Abstract:
A bioprosthesis sealing film strip is attached to a surgical stapler by passing a jaw of the stapler through openings formed in the ends of the strip. Following stapling the strip is released by making a cut from the opening to the edge of the strip. Alternatively, one end of the strip may be releasably secured to pins formed on the jaw.

Description:
This invention relates to surgical stapling guns, and more particularly to a bioprosthesis film strip to prevent air leaks at the staples in lung surgery, and to a method of attaching the strip to a stapling gun. 
    
    
     FIELD OF THE INVENTION 
     In various soft tissue surgery applications such as, for example, the resection of diseased lung tissue, surgeons use linear stapling guns to staple together layers of tissue on each side of a proposed cut along which the diseased tissue is to be severed from the healthy tissue. These stapling guns consist of a pair of elongated jaws which are clamped over, e.g., a lung from which a cancerous lobe is to be removed. One of the jaws carries a cartridge containing parallel rows of biocompatible staples positioned end-to-end, while the other carries parallel rows of anvils for those staples. Once the staples have been placed, a scalpel is drawn lengthwise between the staple rows to sever one stapled lung portion from the other. 
     Because of the nature of lung tissue, air leakage occurs at the points where the staples pierce the lung tissue, This leakage continues until the lung tissue heals around the staples, thus requiring lengthy hospitalization of the patient. To mitigate this problem, it has been proposed to drive the staples through a bioprosthetic film, which can act as a gasket or sealant to the lung tissue punctured by the staples. Suitable materials for this purpose are natural materials such as glutaraldehyde fixed bovine pericardium, or man-made materials such as collagen absorbable hemostat, vicryl (polygalacrin) mesh, or ePTEE (expanded polytetrafluoroethylene). 
     A problem arises when strips of these materials are to be applied to the jaws of the stapler in such a way that they can be conveniently released from the jaws after the stapling operation. For example, one prior method involves suturing a strip of bioprosthetic film to a strip of polyethylene backing to form a sleeve. One of these sleeves is then slipped over each jaw of the stapler, with the strip facing inward. After the stapling operation, the edges of the strips must be cut free of the hacking and Sutures, which are discarded. This method requires caution on the part of the surgeon to avoid leaving remnants of the backing or sutures in the patient. 
     Other methods of attachment have involved the use of glue or adhesive tape, but none of these are simple and satisfactory, A need therefore exists for a method of attaching a bioprosthetic film strip to a stapler jaw which is easy, reliable and allows the strip to be readily severed from the jaw. 
     SUMMARY OF THE INVENTION 
     The present invention fulfills the above-identified need by providing a flat bioprosthetic film strip with apertured ends. In one preferred embodiment of the invention, the perforated ends of the strip are simply turned our of the plane of the strip, and the jaw is slipped through them. 
     After the stapling, the strip can be released from the jaws in the preferred embodiment by cutting the strip adjacent the apertures, and the entire strip can be left in the patient. 
     In another preferred embodiment of the invention, the scrip can be secured to the jaw at the proximal end or at both ends with the aid of retaining pins from which ft can slip off when the jaws are opened following the stapling procedure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is an elevational view of a lung showing a stapled and severed lobe; 
     FIG. 1 b  is a section of the severed lobe edges along line  1   b - 1   b  of FIG. 1 a ; 
     FIG. 2 is a perspective view of a typical stapling gun used for the stapling operation of FIG. 1; 
     FIG. 3 is a plan view of a preferred embodiment of a bioprosthetic film strip used in the invention: 
     FIG. 4 is a perspective view of the jaws of the stapler of FIG. 2 with the strips of FIG. 3 attached; 
     FIG. 5 is a plan view of a bioprosthetic film strip in an alternative embodiment of the invention; and 
     FIG. 6 is a perspective view of a stapler using the strip of FIG. 5 a ; 
     FIG. 7 is a side elevation of stapler jaws with the strip of FIG. 3 attached; and 
     FIG. 8 is a section along line 8-8 of FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates an environment in which the present invention is useful. In that figure, it will be assumed that a lung  10  has a lobe  12  which is diseased and must be surgically removed. This is done by compressing the lung  10  between the jaws of a stapler  14  (FIG. 2) along a line  16  and stapling the lung with two parallel sets of rows of surgical staples  18  on each side of the line  16 . The lung tissue is then cut along line  16  by a scalpel blade  17  traveling along a channel  19  (FIG. 8) between the two sets of rows. Typically, several overlapping stapled cuts are made at an angle to each other (see FIG. 1 a ). 
