesh support aids in preventing the suture, staple, or suture needle from tearing through at least one of layers and especially the defect layer  42  when the suture is pulled to close the gap  44 . 
         [0052]    In  FIG. 2B , the tumor  38  and a portion of the cover layer  46  are shown excised from the base layer  40 . The excision is performed by the trainee using a surgical instrument such as a scalpel or other medical instrument to remove the tumor  38 . The trainee will cut through the cover layer  46  around the tumor  38 , isolate the tumor  38 , lift and remove the tumor  38  away from the site to expose the underlying defect  44  as shown in  FIG. 2B . Then, as shown in  FIG. 2C  the trainee sutures the defect  44  using a surgical suture  48  bringing the lips or edges of the defect layer  42  together as shown in  FIG. 2D , thereby, practicing the closing of a gap or wound created by the surgical removal of a tumor  38 . Cutting the at least one layer to create an opening and removing the artificial tumor and suturing the gap is performed while the simulated tissue structure is disposed inside a simulated body cavity  18  of a surgical training device such that the simulated tissue structure is at least partially obscured from view by the user. 
         [0053]    Turning now to  FIG. 5 , there is shown another variation in which there is no pre-formed gap or defect in the second or defect layer  42 . Instead, upon excising the tumor  38 , the defect is created by the user in one or more of the cover layer  46 , defect layer  42 , base layer  40  and any remaining tumor portion not removed by the user. The user would then practice suturing the created defect in any of these layers  38 ,  40 ,  42 ,  46 . In one such variation, one of the defect layer  42  or base layer  40  is omitted from the construct. In another variation, the tumor  38  is located on a base layer  40  and the defect layer  42  is placed over the tumor  38  such that the defect layer  42  is above the tumor  38 . In such a variation, a cover layer  46  may or may not be included. If a cover layer  46  is included it may be integrally formed together with the defect layer as a separate unitary layer. In any of the constructs described above with respect to  FIGS. 2-5 , the constructs may be flipped upside down or otherwise the layers placed in reverse or otherwise the construct being approachable by the user from either the top or bottom direction with the thicknesses and colors of the layers being adjusted accordingly if necessary to provide the simulated effects of real tissue. 
         [0054]    Turning now to  FIGS. 6A and 6B , in any of the variations in this description, the simulated tissue construct can be modular such that it is not integrally formed with the entire simulated organ  20  but instead configured as a module  50  that is removable and interchangeable. One or more modules  50  are supported or contained in a module support  52 . A module support  52  includes a first surface  51 , a second surface  53  and one or more tumor module receiving portions  54 ,  56 ,  58  formed in the support  52 . The tumor support  52  can be rigid or pliable and made of polymeric material. The tumor support  52  may also comprise a sheet of elastomeric material. The module receiving portions  54 ,  56 ,  58  are each sized and configured to receive a correspondingly sized and configured module  50 . The modules  50  and module receiving portions  54 ,  56 ,  58  in  FIG. 6  are shown to be circular; however, the tumor module  50  can be any shape with a complementary shaped receiving portion formed in the module support  52 . The thickness of the support  52  can vary providing the construct with varying depths of tumor module  50  positioning. The module receiving portions  54 ,  56 ,  58  may include bottom walls onto which the tumor modules  50  may rest. Alternatively, the tumor receiving portions  54 ,  56 ,  58  extend between openings in the first surface  51  and the second surface  53  with the modules  50  with tumor  38  being connected between or at one of the openings at either surface  51 ,  53  or suspended within the tumor receiving portion. In one variation, a single tumor module  50  includes one or more tumors  38 . The module support  52  is loaded with one or more tumor modules  50  and the simulated tissue construct  20  is inserted into the body cavity  18  of the surgical training device  10 , framework or other torso model. It can be placed on the base  12  of the training device  10  or suspended within the body cavity  18  of the training device  10 . The simulated tissue construct  20  and/or training device is fashioned with attachment mechanisms such as clips, fasteners, wires, hook-and-loop type fasteners and the like for placement, suspension or connection of the simulated tissue construct  20  to a training device  10 . 
