Abstract:
A needle shield assembly including a hinged needle shield is provided. A ramp is provided in proximity to a hinge that connects the needle shield to base assembly. The ramp is preferably flexible, and, if compressed, resliently urges the needle shield to a preferred angular position where it is canted at an angle with respect to the syringe and a closed position in which it envelops the needle. One or more locking elements are preferably provided on the needle shield for maintaining it in a locked, needle protection position.

Description:
[0001]     This application claims the benefit of U.S. Provisional Application No. 60/292,680 filed May 22, 2001 and 60/355,907 filed Feb. 11, 2002. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The field of the invention relates to needle shield assemblies for medical devices such as hypodermic needles.  
       BACKGROUND OF THE INVENTION  
       [0003]     Accidental needle sticks from used hypodermic needles can transmit disease. Various types of needle shields have been designed to reduce the possibility of accidental sticks.  
         [0004]     A needle shield that is hinged near the base of the needle has the advantage of allowing one handed needle reshielding. Accordingly, a number of prior art needle shield assemblies have been developed that include such needle shields.  
         [0005]     Various means have been provided for locking a hinged needle shield in the closed, needle protecting, position. Deflectable members have been provided in the needle shield for engaging the needle upon shielding and preventing subsequent unshielding of the needle. Such members trap the needle within the needle shield. Locking has also been accomplished by locking engagement of the needle shield with the needle support structure.  
       SUMMARY OF THE INVENTION  
       [0006]     A needle shield assembly in accordance with the present invention includes a base assembly having a hub and a base member connected to the hub. A needle cannula having a proximal portion secured to the hub and a distal portion extending from the hub defining a longitudinal axis is provided. A coupling on the base assembly includes a channel transverse to the longitudinal axis of the needle cannula and having an opening therein. A projection on the base assembly has a distal end proximal to the channel and a top surface inclined outwardly with respect to the longitudinal axis in a distal direction. A needle shield having a cavity therein is connected to the coupling at the channel. The needle shield is capable of rotating from an open position wherein the needle cannula is exposed for use, to a closed needle protecting position wherein at least the distal portion of the needle cannula is in the cavity. The needle shield preferably includes a proximal end portion having a top surface wherein the top surface is able to contact the projection on the base assembly when the needle shield is rotated to the open position. The needle shield assembly may include a projection that is flexibly mounted to the base assembly and able to be contacted by the needle shield when the needle shield is in the open position. The needle shield assembly may include structure for locking the needle shield in the closed needle protecting position.  
         [0007]     Another embodiment of the needle shield assembly of the present invention includes a base assembly having a hub, a base member connected to the hub and a coupling on the base member. A needle cannula having a proximal portion secured to the hub and a distal portion extending from the hub defining a longitudinal axis is provided. The coupling includes a channel transverse to the longitudinal axis of the needle cannula. A flexible projection is provided on the base assembly. The projection is positioned proximally with respect to the coupling. A needle shield having a cavity therein is hingedly connected to the base assembly at the channel. The needle shield is capable of rotating from an open position wherein the needle cannula is exposed to a closed needle protecting position. The projection of this embodiment preferably includes a proximal end pivotably coupled to the base assembly in a distally extending tab. The channel includes a proximally facing opening and the tab includes a surface in opposed relation to the channel opening. The tab includes a top surface that is inclined outwardly with respect to the longitudinal axis in a distal direction.  
