Abstract:
A fitting for connecting a catheter to a fluid conduit, comprises a housing defining a lumen extending therethrough from a distal end adapted for attachment to a catheter and a proximal end releasably connectable to a second fitting in combination with a wing extending from the housing away from an axis of the lumen, a portion of the housing opposite the wing being substantially rounded and free of projections away from the axis, a radially outermost lateral edge of a first surface of the wing being rounded wherein, when in a desired position, the first surface faces the skin.

Description:
BACKGROUND OF THE INVENTION  
       [0001]    The treatment of chronic diseases often involves repeated and prolonged access to the vascular system for the introduction and/or withdrawal of fluids making it impractical and potentially hazardous to insert and remove a catheter from a vessel access at every session. Thus, semi-permanent catheters have been employed to facilitate repeated access to the vascular system while reducing discomfort and side effects. One such catheter, a Peripherally Inserted Central Catheter (PICC), enters the body via a peripheral vein through which it is advanced through a vessel to the heart. 
         [0002]    High pressure power injection procedures are used for certain applications such as, for example, the injection of contrast media used for visualization. Catheters used for such procedures are selected to withstand the high pressure without damage while the connections to such catheters are adapted to remain attached and resist leaking while passing the high pressure fluid. 
         [0003]    Conventional luer fittings used for power injection procedures have geometry that generally comprise two symmetrical “wings” or other protrusions to give the user sufficient leverage during the connection and disconnection of the luer fittings to obtain the tight fit necessary to effectively seal at the high pressures to which the connection will be exposed. As shown in  FIG. 1 , a typical luer fitting  100  defines a lumen extending therethrough and includes a pair of substantially planar wings  102  extending in a plane including an axis of the luer fitting  100 . The fitting  100  extends from the proximal end of a fluid conduit  106  and comprises a connection portion  104  which may be coupled to and disconnected from a corresponding luer fitting on the distal end of a further device (e.g., a fluid conduit to an external fluid source or destination) as desired to form a fluid connection between the lumen  101  and the further device. To form or remove the connection between fitting  100  and a luer fitting of a further device, the user grasps the wings  102  of the fitting  100  (and corresponding structures of the luer fitting of the further device) and twists the fittings relative to one another while pushing or pulling. When in place on the skin, the fitting  100  is supported by a central portion of the fitting  100  and at least one of the wings  102 . The wings  102  protrude laterally so that outer edges thereof are separated by a width W which may, for example, be approximately 0.50 inches while a length L of the wings  102  is, for example, 0.575 inches. 
       SUMMARY OF THE INVENTION  
       [0004]    In one aspect, the present invention is related to a fitting for connecting a catheter to a fluid conduit, comprises a housing defining a lumen extending therethrough from a distal end adapted for attachment to a catheter and a proximal end releasably connectable to a second fitting in combination with a wing extending from the housing away from an axis of the lumen, a portion of the housing opposite the wing being substantially rounded and free of projections away from the axis, a radially outermost lateral edge of a first surface of the wing being rounded wherein, when in a desired position, the first surface faces the skin. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0005]      FIG. 1  is a perspective view of a conventional luer fitting; 
           [0006]      FIG. 2  is a perspective view of a luer fitting according to an embodiment of the present invention; 
           [0007]      FIG. 3  is a front view of the luer fitting shown in  FIG. 2 ; 
           [0008]      FIG. 4  is a perspective view showing two luer fittings in parallel, according to embodiments of the present invention; 
           [0009]      FIG. 5  is a perspective view showing a second embodiment of a luer fitting according to the invention; 
           [0010]      FIG. 6  is a perspective view showing a third embodiment of a luer fitting according to the invention; 
           [0011]      FIG. 7  is a perspective view showing another embodiment of a luer fitting according to the invention; 
           [0012]      FIG. 8  is a top plan view of the luer fitting shown in  FIG. 7 ; 
           [0013]      FIG. 9  is a top view of two luer fittings according to the present invention side by side with one another laying over two conventional luer fittings side by side with one another; 
           [0014]      FIG. 10  is an end view of the luer fittings of  FIG. 9 ; and 
           [0015]      FIG. 11  is a perspective view of the luer fitting of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION  
       [0016]    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 relates to devices for connecting high pressure fluid sources to catheters and, more specifically, relates to luer fittings for coupling peripherally inserted central venous catheters (PICC) to sources of fluids for introduction at high flow rates and/or pressures. 
