Abstract:
A valve assembly for the sealed reception of a surgical instrument inserted through a cannula assembly includes a valve body defining a central longitudinal axis, and an elongated seal member having a resilient sealing structure defining an aperture in general alignment with the central longitudinal axis. The sealing structure includes a plurality of elongated bristle members positioned to engage the outer surface of the surgical instrument in a fluid-tight manner upon at least partial insertion of the instrument into the valve body. Each bristle member is adapted to be displaced relative to the longitudinal axis to facilitate expansion of the aperture to accommodate variously sized surgical instruments. Bristle members are arranged in a pattern facilitating the reduction of the insertion force required to introduce an instrument while providing robust lateral support for the instrument.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/931,254 filed on May 22, 2007, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to an access apparatus for providing access to an underlying surgical site, and, more particularly, relates to an access apparatus incorporating a novel seal mechanism adapted to permit ease of insertion of a surgical instrument while providing a substantial seal about the instrument upon manipulation during the surgical procedure. 
         [0004]    2. Background of Related Art 
         [0005]    Surgical access apparatii are employed in various minimally invasive procedures including laparoscopic or endoscopic procedures. Such access apparatii are inclusive of portals, trocar cannulas, catheters, or, in the event of a minimally invasive hand assist procedures, hand access devices. Surgical access apparatii typically incorporate a seal mechanism to form a fluid tight seal about an instrument or hand passed through the portal. The seal mechanisms, however, often are limited, in part, due to the large insertion forces required to pass the object through the seal of the seal mechanism. In addition, off-axis movement of the instrument within the seal may be too difficult or easy depending on the type of seal employed within the portal. Moreover, the seal mechanisms are also limited by their ability to sustain their integrity when the surgical instrument is angulated. Such extreme ranges of motion of smaller diameter surgical instruments within the portal can create a “cat eye” or crescent shaped gap about the instrument resulting in fluid loss (e.g., insufflation gas loss). 
       SUMMARY 
       [0006]    Accordingly, the present disclosure is directed to a surgical access assembly for sealed reception of an elongated object. The surgical access assembly includes an access member having at least one opening configured and dimensioned to permit entry of an elongated object and being adapted for positioning within tissue to provide access to an underlying surgical site. A seal member is mounted relative to the access member. The seal member includes an outer substrate and a plurality of flexible bristle members extending radially inwardly from the outer substrate to the central longitudinal axis. The bristle members define free ends remote from the outer substrate and being adapted to flex and form a substantial seal about the elongated object. The bristle members are arranged to define a varying density of the seal member adjacent the free ends of the bristle members to effect at least one of insertion force or lateral stability of the seal member. The bristle members are dimensioned to define a thickness or density which is greater at the free ends thereof relative to remaining portions of the bristle members. The bristle members of the seal member may be arranged to define a cross-sectional dimension of the seal member tapering toward the central longitudinal axis. 
         [0007]    The bristle members may define varying lengths. Alternatively, the seal member may define a series of tapered segments of the bristle members. Each tapered segment define a general saw tooth arrangement of the bristle members. The bristle members further extend from the substrate in a general axial direction relative to the central longitudinal axis. The bristle members may be arranged in a general spiral wound relative to the central longitudinal axis. 
         [0008]    In another embodiment, a surgical access assembly for sealed reception of an elongated object includes an access member having at least one opening configured and dimensioned to permit entry of an elongated object and defining a central longitudinal axis. The access member is adapted for positioning within tissue to provide access to an underlying surgical site. A seal member is mounted relative to the access member. The seal member includes an outer substrate and a plurality of flexible bristle members extending radially inwardly from the outer substrate to the central longitudinal axis. A first set of bristle members is arranged to define a first aperture and to pivot upon insertion of the elongated object such that the free ends of the first set of the bristle members are displaced to expand an aperture for passage of the elongated object therethrough in substantial fluid-tight relation therewith. A second set of bristle members is arranged to define a second aperture greater than the first aperture whereby a congregation of the free ends of the second set of the bristle members provides substantial lateral support to the elongated object. The first set and the second set of the bristle members may be arranged to define a plurality of discrete steps of the seal member. The first and second apertures of the respective first and second sets of the bristle members each may define an internal dimension which is constant along respective axial lengths thereof. The seal member includes at least three sets of the bristle members with a third set of the bristle members being arranged to define a third aperture greater than the second aperture whereby a congregation of free ends of the third set of the bristle members provides substantial lateral support to the elongated object. The seal member includes at least four sets of the bristle members with a fourth set of the bristle members being arranged to define a fourth aperture greater than the third aperture whereby a congregation of free ends of the fourth set of the bristle members provides substantial lateral support to the elongated object. At least one of the first and second sets of the bristle members may include a plurality of radial slots extending toward the central longitudinal axis. The radial slots facilitate passage of the elongated object through the seal member. In the alternative, the at least one of the first and second sets of the bristle members define generally triangular flaps between adjacent radial slots. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure. 
