Abstract:
A needle shield and needle shield assembly are provided for preventing accidental needle sticks. The needle shield includes opposing sidewalls and is pivotable between an open position that allows use of the needle cannula and a closed position that covers at least the tip of the needle cannula. A locking member extends from one of the sidewalls of the needle shield and includes a relatively rigid base portion and a relatively flexible end portion. The needle cannula engages the relatively flexible end portion when entering the needle shield cavity, deflecting it with respect to the base portion. Upon any attempt to move the needle shield from the closed position to the open position, the needle cannula is directed by the locking member towards the relatively rigid base portion, thereby making it very difficult to reuse the needle cannula.

Description:
This application is a continuation of U.S. application Ser. No. 10/488,881, which was filed on Mar. 4, 2004, which claims the benefit of International (PCT) Application No. PCT/US02/20333, filed Jun. 27, 2002, which claims benefit of U.S. Provisional Application No. 60/303,940 filed Jul. 9, 2001. 

   FIELD OF THE INVENTION 
   The field of the invention relates to needle shield assemblies for medical devices such as hypodermic needles. 
   BACKGROUND OF THE INVENTION 
   Accidental needle sticks from used hypodermic needles can transmit disease. Accordingly, various types of needle shields have been designed to reduce the possibility of accidental sticks. 
   A needle shield that is hinged near the base of the needle has the advantage of allowing one handed needle reshielding. A number of prior art needle shield assemblies including such needle shields have been developed. 
   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. U.S. Pat. No. 4,664,259 discloses a needle shield including a deflectable member. Locking has also been accomplished by locking engagement of the needle shield with the needle support structure. U.S. Pat. No. 5,746,726 discloses a shielded needle assembly of this type. 
   Needles are available in a number of gauges and lengths so that they can be used for different purposes. Where a needle shield having a deflectable locking member is used to entrap a needle, it is important that the needle displace the locking member or members as it enters the needle shield cavity. It is also important that, since the needle is entrapped by the deflectable locking member or members, it cannot easily be displaced from the cavity. A relatively large diameter needle can more easily displace a deflectable locking member than a small diameter needle, both entering the needle shield cavity and exiting the cavity. As a needle shield should preferably be usable to protect needles of various sizes, the deflectable locking member or members should be designed such that it is sufficiently flexible to allow even a relatively small diameter needle to deflect it as it enters the needle shield cavity, but provides sufficient resistance to prevent the needle from being re-exposed through the opening of the cavity. 
   U.S. Pat. No. 5,486,163 discloses a sheath that is described as requiring very little force to open a pair of inwardly biased doors as the needle enters the cavity and a much greater force to open them outwardly to expose the needle. Other needle sheaths have deflectable members in the form of hooks, as shown in U.S. Pat. Nos. 4,664,259, 4,944,731, 5,139,489, 5,681,295 and 5,876,381. Still other sheaths include deflectable members integral with a sidewall thereof and extending away from the cavity opening. U.S. Pat. No. 5,490,841 discloses such a sheath wherein the needle is caused to travel towards the resilient hinge of a deflectable member if one attempts to re-expose it. The free end of the deflectable member engages the opposing sidewall of the sheath to prevent it from opening and thereby allowing release of the needle. 
   SUMMARY OF THE INVENTION 
   A needle shield assembly of the present invention includes a needle cannula having a proximal end, a distal end and a lumen therethrough. A hub is provided having a proximal end for connecting to a medical device such as a syringe and a distal end connected to the proximal end of the needle cannula. A base member is connected to or integral with the hub. A needle shield is coupled to the base member by a hinge. A locking assembly having one or more locking members for engaging the needle cannula is provided. The locking member includes an end portion and a base portion. The end portion is relatively flexible while the base portion is relatively stiff. The shaft of a needle cannula can accordingly deflect the end portion of the locking member relatively easily upon entering the needle shield cavity. If the needle shield is pivoted in an attempt to re-expose the trapped needle cannula, the shaft of the needle cannula will engage the more rigid base portion of the locking member. 
