Abstract:
An appendectomy model for surgical training is provided. The model includes a simulated large intestine with a central lumen interconnected with a lumen of an artificial appendix. The model also includes a simulated appendiceal artery, simulated mesoappendix and a simulated ileum. The simulated ileum made of white silicone is embedded between a first layer of pink silicone and a second layer of pink silicone to create a realistic anatomical landmark particularly suitable for laparoscopic appendectomy training.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This patent application claims benefit and priority to U.S. Provisional Patent Application Ser. No. 62/195,439 entitled “Appendectomy model” filed on Jul. 22, 2015 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 simulated tissue structures and models for teaching and practicing various surgical techniques and procedures related but not limited to laparoscopic, endoscopic and minimally invasive surgery. 
       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, cauterizing 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. Different procedures demand different skills. Furthermore, the trainee must practice techniques in various anatomical environs that are influenced by factors such as the size and condition of the patient, the adjacent anatomical landscape and the types of targeted tissues and whether they are readily accessible or relatively inaccessible. 
         [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 models or simulated tissue elements that are likely to be encountered in and that can be used for practicing endoscopic and laparoscopic, minimally invasive, transluminal surgical procedures. In laparoscopic surgery, a trocar or cannula is inserted to access a body cavity and to create a channel for the insertion of a camera such as a laparoscope. The camera provides a live video feed capturing images that are then displayed to the surgeon on one or more monitors. At least one additional small incision is made through which another trocar/cannula is inserted to create a pathway through which surgical instruments can be passed for performing procedures observed on the video monitor. The targeted tissue location such as the abdomen is typically enlarged by delivering carbon dioxide gas to insufflate the body cavity and create a working space large enough to accommodate the scope and instruments used by the surgeon. The insufflation pressure in the tissue cavity is maintained by using specialized trocars. Laparoscopic surgery offers a number of advantages when compared with an open procedure. These advantages include reduced pain, reduced blood and shorter recovery times due to smaller incisions. 
         [0005]    Laparoscopic or endoscopic minimally invasive surgery requires an increased level of skill compared to open surgery because the target tissue is not directly observed by the clinician. The target tissue is observed on monitors displaying a portion of the surgical site that is accessed through a small opening. Therefore, clinicians need to practice visually determining tissue planes, three-dimensional depth perception on a two-dimensional viewing screen, hand-to-hand transfer of instruments, suturing, precision cutting and tissue and instrument manipulation. Typically, models simulating a particular anatomy or procedure are placed in a simulated pelvic trainer where the anatomical model is obscured from direct visualization by the practitioner. Ports in the trainer are employed for passing instruments to practice techniques on the anatomical model hidden from direct visualization. Simulated pelvic trainers provide a functional, inexpensive and practical means to train surgeons and residents the basic skills and typical techniques used in laparoscopic surgery such as grasping, manipulating, cutting, tying knots, suturing, stapling, cauterizing as well as how to perform specific surgical procedures that utilized these basic skills. 
         [0006]    Organ models for use with simulated pelvic trainers on which surgeons can train surgical techniques are needed. These organ models need to be realistic so that the surgeon can properly learn the techniques and improve their skills. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one aspect of the invention, a simulated tissue structure for surgical training is provided. The simulated tissue structure includes a simulated large intestine having a tubular structure defining a central lumen extending along a longitudinal axis between a proximal end and a distal end. The simulated tissue structure includes a simulated appendix connected to the distal end of the simulated large intestine. A simulated teniae coli is connected to and extends longitudinally along the simulated large intestine. The simulated tissue structure includes at least one simulated artery having a middle portion between a proximal end and a distal end. The at least one simulated artery is connected to the simulated appendix. A silicone pocket substantially defines a cavity that encloses the simulated appendix and at least part of the simulated artery. 
         [0008]    According to another aspect of the invention, a simulated tissue structure for surgical training is provided. The simulated tissue structure includes an appendectomy model. The appendectomy model includes a first layer of silicone having an inner surface defining a central lumen having a diameter. A second layer of silicone is provided. A strip of silicone is embedded between the first layer and the second layer. The strip of silicone has an inner surface, an outer surface, a length defined between a top edge and a bottom edge, and a width defined between a first side edge and a second side edge. 
         [0009]    According to another aspect of the invention, a method of manufacturing a simulated tissue structure is provided. The method includes the steps of providing a mandrel and applying a first layer of wet silicone onto the mandrel. The first layer is cured to create a first tubular structure that defines a central lumen occupied by the mandrel. A narrow strip of silicone that is approximately less than half of the diameter of the central lumen is provided and applied longitudinally along the first tubular structure. A second layer of wet silicone is applied over the first tubular structure and narrow strip. After the second layer is allowed to cure, the combination of the first layer, second layer and narrow strip is removed from the mandrel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a top view of an appendectomy model with the second layer of yellow silicone removed to show the simulated appendix and arteries according to the present invention. 
