CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/630,595 filed Nov. 24, 2004, the disclosure of which is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     During many laparoscopic procedures, some of which are already in general clinical use and others of which are soon to be introduced, it is necessary to introduce medical devices for various purposes, such as rigid staplers used to perform anastomoses. Currently available laparoscopic trocars are not large enough to permit entry of such instruments. Further, the valve systems of presently available trocars are not adaptable for this purpose, as gasses used to swell the bodily cavity may readily escape. The shafts of present trocars are also not flexible, and therefore do not accommodate the aforementioned rigid instruments which frequently are curved or may need to be moved about and therefore require a somewhat permissive range of motion.  
         [0003]     Surgeons therefore presently resort to introducing such instruments through surgical openings in the abdominal wall. In doing so, penetrating towel clips may be used to close the opening tightly around the shafts of the instruments being introduced into the body to reduce the rate of pneumoperitoneum loss.  
         [0004]     Although practiced, this method is only partially successful. It has been found that insufflated CO 2  may escape, resulting in the reduction in the size of the operative space and attendant difficulties in achieving the exposure needed for proper execution of the surgical maneuver.  
         [0005]     Furthermore in cases where a bowel anastomosis is performed with a stapler, for example during a gastrojejunostomy for gastric bypass operations or during any endoluminal intervention in a contaminated space such as a cyst gastrostomy for pancreatic cysts, the eventual removal of the instrument which has become contaminated in the process naturally results in the inoculation of vast numbers of bacteria and other pathogens into the body through the abdominal wall.  
         [0006]     The present invention seeks to address these and other concerns.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention overcomes the shortcomings of the prior art by providing, in various combinations, a gel based laparoscopic trocar having features which enable the trocar to be used with a various array of instruments while preventing loss of pneumosperitoneum  
         [0008]     In accordance with certain aspects of the present invention, a gel based laparoscopic trocar may comprise a bivalved gel plug contained within a semi-rigid plastic casing, the casing adapted to penetrate an opening formed in a bodily cavity. The internal bivalved gel plug may yield easily to permit penetration by a rigid instrument, yet may conform to the shape of the instrument to seal against the instrument and thereby prevent leakage of CO 2  from within the body cavity. The gel based laparoscopic trocar may also comprise a splitable sheath extending from the semi-rigid plastic casing. The sheath may be embedded with strips of memory alloy designed to curl once released by a pull wire system such that the curled portion will curl against the underside of the bodily wall surrounding the body cavity to squeeze a portion of the rigid gel casing against the exterior of the bodily wall.  
         [0009]     In accordance with one aspect of the present invention, a gel based laparoscopic trocar may comprise a shaft having an upper portion and a lower portion, the shaft having an interior dimension, a rigid gel casing surrounding the upper portion of the shaft, at least two resilient gel filled membranes filling the interior dimension of the upper portion of the shaft, a plurality of petals surrounding the external portion of the lower portion of the shaft, the petals having a first condition in which the petals are elongated along the length of the shaft and a second condition in which portions of the petals are permitted to curl upward and away from the shaft, and a release mechanism associated with the petals, the release mechanism adapted to permit the petals to move from the first condition to the second condition upon actuation.  
         [0010]     The petals may include a memory metal having a natural condition relating to the second condition of the petals.  
         [0011]     The shaft may be flexible.  
         [0012]     The shaft may be cylindrical and the dimension may be a diameter. The diameter may be between 1 cm and 12 cm.  
         [0013]     The second portion of the shaft may be adapted to be placed through an opening formed in an abdominal wall of a patient such that the petals may pinch the abdominal wall between the rigid casing and the petals to hold the gel based laparoscopic trocar in place.  
         [0014]     A surgical instrument may be inserted between the gel filled membranes and through the shaft, whereby the gel filled membranes may seal against the surgical instrument.  
         [0015]     The trocar may further comprise a plastic membrane within the shaft, the plastic membrane being penetrable by a surgical instrument. The plastic membrane may seal against a surgical instrument penetrating therethrough.  
         [0016]     The release mechanism may be a pull tie system.  