         [0055]    With particular reference to  FIG. 6B , there is shown a module support  52  that includes more than one layer. The module support  52  of  FIG. 6B  includes a first layer  57  connected to a second layer  55 . In one variation, the first layer  57  is made of a sheet of elastomeric material and the second layer  55  is made of any suitable polymeric material such as low-density elastomeric foam. The second layer  55  serves as a support for the first layer  57 . The second layer  55  also advantageously provides depth to the module support  52  permitting the tumors  38  within the modules  50  to be placed deeply into the module support  52  relative to the first surface  51 . Module receiving portions  54 ,  56 ,  58  are formed in one or more than one of the first layer  57  and the second layer  55 . Module receiving portions  54 ,  56 ,  58  formed in the second layer  55  may have a different shape than the shape the same module receiving portion  54 ,  56 ,  58  has in the first layer  57 . In one variation, the tumor module  50  comprises at least only the simulated tumor  38  which is embedded or buried inside the second layer  55  with at least one of the first layer  57  or second layer  55  constituting a defect layer which the user can practice closing. As an alternative, the first layer  57  does not include a module receiving portion but instead the first layer  57  serves as a cover layer which the user practices cutting through to access the tumor  38  located in a tumor receiving portion formed in the second layer  55 . In such variation, the first layer  57  can be a sheet of elastomeric material such as silicone and the second layer  55  is a layer of low-density elastomeric foam. The module support  52  is planar as shown in  FIGS. 6A and 6B  or, alternatively, shaped to mimic a portion of the human anatomy, tissue or organ. 
         [0056]    For example,  FIG. 7  illustrates a support  52  that is shaped to mimic a human uterus. The support  52  includes a first layer  57  connected to a second layer  55 . In one variation, the first layer  57  is made of any suitable polymeric material such as a sheet of elastomeric material and the second layer  55  is made of any suitable polymeric material such as low-density elastomeric foam. The second layer  55  serves as a support for the first layer  57  and advantageously permits the tumors  38  within the modules  50  or the tumors  38  by themselves to be connected to the support  52  and realistically extend deeply into the support  52  and be dispersed throughout the support  52  in various locations and orientations including being embedded into the first layer  57  as shown in  FIG. 7 . Tumor or module receiving portions  61  are formed in at least one of the first layer  57  and second layer  55 . The tumor receiving portions  61  may be pockets that are preformed in the second layer  55  or can be formed by the user by cutting slits into the second layer  55 . In one variation, the tumors  38  are configured to mimic fibroid tumors commonly found in the human uterus. Examples of fibroid tumors that are simulated by the tumors  38  disposed in the support include but are not limited to one or more of the following types of fibroids: pedunculated submucosal fibroids, subserosal fibroids, submucosal fibroids, pedunculated subserosal fibroids and intramural fibroids. The user can approach the support  52  to excise the simulated tumors  38  from the first surface  51  or the second surface  53  via the access channel or opening  63 . In one variation, the opening  63  serves as the only opening to the hollow portion  59  or alternatively the support  52  can have a substantially C-shaped planar configuration with access available to the user from above or below the planar C-shaped structure. 
         [0057]    In one variation, the module support  52  in any of the variations is not planar but is provided with a landscape that includes curves and other structures, mountains and valleys and various textures. The varying landscape provides the user with various levels of difficulty in approaching each tumor location requiring the user to navigate around artifacts and features that may obscure the tumor location. These structural artifacts in the tumor support  52  may be integrally formed with the tumor support  52  or also be modular in structure similar to the tumor modules  50  making the anatomy landscape modules removable and interchangeable. Tumor modules  50  are interchangeable with non-tumor modules that include, for example, features and artifacts or textures made of silicone or other material extending outwardly or inwardly from the one or more of the upper and lower surfaces  51 ,  53  of the module support  52 . The features in such non-tumor modules can have various shapes to mimic anatomy that includes adjacent organ structures or tissues. For example, a non-tumor module can include a tubular form of silicone to mimic an intestine. The non-tumor and tumor modules  50  are removably connected to the module support  52  by any means known to one skilled in the art enabling the user to discard a module after use and then to continue practicing by replacing the discarded module or moving to an adjacent module  50  in the module support  52  or changing out a tumor module  50  for another tumor module  50  having a different feature or level of difficulty. 
