Abstract:
A seal for use with a trocar. The seal includes a first portion terminating in a proximal end, a second portion terminating in a distal end, and a connecting region disposed between the first and the second portion. At least one longitudinal slit extends from the connecting region toward one of the proximal end, toward the distal end, or toward both. When the seal is in an unstressed state, the seal provides a fluid barrier and when the seal is in a stressed state, the at least one longitudinal slit opens to provide access to the inner portion of the seal.

Description:
[0001]     The invention relates to a seal useable with a trocar for introducing surgical instruments, guidewires, dilators, catheters, or similar instruments into a patient. The seal is in a closed (or sealed) position when no instrument is inserted in the seal (i.e., when the seal is in an unstressed condition) and is opened when an instrument is inserted in the seal (i.e., a stressed condition).  
         [0002]     A trocar is a surgical instrument that is used to gain access to a body cavity to perform, for example, laparoscopic or arthroscopic surgery and endoscopic procedures. In order to penetrate the skin and underlying tissue, the distal end of the obturator has a sharp point or cutting edge at its distal end. By applying pressure against the proximal end of the obturator, the sharp point is forced through the skin until it enters the body cavity. The trocar tube is inserted through the perforation made by the obturator and the obturator is withdrawn, leaving the trocar tube as an access way to the body cavity.  
         [0003]     A housing that defines a chamber having an open distal end portion that communicates with the interior lumen defined by the trocar tube typically adjoins the proximal end portion of the trocar tube. An obturator and other surgical implements or tools axially extend into and are withdrawn from the trocar tube through the distal end portion of the chamber. It is the present practice to provide the chamber with a sealing means, such as a sealing grommet or gasket, through which the obturator or other implements extend.  
         [0004]     Seals for trocars are known and two examples of such are described in U.S. Pat. No. 5,350,364 and U.S. Pat. No. 5,788,676. In U.S. Pat. No. 5,350,364, the seal has a generally hourglass shape that defines converging and diverging sidewalls that form a constricted center bore. The seal is open when no instrument is present and the seal acts against the instrument after the instrument is inserted to form a fluid (gas or liquid) seal. To minimize or control the deflection of the seal, a rib cage is provided on the outer surface of the seal.  
         [0005]     U.S. Pat. No. 5,788,676 describes a seal having a pair of conical shapes joined at their tips by a cylindrical member. The seal has a number of slits from one end toward the other. When an instrument is inserted, a compressible member that acts on the outer portion of the conical shapes and cylindrical member to provide a fluid seal biases the seal to a contracted or closed position. This patent also describes that the seal can be biased by the compressible member to a closed or fluid sealing position when no instrument is inserted.  
         [0006]     The art therefore teaches a seal that provides a fluid (gas or liquid) seal when an instrument is inserted into or longitudinally through the seal. The present seal, on the other hand, seeks to provide a zero closure seal that does not provide a fluid (gas or liquid) seal when an instrument is present in the seal (i.e., in the stressed condition), which allows an instrument to be easily inserted and removed from the seal.  
       SUMMARY  
       [0007]     The present invention is an introducer valve or zero closure seal for a trocar that provides a fluid (gas or liquid) seal in an unstressed condition, i.e., when there is no instrument present in the valve or seal and does not provide a fluid (gas or liquid) seal in a stressed condition, i.e., when an instrument is present. The seal may be formed from an expandable, stretchable, and/or elastic material such as an elastomeric material, rubber, latex, silicone, and other known materials.  
         [0008]     The seal has a first portion and a second portion with a connecting region interposed between the two portions. The first portion is defined between the proximal end and the connecting region and the second portion is defined between the distal end and the connecting region. The first portion of the seal may have any suitable shape such as duckbill, conical, pyramidal, or multisided (3, 4, 5, etc.). Likewise, the second portion of the seal may have any suitable shape such as duckbill, conical, pyramidal, or multisided (3, 4, 5, etc.). In one embodiment, the seal tapers inwardly from the proximal end to the connecting region and tapers outwardly from the connecting region to the distal end such that it may resemble an hourglass from one side. Typically, the first and second portion will have the same shape and the first and second portion may have the same size, although it is not necessary.  
         [0009]     At least one, and desirably, more than one, longitudinal slit is provided in the seal. The longitudinal slit extends from the connecting region toward one of the proximal end or the distal end or both. The longitudinal slit, however, does not extend the entire length to intersect the proximal end or the distal end. The longitudinal slit may be provided at any desirable location on the circumference of the seal. If the first or second portion is multisided, it may be convenient to provide the slit at an edge of a side.  
         [0010]     The presence of the longitudinal slit(s) allows the seal to easily open when an instrument is inserted into or withdrawn from the seal; yet allows the seal to be in a closed condition when no instrument is present. In other words, although the connecting region can surround a penetrating instrument, the seal does not provide a fluid seal when an instrument is present, i.e., when the seal is in a stressed condition.  
