Abstract:
A cannula assembly for use in laproscopic surgery includes a cannula having a proximal end for use in orientating the assembly into an abdominal cavity, a distal end for insertion into a patient, and a passage through which surgical instruments can be inserted. An expandable feature in the form of an anchor is located toward the distal end of the cannula and is selectively expandable and collapsible. The feature in its expanded state prevents withdrawal of the cannula. A collar is pushed distally until it releasably cinches to the outside of the abdominal cavity thereby creating an airtight seal and stabilizing the assembly. The collar has a friction fit with the cannula designed to prevent excessive force against the cavity walls.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/881,830, filed Oct. 13, 2015; which is a divisional of U.S. application Ser. No. 14/195,395, filed Mar. 3, 2014 (now U.S. Pat. No. 9,155,550); which is a continuation of U.S. application Ser. No. 13/913,120, filed Jun. 7, 2013 (now abandoned); which is a continuation of U.S. application Ser. No. 12/802,032, filed May 28, 2010 (now U.S. Pat. No. 8,466,659); which is a continuation of U.S. application Ser. No. 11/430,431, filed May 9, 2006 (now abandoned); which is a divisional of U.S. application Ser. No. 10/680,973, filed Oct. 7, 2003 (now U.S. Pat. No. 7,041,055); which claims the benefit of U.S. Provisional Application No. 60/416,665, filed Oct. 7, 2002; U.S. Provisional Application Nos. 60/424,752; 60/424,754; and 60/424,755, each filed Nov. 8, 2002; U.S. provisional Application Nos. 60/425,506; 60/425,522; and 60/425,523, each filed Nov. 12, 2002; and U.S. Provisional Application No. 60/439,759, filed Jan. 13, 2003; all of which are incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    This invention relates to a stabilized cannula adapted to seal against the loss of gas pressure from a body cavity of a patient during a surgical procedure. 
         [0004]    Description of the Prior Art 
         [0005]    The insertion of a cannula into an abdominal cavity during laparoscopic surgery is generally accomplished using one of two methods. In the first method, a hollow needle is inserted into the body cavity prior to the insertion of the cannula so that the cavity can be expanded with a gas, such as carbon dioxide. Thereafter, the cannula is inserted along with a removable sharp obtruator. The obtruator blade cuts through the abdominal wall allowing the surrounding cannula to penetrate into the interior of the cavity. The obtruator is then removed leaving an entry port for various laparoscopic tools to be inserted into the cavity. The cannula is equipped with a seal at its proximal end to ensure that the cavity remains pressurized with the insertion and removal of various instruments. Pressure loss between the cannula and the cavity wall is reduced by the tightness of the fit between the cannula and the cavity wall because the outside diameter of the cannula is larger than the obtruator entry wound. Generally, the obtruator used in this method is equipped with a spring-activated shield that is designed to cover the blade as soon as the interior wall is penetrated to avoid inadvertent puncturing of the organs present inside the cavity. These shields sometimes fail to close quickly enough to avoid injuries, particularly if an organ such as the bowel is attached to the cavity wall. 
         [0006]    A known method that avoids injuries associated with the obtruator shield involves direct incision of the wall by the surgeon. Using a small scalpel, the surgeon makes an incision through the cavity wall into the abdominal cavity and inserts a finger into the cavity to feel for organs that might be attached to, or near the abdominal wall. Upon a determination that no organs are attached to the abdominal wall, a cannula with an obtruator having a blunt tip is inserted through the cut. After placement of the cannula, the obtruator is removed. The purpose of the blunt tip of the obtruator is to guide the cannula through the cut down to wound. 