     In order to prevent excessive air leak from the lung tissue  20  (FIG. 1 b ) where it has been perforated by the staples  18 , the staples  18  are conventionally driven through strips of a bioprosthetic sealing material  22  such as bovine pericardium, collagen absorbable hemostat, vicryl mesh or ePTFE. These materials effectively seal the punctured lung. 
     FIG. 2 illustrates the stapler  14  which is used in the above-described procedure. The stapler  14  includes a handle  24  and a pair of jaws  26 ,  28 . The jaws  26 ,  28  can be widely separated, like the jaws of pliers, prior to use, and then closed and compressed against each other in use. The jaw  26  carries a cartridge of staples  18 , while the jaw  28  carries the anvil  30 . In the use of the stapler  14 , strips of the sealing material  22  (FIGS. 3 and 4) are placed over the staples  18  on jaw  26 , and over the anvil  30  on the jaw  28 . The strips  22  must be so mounted on the jaws  26 ,  28  that they are firmly held on the jaws  26 ,  28  but can be quickly and simply detached from the jaws  26 ,  28  in order to allow the jaws  26 ,  28  to be separated following the stapling. 
     Prior art solutions to this problem have included several different approaches. In one approach, a polymer backing was sutured to the strips  22  along their longitudinal edges, so that the strip and backing would form a sleeve which could be slipped over the jaws  26 ,  28 . Following application of the staples, the sutures were cur, and the backing was removed, This was unsatisfactory because it required the cutting of a substantial number of sutures and the removal of the backing, all while holding the stapler in the closed position - a task sometimes exacerbated by misalignment of the sleeve with the jaw. Thus, this prior art approach presented a risk of accidentally leaving backing and suture fragments in the patient. 
     In another approach, biocompatible adhesives or adhesive rape were used to temporarily secure the strips  22  to the jaws  26 ,  28  but allow them to separate from the jaws when the jaws were opened. This was also unsatisfactory because it introduced additional foreign substances into the body, and because a repeatable acceptable compromise between sufficient adhesion for handling and sufficient releasability to avoid damaging the strips  22  after stapling was difficult to attain. 
     In accordance with a preferred embodiment of the invention, the above-described disadvantages are eliminated by providing strips  22  which extend longitudinally beyond the stapling area of the jaws  26 ,  28 , and which have at least one hole, of a diameter approximating the diameter of the jaws, formed in the extended portion. 
     FIG. 3 shows that preferred embodiment of the invention. In that embodiment, the strip  22  has a central portion  32  whose length corresponds to the length of the stapling area of the jaw  26  or  28 . At each end of the central portion  32 , the strip  22  has an extension  34   a  or  34   b.  In the embodiment of FIG. 3, the extensions  34   a  has formed therein an opening  36   a  of appropriate size and shape (preferably rounded to provide an interference fit along the corners of the square jaws  26 ,  28 ) to allow passage of the jaw  26  or  28  therethrough. Preferably, the opening  36   a  in extension  34   a  is small enough to fit snugly over the distal end of jaw  26  or  28 . In the extension  34   b,  an opening  36   b  is formed, and the strip  22  is cut along line  39 . When the outer end of the extension  34   b  is lifted out of the plane of strip  22 , the tongue  35  remains in the plane of the strip  22 , The opening  36   b  in extension  34   b  is large enough w fit somewhat loosely, though with a small interference fit, over the proximal end of jaw  26  or  28 . 