         [0011]     The seal may be provided with one or more stiffeners that can be disposed on the outer surface of the seal or within the material forming the seal. The stiffeners are generally oriented longitudinally along substantially the entire length of the seal to establish and/or maintain the seal in a closed position when the seal is in an unstressed condition.  
         [0012]     As noted above, the seal is useful with a trocar and therefore, in one aspect, a trocar is provided that includes a seal according to the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective view of one embodiment of the seal according to the present invention and with the seal in an unstressed condition.  
         [0014]      FIG. 2  is a perspective view of the embodiment of the seal of  FIG. 1  and with the seal in a stressed condition, i.e., with an instrument inserted into the seal.  
         [0015]      FIG. 3  is a cross-sectional view of the seal shown in  FIG. 1 , along line  3 - 3 .  
         [0016]      FIG. 4  is a cross-sectional view of the seal shown in  FIG. 1 , along line  4 - 4 . 
     
    
     DESCRIPTION  
       [0017]     Turning now to  FIG. 1 , a seal  10  that is usable with a trocar (not shown) is depicted. The seal  10  has a first portion  20 , a second portion  30 , and a connecting region  40  disposed between and connecting the first portion  20  and the second portion  30 . The first portion  20  is defined between the connecting region  40  and the proximal end  22 . The second portion  30  is defined between the connecting region  40  and the distal end  32 . The seal  10  is also provided with at least one longitudinal slit  50 . When the seal  10  is in a stressed condition, a central longitudinal passageway  60  is provided a central longitudinal axis  62 .  
         [0018]     The proximal end  22  may terminate in a proximal rim or flange  24 . Likewise, the distal end  32  may terminate in a distal rim or flange  34 . The proximal flange  24  and the distal flange  34  may have any suitable size and may have a circumference that closely approximates the inner circumference of the housing. In such an instance, the rims or flanges  24 ,  34  may help to support or locate the seal  10  within the trocar housing (not shown). In this regard, it may be desirable if the proximal flange  24  had a greater outer diameter or circumference than the distal flange  34 . By providing this difference in size, the distal flange  34  can float within the trocar housing. As a result, fluid that is present in the trocar housing and that is moving from the distal end  32  toward the proximal end  22  of the seal  10  will assist in closing or sealing the longitudinal slits  50 , when the seal  10  is in the unstressed condition.  
         [0019]     Alternatively, the distal flange  34  can have the same size as the proximal flange  24 . If the distal flange  34  has approximately the same outer circumference as the inner circumference of the housing, then it is desirable if the distal flange  34  is provided with one or more gaps or holes to allow fluid to move from the distal end  32  toward the proximal end  22  and thus apply pressure on the outer portion of the seal between the distal end  32  and the proximal end  22  to assist in closing or sealing the longitudinal slits  50 , when the seal  10  is in the unstressed condition.  
         [0020]     Although each of the rims or flanges  24 ,  34  can have the same circumferential shape as the first  20  and second  30  portions of the seal  10 , it is desirable if the rims or flanges  24 ,  34  have a circular shape. By providing a circular shape, the seal  10  can be used with the known trocars, which typically have a cylindrical shape.  
         [0021]     The first portion  20  of the seal may have any suitable shape such as duckbill, conical, pyramidal, or multisided (3, 4, 5, etc.). Likewise, the second portion  30  of the seal may have any suitable shape such as duckbill, conical, pyramidal, or multisided (3, 4, 5, etc.). Typically, the first  20  and second  30  portion will have the same shape, although it is not necessary. Likewise, the first  20  and second  30  portion may have the same size, although it is not necessary. In one embodiment, the exterior surface  70  (and the interior  72  surface when the seal  10  is in an unstressed condition) of the seal  10  tapers inwardly from the proximal end  22  to the connecting region  40  and tapers outwardly from the connecting region  40  to the distal end  32  such that it may resemble an hourglass from one side.  
         [0022]     As noted above, the seal  10  may have a duck bill shape. Accordingly, just below the proximal flange  24 , the first portion  20  may be provided with opposite walls that are planar and converge downwardly toward the connecting region  40 . Beginning at the connecting region  40 , the second portion  30  may be provided with opposite walls that diverge outwardly and downwardly from the first portion planar walls to terminate just before the distal flange  34 . The second portion planar walls comprise return panels that protect the integrity of the seal formed in the connecting region by resisting the tendency of instruments to disturb the seal by inverting the first portion planar walls when passing through the seal  10 .  
         [0023]     The inner surface  72  of the seal and, in particular, the portion where the inner surface of the connecting region  42  abuts defines a seal slit  44  that is closed when the seal  10  is in the unstressed condition, as shown in  FIG. 3 . The seal slit  44  will generally have a shape that is defined by the shape of the first portion  20  and the second portion  30 . Therefore, depending on the geometry of the first  20  and second  30  portions, the seal slit  44  may extend straight across the seal  10  or it may come to a point, or be curved, Y-shaped, X-shaped, or the like. For example, as best seen in  FIG. 4 , four sides are provided and the seal slit  44  comes to a point.  