         [0007]    Both of the above described methods of insertion are prone to gas leakage and the lack of a proximal-to-distal stability of the cannula. Various techniques have been attempted to minimize these problems. Known anchors for use with laparoscopic cannula have employed threaded sleeves adapted to be secured to the cannula and screwed into a laparoscopic puncture opening to secure the instrument in place. An anchor of this type is found in U.S. Pat. No. 5,217,441. U.S. Pat. No. 5,002,557 to Hasson discloses an inflatable balloon that seals the cannula against the inside wall of the cavity and stabilizes the cannula by employing a tapered collar that cinches against the outside wall of the cavity, in effect sandwiching the cavity wall between the collar and the inflated balloon. The Hasson device provides a sufficient seal and adequate cannula stability, but is difficult to operate. The balloon must be inflated with an external hypodermic syringe or other means through a stop cock. Additionally, sealing the cannula with the cavity wall involves three steps: inflating the balloon, pushing a tapered collar snugly against the external surface of the cavity wall, and securing the collar in place with a set screw. U.S. Pat. No. 5,697,946 to Hopper et al. discloses a balloon-anchoring device that does not require the use of a proximal collar, but instead relies on a portion of the inflating surface to come in contact with the entry wound, thereby wedging the cannula into position. The Hopper device also involves an external inflation device such as a hypodermic syringe connected to the cannula by a stop cock or check valve. 
         [0008]    U.S. Pat. No. 5,330,497 to Freitas et al. describes an anchored cannula that uses an expandable mushroom-shaped anchor that in one embodiment opens when the user turns a detented actuator. The anchor cinches-up against the peritoneum when a seal is forced distally. The Freitas device offers an improvement over threads, but still suffers from several drawbacks. In particular, the Freitas device is unduly complex at least in that it requires multiple steps in order to expand the anchor and seal the external cavity wall. A multiplicity of steps during a surgical procedure can lead to a serious inefficiency. Devices that are simple to operate make the procedure more efficient and lead to less errors. Therefore what is needed is a simple, easy-to-use cannula anchoring and sealing device and method for use in laparoscopic surgery. 
       SUMMARY OF THE INVENTION 
       [0009]    In accordance with the purposes of the present invention, as embodied and broadly described herein, a cannula assembly of this invention is provided for permitting the insertion of instruments into a body cavity. The cannula assembly includes a proximal end, a distal end, and a longitudinal axis, an inner sleeve, an outer sleeve coaxial with the inner sleeve, and a collar. The outer sleeve is fixedly attached to the inner sleeve at the distal end of the cannula and has an exterior surface. The outer sleeve forms an anchor that is radially expandable from the longitudinal axis from a retracted position to an expanded position to anchor the cannula assembly to the body of a patient. The collar has an internal surface adapted to form a friction fit with the exterior surface of the outer sleeve to permit the collar to move a portion of the outer sleeve relative to the inner sleeve and move the anchor from the retracted position to the expanded position when the collar is moved toward the distal end of the cannula assembly. The friction fit between the collar and the outer sleeve is configured to permit the collar to move relative to the outer sleeve only toward the distal end of the cannula assembly when the anchor is in the expanded position. 
         [0010]    In accordance with the purposes of another embodiment of the present invention, as embodied and broadly described herein, a method of this invention is provided for anchoring and sealing a cannula assembly to the body of a patient. The method includes providing the cannula assembly having a proximal end, a distal end, a radially expandable anchor proximate the distal end, and a longitudinally movable collar; inserting the cannula assembly to a depth sufficient to place the anchor in a retracted position within the patient; and expanding the anchor by moving the collar toward the distal end of the cannula assembly. 
         [0011]    Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
         [0012]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
         [0013]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a side elevation view of a cannula assembly according to one preferred embodiment of the present invention having an anchor in a retracted position; 
           [0015]      FIG. 2  is a side elevation view of the cannula assembly of  FIG. 1  with the anchor deployed in the abdominal cavity in an expanded position and a collar distally applied against the exterior of the abdominal cavity; 
           [0016]      FIG. 3  is a fragmentary cross-sectional side view of the cannula assembly of  FIG. 1  with the anchor shown in the retracted position; and 
           [0017]      FIG. 4  is a fragmentary side elevation view of the cannula assembly of  FIG. 1  with the anchor shown in the expanded position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0019]      FIGS. 1-4  show a trocar cannula assembly for use with the present invention generally referred to by the number  100 . As shown in  FIG. 1 , cannula assembly  100  includes a cannula  102  having a distal end  104 , a proximal end  106  opposite distal end  104  along a longitudinal axis L, an inner sleeve  108 , and an outer sleeve  110  that is preferably coaxial with inner sleeve  108 ; and a movable annular collar  112 . 
