Abstract:
A mechanism for locking a catheter to a port comprises an elongate body defining a flow passage, a port end of the elongate body adapted for attachment to a port, a collet end of the elongate body opposite the port end being biased toward an open configuration in which an in inner diameter of the collet end is sized to receive therein an end of a catheter to be coupled to the port and a tightening device mounted to the elongate body for movement relative thereto between a first position in which the collet end is released to the open configuration and a second position in which the collet end is constricted to a closed configuration in which the inner diameter of the collet end grips the end of the catheter to retain the end of the catheter therewithin.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Catheters are often used to form semi-permanent paths into the body so that fluids may be introduced to and removed from the body without repeatedly inserting needles or tubes. For example, a central port catheter is generally used to access the vascular system with a subcutaneous portion of the catheters tunneled from a location of the central port to a remote vessel access location. Thus, the location of the central port may be selected to maximize ease of access, and patient comfort, etc., while the target vessel is accessed at a desired remote location.  
         [0002]     The catheter is generally connected to the central port by inserting a barb extending from the port into a lumen of the catheter with a twist lock being tightened to the port housing to secure the port thereto. However, tightening of the lock adds a step to the procedure and may rotate the catheter around the barb, twisting the catheter body. This twisting may be transmitted to the distal end of the catheter, where it may move the distal end out of a desired positioning within the target vessel.  
       SUMMARY OF THE INVENTION  
       [0003]     In one aspect, the present invention is directed to a mechanism for locking a catheter to a port, comprising a elongate body defining a flow passage, a port end of the elongate body adapted for attachment to a port, a collet end of the elongate body opposite the port end being biased toward an open configuration in which an in inner diameter of the collet end is sized to receive therein an end of a catheter to be coupled to the port and a tightening device mounted to the elongate body for movement relative thereto between a first position in which the collet end is released to the open configuration and a second position in which the collet end is constricted to a closed configuration in which the inner diameter of the collet end grips the end of the catheter to retain the end of the catheter therewithin. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is a perspective view showing a catheter attachment collet lock according to an embodiment of the present invention; and  
         [0005]      FIG. 2  is a cross-sectional perspective view of a catheter attachment collet lock according to a further embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0006]     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The invention is related to medical devices used to withdraw fluids from and/or infuse fluids into the body. More specifically, the invention is related to a device for securely connecting a catheter to a central port.  
         [0007]     As described above, a catheter may be used in conjunction with a central port to facilitate repeated access to blood vessels. Regardless of its use, the central port is designed to be repeatedly connected to and disconnected from an external catheter, which in turn may be connected to an external medical device.  
         [0008]     The connection between a central port and a catheter is conventionally formed by pushing an open end of the catheter over a barb extending from the port with a passage in the barb providing fluid communication between a lumen of the catheter and a flow passage of the port.  
         [0009]     A catheter attachment apparatus and method according to the present invention eliminates the twisting and displacement common with conventional locks. In addition, the locking device according to the invention eliminates the difficulties inherent in handling the multiple parts that form current twist locks, by providing a lock more integrated with the central port. The attachment procedure is thus simplified as securing the catheter to the outlet of the port does not displace the distal tip and the integrated locking device is easier to handle, since there are no lose parts that may be dropped or misplaced.  
         [0010]     The embodiments of the present invention comprise an attachment collet that is fastened to the inlet/outlet of a central port, facing the catheter. The attachment collet is designed to receive one end of the catheter and to compress it, thereby mechanically retaining it therewithin. For example, the catheter may be retained against the collet by friction. A barb may extend from the port along the centerline of the attachment collet, to receive the end of the catheter. The attachment collet, in that case, compresses the catheter between an inner surface of the collet and an outer surface of the barb, to mechanically retain the catheter in place so that fluids may flow from a lumen of the catheter through a passage in the barb to the port.  
         [0011]      FIG. 1  shows an exemplary embodiment of a catheter attachment collet lock  100  for a central port according to the present invention. The collet lock  100  comprises two principal portions: a collet  104  and a thumb wheel  102 . The collet  104  is formed of an elongated tubular body having a port end  106  that can be secured to an inlet or outlet opening of the central port by conventional means such as, for example, an adhesive or mechanical connection. An internal lumen of the collet  104  has a minimum inner diameter sufficient to receive the barb, while providing sufficient flow area to convey a fluid therethrough.  
