Patent Publication Number: US-2005131349-A1

Title: Shielded septum trocar seal

Description:
This is a non-provisional application claiming the priority of provisional application Ser. No. 60/529,455, filed on Dec. 12, 2003, entitled “Shielded Septum Trocar Seal,” which is fully incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention generally relates to medical access devices and, more specifically, to a shielded septum trocar seal.  
      2. Discussion of the Prior Art  
      Mechanical trocars typically include a cannula defining a working channel and a housing which encloses valves that function to inhibit the escape of insufflation gasses. The cannula of the trocar is adapted to be positioned across the abdominal wall of a patient using an obturator which is initially inserted into the working channel and then removed once the cannula is in place. Various elongated instruments can be inserted through the working channel of the trocar to reach and perform operative functions at a site within the abdomen. It is the function of the valves to engage the outer surface of such an instrument and form seals around the instrument to prevent the escape of insufflation gases.  
      Trocar valves are commonly formed from elastomeric materials which are highly susceptible to puncture and tearing by sharp instrument configurations. Since many instruments typically have sharp distal tips, it has become particularly desirable to protect the valves from these objects. More specifically, it is desirable to provide a mechanism that can protect the septum seal during the insertion of surgical instruments, to reduce the drag force encountered when placing or removing instruments through the seal, and to restrict septum seal movement in the axial direction of the seal and surgical instruments.  
     SUMMARY OF THE INVENTION  
      In one embodiment of the invention, there is disclosed a trocar assembly having a channel defined along an elongate axis, the trocar assembly being adapted to receive a surgical instrument, the trocar assembly comprising a septum seal disposed in the channel including a seal tip having a proximal facing surface, the seal tip including portions defining an orifice; and a septum shield including a tubular member having a proximal end and a distal end, and a plurality of blades or leaflets protruding distally from the distal end of the tubular member, the septum shield being placed inside the septum seal such that the blades or leaflets engage the proximal facing surface of the seal tip. The trocar assembly may further comprise a zero closure seal such as a double duckbill valve disposed in the channel outside of the septum seal. The septum shield operates to reduce the drag force and to minimize axial movement of the septum shield and the instrument during insertion and removal of the instrument through the septum seal. The septum shield further operates to center and guide the surgical instrument through the blades or leaflets before expanding the orifice of the septum seal. The septum shield may be formed from a rigid plastic material, and the septum seal may be formed of an elastomeric material including a low durometer polymer. The blades or leaflets of the septum shield may overlap or offset one another.  
      In another aspect of the invention, the septum shield may be placed inside the septum seal such that the blades or leaflets engage the septum seal radially of the portions defining the orifice. The orifice may be expandable to accommodate the instrument having a diameter of about 5 mm to about 15 mm. Each of the blades or leaflets has a distal tip that glides or rolls against the instrument during insertion and removal of the instrument. In another aspect, the distal tip of each of the blades may further comprise a first material having a first durometer and a second material distal to the first material having a second durometer. With this aspect, the first durometer may be greater than or equal to the second durometer, or the first durometer may be less than the second durometer. In another aspect, the trocar assembly may further comprise a second septum shield disposed outside of the septum seal.  
      By locating the blades or leaflets of the septum shield near the septum seal, the drag force required to insert or remove the instrument can be reduced by allowing the instrument to slide on a lubricious material of the septum shield rather than the soft, flexible material of the septum seal. In addition, the septum shield can be used to support the septum seal and reduce any axial movement of the septum seal as the instrument is introduced or removed from the septum seal. Moreover, the blades or leaflets may be offset from each other so that as the instrument is inserted or removed, the blades or leaflets will not hang up on each other and will overlap each other repeatedly in the same fashion.  
      In another embodiment of the invention, a valve assembly is disclosed that is adapted to receive a surgical instrument having a cross-sectional dimension, the valve assembly comprising a housing defining a channel extending therethrough along an elongate axis; a septum seal disposed in the housing having distal portions defining an orifice, the distal portions being expandable radially outwardly to enlarge the orifice; and a septum shield operably attached to the housing and engaging the septum seal outwardly of the orifice for enlarging the orifice, the septum shield being responsive to the instrument for enlarging the orifice in proportion to the cross-sectional dimension of the instrument, the septum shield including a proximal end and a distal end, the distal end comprising a plurality of blades, each of the blades having a distal end being adapted to engage the septum seal radially of the distal portions defining the orifice.  
      In yet another embodiment of the invention, a seal assembly is disclosed that is adapted to receive an elongate object and to form a seal around the object, the seal assembly comprising a housing defining a channel configured to receive the object moving generally axially through the channel; a septum extending across the channel of the housing; portions of the septum defining a hole adapted to receive the object with the septum portions engaging the object through the channel; and a septum shield placed within the housing having a proximal end a distal end, the distal end comprising a plurality of blades that facilitate guidance of the object toward the hole and enlargement of the hole in response to insertion of the object into the channel.  