         [0020]    As shown in  FIG. 3 , inner sleeve  108  has an interior surface  114  forming a passage  116  through which one or more instruments may pass, and an exterior surface  118 . Referring again to  FIG. 1 , inner sleeve  108  has a proximal portion  120  that preferably includes a valve and/or seal to maintain pressure when the cannula is inserted into a pressurized cavity. 
         [0021]    As shown in  FIGS. 1 and 3 , outer sleeve  110  has an interior surface  122  and an exterior surface  124 . At least a portion of interior surface  122  is preferably adapted for slidable engagement with exterior surface  118  of inner sleeve  108 . Outer sleeve  110  forms an anchor  126  preferably located toward distal end  104  of cannula  102 . Anchor  126  provides stability to the cannula assembly when deployed within the abdominal cavity, as will be described in more detail below. 
         [0022]      FIG. 3  shows anchor  126  preferably having a plurality of finger hinges  128  that are each separated by a slit  130 . When anchor  126  moves from a retracted position shown in  FIG. 3  to an expanded position shown in  FIG. 4 , fingers  128  radially expand away from longitudinal axis L of cannula  102  to anchor the cannula assembly to the patient. In order to prevent internal tissue from becoming entangled within fingers  128 , anchor  126  preferably includes a flexible cover membrane  132 . Cover  132  may be resilient to bias anchor  126  to the retracted position to permit easy insertion of cannula  102  into the abdominal cavity. 
         [0023]    Inner sleeve  108  and outer sleeve  110  are preferably joined at distal end  104  of cannula  102  by conventional bonding materials. It will be appreciated by those skilled in the art that other ways to join the inner and outer sleeves together, whether chemically (e.g., glue), physically (e.g., ultrasonically weld or heat application), or mechanically, may be used and are within the broad scope of the present invention. 
         [0024]      FIG. 1  shows an annular collar  112  preferably surrounding at least a portion of exterior surface  124  of outer sleeve  110 . Annular collar  112  preferably has an internal surface that forms a friction fit with exterior surface  124  to sealingly engage the outer surface of the body cavity when anchor  126  is inserted into the patient and deployed. Preferably, annular collar  112 , outer sleeve  110 , and inner sleeve  108  are constructed such that the force of the friction fit between annular collar  112  and outer sleeve  110  is greater than the friction force acting between outer sleeve  110  and inner sleeve  108 . This may be accomplished, for example, by selecting a material and snugness of fit between annular collar  112  and exterior surface  124  of outer sleeve  110  and the fit between internal sleeve  108  and outer sleeve  110 . This permits inner sleeve  108  to move relative to outer sleeve  110  before annular collar  112  will move relative to outer sleeve  110 . The interaction between inner sleeve  108 , outer sleeve  110 , and annular collar  112  is described in more detail below. It will be appreciated that annular collar  112  may exist in a variety of shapes and sizes, and need not completely surround outer sleeve  110  in order to function for its intended purpose. 
         [0025]    Having described the physical components of one preferred embodiment of the present invention, a method for its operation will now be described. Returning now to  FIG. 1 , cannula assembly  100  is positioned proximate the surgical site to be operated upon, such as the abdominal cavity, with annular collar  112  in its proximal-most position and anchor  126  in the retracted position. An obtruator is placed through proximal portion  120 , into passage  116  of inner sleeve  108 , and beyond distal end  104  of cannula  102 . 
         [0026]    The distal-most end of the obtruator is generally blade-shaped and punctures the abdominal cavity, allowing cannula  102  to be forced into the defect. Cannula  102  is inserted into the puncture to a sufficient depth so that anchor  126  is below the peritoneum of the abdominal cavity. The obtruator is then removed from cannula  102 . 
