CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 12/557,042 filed Sep. 10, 2009, which claims priority to, and the benefit of, U.S. Provisional Patent Application Ser. No. 61/099,015 filed on Sep. 22, 2008; U.S. patent application Ser. No. 12/486,333 filed Jun. 17, 2009, which claims priority to U.S. Provisional Patent Application Ser. No. 61/079,198, filed on Jul. 9, 2008; U.S. patent application Ser. No. 12/486,346 filed Jun. 17, 2009, which claims priority to U.S. Provisional Patent Application Ser. No. 61/079,200, filed on Jul. 9, 2008; U.S. patent application Ser. No. 12/486,352 filed Jun. 17, 2009, which claims priority to U.S. Provisional Patent Application Ser. No. 61/079,202, filed on Jul. 9, 2008, the entire content of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to a sheath for use with an anastomosis, and more particularly to sheaths in a compressed position for delivery to a surgical site. 
       BACKGROUND 
       [0003]    An anastomosis, or the joining of two vessels, such as esophagus, colon, or other parts of the digestive tract, is a common procedure. Sheaths may be placed over the anastomotic site to protect the anastomotic site during healing. 
         [0004]    Specific patient populations such as patients with diabetes T 1 , T 2 , or other immuno-compromised patients {such as chemotherapy patients) are more prone to anastomotic leaks. These patient populations have longer healing profiles and sometimes weaker immune systems and these factors may lead to an increase in leak occurrence. Unfortunately, in most cases, anastomotic leaks are not detected until clinical symptoms present themselves. 
         [0005]    Copending, commonly assigned patent applications 61/079,198, 61/079,200, and 61/079,202 disclose various embodiments of sheaths which may assist in decreasing leaks and the risks associated with anastomotic leaks. However, it would be advantageous to retain the sheath in a compressed position at least for insertion. 
       SUMMARY 
       [0006]    Medical devices, and more particularly sheaths are described herein which provide for protection of an anastomosis and more particularly sheaths which are provided in a compressed position for at least insertion. The sheath is configured for elongation in situ from a first length to a second, longer length; the sheath is provided in combination with a retention member, the retention members retaining the sheath at the first length. In some embodiments, upon disengagement of at least a portion of the retention member from the sheath, the sheath is capable of elongation longitudinally from the first length to the second, longer length. In other embodiments, upon removal of at least a portion of the retention member, the sheath extends to the second, longer length. Alternatively, upon severing of the retention member, the sheath may elongate from the first length to the second, longer length. 
         [0007]    In one alternate embodiment, a sheath includes a distal portion and a proximal portion, and the sheath is retained in a first position having a first length for insertion into a body lumen and is elongated to a second position having a second greater length for placement in a body lumen, the distal portion of the sheath longitudinally extending past an anastomotic site. Furthermore, the sheath may be retained in the first position by a retention member. 
         [0008]    Retention members of the present disclosure are selected from the group consisting of fibers, sutures, clips, pins, and staples. The retention members may also be glues or adhesives. The retention member may penetrate at least a portion of the sleeve. Materials which may be used to make the retention member include materials selected from the group consisting of polysaccharides, proteins, vinyl polymers, PEG-based polymers, and combinations thereof. The retention member may also be water soluble. In some embodiments, the retention member may be in the form of a polymer coating. In other embodiments, the retention member encapsulates the sheath. 
         [0009]    A method of treating a patient is also disclosed, the method including the steps of providing a sheath having a distal end and a proximal end, the sheath configured for elongation in situ from first length to a second, longer length, and a retention member; attaching the proximal end of the sheath to a body lumen at a region proximal of an anastomosis; and, releasing the retention member so the sheath is extendable to the second length. The method may further include the step of grasping the sheath and applying a force to extend the sheath distally past an anastomotic site. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Various preferred embodiments of the medical devices are described herein with reference to the drawings, in which: 
           [0011]      FIG. 1A  is a cross-sectional view of a sheath in a compressed position, with a retention member intact; 
           [0012]      FIG. 1B  is a cross-sectional view of the sheath of  FIG. 1  in an expanded position, after the retention member of  FIG. 1A  has been severed; 
           [0013]      FIGS. 2A-2D  are side views of different embodiments of sheath retention members according to the present disclosure; 
           [0014]      FIG. 3A  is a cross-sectional perspective view of the device of  FIG. 2C  in a first compressed position, with the retention member intact; and, 
           [0015]      FIG. 3B  is another cross-sectional perspective view of the device of  FIG. 2C  after the retention member has been severed. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0016]    The present disclosure is directed to a retention member which retains an anastomotic sheath at a first length for insertion into a body lumen, and upon disengagement or release of the retention member, the sheath may elongate in situ to a second, longer length. The term “sheath” as used herein includes a medical device defining a passage, which allows for the transport and flow of fluids therethrough. The term “body lumen” as used herein, means an inner open space of cavity of a tubular organ, such as a blood vessel, intestine, or esophagus. The term “proximal” as used herein means portion of the device which is closer to the user, while the term “distal” refers to a portion of the device which is further from the user. 