   In accordance with one embodiment of the invention, a needle shield is provided which includes a proximal end portion, a distal end portion and a needle cannula locking member. The proximal end portion includes a connector while the distal end portion defines an elongate cavity for enveloping at least part of a needle cannula and an elongate cavity opening. The needle cannula locking member is coupled to the distal end portion and extends away from the elongate cavity opening and into the elongate cavity. The locking member includes a relatively rigid base portion and a plurality of relatively flexible end portions coupled to the base portion. 
   A needle shield assembly according to the invention includes a needle cannula having a proximal end, a distal and a lumen therethrough. It further includes a needle support wherein the needle cannula is connected to the needle support. A needle shield is hingedly connected to the needle support and includes an elongate cavity, a pair of opposing sidewalls bordering the cavity, and a cavity opening. A locking member is connected to one of the sidewalls and extends into the elongate cavity away from the cavity opening. The locking member includes a base portion adjoining one of the side walls, a flexible end portion adjoining the base portion, and inner and outer surfaces that converge in the direction away from one of the side walls. The end portion of the locking member is relatively flexible with respect to the base portion. The flexible end portion is deflectable with respect to the base portion by the needle cannula as the needle shield is moved towards a closed position to protect the needle cannula. If one attempts to move the needle shield from the closed position to the open position, the needle cannula is directed towards one of the sidewalls by the inner surface of the locking member. The needle cannula is accordingly directed towards the base portion of the locking member. 
   The invention is further directed to a medical device such as a syringe assembly. The device includes a vessel having a first end and a second end. A needle cannula is connected to the first end of the vessel, and includes a proximal end, a distal end and a lumen therethrough. A needle shield is pivotably coupled to the vessel and includes first and second opposing sidewalls, a cavity between the sidewalls for receiving at least part of the needle cannula, and a cavity opening. The needle shield is pivotable between an open position where at least the distal end of the needle cannula is exposed and a closed position where at least the distal end of the needle cannula is positioned within the cavity. A locking member is connected to the first sidewall of the needle shield and extends away from the cavity opening and into the cavity. It includes a relatively rigid base portion adjoining the first sidewall and a relatively flexible end portion extending from the base portion and defining a free end. The locking member is positioned such that the needle cannula contacts and displaces the relatively flexible end portion upon movement of the needle shield into the closed position. The locking member further includes an outer surface opposing the cavity opening and an inner surface extending at an acute angle with respect to the first sidewall of the needle shield. When the needle shield is moved from the closed position towards the open position, the needle cannula is accordingly urged by the inner surface of the locking member towards the first sidewall. The medical device of this embodiment may include a plurality of relatively flexible end portions. The end portion may be long enough to be flexed so that the free end contacts the second sidewall to help prevent the needle from leaving the shield cavity. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top perspective view showing a needle shield assembly in accordance with a first embodiment of the invention; 
       FIG. 2  is an exploded, top perspective view showing parts of the needle shield assembly in combination with a medical fluid delivery device; 
       FIG. 3  is an exploded, bottom perspective view thereof; 
       FIG. 4  is an enlarged, bottom perspective view showing the needle shield; 
       FIG. 5  is a sectional view of the needle shield assembly and the medical fluid delivery device showing the needle shield in a first position; 
       FIG. 6  is a sectional view thereof showing the needle shield pivoted towards a protective position covering the needle cannula; 
       FIG. 7  is a sectional view thereof showing the needle shield in a protective position, the needle being trapped within the needle shield; 
       FIG. 8  is a sectional view of the needle shield showing a needle cannula entering the cavity in the needle shield; 
       FIG. 9  is a sectional view of the needle cannula engaging a locking member in the needle shield; 
       FIG. 10  is a sectional view thereof taken along line  10 - 10  of  FIG. 6 ; 
       FIG. 11  is a sectional view of the needle cannula positioned behind the locking member; 
       FIG. 12  is a sectional view showing movement of the needle with respect to the inner surface of the locking member, and 
       FIG. 13  is a sectional view taken along line  13 - 13  of  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While this invention is satisfied by embodiments in many different forms, there is shown in the drawings and herein described in detail, a preferred embodiment 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 invention to the embodiment illustrated. The scope of the invention is measured by the appended claims and their equivalents. 