         [0058]    A variation of the tumor module  50  is shown in  FIGS. 8 and 9 . The tumor module  50  includes a simulated tissue portion  60  connected to a support  62 . In the variation shown, the support  62  includes a top frame  64  connected to a bottom frame  66 . At least one of the top frame  64  and bottom frame  66  includes a window. The top frame  64  having a window  68  is shown in  FIG. 8 . The bottom frame  66  may or may not include a window. If windows are provided in both the top frame  64  and the bottom frame  66 , the windows are aligned at least in part. The support  62  is sized and configured to receive a simulated tissue portion  60  between the top frame  64  and the bottom frame  66 . The top frame  64  is connectable to the bottom frame  66  to capture the unitary simulated tissue portion  60  or a simulated tissue portion  60  formed from multiple layers and, in one variation, separable. In one variation, the frames  64 ,  66  are spaced apart from each other using spacers  70 . Furthermore, at least one of the top and bottom frames  64 ,  66  includes one or more connecting features  72  configured to secure the tumor module  50  to a tumor support  52  (not shown). In  FIG. 9 , the connecting features  72  are shown as extending pegs for insertion into corresponding holes formed in the tumor support  52  to provide a snap-fit engagement. A friction fit or other fasteners or connecting means such as hook-and-loop type materials can be employed on the module  50  and module support  52  to connect the module  50  to the support  52  in a removable fashion. 
         [0059]    Still referencing  FIGS. 8 and 9 , the simulated tissue portion  60  can be any of the constructs described above with reference to  FIGS. 2-5 . With windows formed in both the first and second frames  64 ,  66 , the simulated tissue portion  60  can be approached from either side of the module  50 . Any layer described above as a cover layer may act as a top layer or as a bottom layer depending on from which side or direction the simulated tissue portion  60  is approached. For example, a base layer may also serve as a top layer or as a bottom layer depending on which side or direction the simulated tissue portion  60  is approached. In such bi-directional constructs, the thicknesses and colors of the layers may be adjusted accordingly to provide the desired simulated effect. 
         [0060]    The simulated tissue portion  60  in  FIG. 9  includes a first layer  74  and a second layer  76 . The first and second layers  74 ,  76  are made from a polymeric material configured to mimic real live tissue such as silicone or other polymer and can include dye of any one or more appropriate colors or mesh, fabric, or other reinforcement. Each of the layers  74 ,  76  includes a tumor-receiving portion  78 ,  80 , respectively. Each tumor-receiving portion  78 ,  80  is a concavity, indent, half-pocket or a location of reduced layer thickness that is formed in the layers  74 ,  76 . The tumor-receiving portions  78 ,  80  are substantially aligned to form a pocket for the tumor  38 . Although each layer  74 ,  76  in  FIG. 9  is shown with a tumor-receiving portion  78 ,  80 , a single tumor-receiving portion is formed in at least one of the first and second layers  74 ,  76  in one variation. A tumor  38  is disposed within the pocket formed by one or more tumor-receiving portions  78 ,  80  formed in the one or more layers  74 ,  76 . The tumor  38  may be adhered to either layer  74 ,  76  or free-floating inside the pocket. As shown in  FIG. 9 , the tumor-receiving portion formed in a layer can be considered to be one type of defect and the variation of  FIG. 9  describes a simulated tissue construct comprising two defect layers with a tumor therebetween. As a user approaches the simulated tissue portion  60 , the user will see the target tumor location. Visualization of the target tumor  38  is enhanced by the tumor-receiving portion being thinner in thickness relative to the rest of the layer with the thinning of the layer being provided by the concavity or pocket. The user will then cut in the general location of the tumor cutting into at least one of the layers  74 ,  76  to remove the tumor  38 . Cutting through one or more layers completes the creation of a gap or full defect, which the user can then practice suturing or otherwise closing together. In another variation, there is no tumor-receiving portion formed in the layers  74 ,  76 . In such a variation, at least one tumor is disposed between the two layers  74 ,  76  wherein the layers  74 ,  76  have a substantially uniform thickness with the tumor  38  creating a minor bulge in the layers. 