         [0024]     The seal  10  is also provided with at least one longitudinal slit  50  that extends from the exterior surface  70  through the interior surface  72 . The longitudinal slit  50  may extend from the connecting region  40  toward one of the proximal end  22  or toward the distal end  32  or both. The longitudinal slit  50  does not extend the entire length to intersect the proximal end  22  or the distal end  32 . Accordingly, the longitudinal slit  50  does not intersect the proximal flange  24  or the distal flange  34 , if present.  
         [0025]     The longitudinal slit  50  may be provided at any desirable location on the circumference of the seal  10 . If the first portion  20  or second portion  30  is multisided, it may be convenient to provide a slit  50  at an edge of a side. The longitudinal slit  50  allows the connecting region  40  to more easily deform and outwardly expand when the seal  10  is in a stressed condition. Desirably, the seal  10  is provided with two longitudinal slits  50 , with the slits  50  being opposite each other. More desirably, the seal  10  is provided with four longitudinal slits  50 .  
         [0026]     The presence of the slit(s)  50  allows the seal  10  to easily open when an instrument  80  is inserted into or withdrawn from the seal; yet allows the seal  10  (and the seal slit  44 ) to be in a closed condition when no instrument  80  is present. In other words, although the connecting region  40  can surround a penetrating instrument  80 , the seal  10  does not provide a fluid seal when an instrument  80  is present, i.e., when the seal  10  is in a stressed condition.  
         [0027]     The seal  10  will generally be compliant enough to allow an instrument  80  to pass through the seal  10 , and sufficiently resilient to return to its original shape once the instrument  80  is removed. In this regard, the seal  10  is formed of a material that, when the seal  10  is in an unstressed condition, the inner surface  72  of the seal and, in particular the seal slit  44  will be in a closed sealing position. At the same time, the seal  10  will generally be capable of easily passing any instrument  80  having the desired size. Typically, instruments  80  used with the seal  10  will have a size in the range from about 5.0 mm to about 10 mm in diameter.  
         [0028]     The seal  10  is typically a one-piece assembly with a wall thickness sufficient to withstand and maintain peritoneal overpressure within the trocar shell. The seal  10  may be formed of an expandable, stretchable, and/or elastic material such as an elastomeric material, polyurethane, nitrile, thermoplastic elastomer, rubber, latex, silicone and other known materials. The seal  10  may be formed from an elastic material having a Shore hardness of about 20 to about 50.  
         [0029]     The seal  10  may be provided with one or more stiffeners  90  that can be disposed on a surface of the seal or within the material forming the seal  10 . The stiffeners  90  are generally oriented longitudinally along substantially the entire length of the longitudinal slit  50  and may extend the entire length of the seal  10  or to the flanges  24 ,  34 . The stiffeners  90  aid in establishing or maintaining the seal  10  in a closed position when the seal  10  is in an unstressed condition. The stiffeners  90  can be located adjacent the edge of the longitudinal slit  50 , as shown in  FIG. 1  or in the area between two longitudinal slits  50 , as shown in  FIG. 2 . The stiffeners  90  can then aid in maintaining the longitudinal slits  50  and the seal slit  44  in a substantially closed or a closed position when the seal  10  is in an unstressed condition.  
         [0030]     Alternatively, the seal  10  may be provided with varying wall thicknesses strategically located to aid in moving or maintaining the longitudinal slits  50  in a closed or substantially closed position.  
         [0031]     The length of the seal  10  may be configured to engage a valve body provided within the trocar housing. The seal  10  may be symmetrical in relation to its longitudinal axis  62 , to exert equal push and pull forces upon the instrument  80  and to ensure that the valve body cannot be incorrectly assembled. It is not necessary, however, that the seal  10  be symmetrical or that the first portion  20  and the second portion  30  converge at the center of the seal  10 .  
         [0032]     The inner surface  72  of the seal may be coated with a lubricant such as a hydrogel material or silicon to minimize or reduce the frictional forces while inserting or moving instruments inside the seal  10 .  
         [0033]     Referring now to  FIG. 2 , as a penetrating instrument  80  such as a guidewire or other instrument is inserted into the seal  10 , the connecting region  40  and the seal slit  44  expand to define a stressed condition of the seal  10 . At the same time, the longitudinal slits  50  expand such that the edges  52  of the longitudinal slits are disposed away from each other. As a result, the seal  10  allows passage of fluids through the longitudinal slits  50 .  
         [0034]     It is to be understood that, while the invention has been described above in conjunction with the specific embodiments, the description is intended to illustrate and to limit the scope of the present invention, which is defined by the scope of the claims.