      In yet another aspect of the invention, the material, durometer and shield geometry of the blades or leaflets may be modified to control the behavior of the septum shield as an instrument comes into contact with the septum shield. It is further contemplated that the septum shield would work to open and protect the septum seal during insertion and removal of an instrument yet deflect away from the instrument as the instrument is removed in order to avoid collapsing the shield, septum seal and shield inversion phenomena, and causing a lockup or jam as the instrument is removed from the trocar.  
      These and other features of the invention will become more apparent with a discussion of the various embodiments in reference to the associated drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are included in and constitute a part of this specification, illustrate the embodiments of the invention and, together with the description, explain the features, advantages and principles of the invention. In the drawings:  
       FIG. 1  is a side elevation view of a prior art trocar partially cut away to illustrate a zero closure valve;  
       FIG. 2  is a perspective view of a prior art trocar seal including a seal sleeve;  
       FIG. 3  is an enlarged cross-sectional view of a septum shield of the invention replacing the seal sleeve in  FIG. 2 ;  
       FIG. 4  is an enlarged cross-sectional view of a trocar seal including the septum shield of the invention;  
       FIG. 5  is an enlarged side view of the septum shield of the invention;  
       FIG. 6  is a bottom view of the blades or leaflets of the septum shield of the invention;  
       FIG. 7  is an enlarged side view of a septum shield in accordance with another embodiment of the invention;  
       FIG. 8  is a perspective view of a septum shield in accordance with another embodiment of the invention; and  
       FIGS. 9   a - 9   c  illustrate additional embodiments of the shield geometry of the invention. 
    
    
     DESCRIPTION OF THE INVENTION  
      A trocar of the prior art is illustrated in  FIG. 1  and designated generally by the reference numeral  10 . The trocar  10  is representative of many types of surgical access devices which include a housing  12  and a cannula  14  which is adapted to extend across a body wall  16  into a body cavity  18 . In the case of the trocar  10 , the cannula  14  is configured to extend through an abdominal wall  16  into a cavity, such as the abdominal cavity  18 . The housing  12  includes a chamber  21  which is defined by an inner surface  23 . This chamber  21  of the housing  12  communicates with a lumen  25  in the cannula  14  which is defined by an inner surface  27 .  
      The trocar  10  is commonly used in laparoscopic surgery wherein the abdominal cavity  18  is pressurized with an insufflation gas in order to provide for organ separation and otherwise increase the size of the operative environment. With these features, the trocar  10  is adapted to receive an instrument  28  having an elongate configuration and an outer surface  29 . The instrument  28  is illustrated to be a pair of scissors having a length sufficient to pass through the trocar  10  and into the cavity  18  to perform a surgical operation. Although scissors are illustrated in  FIG. 1 , it will be understood that the instrument  28  may include any variety of devices such as needles, retractors, scalpels, clamps and various other surgical devices.  
      The housing  12  is configured to provide structural support for a seal mechanism, which includes an aperture or septum seal  30  and a zero closure seal  32 . It is the function of these seals  30 ,  32  to prevent the escape of any pressurized fluid from the cavity  18  whether the instrument  28  is operatively disposed in the trocar  10  or whether the instrument  28  is removed from the trocar  10 . In either case, it is desirable that the valves  30 ,  32  be configured to produce minimal friction forces as the instrument  28  is inserted into and removed from the trocar  10 . Currently, the valve  30  will typically be formed of an elastomeric material so that the aperture  34  is biased to seal against the outer surface  29 . In order to avoid significant friction forces, this aperture  34  is preferably sized to a diameter slightly less than the diameter of the surface  29 . However, since various instruments and various diameters for the outer surface  29  may be required in a particular surgery, the valve  30  may have to be changed in order to accommodate a range of instrument sizes.  
      Referring to  FIG. 2 , there is shown a trocar seal  50  that is also presently being used. Trocar seal  50  comprises a seal housing  52 , a cannula seal  54 , a seal spacer  56 , a double duckbill valve  58 , a septum seal  60 , a seal sleeve  62 , and a seal cap  64 . A drawback of the trocar seal  50 , however, is that the seal sleeve  62  does not provide protection to tip  60   a  of the septum seal  60  during insertion of surgical instruments. Moreover, the seal sleeve  62  does not sufficiently reduce the drag force encountered when placing or removing instruments through the septum seal  60 , and restrict seal movement in the axial direction of the seal and surgical instruments.  
       FIG. 3  illustrates a septum shield  70  of the invention that may be used in place of the seal sleeve  62  in  FIG. 2  to protect septum seal  60  during the insertion and removal of surgical instruments. As explained above, the septum seal  60  operates to retain pneumoperitoneum while an instrument is placed through the respective trocar seal. The septum shield  70  of the invention includes a tubular member  72  having a proximal end and a distal end, and a plurality of blades or leaflets  74  protruding from the distal end of the tubular member  72 . The septum shield  70  is placed inside the septum seal  60  such that the blades or leaflets  74  cover the top or proximal surface of the septum seal  60 , including tip  60   a.    