         [0061]    Turning now to  FIGS. 10A ,  10 B,  11 A,  11 B and  12 , there is shown another variation of a simulated tissue portion  86 . The tissue portion  86  can be integral or modular as described above. The tissue portion  86  includes a base layer  88  formed of any suitable polymeric material such as silicone or other elastomeric polymer that may or may not include a reinforcement material such as fabric, mesh, nylon or other reinforcement material or filler that will resist tearing while carrying sutures or while being sutured. The base layer  88  is connected to a defect layer  90  that is overlaid onto the base layer  88 . The defect layer  90  includes a plurality of protrusions extending upwardly from the base layer  88 . The defect layer  90  may be integrally formed with the base layer  88  or be a separate layer that is adhered to the base layer  88 . As can be seen in  FIGS. 10A ,  11 A and  12 , the defect layer  90  is configured into a lattice shaped pattern such that the lattice is raised above the base layer  88  or projects upwardly from the base layer  88 . A lattice pattern is exemplary and any shape may be formed by the defect layer  90  such that it contains a plurality of adjacent projections. These projections of the base layer  90  provide the user with locations to hook a suture needle into and as a platform to raise the tumor  38   a ,  38   b  above the base layer  88  for easy excision. The tumors  38   a ,  38   b  may be adhered to the defect layer  90  and a cover layer  92  may be included in one variation.  FIGS. 10A and 11A  show the base layer  88 , defect layer  90 , tumors  38   a ,  38   b  and a cover layer  92  in a semi-exploded view of the simulated tissue portion  86  wherein the cover layer  92  is raised above the other layers. The tumor  38   a  of  FIG. 10   a  is substantially planar and is shown covered in  FIG. 10B  by the cover layer  92 . Tumor  38   b  of  FIG. 11A  has greater height and is substantially spherical in shape and  FIG. 11B  shows the spherical tumor  38   b  covered with the cover layer  92  leaving a raised portion or protuberance in the construct.  FIG. 12  shows the tumor  38  being removed leaving a remnant defect  94  in the base layer  88  and a suture needle crossing the gap in the defect  94  with the defect having been accessed under or through the cover layer  92 . 
         [0062]    Synthetic materials that mimic the characteristics of living tissue may include silicone elastomers, natural latex, polyurethane elastomers, hydrogels and styrenic-block-copolymers. Generally, the elastomeric materials are dielectric unless specially treated. An elastomer is generally any of various polymers with elastic properties resembling those of natural rubber. A hydrogel is generally a hydrophilic polymer containing between 50% and 99% water. A thermoplastic generally pertains to materials that may be repeatedly made soft and hard by heating and cooling. Thermoplastics are non-conductive and are suitable for making the tray or base, bone and other similar structures. A thermoset generally pertains to elastomeric materials that permanently harden or solidify upon being heated or cured. Thermoset plastics are non-conductive such as silicone and polyester and are suitable for forming pathologies, tumors and the like. Silicone elastomers are usually very soft, stable and non-conductive and therefore suitable for forming artificial organs such as the liver, kidney, spleen, ovaries, gallbladder, stomach, major arteries, colon, intestine, major veins, omentum, mesentery, pathologies and other anatomy. Natural latex is very resilient and non-conductive and suitable for forming artificial muscle, cartilage and the like. Polyurethane elastomers and foams are non-conductive and suitable for filling hollow structures, bone and the like. Hydrogels SBCs may be conductive and are good for any soft structure to be operated upon by electrosurgery. 