         [0017]    The luer fittings according to the exemplary embodiments of the present invention are shaped to increase comfort while facilitating leak-free connections even when exposed to high pressures such as those employed in power injections. 
         [0018]    An exemplary embodiment of a luer fitting according to the present invention is shown in  FIG. 2 . The luer fitting  200  defines a fluid lumen  205  which, when the fitting  200  is attached to a fluid conduit  206  of a separate device in a conventional manner, fluidly couples a distal end of the conduit  206  to the lumen  205 . Those skilled in the art will understand that the conduit  206  may, for example, be a catheter such as a PICC catheter adapted for use in power injection procedures. The luer fitting  200  comprises a connection portion  204  forming a fluid tight connection with a corresponding connection portion of a second luer fitting of another medical device. The connection portion  204  may have threads, lugs or other mechanical features to engage the second luer fitting as would be understood by those skilled in the art. In a common implementation, the two luer fittings are pushed together and rotated about a common longitudinal axis to form the connection. To release the connection, the luer fittings are rotated in the opposite direction, then pulled apart. 
         [0019]    When the luers are used for power injection procedures, a significant amount of force may be necessary to push the fittings together and rotate them into a sealing relationship sufficient to withstand the pressures. As described above, it is important to form the luer fitting so that a user may easily apply force sufficient to engage and detach the connection. According to the invention, the exemplary luer fitting  200  comprises a single “wing” or protrusion  202  extending from one side of a housing  208  of the device. Lateral edges (e.g., edges extending along a radially outermost portion of the wing  202 ) of skin contacting surfaces are all rounded and free of sharp edges. As shown in  FIG. 3 , a curved surface with a radius R joins the surfaces of the protrusion  202 . The radius R is preferably at least 0.015 inches and more preferably at least 0.030 inches. Those skilled in the art will understand that, for fittings  200  that are symmetric and designed for placement with either of the surfaces  212  facing the skin, all of the lateral edges will be rounded while asymmetric fittings  200  designed for placement in only one orientation may include rounded lateral edges only on those surfaces which will face the skin. The shape and dimensions of the protrusion  202  are selected to provide a lever arm sufficiently long that a user may easily generate an amount of torque sufficient to easily attach and detach the luer fitting  200  from the corresponding second fitting. For example, a length L′ of the protrusion  202  may be between approximately 0.40 and approximately 0.80 inches while a width of the protrusion  202  is between approximately 0.45 and approximately 0.50 inches. The protrusion  202  may more preferably extend approximately 0.60 inches between the distal and proximal ends with a lateral extent of approximately 0.476 inches from a laterally outer-most portion of the protrusion  202  to a laterally opposite side of the housing  208 . Those skilled in the art will understand that these dimensions are exemplary only and that any dimension that provides sufficient leverage to enable the user to achieve and release the connection will be suitable. 
         [0020]    The protrusion  202  comprises first and second flat surfaces  212  connected to one another by curved edges  214 . This removes all sharp edges and abrupt shape changes from the surfaces of the luer fitting  200  which will be in contact with the skin. Both of the flat surfaces  212  lie flat on the skin and, together with the curved surfaces  214 , present an overall surface profile free of pressure points that may cause discomfort and/or other complications such as sores and resulting infections, etc. In addition, the relatively large flat surfaces  212  are well suited to receive printed materials, molded information or other types of graphics thereon such as, for example, instructions for use, safety notices, brand information, etc. 
         [0021]      FIG. 3  shows a different view of the luer fitting  200 , depicting additional flat surfaces  213  on the ends of the fitting  200  which are also available to receive graphics. The protrusion  202  is sized and shaped to obviate the need for a separate balancing ‘wing’ on the opposite side of the lumen  205  as in conventional luers, while giving the user a mechanical advantage to facilitate the application of torque sufficient to lock and unlock the fitting  200 . In the exemplary embodiment, the protrusion  202  combines with the housing  208  to form a generally wedge shaped element that is easily grasped and which, as described above, provides a lever to facilitate rotation about the axis of the lumen  205  in locking and unlocking the fitting  200 . 