      A feature of the septum shield  70  is it protects the seal  60  during the insertion of surgical instruments, it reduces the drag force encountered when placing or removing instruments through the seal  60 , it restricts septum seal movement in the axial direction of the seal and surgical instruments, and it is easy to manufacture. Similarly to the trocar seal  50  of  FIG. 2 ,  FIG. 4  illustrates the interior structure of a trocar seal  50   a  of the invention which comprises a seal housing  52   a , a cannula seal  54   a , a seal spacer  56   a , a double duckbill valve  58   a , a septum seal  60   a , a septum shield  70 , and a seal cap  64   a . The double duckbill valve  58   a  operates to provide zero seal when no instruments have been located through the trocar seal.  
      The septum seal  60   a  is preferably made of a soft, flexible material with an opening that expands to seal instruments ranging from about 5 mm to about 15 mm in diameter. Located within the cylinders of both the double duckbill valve  58   a  and the septum seal  60   a  is the septum shield  70  of the invention. The septum shield  70  may be formed of a rigid plastic cylinder, which operates to center and guide an instrument as it is inserted through the trocar seal  50   a  to the septum seal  60   a . An advantage of the septum shield  70  of the invention over the sleeve  62  as shown in  FIG. 2  is that the new design includes a plurality of blades or leaflets  74  that are molded into the rigid cylinder or tubular member  72 . The blades or leaflets  74  protrude distally of the cylinder or tubular member  72  to cover the top or proximal surface of the septum seal  60   a , including the tip  60   a .  FIGS. 5-8  illustrate additional views and embodiments of the septum shield  70  of the invention.  
      In another aspect of the invention, the blades or leaflets  74  may overlap one another and cover the proximal surface of the septum seal  60   a . As the septum expands to accommodate instruments ranging from about 5 mm to about 15 mm, the respective blades or leaflets  74  work to open or expand the septum seal  60   a  and protect the soft, flexible material of the septum from damage due to the surgical instruments. In order to avoid potential “lock-up” as instruments are removed, the septum shield  70  of the invention is designed to deform at the tip  74   a  of each blade or leaflet such that each individual leaflet&#39;s tip will roll inward toward the instrument and create a variable radius for the instrument to glide on as it is removed from the seal. As the tip  74   a  of each leaflet is deformed inward, the body or proximal portion of the blades or leaflets  74  are forced away from the axial position of the instrument. This characteristic is accomplished by providing two stress concentrations within the design of each leaflet. The distal stress concentration allows the tip of the leaflet to move inward while creating a moment to cause the body of the leaflet to move outward and away from the instrument. The proximal stress concentration allows each leaflet to move independently from each other and the support structure of the cylinder that each leaflet attaches to.  
      In previous designs as illustrated in  FIGS. 1 and 2 , the shields such as sleeve  62  had been mounted perpendicular to the instrument movement. In the invention, the blades or leaflets  74  as illustrated in  FIG. 3  are located within the conical shape of the septum seal  60   a . By locating the blades or leaflets  74  of the shield near the septum, the drag force required to insert or remove instruments can be reduced by allowing the instruments to slide on a lubricious material of the shield rather then the soft, flexible material of the actual septum. This is a significant advantage over the shields of the prior art. In addition, the shield  70  of the invention can be used to support the septum and reduce any axial movement of the septum as instruments are introduced or removed from the seal  60   a . Furthermore, the blades or leaflets  74  have been offset from each other and are not circumferential so that as the shield  70  is installed during manufacturing or after a large instrument has been removed, the blades or leaflets  74  will not hang up on each other and will overlap each other repeatedly in the same fashion.  
      In another aspect of the invention, the material, durometer and shield geometry of the blades or leaflets may be modified to control the behavior of the shield as instruments and tools come into contact with it. For example, referring to  FIG. 9   a , the tip  74   a  may comprise of a first material  80  having a first durometer and a second material having a second durometer. The first durometer may be greater than, equal to or less than the second durometer. In another aspect of the invention as illustrated in  FIG. 9   b , another layer  84  may be sandwiched between the septum seal  60   b  and the shield  70   b , the layer  84  may be formed of the same material as the shield  70   b  and may extend longer than the blades or leaflets  74   b . In yet another aspect of the invention as illustrated in  FIG. 9   c , a shield  70   d  is provided outside the septum seal  60   c . It is contemplated that the durometer or stiffness of inner shield  70   c  may be greater than, equal to or less than outer shield  70   d , and that inner shield  70   c  may be shorter in length than outer shield  70   d . It is further contemplated that the shields would work to open and protect the septum seal during insertion and removal of an instrument yet deflect away from the instrument as the tool is removed in order to avoid collapsing the shields, septum and shield inversion phenomena, and causing a lockup or jam as an instrument is removed from the trocar.  
      Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. For example, it is contemplated that the geometry, material, and placement of the blades or leaflets and shield may be modified for different applications. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of examples and that they should not be taken as limiting the invention.