         [0017]      FIG. 1  illustrates a cross-sectional view of a sheath  12  positioned in a body lumen  20 , proximal of an anastomotic site  22 . A proximal portion of the sheath  12  includes a ring member  14  and a distal portion of the sheath includes a sleeve  16 , which is subsequently elongated distally past an anastomotic site  22 . The sheath  12  is held in a compressed position by a retention member  10 . The retention member  10  is an elongate polymeric member, e.g. a suture, which is positioned on an interior surface of the sheath  12 . Alternately, the retention member  10  may be positioned exterior of the sheath  12 . A first portion of the retention member  10   a  is connected to the ring member  14  at a first connection point  13   a,  and a second portion of the retention member  10   b  is connected to the sleeve  16  at a second connection point  13 , the second connection point  13   b  being distal to the first connection point  13   a.  The retention member  10  may be connected to the sheath  12  at least two connection points ( 13   a,    13   b ) which enable to sheath be retained in a compressed position. For example, a first connection point may be located at a proximal portion of the sheath and a second connection point may be located at a distal portion of the sheath. At least one retention member  10  (two are shown) may be used to retain the sheath  12  in a first, compressed position for insertion. It is also envisioned that more than two retention members  10  may be used to retain the sheath  12  in a compressed position. Additionally, the retention member  10  may include more than two connection points ( 13   a,    13   b ), which may enable a more uniform compression of the sheath  12 . The retention member  10  may be connected to the sheath  12  using any method within the purview of those skilled in the art including, but not limited to welding, tacking or gluing. 
         [0018]    The sheath  12  may be inserted into a body lumen  20  in a first compressed position, through use of an insertion device (not shown). Once inserted and positioned in a body lumen  20  proximal to an anastomotic site  22 , the retention member  10  may be severed, for example, along line A-A, releasing the sheath  12  from a compressed position ( FIG. 1B ). The sheath  12  may then self expand or elongate distally past an anastomosis  22 . Alternately, a separate device, such as a grasper (not shown), may be used to extend a length of the sleeve  16  distally past an anastomotic site. 
         [0019]    Various alternate embodiments of retention members are illustrated in  FIGS. 2A-2D .  FIG. 2A  shows a sheath  40  in a compressed position. The sheath  40  includes a ring member  42  and a sleeve  44 , the sleeve  44  extending distally from the ring member  42 . The ring member  42  is generally rigid so as to maintain the sheath  40  in a fixed position in situ, applying radial pressure to a body lumen. The sheath  40  is retained in a compressed position by a retention member  46 , as shown in  FIG. 2A . The retention member  46  is a suture which is wrapped around an inner portion  40   a  and an outer portion  40   b  of the sheath and ends of the suture  46  are fastened or knotted together at  46   a,  creating a closed loop around the sheath  40 .  FIG. 2A  shows two retention members  46  positioned about  180  degrees apart, so as to uniformly confine the sheath  40  to a shorter length at least for insertion. The retention members  46  may be moveably (i.e. slideably) positioned on the sheath  40  (as shown). Alternately, the retention members  46  may be positioned at a fixed location or series of locations along the circumference of the sheath  40 . It is also contemplated that more than two retention members  46  may be used to confine the sheath  40  to a shorter length. Once the sheath  40  is positioned in a body lumen, a user may sever and optionally remove the retention members  46 . The sheath  40  may then be elongated distally past an anastomotic site, enabling fluids to bypass the anastomotic site and protecting the anastomotic site throughout the wound healing cycle. It should also be understood that although the illustrated sheaths have a ring member, various embodiments of sheaths, with or without ring members, may be used in combination with the retention members of the present disclosure. 