           [0011]      FIG. 2  is top view of an appendectomy model with a second layer of yellow silicone forming a pocket with the first yellow silicone layer beneath to contain the simulated appendix arteries according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    An appendectomy model for laparoscopic procedures is provided. The appendectomy model has been designed to teach surgeons and residents the anatomy and steps involved in an appendectomy procedure. The model is made of silicone, thermoplastic elastomer (TPE) and foam and contains all the important anatomical landmarks. The appendectomy model is placed inside a laparoscopic trainer concealed from direct observation with the naked eye so that laparoscopic surgical skills may be practiced while viewing the operation on a video monitor. 
         [0013]      FIG. 1  illustrates an appendectomy model  10  according to the present invention. The model  10  includes a portion of a simulated large intestine  12  that includes a plurality of transverse folds  14 . The distal end of the simulated large intestine  12  is integrally molded together with an appendix  16  by applying a first layer of wet silicone to a rotating mandrel. The mandrel has the shape of the simulated large intestine with the shape of the simulated appendix  16  connected to the end of the mandrel. The diameter of the simulated appendix  16  is smaller than the diameter of the simulated large intestine  12 . The first layer of silicone is allowed to cure around the mandrel. The mandrel is rotated to allow an even layer to cure taking the shape of the mandrel. Then a white narrow strip  18  of pre-formed silicone is laid over along the longitudinal axis of the tubular simulated large intestine  12  as shown in  FIGS. 1 and 2  to define a simulated teniae coli. Silicone adhesive may be used to attach the white narrow strip to the first layer of silicone. Then a second layer of wet silicone is applied to sandwich the white narrow strip  18  between the first layer and the second layer of silicone. The narrow long white narrow strip  18  of silicone is substantially rectangular in shape. In another variation, the narrow strip  18  may have wider lateral portions interspersed with narrower lateral portions along the longitudinal length of the simulated large intestine  12 . The wider portions of the narrow strip  18  are substantially spaced apart and aligned with the transverse folds  14  of the large intestine  12  before being attached and embedded between two layers of silicone. The cured silicone structure is removed from the mandrel. 
         [0014]    Still referencing  FIG. 1 , a small thin first layer  20  of yellow silicone is attached to the bottom of the simulated large intestine  12  and may or may not be attached to the bottom of the appendix  16 . One or more red silicone tubes  22  representing arteries are attached to the first layer  20  of yellow silicone along the middle of the simulated arteries such as a simulated appendiceal artery. The tubes  22  may be solid or hollow. The distal ends of the red artery tubes  22  are attached to the top of the appendix  16  with adhesive as shown. A hole  24  is formed near the distal end of the simulated large intestine  12  and a pre-formed tube  26  of silicone is inserted into the hole  24  to simulate the ileum. The proximal ends of the red tubes  22  are placed under the ileum as shown in  FIG. 1 . A thin second layer  28  of yellow silicone is then applied above the first layer  20  of silicone and attached to the lower edge of the yellow first layer  20  and to the artificial large intestine  12  to create a cave or pocket-like structure that covers and contains the appendix  16 , part of the large intestine  12 , red tubes  22  and part of the artificial ileum  26  as shown in  FIG. 2 . The whole model is attached to a red background sheet  30  of textured silicone. Hook-and-loop type fastening means may be used under the model  10  and, in one variation, under the background sheet  30  to attach and secure the model  10  to the inside of a laparoscopic trainer. In one variation, the background sheet  30  is made of high density ethylene vinyl acetate foam. 
         [0015]    The practitioner will practice a laparoscopic appendectomy by placing the appendectomy model  10  inside a laparoscopic trainer. The model  10  is secured to the base of a trainer with the fastening means. A scalpel or other instrument is used to cut through the top yellow second layer  28  of silicone to open the pocket and visualize the arteries  22  beneath. The practitioner will then practice cutting through the red arteries  22  and retracting them. The appendix  16  will then be cut and removed. 
         [0016]    In another variation, the model  10  is formed as part of another larger model or tissue structure such as an abdominal organ model or pelvic model and is sized and configured to be placed inside a simulated laparoscopic environment such as a surgical training device which will now be described. 