   Referring to  FIGS. 1 and 2 , a needle shield assembly  20  is provided that includes a needle hub  22 , a base member  24  connected to or integral with the needle hub, a needle shield  26 , and a needle cover  28 . The needle shield includes a proximal end portion that can be connected to the needle hub or base member, and a distal end portion that includes an elongate cavity for enveloping at least part of a needle cannula  30 . The proximal end portion of the needle shield  26  includes an integral hinge pin  32  and a curved upper surface  34 . The upper surface  34  is designed for engagement by a user&#39;s finger in order to pivot the needle shield about the hinge pin. Projections  36  may be provided on the curved upper surface. A pair of projections  38  extend inwardly from the proximal end of the needle shield. The needle cannula includes a proximal end  30 A and a sharp distal end  30 B. The proximal end thereof is secured to the needle hub  22  using adhesive such as epoxy or other appropriate means. 
   The base member  24  of the preferred embodiment includes a projection  40  having notches  42  for receiving the locking projections  38  at the proximal end of the needle shield  26 . The projection  40  includes angled surfaces  40 A that are engageable with the locking projections  38 . The base member further includes a channel  44  having arcuate walls for receiving the hinge pin  32  on the needle shield. The channel  44  is positioned between a C-shaped projection  46  and a ramp  48 . A cylindrical recess  52  in the base member is provided for receiving the proximal end of the needle cover. 
   The needle hub includes a proximal end  22 A adapted for connection to a medical device such as a syringe  54 . Various types of connectors are known and considered to be within the purview of the present invention. When secured to the medical device, fluid communication is established between the needle cannula  30  and the inner chamber  56  of the device. The distal end  22 B of the hub is secured to the needle cannula  30 . 
   The needle shield  26  can be pivoted about the hinge pin  32  between the open position shown in  FIG. 5  and the closed position shown in  FIG. 7 . The needle cannula is entrapped with a cavity  58  defined by the needle shield  26  when the needle shield is in the closed position. One or more locking members  60  are provided for retaining the needle cannula in the needle shield. The needle shield  26  is further retained in the protective position by the movement of the projections  38  into the notches  42  in the base member  24 . 
   Needle cannulas are available in many different lengths and gauges as they maybe used for different purposes. If the needle shield is to be locked in the protective position by the engagement of a deflectable locking member with the needle shaft, it is important that the locking member (or members) be sufficiently flexible that the needle is capable of temporarily displacing the locking member as it enters the needle shield cavity. The locking member must also exhibit sufficient rigidity to resist displacement so that the needle cannula, once entrapped, cannot easily be re-exposed by pivoting the needle shield and deflecting the locking member. 
   In accordance with a preferred embodiment of the invention, the locking member  60  is integral with a sidewall of the needle shield  26 . These elements are preferably constructed from a semi-rigid plastic material such as polypropylene. The locking member includes a base portion  60 A and three end portions  60 B. It includes a tapered body that is thickest where it adjoins the wall of the needle shield. The base portion is relatively rigid and substantially more resistant to deflection than the end portions. This is due to several reasons, including the relative thickness of the two portions, the location of the base portion and the gaps between each of the end portions. 