         [0017]     In accordance with a further embodiment, a surgical access port may comprise a shaft having a first portion and a second portion, the first portion filled with at least two gel filled membranes, a casing surrounding the first portion of the shaft, a plurality of petals surrounding the second portion of the shaft, the petals having a first position in which the petals are elongated along the length of the second portion of the shaft and a second position in which the petals are permitted to curl away from the second portion of the shaft toward the casing, wherein the second portion of the shaft is adapted to be placed through an opening formed in an abdominal wall of a patient such that the petals may compress the abdominal wall against the casing to hold the surgical access port in place.  
         [0018]     The petals may include a memory metal having a natural condition relating to the second position of the petals.  
         [0019]     The shaft may be flexible.  
         [0020]     The shaft may be cylindrical and the dimension may be a diameter, the diameter being between 1 cm and 12 cm.  
         [0021]     A surgical instrument may be inserted between the at least two gel filled membranes and through the shaft, whereby the at least two gel filled membranes seal against the surgical instrument.  
         [0022]     The port may further comprise a release mechanism, the release mechanism adapted to permit the petals to move from the first position to the second position.  
         [0023]     The surgical access port may further comprise a plastic membrane within the shaft, the plastic membrane being penetrable by a surgical instrument. The plastic membrane may seal against a surgical instrument penetrating therethrough.  
         [0024]     In accordance with another aspect of the present invention, a method of inserting a gel based laparoscopic trocar having a shaft with an upper portion and a lower portion, a rigid gel casing surrounding the upper portion of the shaft, at least two resilient gel filled membranes filling the first portion of the shaft, a plurality of petals surrounding the outside of the lower portion of the shaft, the petals having a first condition in which the petals are elongated along the length of the shaft and a second condition in which portions of the petals are permitted to curl upward and away from the shaft, the method may comprise the steps of forming a surgical incision in a patient, spreading the surgical incision, and inserting the lower portion of the gel based laparoscopic trocar into the incision.  
         [0025]     The step of inserting may force the gel based laparoscopic trocar into the incision such that the gel casing abuts an exterior portion of the incision.  
         [0026]     The method may further comprise the step of moving the petals from the first condition to the second condition such that the petals abut an interior portion of the incision. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]     The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and methods of operation, together with features objects, and advantages thereof, may be best understood by reference to the following detailed description when read with the accompanying drawings in which:  
         [0028]      FIG. 1  depicts a top plan view of a gel based laparoscopic trocar in accordance with a first embodiment of the present invention;  
         [0029]      FIG. 2  depicts a side view of the gel based laparoscopic trocar of  FIG. 1 , prior to release of the pull ties;  
         [0030]      FIG. 3  depicts a cross-sectional side view of the gel based laparoscopic trocar of  FIG. 1 , prior to release of the pull ties; and,  
         [0031]      FIG. 4  depicts a side view of the gel based laparoscopic trocar of  FIG. 1  installed through an abdominal wall after release of the pull ties. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0032]     As previously discussed, existing laparoscopic trocars are unsuitable for use with many surgical instruments, particularly surgical staplers. In accordance with certain aspects of the present invention, an inventive gel based laparoscopic trocar solves this problem. The gel based laparoscopic trocar may comprise a bivalved gel plug contained within a semi-rigid plastic casing, the casing being adapted to penetrate an opening in a bodily cavity, particularly the abdomen. The internal bivalved gel plug may be resilient and yield upon entry to permit penetration by a rigid instrument, yet may conform to the shape of the instrument to seal against the instrument and thereby prevent leakage of CO 2  from within the body cavity once the instrument is inserted. The gel based laparoscopic trocar may also comprise a splitable sheath extending from the semi-rigid plastic casing. The sheath may be embedded with strips of memory alloy designed to curl once released by a retaining system such that the curled portion will abut the underside of the bodily wall surrounding the body cavity to squeeze a portion of the rigid gel casing against the exterior of the bodily wall, thus holding the trocar in position.  