         [0020]    The sheaths shown in  FIGS. 2B-2D  are similar, with various embodiments of retention members.  FIG. 2B  illustrates retention members  150  being formed surgical staples having a generally “B”-shaped geometry. The retention members  150  have at least two legs ( 150   a ) which are connected therebetween by a backspan  150   b.  It should be noted that although the legs of the staples ( 150   a,    150   b ) overlap exterior to the sheath, the legs of the staples ( 150   a ) may overlap on the interior portion  140   a  of the sheath  140 , with the backspan  150   b  positioned exterior to the sheath  140 . Two retention members  150  are shown positioned approximately 180 degrees apart so as to uniformly compress the sheath  140 . It is contemplated that more than two retention members  150  may be used to retain the sheath  140  in a compressed position. The retention members  150  may be positioned at a fixed location or series of locations along the circumference of the sheath  140  (as shown). Alternately, the retention members  150  may be slideably positioned on the sheath  140 . In one embodiment, the retention members  150  may be shape memory polymeric or metallic surgical staples, which once positioned in situ, the retention members  150  may self expand upon reaching body temperature, releasing the sheath  140  from a compressed position and enabling the sheath  140  to longitudinally extend to a second position (not shown). The retention members  150  may be removed from the body once the sheath  140  has been released. 
         [0021]    Alternatively, the retention members may be pins or strings which pierce at least a portion of the sheath.  FIG. 2C  illustrates the sheath  240  in which the sleeve  244  is rolled proximally, towards the ring member  242 .  FIG. 3A  illustrates a cross-sectional view of the sheath  240  (of  FIG. 2C ), including a retention member  260  which defines an elongate body, such as a pin or a suture, penetrating at least a portion of the sheath  240 . More specifically, the sleeve  244  defines an outer wall  244   b  and inner wall  244   a,  the distance between which defines a wall thickness w 2 . The ring member  242  also has a wall thickness w 1  , which is the diameter of the ring member  242 , the ring member  242  being circular in cross-sectional area. The retention member  260  penetrates at least a portion of the sleeve and the ring member. 
         [0022]    The retention member  260  includes at least two ends, a first end of the retention member  260  penetrates the wall thickness w 2  of the sleeve  240 , and a second end of the retention member  260  penetrates at least a portion of the wall thickness w 1  of the ring member  242 . Alternatively, the retention member  260  may only penetrate the sleeve  244 . The elongate body  260  runs through the walls of the sleeve  244  and ring member  242 , connecting the first end to the second end. As shown, the retention member penetrates the sheath  240  along a centerline. The ends of the retention member  260  may include a portion which is tacked or welded at  260   a  to the sleeve  244 . Alternatively, at least one end  260   b  of the retention member  260  may be secured to the sheath  240  by piercing the sheath wall and knotting or tying the ends of the retention member  260 . The retention member  260  retains the sheath  240  in a compressed position and the two ends of the elongate body  260  prevent the sheath from unraveling. When at least one end of the retention member is severed ( FIG. 3B ), the sheath  240  may be elongated distally past an anastomotic site. It should be noted that although the retention member  260  penetrates both sleeve  244  and the ring member  242 , the retention member  260  may penetrate the sheath  240  at any point or series of points, which enables the sheath  240  to be restricted in a compressed position. 
         [0023]    In another embodiment, a retention member  370  may encapsulate at least a portion of the sheath  340 . For example, as shown in  FIG. 20 , the retention member  370  may be similar to a balloon or a net, surrounding or encapsulating the entire sheath  340 , maintaining the sheath  340  in a compressed position. The retention member  370  may be severed or pierced and the retention member  370  may be removed in situ, allowing the sheath to expand to a second, longer length. In some embodiments, the retention member  370  may comprise a water soluble material, e.g. gelatin or cellulose, wherein the retention member  370  may dissolve upon contact with fluids and the sheath  340  can be longitudinally extended past an anastomotic site. 
         [0024]    In alternate embodiments, retention members may include polymeric materials which, for example, upon drying, would assist in maintaining the sheath in a compressed state. For example, certain polymeric materials, including polymer solutions, may be processed with the sheath. The sheath may be folded, rolled, or crimped into a compressed position. The sheath may then be dried in an oven or at ambient temperature and upon evaporation of the polymer solution, the dried polymer coating (retention member), retains the sheath in a shorter, compressed position. Upon implantation into tissue, the retention member may wet or hydrate, allowing the sheath to expand into a second, longer position. Suitable polymeric materials include but are not limited to those listed below including polysaccharides such as starch, alginate or chitosan and water soluble adhesives. Suitable water soluble adhesives include succinimide-based PEG esters, photocurable vinyl adhesives and aldehydes. 