         [0063]    In one variation, a surgical simulation tray, that is insertable into a lap trainer  10  for practicing surgical techniques including laparoscopic and electro-surgical methods, comprises a base, an arrangement of anatomical organs, and a covering layer. The base comprises a rigid or semi-rigid structure that is sized and configured to fit within or upon a surgical training device  10 . The base is additionally supplied with anatomical support features or receptacle portions formed by upstanding walls that cooperate and conform in size and shape with the placement of body organs within the receptacle portion or upon the base. Body organs, made of elastomeric materials, are placed strategically within or upon the base according to the specific needs of the training device and/or according to the target anatomy. At least one covering layer may be placed over the entire assembly or upon specific areas thereof. The covering layer is sized and configured to represent one or more of the omentum, mesentery, fat, connective tissue, peritoneum, mesothelium, broad ligaments or the like. The covering layer may comprise silicone elastomer, which is non-conductive. The non-conductive covering layer is suitable if no electrosurgical activity is used on the covering layer. If electrosurgical activity is contemplated, the covering layer is comprised of a conductive gel such as a hydrogel. A combination of conductive and non-conductive layers is provided when electrosurgery is directed to one of the layers. 
         [0064]    In addition to the organs placed within or upon the base, there may be a plurality of pathologies or defects also placed strategically relative to the organs or within the simulated organs themselves. The pathologies or defects may represent tumors, cysts, ectopic pregnancies or the like. For instance, a uterus may be formed having an outer layer of silicone rubber and a substantially hollow inner layer of soft polyurethane foam as described above with respect to  FIG. 7 . At various locations between the silicone layer and the foam layer, synthetic fibroid tumors may be placed for identification and removal by a surgical trainee. One simulated construction of a synthetic fibroid tumor comprises a small quantity of very soft uncured silicone rubber. The uncured silicone rubber is mixed with a quantity of amorphous, untreated fumed silicon dioxide, which acts as a filler and flow controller. The combination of the uncured silicone rubber and the silicon dioxide is shaped and allowed to cure. When fully cured, this combination results in an irregularly shaped, somewhat fibrous structure that resembles a human fibroid tumor. This construction of a simulated human fibroid tumor is then placed into a simulated organ model such as that of a uterus. This tumor simulation is not limited for use to mimic a tumor in a gynecological model, but also can be used in other organ models that include tumors for practicing their removal. This tumor simulation comprising the cured mixture of silicone rubber and silicon dioxide strikingly resembles real-life tumors that are found in a gynecological surgical situation and provides an amorphous and realistic look and feel when practicing surgical techniques. Dark colored dye such as red or black may be added to the mixture before curing and mixed throughout. This construction may also be used to construct simulated ectopic pregnancies for insertion into a simulated fallopian tube of a simulated organ placed within the training device  10 . The mixed consistency of the silicone and filler, being very dry and shape-able, advantageously allows the tumors or other pathologies to be formed very creatively, easily and at any size to mimic actual physical conditions. Tumors made of silicone and filler are non-conductive and may be fractured or torn if not properly handled. 
         [0065]    A few examples of organ simulation models that include the combination of conductive and non-conductive portions will now be discussed. In the surgical procedure of a liver resection, a simulated organ model tray for training electrosurgical procedures will have a conductive hydrogel liver, cystic duct and mesentery. These conductive portions of the model are located adjacent to non-conductive portions of the anatomy comprising the same organ or different organs. For example, for practicing the surgical procedure of a cholecystectomy, the organ model includes a cystic duct and mesothelium made from electro-conductive hydrogel and the liver and gallbladder are non-conductive. For practicing a sleeve gastrectomy, the simulated organ model includes one or more of the blood vessels and the greater omentum/mesentery along the greater curvature of the stomach made of electro-conductive hydrogel material and one or more of the stomach, large intestine, and small intestine made of non-conductive material. For practicing a gastric bypass, the simulated organ model includes one or more of the short gastric vessels and the mesentery/omentum along the greater curvature of the stomach made of electro-conductive hydrogel material and the stomach made of non-conductive material. In one variation, at least a portion of the jejunum and/or stomach is made of electro-conductive hydrogel. For practicing ovarian procedures such as the removal of fibroid tumors, treatment of ectopic pregnancy, ovarian cysts, and hysterectomy, the training model includes both conductive and non-conductive materials. For