           [0010]      FIG. 1  is a perspective view with parts separated of an access apparatus in accordance with the principles of the present disclosure, illustrating a cannula assembly, an obturator assembly positionable within the cannula assembly and a seal assembly; 
           [0011]      FIG. 2  is an enlarged perspective view with parts separated of the seal assembly of  FIG. 1  illustrating the seal housing and the seal member; 
           [0012]      FIG. 3A  is an enlarged perspective view of a flat brush profile for use as the seal member; 
           [0013]      FIG. 3B  is an enlarged perspective view of the seal member formed with the flat brush profile of  FIG. 3A ; 
           [0014]      FIG. 4  is a side elevational view of an alternate embodiment of the seal member of  FIGS. 3A-3B ; 
           [0015]      FIGS. 5-6  depict alternative brush profiles which may be used to form the seal member; 
           [0016]      FIG. 7A  is a perspective view of an alternate embodiment of a seal member having a step brush profile; 
           [0017]      FIG. 7B  is a cutaway perspective view of the seal member of  FIG. 7A ; 
           [0018]      FIG. 8  is a side plan view in partial cross section of the access apparatus of  FIGS. 7A-7B ; 
           [0019]      FIG. 9  is an enlarged, partial cross-sectional view of the area of detail indicated in  FIG. 8  illustrating a surgical instrument inserted through the seal assembly; 
           [0020]      FIG. 10  is a view similar to  FIG. 9  illustrating the adaptability of the seal assembly to variously sized surgical instruments and radial movement of those instruments; and 
           [0021]      FIGS. 11-14  are views illustrating alternate embodiments of the seal assembly of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0022]    In the drawings and in the description which follows, the term “proximal”, as is traditional, will refer to the end of the apparatus which is closest to the clinician, while the term “distal” will refer to the end which is furthest from the clinician. 
         [0023]    The present disclosure contemplates the introduction into a body cavity of all types of surgical instruments including clip appliers, graspers, dissectors, retractors, staplers, laser fibers, photographic devices, endoscopes and laparoscopes, tubes, and the like. All such objects are referred to herein as “instrument(s)”. 
         [0024]    Referring now in detail to the drawing figures, in which like references numerals identify similar or identical elements, there is illustrated, in  FIG. 1 , a surgical system in accordance with the present disclosure. System  10  has particular application in laparoscopic procedures with respect to accessing the abdominal cavity, and the like, and may be used in any such surgical procedure where the peritoneal cavity is insufflated with a suitable gas, e.g., CO 2 , to separate the cavity wall from the internal organs housed therein. System  10  includes cannula assembly  100  and obturator assembly  200 , which is positionable therein. 
         [0025]    Obturator assembly  200  includes obturator  202 , which includes obturator housing  204  and sleeve or outer member  206  extending therefrom. Obturator housing  204  is advantageously dimensioned for grasping by a clinician. Obturator  202  further includes penetrating member  208  within sleeve  206 . Penetrating member  208  punctures the abdominal cavity or the like, thereby creating an access point through which at least a portion of a surgical procedure may be conducted. Sleeve  206  may be adapted to retract upon insertion into tissue to expose penetrating member  208  to permit the penetrating member  208  to incise the tissue. Alternatively, penetrating member  208  may be adapted to advance within sleeve  206 . Following penetration, obturator assembly  200  is removed from cannula assembly  100  to permit the subsequent introduction of surgical instrumentation utilized to carry out the remainder of the procedure through cannula assembly  100 . 