         [0008]     Another embodiment of the needle shield assembly of the present invention includes a base assembly having a hub, a base member connected to the hub, and a coupling on the base member. A needle cannula having a proximal portion secured to the hub and a distal portion extending from the hub defining a longitudinal axis is provided. A projection on the base assembly is positioned proximally with respect to the coupling and includes a top finger-guiding surface inclined outwardly with respect to the longitudinal axis in a distal direction. A needle shield having a cavity therein is hingedly connected to the coupling. The needle shield is capable of rotating from an open position wherein the needle cannula is exposed, to a closed needle protecting position wherein at least the distal portion of the needle cannula is in the cavity. The needle shield is able to contact the projection when the needle shield is rotated to the open position. The needle shield assembly can also have a projection which is flexibly mounted to the base assembly. The projection on the base may be deflectable and can include a proximal end coupled to the base and a distally extending tab, wherein the tab is able to contact both the base member and the needle shield when the needle shield is in the open position. One way of hingedly connecting the needle shield to the coupling is by providing a channel in the coupling which is transverse to the longitudinal axis of the needle cannula. The channel has a channel opening for engaging a pin on the proximal end of the needle shield so that the needle shield may rotate around the channel from the open position to the closed needle protecting position. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a top perspective view of a needle shield assembly according to the invention;  
         [0010]      FIG. 2  is an exploded top perspective view showing a medical device including a syringe barrel, a needle hub and base member, and a needle shield;  
         [0011]      FIG. 3  is an exploded bottom perspective view of the medical device of  FIG. 2 ;  
         [0012]      FIG. 4  is a top perspective view of a medical device showing the needle shield in the open position;  
         [0013]      FIG. 5  is a top perspective view of the medical device of  FIG. 4  showing the needle shield in the closed position;  
         [0014]      FIG. 6  is a cross-sectional view of the medical device of  FIG. 4  showing the needle shield in the fully open position;  
         [0015]      FIG. 7  is a cross-sectional view of the medical device of  FIG. 4  showing the needle shield rotated partially towards the closed position;  
         [0016]      FIG. 8  is a cross-sectional view of the medical device of  FIG. 4  showing the needle shield in the closed position;  
         [0017]      FIG. 9  is a cross-sectional view of the medical device of  FIG. 8  taken along line  6 - 6 ;  
         [0018]      FIG. 10  is a top perspective view showing the base member, hub and needle of the needle shield assembly of the present invention;  
         [0019]      FIG. 11  is another top perspective view showing the base member, hub and needle of the needle shield assembly of  FIG. 10  from a different angle;  
         [0020]      FIG. 12  is a cross-sectional view showing the needle hub and base member as an integral assembly;  
         [0021]      FIG. 13  is a cross-sectional view of a needle hub and base member according to a second embodiment of the present invention; and  
         [0022]      FIG. 14  is a cross-sectional view of a needle shield assembly according to the second embodiment of the invention with the needle shield thereof being forced to a fully open position. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     While this invention is satisfied by embodiments in many different forms, there are shown in the drawings and will be herein described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered exemplary of the principles of the invention and is not intended to limit the scope of the invention to these embodiments illustrated. The scope of the invention will be measured by the appended claims and their equivalents.  
         [0024]     Referring to  FIG. 1 , a needle shield assembly  20  includes a hub  22 , a base member  23 , a needle shield  26  and an elongate hollow needle cover  28 . A needle cannula  30  is attached to the needle hub. As shown in  FIGS. 6-8 , the needle cannula  30  includes a proximal end  31  and a distal end  32 . In this embodiment, the distal end of the needle cannula preferably includes a sharpened tip. Blunt cannula are, however, known to the art and are often used to inject liquid into the injection site of an IV set. The principles of the invention are applicable to assemblies including blunt cannulas as well as needle cannulas having sharpened tips and various other known needle tip shapes.  
         [0025]     The hub  22  includes a proximal end  24  and a distal end  25  that is connected to the proximal end of the needle cannula. The base member may be and is preferably integral with the hub, as shown, or joined thereto by an interference fit, adhesives, ultrasonic welding and the like. All such hub/base member assemblies are within the purview of the present invention. The proximal end of the hub defines a connector for connecting the needle shield assembly to a medical device such as a syringe  33 . In this embodiment the proximal end of the hub includes a frusto-conically shaped cavity  51  which frictionally engages a frusto-conically shaped elongate tip  56  on syringe  33 . Various assemblies for connecting needle assemblies to syringes are known and are considered within the purview of the present invention.  
         [0026]     Base member  23  comprises a coupling, which in this embodiment includes a hook shaped projection  34  and a channel  36  having an arcuate surface as defined by the projection  34  and the body of the base member  23 . The channel includes an opening that preferably faces proximally. A finger guiding projection  37  is located proximal to the channel  36  and the channel opening, and includes a top surface  38  that is inclined outwardly in the distal direction. The top surface is inclined outwardly in the views shown in  FIGS. 6-8 . The projection  37  also includes a curved distal end face  39  that is in substantially opposing relation to the channel opening, as shown in  FIG. 12 . Top surface  38  is shown as a relatively flat surface, however, it is within the purview of the present invention to include top surfaces of various shapes such as convex or concave or combinations thereof. The base member  23  further includes a projection  40  including a pair of inclined surfaces  41 . The proximal end of the projection  40  includes a pair of notches  42 .  FIG. 3  shows these elements.  