example, the organ model may include one or more simulated fallopian tubes, round ligament, ovarian ligament, IP ligament, broad ligament, bladder flap, uterine artery/vein, cardinal ligament, uterosacral ligament, made of electro-conductive hydrogel and one or more of the uterus, ovaries, rectum, urinary bladder, ureters and kidneys are non-conductive. In one variation, the location just above the cervix and/or just below the cervix is made of electro-conductive hydrogel for practicing a supracervical or total colpotomy. Procedures that involve the colon, small intestine, sigmoid or rectum may also require that specific portions be electrically conductive. These conductive portions are located adjacent to non-conductive portions. For example, to practice transanal minimally invasive surgery for the local excision of tumors, the organ model would include a colon and/or rectum, and tumor made of non-conductive elastomeric material except for the area surrounding the tumor which would be made of electro-conductive hydrogel material. In another variation, at least a portion of the rectum is made of electro-conductive hydrogel such as for the practice of transanal total mesorectal excision. In the practice of an appendectomy, the simulated organ model may include one or more of the mesentery/mesoappendix, appendiceal artery and blood vessels made of electro-conductive hydrogel and one or more of the appendix, cecum and terminal ileum made of non-conductive elastomeric material. For practicing a colectomy, the simulated organ model may include one or more of the mesentery, ileocolic artery, middle colic artery, right colic artery, inferior mesenteric artery, inferior mesenteric vein, left colic artery, sigmoid arteries, rectal arteries, marginal arteries, corresponding veins, omentum, white line of Toldt, mesenteric attachments to the retroperitoneum, and mesorectum made of electro-conductive hydrogel and one or more of the colon, liver, spleen, stomach, kidney, duodenum, retroperitoneum made of non-conductive material. Hydrogel material must be hydrated in order to be sufficiently conductive and therefore it may be difficult to maintain a long shelf-life. 
         [0066]    With reference to the covering layer, in one variation, the covering layer comprises a thin semi-transparent sheet of silicone rubber that is calendared or press-formed so as to have a texture and finish that appears to be naturally occurring. An alternate variation of the covering layer may further comprise a thin semi-transparent sheet of hydrogel material that is cured from slurry and allowed to develop surface features as it cures. The hydrogel material, when hydrated becomes conductive and allows the use of electrosurgical devices. A composite structure for the covering layer comprises a conductive gel layer sandwiched between two silicone elastomer non-conductive layers. In such a case, one or more of the outer non-conductive layers are removed to expose the conductive gel layer. The non-conductive silicone layers advantageously provide a sealing for the hydrogel layer retaining the fluid content of the conductive gel. 
         [0067]    In another variation of the covering layer, a thin film of two-part platinum or tin cured liquid silicone, thoroughly mixed, is placed upon a sheet of textured polyethylene foam. A notched trowel or spreader is then used to spread the silicone material over the surface of the first layer of foam leaving an irregular pattern of material thickness. A second layer of textured polyethylene foam is placed over the first layer of foam leaving the silicone between. A textured roller or stamping device is then moved over the surface of the second layer of foam to calendar the silicone material between the foam layers. The resulting silicone sheet, when cured, is non-tacky and exhibits the characteristics of omentum, mesentery, fat etc. The sheet advantageously has strong and weak regions that can be used to demonstrate the use of mechanical dissecting instruments and scissors. 
         [0068]    The specific organs that may be used in a surgical simulation device include a uterus  100  as shown in  FIG. 13 . The uterus comprises an outer shell constructed of soft silicone rubber molded over a uterine form. When the shell is fully cured, it is placed over a molded foam rubber uterine form that is substantially hollow, having about a 7 to 9 millimeter thick wall. Various pathologies may be placed between the silicone shell and the foam wall. Some pathologies may be inserted into the foam wall to mimic intramural tumors, fibroid tumors  102  or cysts. Fallopian tubes  104 , ovarian ligaments  106  and other attendant structures may be inserted into the silicone/foam structure and attached with adhesive. Ovarian cysts  124  may also be provided and made of the same tumor material. Attendant structures may include the aorta  114 , the internal iliac artery  116 , the ovarian artery  118 , the uterine artery  120 , the vaginal artery  121 , and the uterosacral ligament  122 . The uterine shell is the primary portion to be operated upon. In one variation, it is constructed of silicone elastomer and therefore suitable if the uterine model is intended to be cut or incised in training. If electrosurgery is being practiced upon the uterine model, a uterine model is selected that comprises conductive gel. Connecting structures and tubes are constructed of silicone elastomer or conductive gel depending on the surgical modality. 