         [0033]     As shown in  FIG. 1 , a top view of a gel based laparoscopic trocar in accordance with certain aspects of the present invention, a gel based laparoscopic trocar  10  may comprise a flexible shaft  12  with two half cylinder segments,  14   a ,  14   b  filling the interior diameter thereof. The half-cylinder segments  14   a ,  14   b  typically comprise a resilient gel filled flexible membrane, such that the two segments are air tight against each other at their intersection  16  in the default position. The half-cylinder segments  14   a ,  14   b  are also preferably resilient such that they may be separated at their intersection  16  by force, yet will return to their default position to seal against a penetrating object. Accordingly, when a medical instrument is inserted into the intersection  16  of the half-cylinder segments  14   a ,  14   b , the half-cylinder segments will yield to permit penetration, but will seal against the instrument once inserted.  
         [0034]     It will be appreciated that greater than two gel filled membranes may also be provided. For example, three, four, or even a greater number of segments may be utilized. In such cases, there may be a plurality of intersections through which surgical objects may be inserted.  
         [0035]     The shaft  12  is typically manufactured from plastics that are relatively firm, yet flexible. The half-cylinder segments  14   a ,  14   b , may be made from various gel materials, and may include an external skin or membrane. Preferably each of the components of the trocar  10 , whether previously mentioned or to be discussed, are biocompatible.  
         [0036]     As shown in  FIG. 2 , a side view of the gel based laparoscopic trocar  10  of  FIG. 1 , the upper portion  18  of the shaft  12  may be externally surrounded by a rigid gel casing  20 . A portion of the rigid gel casing  20  is designed to be of a much greater diameter than the shaft  12 , such that the gel casing may be utilized to form a collar which prevents the trocar  10  from being pushed completely through a bodily opening sized to accept the shaft, as will be discussed.  
         [0037]     The rigid gel casing  20  may comprise and outer shell formed from various metals, and may be filled with a viscous gel. Alternatively, the casing may be formed completely from plastic or metal, or may be formed entirely from a thick gel. Typically, the firmness of the rigid gel casing  20  is much greater than the firmness of the gel filled half-cylinder segments  14   a ,  14   b.    
         [0038]     A lower portion  22  of the shaft  12  may be surrounded by a splitable sheath  24 , having a plurality of petals  26 . Each of the petals  26  may be tied into a first position, shown in  FIG. 2 , with pull ties  28  such that the petals are adjacent the shaft  12 . In this regard, the petals  26  are relatively straight and may be held firmly against the shaft  12 . In this position, the gel based laparoscopic trocar  10  may be readily pushed through a bodily opening, such that the rigid gel casing  20  abuts the bodily opening.  
         [0039]     The petals  28  may each contain at least one embedded strip of memory alloy such as Nitinol (not shown) which is curled in its natural state (such that the Nitinol is not in its natural state when the petals  28  are in the position shown in  FIG. 2 ). This curled Nitinol forces the petals  26  to curl outwardly when the pull ties  28  are pulled, thus releasing the petals and allowing the Nitinol to return to its natural state. In other embodiments, the petals  26  may be glued in place. The pull ties  14  may then be utilized to sever the glue, such that the petals  26  are free to curl. Other release mechanisms in addition to pull ties  28  may also be utilized, so long as they serve to restrain the petals  26  in one mode of operation, and release the petals in another.  
         [0040]      FIG. 3  depicts a cross-sectional side view of the gel based laparoscopic trocar of  FIG. 1 , prior to release of the pull ties  28 . As shown, the gel based laparoscopic trocar  10  may further comprise a perforated plastic membrane  30  in the upper portion  18  thereof, just below the level of the half-cylinder segments  14   a ,  14   b . The perforated plastic membrane  30  may include a perforation  32 , which is adapted to rupture upon entry of a surgical instrument. The membrane  30  serves as an additional barrier guarding against the escape of insufflated CO 2 . In this regard, it is preferred that the membrane  30  be formed from an elastic material, such that the membrane will seal against an inserted instrument.  
         [0041]     As previously discussed, the gel based laparoscopic trocar  10  may be inserted into a surgical opening formed in a body, such as through an abdominal wall. Preferably, the surgical opening is sized approximately of equal dimension to that of the shaft  12  diameter, such that the gel based laparoscopic trocar  10  will be tight against the surgical opening throughout it&#39;s 360 degree exterior.  