         [0027]     Elongate hollow needle cover  28  is provided to protect the needle cannula before the needle shield assembly of the present invention is used for its intended purpose. Elongate hollow needle cover  28  includes an open proximal end  29  which is releasably engaged to the base so that the needle cannula is in the hollow needle cover. The base member is preferably generally cylindrical, and preferably includes a distal opening  45  for receiving open proximal end  29  of hollow needle cover  28  in a preferably snap-fit engaging manner. The snap fit engaging structure can comprise one or more projections or recesses on the needle shield and on the base member.  
         [0028]     Needle shield  26  includes a cavity  43  for enveloping needle  30 . At least one projection  44  extends from a side wall of the needle shield into the cavity  43 . The projection is deflectable towards the side wall of the needle shield  26  when engaged by the needle  30 . Once the needle is far enough within the cavity  43  to be positioned beyond free end  55  of the projection  44 , as shown in  FIGS. 8 and 9 , the projection springs back to its original position. The projection is preferably long enough so that any attempt to move the needle cannula out of the cavity will cause free end  55  of projection  44  to contact the interior surface of the cavity to resist re-exposure of the needle cannula. The projection is preferably integral with the sidewall of the needle shield and coupled thereto near the opening of the cavity  43 . The projection may include a living hinge at or near the point where it extends from the side wall.  
         [0029]     A pin  46  is coupled to the proximal end of the needle shield as shown in  FIGS. 2, 6 ,  7  and  8 . Pin  46  is of such dimensions that it can be snapped into channel  36  in the base member  23  and retained therein by the channel walls. With pin  46  in channel  36 , the needle shield is capable of rotating from an open position wherein the needle cannula is exposed to a closed needle protecting position wherein at least the distal end of the needle cannula is in the cavity of the needle shield. Preferably most or all of the exposed needle cannula should be within in the cavity when the needle shield is in the closed position. While needle shield  26  is readily coupled to base member  24  during manufacture of needle shield assembly  20 , these components are configured to make it very difficult to dislodge the hinge pin  46  from the channel  36  as the shield is rotated in either direction. There are many structures to hingedly connect the needle shield to the base member such as a living hinge, a flexible connection, and various structures which function in the hinge-like manner and all of these structures are within the purview of the present invention. The pin and channel structure described herein is representative of these many possibilities. It is preferred that the base member and the hub be integrally formed of a plastic material. A wide variety of plastic materials can be used to form the base and the hub. Polypropylene is preferred and especially useful for forming structure of the channel opening and the pin on the needle shield to make a hingeable assembly with enough friction to keep the needle shield from moving freely under its own weight and requiring some force to change position of the needle shield when it is not locked in the closed needle protecting position.  
         [0030]     The needle shield  26  further includes a top surface  48  defining a finger guide area near pin  46 . The top surface of the needle shield is preferably curved between its proximal and distal ends, and preferably includes projections  50  or similar features to facilitate rotating the needle shield with a finger. The needle shield includes a pair of opposing projections  52  that extend from the sidewalls of the needle shield near the proximal end of the needle shield. Each of the projections  52  includes an inclined proximal surface and a distal surface that is substantially perpendicular to the side walls of the needle shield. The projections are spaced such that the proximal surfaces thereof are engageable with the inclined surfaces  41  of the base member projection  40  as the needle shield is rotated about the pin  46 . As the side walls near the proximal end of the needle shield are flexible, continued rotation of the needle shield causes the side walls to flex outwardly until the projections  52  snap into the notches  42  in the base member projection  40 . While two locking projections and notches are provided for locking the needle shield in the closed needle protecting position, it will be appreciated that one or more locking mechanism may be used. Also it is not necessary to lock the shield to both the needle and the base member, and the shield may be locked to one of the base member or the needle to provide locking means for the present invention.  
         [0031]     The needle shield assembly may be integral with the medical device or removably coupled thereto. The assembly  20  may be provided to the end user in a sterile package (not shown). Once removed from the package, it is in the form shown in  FIG. 1 . and may be coupled to a medical device such as syringe  33 . The needle shield  26  is then rotated in the proximal direction about the hinge pin  46  and the needle cover  28  is removed. The medical device is then ready for use when the needle shield  26  extends generally proximally at an acute angle with respect to the medical device, as shown in  FIG. 6 . In the preferred embodiment, this acute angle is about forty-five degrees as measured between the longitudinal axis of the syringe/needle and the longitudinal axis of needle shield  26 . Projection  37  limits the rotation of the needle shield in a proximal direction, and allows it to be positioned where the medical device can be easily used and the shield can be readily utilized. Inclined top surface  38  of projection  37  functions as a finger-guiding ramp in that it directs the users finger outwardly to facilitate rotating the shield from the open position shown in  FIG. 6  to the closed needle protecting position shown in  FIG. 8 . Projection  37  is a very important feature of the present invention. In addition to facilitating the rotation of the needle shield to the closed needle protecting position, it redirects the digital force being supplied by the user&#39;s fingertip from a distally directed axial force to distally outwardly directed force. This redirection of the digital force reduces the potential for the digital force to overcome the frictional engagement of the hub cavity and the syringe tip and cause the needle assembly to become disengaged from the syringe while the needle shield is being rotated into the closed needle protecting position. The shield  26  is locked to the needle by the projection  44  and to the base member by engagement of the projections  52  with the base member projection  40 . It is then substantially non-reusable, and can be discarded in accordance with procedures used for discarding sharps.  