         [0025]    Retention members may comprise both absorbable and non absorbable materials, which may be synthetic or natural materials. Suitable synthetic absorbable materials include polymers such as those made from lactide, glycolide, caprolactone, valerolactone, carbonates (e.g., trimethylene carbonate, tetramethylene carbonate, and the like), dioxanones (e.g., 1,4-dioxanone) i5-valerolactone, 1,dioxepanones (e.g., 1,4-dioxepan-2-one and 1,5- dioxepan-2-one), ethylene glycol, ethylene oxide, esteramides, y-hydroxyvalerate, —hydroxypropionate, alpha-hydroxy acid, hydroxybuterates, orthoesters, hydroxy alkanoates, tyrosine carbonates, polyimide carbonates, polyimino carbonates such as poly (bisphenol A-iminocarbonate) and poly (hydroquinone-iminocarbonate), and polymer drugs (e.g., polydiflunisol, polyaspirin, and protein therapeutics) and copolymers and combinations thereof. Suitable natural absorbable polymers include, fibrin, proteins (e.g. albumin, collagen, gelatin, casein, lactoferrin), and gut and combinations thereof. Additionally, polysaccharides may also be used to as retention members, including agarose, cellulose, carboxymethyl cellulose, methyl cellulose, dextran (e.g. carboxylated dextran, aminated dextran, sulfonated dextran), alginates, chitosan, hyaluronic acid, and fucans. Synthetic polymers and natural polymers may also be combined to make retention members of the enclosed disclosure. 
         [0026]    Suitable non-absorbable materials which may be used to form the retention member include non-absorbable natural materials such as cotton, silk, and rubber. Suitable non-absorbable synthetic materials include monomers and polymers derived from materials such as nylons, polyolefins such as polypropylene and polyethylene, ultra high molecular weight polyethylene (UHMWPE), polyamides, polyesters such as poly ethylene terepththalate (PET), polyaryletherketone, polyvinylidene difluoride (PVDF), acrylics such as poly acrylic acid, aramids, fluoropolymers, polybutesters, silicones, and polymer blends, copolymers thereof and combinations with degradable polymers. Hydrophilic vinyl polymers and copolymers such as acrylic acid, polyvinylpyrrolidone, methacrylic acid, potassium sulfopropyl acrylates, bisacrylates, methacrylates including hydroxyethyl methacrylate (HEMA), methacryloyloxyethyl phosphorylcholine (MPC), acrylamide, polypyrrole, vinyl acetate, styrene sulfonic, and hydroxyamates may also be employed as suitable materials for retention members. Combinations and copolymers of various non-absorbable materials may also be used as retention members. Additionally, non-absorbable synthetic and natural polymers and monomers may be combined with each other and may also be combined with various absorbable polymers and monomers to create the retention member. 
         [0027]    In other embodiments, the retention member may be constructed using shape memory materials. A thermal shape memory material may be used in certain described embodiments, such as the staple-shaped retention member, where upon temperature activation of a material, the retention member opens and releases a portion of the sheath, allowing it to elongate. Suitable polymers used to prepare hard and soft segments of shape memory polymers include polycaprolactone, dioxanone, lactide, glycolide, polyacrylates, polyamides, polysiloxanes, polyurethanes, polyether amides, polyurethane/ureas, polyether esters, and urethane/butadiene copolymers and combinations thereof. 
         [0028]    Absorbable metallic materials may also be used to construct retention members. Suitable absorbable metals and metal alloys include magnesium-based and iron-based alloys. The magnesium-based alloys may additionally include about 1 to 10 wt. % scandium, up to about 3 wt. % yttrium, about 1 to 3 wt. % rare earth metal, and about 0.1 to 0.5 wt. % zirconium. 
         [0029]    It should be noted that the present disclosure is not limited to use with specific sheaths for use with colonic and intestinal anastomoses and contemplates retaining other sheath embodiments. Additionally, the above description contains many specifics; these specifics should not be construed as limitations on the scope of the disclosure herein but merely as exemplifications of particularly useful embodiments thereof. Those skilled in the art will envision many other possibilities within the scope and spirit of the disclosure as defined by the claims appended hereto.
A sheath is configured for elongation from a first length to a second, longer length and a retention member retains the sheath at the first length. A portion of the retention member is removed or disengaged, the sheath is released and expands in situ to the second longer length. A method for releasing the retention member is also disclosed.