         [0042]      FIG. 4  depicts a side view of the gel based laparoscopic trocar of  FIG. 1  installed through an abdominal wall  34 . As previously stated, the gel based trocar  10  may be inserted into a surgical opening formed in the abdominal wall  34  while in the position shown in  FIG. 2 , with the petals  26  held adjacent to the shaft  12  by release mechanisms, such as pull ties  28 . Preferably, the gel based laparoscopic trocar  10  is inserted until the rigid gel casing  20  abuts the exterior portion  36  of the abdominal wall  34 . Once so inserted, the surgeon may actuate the release mechanism to permit the petals  26  to curl.  
         [0043]     This curling continues until the inner surface  38  of the abdominal wall  36  is encountered by the petals  26 , as shown in  FIG. 4 . The trocar  10  is therefore retained as the rigid gel casing  20  and petals  26  squeeze each other against the abdominal wall  34 , and it is unlikely to be dislodged by usual surgical activity.  
         [0044]     The curling action of the petals  26  allows the gel based laparoscopic trocar  10  to be utilized for patients of various girth. For example, in a thin patient, the petals  26  will curl a larger distance than in a more obese patient, where the abdominal wall  34  is thicker. In this regard, the gel based laparoscopic trocar  10  may be sized such that a single unit will be capable of use for the vast majority of patients, even though multiple sizes may also be manufactured, depending on the need.  
         [0045]     When the petals  26  are permitted to peel apart and curl in the fashion shown in  FIG. 4 , the internal cylindrical shaft  12  is exposed. Instruments or other objects may be introduced into, and removed from, the abdomen through the shaft  12  without fear of contact with or contamination of the abdominal wall  36  as the instruments are completely contained within the shaft. The shaft  12  is preferably compliant, such that instruments or other objects placed therein may be shifted, bent or otherwise manipulated freely.  
         [0046]     The shaft  12  within the gel based laparoscopic trocar  10  may be of any diameter ranging from 1 cm for the introduction of standard laparoscopic instruments such as a laparoscope telescope, 4 cm for the introduction of laparoscopic EEA staplers and vascular staplers, or up to 12 cm or more for the introduction of a large male hand. It is preferred that the overall length L of the gel based laparoscopic trocar  10  be approximately 10 cm, such that the trocar is long enough to extend into the thickness of the patient&#39;s abdomen. Of course, this dimension may be adjusted for different sized trocars, or for different sized intended patients, for example obese patients. Of the overall length, a portion will be taken up by the height H of the rigid gel casing  20 . This height H may vary, as it is exposed above the patient&#39;s skin.  
         [0047]     In order to insert the gel based laparoscopic trocar  10  into the surgical opening, a surgeon may form the surgical opening by making a surgical cut. The surgeon may then spread open the surgical cut with his or her hands to open the incision. The gel based laparoscopic trocar  10  may then be inserted such that the casing  20  abuts the exterior portion of the opening. The surgeon may then operate the release mechanism to allow the petals  26  to curl against the inside portion  38  of the opening, thus preventing the trocar  10  from being pulled out.  
         [0048]     In accordance with other aspects of the present invention, a gel based laparoscopic trocar may also incorporate a retractable blade mechanism, such that the trocar itself is capable of making a surgical cut into the bodily cavity. Devices incorporating retractable blades are known in the industry, and the teachings of which may be combined with the present teachings to form such a trocar. Generally, a small incision may be made into the patient in the conventional manner. The blade of the gel based laparoscopic trocar may then be used to lengthen the incision, whereby the actual trocar may follow.  
         [0049]     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
A gel based laparoscopic trocar having a shaft with upper and lower portions, the shaft having an interior dimension, a rigid gel casing surrounding the upper portion of the shaft, at least two resilient gel filled membranes filling the interior dimension of the upper portion of the shaft, a plurality of petals surrounding the external portion of the lower portion of the shaft, the petals having a first condition in which the petals are elongated along the length of the shaft and a second condition in which portions of the petals are permitted to curl upward and away from the shaft, and a release mechanism associated with the petals, the release mechanism adapted to permit the petals to move from the first condition to the second condition upon actuation. The petals may include a memory metal having a natural condition relating to the second condition of the petals.