         [0022]    The cross-section of the protrusion  202  of the fitting  200  is preferably substantially symmetrical so that the device may be used in a left hand or a right hand orientation with equal ease. However, those skilled in the art will understand that such symmetry is not necessary and asymmetric designs may provide advantages such as, for example, allowing more ergonomic shapes to be employed. Because only one “wing” is used in the exemplary embodiment, two luer fittings  200 ,  200 ′ may be placed side by side as shown in  FIG. 4  with a reduced overall width of the two fittings as compared to two conventional luer fittings with dual wings. The reduced footprint of the exemplary fittings  200 ,  200 ′ lets two of the devices occupy little more room on the patient&#39;s skin than a single conventional device. As shown in  FIGS. 9 and 10 , the single wing  202  of each of the luer fittings  200 ,  200 ′ allows these luer fittings  200 ,  200 ′ to be placed closer to one another than is possible with the conventional dual wing fittings  100 , 100 ′. For example, in this embodiment, the fittings  200 ,  200 ′ may be placed adjacent one another for a total width of 0.925 inches while the total width of the two dual wing fittings  100 , 100 ′ is 1.012 inches. 
         [0023]    Those of skill in the art will understand that different shapes of the protrusion extending from the luer fittings according to the invention may be used. For example, the radiuses of the curved corners and edges may be varied, as well as the thickness of the flat portions.  FIG. 5  shows a different exemplary embodiment of a luer fitting  250  comprising a housing  256  and a protrusion  258 . The exemplary protrusion  258  comprises a reduced cross-sectional thickness of the portion  252  with reinforcing structures  254  increasing the structural strength of the protrusion  258  to counteract the effects of the reduced cross-sectional area. 
         [0024]    Another exemplary embodiment is shown in  FIG. 6 . The luer fitting  270  comprises a protrusion  276  having a first concave surface  272  and a second convex surface  274  on a side opposite the surface  272  to provide a better ‘feel’ when applying a large force to twist the connectors. That is, the combination of the concave first surface  272  and the convex second surface  274  provide a more ergonomic form for grasping between the thumb and forefinger.  FIG. 11  shows a luer fitting  270 ′ according to a further embodiment of the invention which is substantially similar to the fitting  270  but with two substantially symmetrical concave surfaces  272 ′ on opposite sides of the protrusion  276 ′. As would be understood by those skilled in the art, this arrangement generates a slightly different ergonomic feel and a slightly altered feel when in position against the skin. 
         [0025]    Because the protrusion used to rotate the luer fitting according to the invention is large, it is possible to modify its outline to achieve desired visual effects. Letters, symbols, or other characteristic shapes may be obtained by changing the perimeter of the protrusion, while retaining suitability of the fitting for grasping and turning to form the connection. For example, as shown in  FIGS. 7 and 8 , the luer fitting  290  may comprise a housing  292  with a protrusion  294  that is shaped like the letter “P”. The symbolic shape of the protrusion  294  may indicate, for example, that the luer fitting  290  is suitable for power injection procedures. Those of skill in the art will understand that different letters, numbers and other shapes may be used to convey a variety of messages and/or data. 
         [0026]    The luer fittings according to exemplary embodiments of the invention are preferably formed of plastics or other suitable moldable materials. For example, the housing and the protrusion of the fitting may be molded in a conventional procedure to achieve the desired flat, rounded shape. However, as would be understood by those skilled in the art, a variety of other conventional manufacturing techniques may be used to produce the luer fittings according to the invention and different materials may be employed, depending on the manufacturing costs and/or difficulties as well as the properties desired of the finished product. 
         [0027]    The present invention has been described with reference to specific embodiments, and more specifically to a luer fitting for power injecting a fluid and to infuse a fluid into PICC. However, other embodiments may be devised that are applicable to other medical devices, without departing from the scope of the invention. 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.