         [0069]    Fallopian tubes  104  constructed of two-part platinum or tin cured silicone comprising a first open end and a second open end and a through lumen. The first open end forms a tubular structure that extends a distance of about 20 centimeters and has a diameter of about 6.5 millimeters and a very thin wall of approximately 1-1.5 millimeters. Toward the end of the tubular structure, a bulbous portion is formed having a diameter of about 1.5 centimeters and a length of about 3 centimeters. The bulbous portion transitions to a narrowing of the tubular structure to about 7 millimeters. The narrowed tubular structure then gradually enlarges into a funnel shaped structure having a final open diameter of about 2 centimeters over a length of about 3.5 centimeters. Before the fallopian tube  104  is removed from the form upon which it is made, a plurality of axial cuts  108  is made at the second enlarged open end. When removed from the form, these cuts allow the silicone material to move in a way that resembles human fimbria. Pathology such as an ectopic pregnancy  110  may be inserted into the bulbous portion of the fallopian tube  104  for identification or excision. In addition, to maintain the shape of the thin walled conduit portion of the fallopian tube when folded, a length of soft fibrous yarn, such as used in knitting, may be placed within the lumen. 
         [0070]    In the simulated uterine model, the ovaries  112  are hollow bulbous structures formed from two-part platinum or tin cured silicone. A soft polyurethane foam support is placed within the ovarian structure. The polyurethane support is sized and configured to fit neatly within the ovarian shell and have a nest or receptacle for pathology such as an ovarian cyst  124 . The trainee may cut through the ovarian wall and into the polyurethane foam to remove the pathology and subsequently suture the defect to close. Ovaries are made of non-conductive material and are cut with scissors or scalpel. In another variation, the ovaries are made of conductive gel so they could be cut with electrosurgery. The cyst is made of non-conductive material. 
         [0071]    In another simulated organ model, a stomach comprises a hollow stomach-shaped bladder having a first open end, a second open end and an enlarged central portion. The enlarged central portion is divided by a pathway that extends from near the first open end to near the second open end. The pathway comprises a region of silicone adhesive placed strategically along a desired trajectory adjacent to the lesser curvature of the stomach. The opposing walls of the stomach bladder are approximated and held together by the adhesive. The stomach may be divided along the adhesive pathway to simulate a particular procedure. That is, the adhesive pathway directs the trainee to staple or cut along a preferred surgical pathway. The adhesive simulates the condition in which several rows of staples would be placed before the cutting element in a surgical stapler is deployed. As a result, the dissected stomach portion appears to be stapled securely and the residual stomach portion is gas tight and secure. In another variation, the adhered portion of the stomach is formed of conductive gel material adjacent to non-conductive adjacent portions of the stomach. In yet another variation, the predetermined surgical pathway across the stomach or other organ is constructed of conductive gel material adjacent to non-conductive material of the same organ or adjacent to non-conductive material of different organs and anatomical structures. 
         [0072]    In another simulated organ model, a liver constructed of hydrogel may be placed into the training module  10  where the procedure would involve electrosurgical dissection. In one variation, the base or tray of the training module  10  receives and holds in place either a silicone liver or a hydrogel liver. A receiving feature may comprise a nest, pocket or receptacle sized and configured to maintain in position a silicone or hydrogel or foam rubber liver depending on the needs of the particular training module. If a procedure required electrosurgical activity, such as a liver resection, the liver is made of conductive gel. The base or tray is configured to accept a liver made of gel, silicone or foam depending on the specific procedure. If the procedure to be practiced does not involve electrosurgery, it is far more economical to use a silicone or foam model. 
         [0073]    While certain embodiments have been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope thereof as defined by the following claims.