         [0026]    Referring still to  FIG. 1 , cannula assembly  100  will be discussed. In one embodiment, cannula assembly  100  includes cannula housing  102  and cannula member  104  having an outer wall  106  and defining longitudinal axis “A”. Cannula member  104  defines an internal longitudinal lumen  108  within outer wall  106  dimensioned to permit the passage of surgical instrumentation therethrough. Either or both of cannula housing  102  and cannula member  104  may be opaque or transparent, either wholly or in part, and may be fabricated from any biocompatible material including metals or polymers. Cannula housing  102  also incorporates cannula valve  110 , and stabilizing plate  112  which secures the cannula valve  110  to cannula housing  102 . Cannula valve  110  is a zero closure valve adapted to assume a substantially closed position in the absence of an instrument to prevent passage of gases therethrough. In one embodiment, cannula valve  110  is a duckbill or trumpet valve. Cannula housing  102  further includes stop cock valve  114  which is connectable to a source of insufflation fluids to distribute the fluids to the underlying body cavity. 
         [0027]    Referring now to  FIG. 2  in conjunction with  FIG. 1 , instrument seal assembly  300  of the present disclosure is adapted to provide a substantial seal between a body cavity of a patient and the atmosphere outside the patient while an instrument is inserted through the cannula assembly  100 . Seal assembly  300  may be formed integrally with cannula assembly  200 , or may preferably be detachably mounted to cannula assembly  200 . Additionally, seal assembly  300  may be readily adapted to be mounted to conventional cannulas of differing structures. Among other advantages, the detachability of seal assembly  300  facilitates the removal of irregularly shaped body tissue and reduces the profile of the cannula whenever the seal assembly is unnecessary for a portion of the surgical procedure. 
         [0028]    Seal assembly  300  includes end cap  302 , stabilizer plate  304 , seal member  306  and seal housing  308 . End cap  302 , stabilizer plate  304  and seal housing  308  form the outer seal body of seal assembly  100 , which houses the sealing component, i.e., seal member  306 . End cap  302  is generally cylindrically-shaped and includes proximal end portion  310  defining a diameter which is less than the diameter of the remaining portion of the end cap  302 , and an inner peripheral ledge  312  which supports stabilizer plate  304 . Seal housing  308  includes central opening  314 , inner cylindrical portion  316  and distal outer flange  318  having a scalloped surface to facilitate handling thereof. Cylindrical portion  316  is received within end cap  302  when the seal assembly  300  is fully assembled to enclose the sealing components. Seal housing  308  includes peripheral groove  320  and two opposed ribs  322  extending radially inwardly adjacent the groove  320 . Groove  320  and ribs  322  assist in mounting seal assembly  300  to cannula assembly  200  as will be appreciated from the description provided below. Seal housing  308  also includes second groove  324  adjacent opening  314  for accommodating seal member  306 . 
         [0029]    Referring now to FIGS.  2  and  3 A- 3 C, seal member  306  includes substrate  326  and a plurality of bristle members  328  attached to the substrate  326  and extending therefrom. Bristle members  328  define aperture  330 , which as will be described in greater detail below, need not be dimensioned uniformly through the seal member  306 . As best depicted in  FIG. 3A , substrate  326  may be formed as a u-shaped channel such that a plurality of perpendicularly projecting bristle members  328  may be clamped therein by crimping the ends of the u-shaped channel. Alternatively, substrate  326  may be a strip of adhesive material, an overmolded element molded onto one end of bristle members  328  or the like. Each bristle member  328  thus will have a secured end  332  adjacent to substrate  326  and a free end  334  opposite the secured end  332 . Of course, other similar methods may be used to provide a generally flat substrate with bristle members  328  projecting perpendicularly from a single face of the substrate. This arrangement defines a flat brush profile wherein all bristle members are generally the same length. A generally flat surface is formed by the free ends  334  of the bristle members  328  being generally parallel to substrate  326 . 
         [0030]    Bristle members  328  are preferably fabricated from an elastomeric material such as synthetic or natural rubber which is preferably sufficiently resilient to accommodate and provide a substantial seal with instruments of varying diameters. The geometry of bristle members  328  is preferably long and slender. 