     FIGS. 8-13  show, in sequence, the needle cannula  30  entering the cavity  58  of the needle shield  26 , becoming trapped within the shield, and engaging the locking member upon attempted pivoting of the needle shield  26  about the hinge pin from the needle cannula protective position. Referring first to  FIG. 8 , the needle cannula  30  is shown entering the cavity  58  of the needle shield as the needle shield is pivoted from the position shown in  FIG. 5  to the protective position. The angular orientation of the locking member  60  away from the cavity opening is clearly shown. The locking member forms an angle A, as shown in  FIG. 8 , with the sidewall of the needle shield between about 20-70 degrees, and more preferably between 30-45 degrees. It also preferably extends over more than half the width of the cavity  58 . Further rotation of the needle shield about the hinge pin  32  causes the needle cannula  30  to engage outer surface  61  of locking member  60 , and preferably the relatively flexible end portions  60 B of the locking member. It will be appreciated that a relatively long needle cannula may engage all three end portions  60 B, while a shorter needle cannula may only engage one of them. Continued rotation of the needle shield causes the needle cannula to deflect flexible end portions  60 B of the locking member relative to the base portion  60 A, as shown in  FIG. 10 . The end portions  60 B are preferably increasingly flexible from their connections to the base portion  60 A to the tips thereof. The angular orientation of the locking member causes the needle cannula to be urged away from the side wall to which the locking member is attached and towards the tips of the end portions  60 B as it moves into the cavity  58 . A thicker (lower gauge) needle may deflect the end portions closer to the base portion  60 A than a thinner (higher gauge) needle. Once the shaft of the needle cannula passes by the locking member  60 , as shown in  FIG. 11 , the deflected end portion(s)  60 B return substantially to their original position(s). The shaft of the needle cannula  30  is then blocked by the locking member  60 . The locking projections  38  at the proximal end of the needle shield  26  simultaneously move into engagement with the projection  40  on the base member  24 , further increasing the difficulty of re-exposing the needle. 
   Attempted rotation of the needle shield  26  away from the protective position causes the shaft of the needle cannula  30  to engage inner surface  62  of the locking member which, like the outer surface, is angled away from the opening to the needle shield cavity  58 . Also, end portions  60 B of the locking member are sized and shaped to deflect toward and contact the side wall of the cavity opposite the side wall connected to the base portion in response to contact with the needle cannula. Accordingly, if the needle cannula contacts the end portions  60 B during an attempt to rotate the needle shield away from the protective position, the distal portions can deflect to contact the side wall, as shown in  FIG. 12  thus preventing further deflection of the flexible distal portions that could allow the needle cannula to leave the shield and further urging the needle toward base portion  60 A. Continued attempted rotation of the needle shield  26  causes the needle cannula to be directed towards the relatively rigid base portion  60 A of the locking member, as shown in  FIG. 12 . As the locking member is substantially more difficult to deflect as the side wall of the needle shield is approached and the needle contacts base portion  60 A, the needle cannula is highly unlikely to be re-exposed once trapped within the cavity  58 . A substantially permanent locking of the needle cannula is accordingly achieved by the present invention. 
   It will be appreciated that various modifications could be made to the invention without departing from the spirit thereof. For example, the needle cannula, needle hub and adapter could be integral with the syringe instead of releasably coupled thereto. The locking member may be integral with the needle shield as shown, or be manufactured separately and then secured to the needle shield by an adhesive or mechanical fasteners. The end portion(s) of the locking member, which are integral with the base portion in the preferred embodiment, can be separate elements. One or more locking members may be employed within a needle shield. Each locking member may have one or a plurality of relatively flexible end portions that can be deflected relative to a relatively stiff base portion. The needle shield can be connected to the base member by a living hinge (not shown) or other suitable structure rather than through the use of a hinge pin. 
   The present invention provides a needle shield assembly that can be used to entrap relatively small diameter needles as well as those of larger diameter. The relatively flexible end portion(s) of the locking member can be designed to be deflected by small diameter needle cannulas that might otherwise be too flexible to deflect a locking element of uniform thickness or flexibility. Also, the ability of the end portions to contact the sidewall makes them relatively resistant to needle cannula leaving the cavity while being very flexible and able to allow the needle cannula to enter the cavity. The rigid base portion provides aggressive resistance to flexing even to forces that a large diameter needle cannula could apply. The relatively flexible end portion, acting as a cannula guide, directs the needle cannula towards the thicker, stronger base portion if one attempts to displace the needle shield. The same locking element will still have sufficient strength to substantially prevent the needle cannula from displacing the locking element once entrapped. The relative size and shape of the base portion and the end portions should be selected based on the length and diameter of the needle cannula being used with the needle shield.