         [0032]     Needle shield  26  preferably includes parallel sidewalls  27 . In applications with very long needle cannula it may be desirable to have the parallel sidewalls at the distal end of the needle shield be longer to define a deeper cavity than at the proximal end of the needle shield. The needle shield can still get close to the longitudinal axis of the needle, as illustrated in  FIG. 1 , while further isolating the distal end of the needle cannula after the needle is in the closed needle protecting position.  
         [0033]      FIG. 13  shows a needle hub  122  in accordance with a second and preferred embodiment of the invention. Needle hub  122  includes a proximal end  124  and a distal end  125 . The distal end  125  is adapted to receive the proximal end of a needle cannula. The proximal end  124  thereof defines a connector for connecting the hub to a medical device such as a syringe.  
         [0034]     A base member  123  is integral with the hub  122 , though alternatively it could be joined thereto by an interference fit, adhesives, ultrasonic welding, or the like. The base member includes a hook-shaped projection  134  and a channel  136  having an arcuate surface defined by the projection  134  on the body of the base member. A ridge  158  extends radially outwardly from the base member  123  and extends towards the free end of the projection  134 . The base member  123  preferably but not necessarily includes an opening  145  for receiving the proximal end of a needle cover (not shown).  
         [0035]     A resilient projection  137  extends from the base member. The projection  137  comprises a hinged or cantilevered area represented by a hinge  160  that is integral with the base member and a tab  162  that extends generally in the direction of the hook-shaped projection  134 . Hinge  160  can be a living hinge or a portion configured to facilitate bending. The tab, in this embodiment, is in opposing relation to the opening to the channel  136  when the projection is unflexed, as shown in  FIG. 13 . A shoulder  164  is defined by the base member  123 . The projection  137  is configured such that the tab  162  preferably contacts the shoulder of the base member  123  when projection  137  is urged towards the longitudinal axis of the hub.  
         [0036]     Referring to  FIG. 14 , a needle shield  26  as described above is pivotably attached to the base member  123 . The shield is shown rotated back towards the syringe  33  by application of force A. The top surface of the needle shield engages the tab  162  and displaces projection  137  since it is not a rigid structure. This flexibility is an important feature of the present embodiment since it reduces the possibility of dislodging the hinge pin  46  from the channel  136  if the needle shield is urged against projection  137 . A projection such as ridge  158  also helps prevent displacement or dislodging of the hinge pin from the channel during normal use. As the tab  162  tends to assume its resting position shown in  FIG. 13 , it will urge the needle shield  26  about the hinge pin  46  from the position shown in  FIG. 14  to the preferred position, where projection  137  is unstressed, which is about a forty-five degree angle from the longitudinal axis of the needle and syringe  33 . While in this position, which corresponds to that shown in  FIG. 6  of the first-described embodiment, the user is easily able to rotate the needle shield  26  into the needle-protecting position while employing only one hand. There is sufficient space between the finger guide area  48  of the needle shield and the inclined surface of the tab  162  to allow the insertion of finger tip by most users, thereby initiating shield rotation. The shield is appropriately contoured elsewhere to protect the user while facilitating use of the shield.  
         [0037]     Resilient projection  137  is an important feature of the present invention. It provides guidance to the user&#39;s finger tip to guide it radially distally outwardly into a smooth transition onto the needle shield. Also, it is intended that the user should not apply excessive force, such as Force A in  FIG. 14 , to the needle shield. Excessive and unnecessary force applied to the needle shield will force the needle shield against projection  137  which, if not resilient, could act as a fulcrum to magnify forces on hinge pin  46  which could possibly break it or dislodge it from channel  136 . However, because projection  137  is resilient, it pivots inwardly to reduce forces being applied to hinge pin  46 . When the excessive and unnecessary force is discontinued, the resilient projection pivots outwardly moving the needle shield with it to the desired needle shield position for shielding the needle after use.