         [0031]    Flat substrate  326  is curved to form a generally round ring structure to provide seal member  306  generally as seen in  FIG. 3B . With this arrangement of substrate  326 , bristle member  328  are directed radially inwardly to define aperture  330  with free ends  334  of the bristle members  328  in close proximity with each other as compared to secured ends  332  of the bristle members  328  which substantially maintain their spacing near the substrate  326 . This congregation of free ends  334  of bristle member  328  can result in a higher bristle density at the center of the ring near aperture  330  than at the outer regions near substrate  326 . If the number and geometry of bristle member  328  is sufficient, a saturation point may be reached where free ends  334  of the bristle member  328  require more space than is available within the confines of the cylinder defined by the substrate  326  thereby resulting in opposed bulges  336  formed near the center of the ring as can be seen in the alternate embodiment of  FIG. 4  whereby free ends  334  have an axial component of direction. Seal member  306  arranged in this manner can provide robust lateral support for relatively small instruments having outer dimensions approximating the diameter of aperture  330 . 
         [0032]    To provide for a decreased insertion force, particularly for larger instruments, several alternate brush profiles may be considered. For example, a tapered brush profile, as shown in  FIG. 5 , can produce a seal member having a lower required insertion force for larger instruments. This is because fewer bristles will need to compete for the limited space near the aperture  330 , and fewer bristles will need to bend to accommodate the instrument. This arrangement is characterized by a brush profile which is uniform along the length of the substrate  326  with a decreasing bristle cross-sectional dimension in the direction of the free ends of the bristles. Depending on the decrease in bristle cross-section, when this profile is formed into a ring, any bulge created in the case of the straight brush profile may be reduced or eliminated resulting in a relatively thin seal member. 
         [0033]    Alternatively, a saw-tooth brush profile as shown in  FIG. 6  may be provided. The saw-tooth profile is characterized by bristle members  328  arranged in groups or sets  350  shaped to form a triangular arrangement along the length of the substrate  130 . Each series  350  has a base  352  formed by the secured ends of bristle members  328 , vertex  354 , and two sides  356  formed by the free ends of the bristle members  328 . As the substrate  326  is formed into a round ring shape, the triangular teeth will begin to converge as the bristles begin to compete for space. Only the longest bristles forming vertex  354  will reach the center of the ring to define the aperture of the seal thereby resulting in a reduced bristle density at the center of the ring. At several internal diameters of the ring, the free ends of the bristles forming the sides of the triangular arrangement will tend to congregate forming multiple bands where relatively robust lateral support will be provided. 
         [0034]    Referring now to  FIGS. 7A and 7B , a stepped brush profile may be provided to create interior rings of high bristle density at the free ends of the bristles and corresponding lateral stiffness. This profile is characterized by bristles of several discrete lengths protruding from the substrate and arranged in distinct steps. The profile depicted in  FIGS. 7A and 7B  of seal member  400  includes seven distinct linear levels or annular steps. Preferably, the longest bristles members are centrally located extending from the center of the substrate  402  to form the tallest step  404  with the shorter steps  406 ,  408 ,  410  arranged in descending order on each side of substrate. With this arrangement, seven bands or annular steps of relatively high lateral stiffness will be formed at the levels where the free ends congregate. Each step  404 ,  406 ,  408 ,  410  defines a central aperture with the dimension of the apertures increasing relative to each other toward each of the proximal end distal faces of seal member. This high lateral stiffness will tend to prevent an instrument from slipping radially between the bristles and compromising the fluid-tight seal. Alternatively, steps could be arranged in descending order from one end of the substrate to the other and a seal member may include a different number of steps. 