     The actual size of the openings  36   a  and  36   b  is dictated by several factors. On the one hand, the openings  36  must be large enough to allow the surgeon or stapler operator to slip or slide the strip  22  along the jaws  26 ,  28 , yet small enough to hold the strip in position on the jaws  26 ,  28 . On the other hand, the openings  36   a  and  36   b  must not be so small as to cause difficulty in slipping the strip  22  onto the jaws  26 ,  28 , or to risk tearing the strip  22  during installation. As a practical matter, the openings  36   a  and  36   b  may be about 0.5-1.0 cm in diameter, the exact size depending upon the size and geometry of the jaws  26 ,  28 . The strip  22  may, for example, be about 2 cm wide for a staple cartridge width of 1 cm. 
     In a typical stapler (FIGS.  2  and  7 ), the staple cartridge  18  extends all the way to the proximal end of the jaw  26 . Because the end portion  34   b  of the strip  22  lies at an angle to the jaw  26  or  28  (FIG. 7) when in stapling position, the end portion  34   b  is pre-cut along line  39  (FIG.  3 ). By bending the outer end of the extension  34   b  out of the plane of the strip  22 , the opening  36   b  can be slipped over the end of the jaw, but the tongue  35  remains in the plane of strip  22  and covers the staple cartridge  18  or anvil  30  all the way to (he proximal end of the jaw  26  or  28 . 
     In use, the extensions  34   a  and  34   b  are bent out of the plane of the strip  22 , as shown in FIG. 4, and are simply slipped over the jaw  26  or  28 . The resiliency of the flexible strip material (e.g. bovine pericardium) holds the strip  22  securely to the jaw  26  or  28 . Following the stapling operation, the scalpel blade  17  is actuated to cut the lung tissue and the strips  22  along the dotted line  37 . To release the strips  22  from the stapler, scalpel cuts are made by the operator at  38  in the protruding end portions  34   a  and  34   b . Because in a typical stapler, the blade  17  does not travel all the way to the distal end of the stapling cartridge  18  (see FIG.  7 ), a further scalpel cut is needed at  43  after the jaws  26 ,  28  are removed to completely sever the healthy lung tissue and stapled strip halves from the diseased lung tissue and the stapled strip halves associated therewith. 
     FIGS. 5 a  and  6  illustrate another preferred embodiment of the invention. In that embodiment, the stapler  14  has one or more pins  40  formed at the proximal end of at least one of the jaws  26 ,  28 . The extension  34   b  has formed therein not a large opening  36   b,  but rather one or more small openings  42  that are preferably slightly smaller in diameter than the pins  40 . 
     In the embodiment of FIGS. 5 and 6, the strips  22  are attached to the jaws  26 ,  28  by slipping opening  36  in extension  34   a  over the jaw  26  or  28 , and then slipping the openings  42  of both strips  22  over the pins  40  on the jaw  26 . The resilience of the strip material holds the strip  22  on the pins  40  prior to stapling but allows the scrip  22  to easily be pulled free of the pins  40  when the jaws  26 ,  28  are opened following stapling. It would also he possible to use pins  40  on both jaws  26 ,  28  and small openings  42  on both ends of the strip  22 , in which case the opening  36  is unneeded (FIG. 5 b ). In that case, the strips  22  can be secured by simply hooking the openings  42  over the pins  40  and pushing the strips  22  against the stapling surfaces of the jaws  26 ,  28 . With the diameter of the openings  42  being slightly smaller than the diameter of the pins  40 , a firm but readily releasable engagement of the openings  42  with the pins  40  is achieved. 
     It is understood that the exemplary bioprosthesis film strips for surgical stapler described herein and shown in the drawings represent only presently preferred embodiments of the invention. Indeed, various modifications and additions may be made to such embodiments without departing from the spirit and scope of the invention. Thus other modifications and additions may be obvious to those skilled in the art and may be implemented to adapt the present invention for use in a variety of different applications.