         [0027]    With cannula assembly  100  properly positioned and inserted into the abdominal cavity, anchor  126  is deployed. Holding proximal portion  120  stationary, annular collar  112  is moved away from proximal portion  120  toward distal end  104 . Annular collar  112  is preferably tightly fitted around external surface  124  of outer sleeve  110  to form a friction fit such that movement of annular collar  112  will cause a corresponding movement of a movable portion  134  of outer sleeve  110 , which includes anchor  126 . As annular collar  112  moves in the distal direction, movable portion  134  of outer sleeve  110  runs against a stationary portion  136  of outer sleeve  110 , which is joined to inner sleeve  108  at distal end  104 . Finger hinges  128  of anchor  126  radially expand away from longitudinal axis L to deploy anchor  126  into an arc shape so that anchor  126  moves from the retracted position shown in  FIG. 3  to the expanded position shown in  FIG. 4 . As annular collar  112  and outer sleeve  110  continue to move distally, anchor  126  becomes fully deployed. 
         [0028]    Once anchor  126  becomes fully deployed, movable portion  134  of outer sleeve  110  reaches its maximum longitudinal distance of travel and becomes stationary. At this point, the force of the friction fit between annular collar  112  and outer sleeve  110  is overcome by the force being applied to move annular collar  112  toward distal end  104 . Annular collar  112  begins to move relative to outer sleeve  110  and cinches-up against the outer surface of the abdominal wall as shown in  FIG. 2 . After annular collar  112  is sufficiently pressed against the skin so that both sides of the abdominal cavity are sealed between annular collar  112  and anchor  126 , annular collar  112  and proximal portion  120  are released. 
         [0029]    While released, annular collar  112  and anchor  126  maintain a compression of the abdominal wall between them. Movement of annular collar away from the abdominal wall is retarded by the friction fit between annular collar  112  and outer sleeve  110 . Anchor  126 , owing to the resiliency of membrane  132  and to the elasticity of fingers  128 , supplies a force that tends to restore the position of outer sleeve  110  relative to inner sleeve  108  to its original position. The surfaces and/or materials of outer sleeve  110  and inner sleeve  108  are designed such that the friction force between them counters the restoring force of anchor  126 . Thus, after annular collar  112  is moved distally and anchor  126  is deployed, the friction force between inner sleeve  108  and outer sleeve  110  is larger than the restoring force being exerted from anchor  126  such that the relative position of inner sleeve  108  and outer sleeve  110  is maintained once cannula assembly  100  is released. A sufficient seal between anchor  126  and annular collar  112  is maintained in part because the force of the friction fit between annular collar  112  and outer sleeve  110  is greater than the friction force acting between inner sleeve  108  and outer sleeve  110 , which in turn acts to overcome the force biasing anchor  126  to the retracted position. 
         [0030]    After the surgical procedure, cannula assembly  100  is removed from the abdominal cavity by moving annular collar  112  toward proximal end  106  of cannula  102 . Because the friction force of the friction fit between annular collar  112  and outer sleeve  110  is greater than the friction force between outer sleeve  110  and inner sleeve  108 , outer sleeve  110  and inner sleeve  108  move relative to each other with a proximal movement of annular collar  112 . Anchor  126  collapses to the retracted position as shown in  FIG. 3 , thus permitting the withdrawal of cannula assembly  100  from the patient. 
         [0031]    To summarize, the user holds proximal portion  120  in one hand and annular collar  112  in the other hand and applies a force separating the two. This action moves portion  134  of outer sleeve  110  and inner sleeve  108  relative to one another, and therefore deploys anchor  126 . As annular collar  112  and the movable portion of outer sleeve  110  continue to move toward distal end  104 , anchor  126  becomes fully deployed. Thereafter, annular collar  112  begins to move relative to outer sleeve  110  and cinches-up against the skin. The friction fit force between annular collar  112  and outer sleeve  110  is preferably sized such that the force needed to overcome the friction fit force to move annular collar  112  relative to outer sleeve  110  is within the safe limits to prevent over insertion of cannula assembly  100  into the abdominal cavity. 
         [0032]    Cannula assembly  100  may be used in surgeries other than laproscopic surgery. Additionally, it will be appreciated that other forms of anchors may be used with the cannula of the present invention and still remain within the broad scope of the present invention. 
         [0033]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.