         [0012]     An opposite end  108  of the collet  104 , which flares outwardly when in an unconstrained open configuration, is formed of a plurality of jaws  122  separated by slots  124 . The flared opposite end  108  be squeezed to a closed configuration having a reduced inner diameter by application of an inwardly directed radial force. The jaws  122  are biased toward the increased diameter open configuration. However, when compressed by a radially inward force, the jaws  122  flex inward to abut one another in closed configuration. The opening  110  is designed to receive therein an end of a catheter when in the open configuration. After the catheter end has been inserted therein, the opening  110  is closed down to the reduced diameter, closed configuration by actuating a tightening device to lock the catheter in place on the central port.  
         [0013]     In one exemplary embodiment, the flared end  108  of the collet  104  is squeezed by a tightening device such as a thumb wheel  102 , in order to reduce the diameter of the opening  110 . For example, an external surface of the collet  104  may comprise threads  120  matching corresponding threads on an inner surface of the thumb wheel  102 , to form a threaded interface between the two components. The thumb wheel  102  may optionally comprise grooves  114  to facilitate gripping of the device and turning of the thumb wheel  102 . With this threaded interface, as the thumb wheel  102  is rotated about the collet  104  in a first direction, it advances towards the flared end  108  of the collet  104 , causing the collet  104  to collapse to the reduced diameter configuration. Rotating the thumb wheel  102  about the collet  104  in a second direction moves the thumb wheel  102  away from the flared end  108  allowing the jaws  122  to spring outward to the increased diameter configuration. As the thumb wheel  102  rotates around the collet  104  and locks the catheter to the collet  104  without any relative rotation of the collet  104  and the catheter, the catheter is not twisted by the locking procedure.  
         [0014]     Those skilled in the art will understand that the threads  120  and the corresponding threads of the thumb wheel  102  may be right handed or left handed. In the latter case, when the user turns the thumb wheel  102  clockwise relative to the collet  104 , the thumb wheel is advanced toward the flared end  108  (i.e., toward the reduced diameter configuration). Using left handed threading for the thumb wheel  102  thus results in a more natural motion to tighten the collet  104  over the catheter, further simplifying the procedure. Furthermore, those skilled in the art will understand that the thumb wheel  102  may be replaced by any conventional apparatus for tightening the collet  104  over the catheter.  
         [0015]     A mechanical stop may optionally be incorporated on the collet  104  to prevent the thumb wheel  102  from becoming detached from the collet lock  100 . For example, a positive stop  112  may be formed at the lip of the collet  104 , to mechanically prevent the thumb wheel  102  from being advanced too far along the collet  104 . In that way, the collet lock  100  remains a single piece, securely attached to the central port. The procedure is therefore simplified, since there are no separate parts of the locking mechanism that can fall or be misplaced during attachment of the catheter or after the catheter has been secured in place. According to the invention, once the catheter has been inserted into the collet  104 , there are no parts that need to be assembled to secure the catheter to the port.  
         [0016]     According to exemplary embodiments of the invention, the inner diameter of the collet  104 , both in the increased and reduced diameter configurations, is selected to prevent damage to the catheter. For example, the collapsed inner diameter is preferably chosen to prevent tightening of the collet  104  to a degree that the structural integrity of the catheter is threatened. At the same time, the collapsed inner diameter of the collet  104  must be sufficiently small that, when closed around the catheter, the collet  104  closes down with sufficient force to prevent leaks between the collet  104  and the catheter and to prevent undesired movement of the catheter relative to the port. A port with no inner barb may be connected to a catheter using the device according to the invention when a sufficient contact area and force between the collapsed collet  104  and the catheter is provided. Since it is difficult to slide the catheter over the barb, removing the barb further simplifies forming the connection of the catheter to the central port.  
         [0017]      FIG. 2  shows a catheter attachment collet lock  200  according to a further embodiment of the present invention. The collet lock  200  is constructed substantially similarly to the collet lock  100  except for a detent projection  202  extending from the distal end(s) of one or more jaws  122 . A profile of each of the detent projections  202  preferably substantially matches a profile of a detent recess  206  formed at a distal end of the barb. Thus, when the jaws  122  are forced radially inward compressing a portion of a catheter received between an inner surface of the jaws  122  and an outer surface of the barb, the detent projection(s)  202  will urge portions of the wall of the catheter into the detent recess to further secure the catheter within the collet lock  200 . Those skilled in the art will understand that the collet lock  200  preferably includes a thumb wheel  102  as described above for securing the catheter within the collet lock  200  and for releasing the catheter therefrom.  
         [0018]     The present invention has been described with reference to specific embodiments, and more specifically to catheter attachment collet used for a central port. However, other embodiments may be devised that are applicable to other types of catheters and ports. Accordingly, various modifications and changes may be made to the embodiments, without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.