         [0017]    A surgical training device that is configured to mimic the torso of a patient such as the abdominal region. The surgical training device provides a body cavity substantially obscured from the user for receiving simulated or live tissue or model organs or training models of the like described in this invention. The body cavity is accessed via a tissue simulation region that is penetrated by the user employing devices to practice surgical techniques on the tissue or practice model found located in the body cavity. Although the body cavity is shown to be accessible through a tissue simulation region, a hand-assisted access device or single-site port device may be alternatively employed to access the body cavity. An exemplary surgical training device is described in U.S. Pat. No. 8,764,452 entitled “Portable Laparoscopic Trainer” filed on Sep. 29, 2011 and incorporated herein by reference in its entirety. The surgical training device is particularly well suited for practicing laparoscopic or other minimally invasive surgical procedures. 
         [0018]    The surgical training device includes a top cover connected to and spaced apart from a base by at least one leg. A plurality of legs may be employed to space apart the top cover. The surgical training device is configured to mimic the torso of a patient such as the abdominal region. The top cover is representative of the anterior surface of the patient and the space between the top cover and the base is representative of an interior of the patient or body cavity where organs reside. The surgical trainer is a useful tool for teaching, practicing and demonstrating various surgical procedures and their related instruments in simulation of a patient undergoing a surgical procedure. Surgical instruments are inserted into the cavity through the tissue simulation region as well as through pre-established apertures in the top cover. Various tools and techniques may be used to penetrate the top cover to perform mock procedures on simulated organs or practice models placed between the top cover and the base. The base includes a model-receiving area or tray for staging or holding a simulated tissue model or live tissue. The model-receiving area of the base includes frame-like elements for holding the model in place. To help retain a simulated tissue model or live organs on the base, a clip attached to a retractable wire is provided at locations. The retractable wire is extended and then clipped to hold the tissue model in position substantially beneath the tissue simulation region. Other means for retaining the tissue model include a patch of hook-and-loop type fastening material affixed to the base in the model receiving area such that it is removably connectable to a complementary piece of hook-and-loop type fastening material affixed to the model  10 . 
         [0019]    A video display monitor is hinged to the top. The video monitor is connectable to a variety of visual systems for delivering an image to the monitor. For example, a laparoscope inserted through one of the pre-established apertures or a webcam located in the cavity and used to observe the simulated procedure can be connected to the video monitor and/or a mobile computing device to provide an image to the user. Also, audio recording or delivery means may also be provided and integrated with the trainer to provide audio and visual capabilities. Means for connecting a portable memory storage device such as a flash drive, smart phone, digital audio or video player, or other digital mobile device is also provided, to record training procedures and/or play back pre-recorded videos on the monitor for demonstration purposes. Of course, connection means for providing an audio visual output to a screen larger than the monitor is provided. In another variation, the top cover  10  does not include a video display but includes means for connecting with a laptop computer, a mobile digital device or tablet and connecting it by wire or wirelessly to the trainer. 
         [0020]    When assembled, the top cover is positioned directly above the base with the legs located substantially around the periphery and interconnected between the top cover and base. The top cover and base are substantially the same shape and size and have substantially the same peripheral outline. The internal cavity is partially or entirely obscured from view. The legs include openings to allow ambient light to illuminate the internal cavity as much as possible and also to advantageously provide as much weight reduction as possible for convenient portability. The top cover is removable from the legs which in turn are removable or collapsible via hinges or the like with respect to the base. Therefore, the unassembled trainer has a reduced height that makes for easier portability. In essence, the surgical trainer provides a simulated body cavity that is obscured from the user. The body cavity is configured to receive at least one surgical model accessible via at least one tissue simulation region and/or apertures in the top cover through which the user may access the models to practice laparoscopic or endoscopic minimally invasive surgical techniques. 
         [0021]    Any portion of the model can be made of one or more organic base polymer including but not limited to hydrogel, single-polymer hydrogel, multi-polymer hydrogel, rubber, latex, nitrile, protein, gelatin, collagen, soy, non-organic base polymer such as thermo plastic elastomer, kraton, silicone, foam, silicone-based foam, urethane-based foam and ethylene vinyl acetate foam and the like. Into any base polymer one or more filler may be employed such as a fabric, woven or non-woven fiber, polyester, nylon, cotton and silk, conductive filler material such as graphite, platinum, silver, gold, copper, miscellaneous additives, gels, oil, cornstarch, glass, dolomite, carbonate mineral, alcohol, deadener, silicone oil, pigment, foam, poloxamer, collagen, gelatin and the like. The adhesives employed may include but are not limited to cyanoacrylate, silicone, epoxy, spray adhesive, rubber adhesive and the like. 
         [0022]    It is understood that various modifications may be made to the embodiments and variations disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.