         [0035]    Referring to  FIGS. 8 and 9 , seal member  400  of  FIGS. 7A and 7B  is shown mounted to cannula assembly  200 . An elongated object such as a surgical instrument, identified generally by reference numeral “i” may be inserted through central aperture  412  of seal assembly  400  and the cannula assembly  200  to perform the desired surgical procedure. As the surgical instrument “i” enters seal assembly  400 , the tip of the surgical instrument “i” is engaged by the bristle members of the seal assembly  400 . In one arrangement, first (most proximal) step  406  of bristles does not engage the instrument, and the second step  408  of bristles engages the instrument without substantial bending. Steps  410  and  404  are shown as engaging the outer surface of the surgical instrument and pivoting distally to permit passage of the instrument “i”. The remaining distal steps  406 , 408  do not engage the instrument “i”, but must pivot to accommodate the pivoting of the adjacent bristles. The second proximal step  408  of bristles provides a robust lateral support for the instrument while steps  410 ,  404  create the fluid-tight seal. This arrangement is possible due in part to the design of the individual bristles to be relatively strong in buckling when loaded axially when compared to the strength in bending when loaded obliquely. The weakness in bending is desirable because it facilitates the introduction of surgical instruments, while the strength in buckling is desirable it assists in maintaining a central position for the instrument where it can engage sealing bristle members on all sides. Having a step sized such that the bristles forming that step do not bend substantially allows for the axial loading of those bristles by the surgical instrument. The flexibility of the bending bristles permits relatively easy passage of instrument “i” through the seal assembly  400 . The ease of instrument passage is further enhanced by the arrangement of the bristle members into a stepped profile because no force is required to pivot the bristle members forming the shortest steps on the proximal end of the seal member, and a reduced force is required to pivot any corresponding steps on the distal end of the seal member which only need to pivot in order to accommodate the displacement of the longer bristles actually forming the fluid-tight seal about the instrument. Instrument “i” is advanced through the cannula assembly  200  whereby the duck-bill seal  208  of the cannula  200  also spreads to allow passage of instrument i. Once positioned within the instrument-seal  400  and cannula assembly  200 , surgical instrument “i” may be maneuvered about the internal body cavity. 
         [0036]    Referring now to  FIG. 10 , surgical instrument “i” is shown having a lateral offset relative to the central longitudinal axis “k”. The seal assembly  100  permits limited unencumbered movement of instrument “i” in a lateral direction (relative to the central longitudinal axis) while maintaining an adequate seal about the instrument. Thus, manipulation of the instrument in any direction, either, longitudinally or radially, will not affect the integrity of the seal, since the resilient material of sealing member  110  will conform to the movements of the instrument and assume a shape necessary to retain a sealing contact with the instrument. 
         [0037]      FIGS. 11-13  illustrate another alternate embodiment of a seal member. Seal member  500  illustrates a flat brush design incorporating bristle members  502 ,  504  having varying lengths extending from substrate  506 . In particular, bristle members  502  have a length which is less then the lengths of bristle members  504 . In one embodiment, bristle members  504  are centrally located. In the alternative, bristle members  502 ,  504 , may be arranged in alternating manner to define several series of bristle members  502 ,  504 . When substrate  506  is wound for placement in the seal housing, seal member  500  defines a multilayer arrangement of bristle members with varying aperture sizes due to the varied lengths of bristles  502 ,  504  (see  FIG. 13 ). 
         [0038]      FIG. 15  illustrates an alternate embodiment of the seal member. In accordance with this embodiment, seal member  600  includes substrate  602  and bristle members  604 . Bristle members  604  are of constant length. Substrate  602  is arranged such that the outer diameter of the substrate  602  is varied. This arrangement allows for portions of the seal member to expand axially (here the center coil or substrate  602 ) as the instrument is inserted. 
         [0039]      FIG. 16  is another embodiment where seal member  700  has a series of triangular-shaped bristle arrangements  702 . Each bristle arrangement  702  includes a plurality of steps having a central located step  704 , first lateral steps  706  on each side of the central located step  704  and second lateral steps  708  adjacent respective first lateral steps  706 . Seal member  700  formed from this profile is capable of providing high lateral support in predetermined diameters while maintaining a low insertion force. 
         [0040]      FIG. 17  shows a seal member  800  created from a stack of substantially flat flexible components  802  having various inner diameters. Each component  802  may have a substrate around its outer circumference where the component is substantially solid. Relatively large, roughly triangular-shaped elements  804  are disposed between a plurality of slits  806  extending through the components. The components are stacked or in superposed relation such that elements  804  and slits  806  are staggered whereby no continuous linear passage extends through seal member  800 . Elements  804  may be formed of bristles or alternatively fabricated from a suitable solid elastomeric material. 
         [0041]    Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.