Needle shield assembly having a releasable lock

A needle shield assembly having a releasable lock of the present invention includes a needle cannula and a hub having a proximal end for connecting to a medical instrument and a distal end connected to the proximal end of the needle cannula. A base member is connected to the hub and includes a deflectable locking arm having a latch surface. A needle shield is hingedly connected to the base member. The needle shield includes a longitudinal opening therein and is capable of rotating back and forth between a first needle protecting position wherein the needle cannula is within the longitudinal opening of the needle shield and a second position exposing at least the distal end of the needle cannula. The needle shield includes a latch surface positioned to engage the latch surface of the base member when the needle shield is in the first position for locking the needle shield in the first position. The needle shield includes an activating member movably connected to the needle shield having an outwardly facing finger pad and a tip portion. The activating member is positioned so that digital pressure applied to the finger pad causes the tip portion of the activating member to push against the locking arm of the base member and deflect the locking arm so that the latch surface of the locking arm disengages the latch surface of the needle shield and so that continued digital pressure on the finger pad causes the needle shield to rotate from the first position to the second position.

FIELD OF THE INVENTION 
The subject invention relates to needle shields for hypodermic needles, 
collection needles, catheter needles and other medical implements to help 
prevent accidental needle sticks. 
DESCRIPTION OF THE PRIOR ART 
Accidental needle sticks with a new unused needle can cause injury and 
render the needle unfit for further use. Accidental needle sticks with a 
used needle can transmit disease. As a result, most prior art needle 
assemblies have a needle shield. Some prior art needle shields define a 
rigid sleeve that can be telescoped over a needle cannula. This procedure 
requires a healthcare worker to hold the needle cannula and the associated 
medical implement in one hand and the shield in the other. Some medical 
procedures require the application of pressure to the penetration site 
after the needle has been removed. Thus, healthcare workers are often 
unable to use both hands for shielding the needle cannula. In these 
situations, workers merely deposit the used medical implement on a nearby 
surface with the intention of shielding at a more convenient time. 
However, until the needle is shielded or properly disposed of it presents 
a potential danger to other people. In some medical situations it is also 
desirable to be able to unshield the needle cannula using a one-hand 
procedure. Telescoping needle shields which are capable of shielding and 
unshielding a needle cannula require a two-hand procedure. 
A needle shield which is hinged near the base of the needle has the 
advantage of allowing one handed needle reshielding. Thus providing the 
opportunity for immediate reshielding, under most circumstances, 
immediately after use. However, pivotable needle shields still require a 
two-handed procedure to unshield the needle. Also, the reshielding 
procedure requires the healthcare worker to place his or her hand close to 
the needle tip in order to grasp the needle shield and rotate it out of 
the needle shielding position. This procedure also creates the possibility 
of accidental needle contamination by inadvertent contact with the 
healthcare worker's hand. Further, pivoting needle shields which lock 
usually contain deflectable members in the needle shield which engage the 
needle upon shielding and prevent subsequent unshielding of the needle 
because the needle is trapped within the needle shield. Further attempts 
to rotate the shield out of the needle shielding position will bend the 
cannula but not expose it. 
Another prior art hinged needle shield has a rotating cylinder with a 
longitudinal slot which is normally aligned with the slot in the needle 
shield. After the needle shield is rotated into the needle shielding 
position, the cylinder is rotated to occlude the longitudinal opening of 
the needle shield and trap the needle therein. This locking procedure 
allows subsequent unlocking but again requires a two-handed procedure. 
As mentioned above, many prior art self-contained needle shield assemblies 
lock permanently in place once the needle is shielded for the first time. 
Accordingly, once the needle is used for filling through a medication vial 
having a pierceable stopper, it must be transported to the injection site 
unshielded. Under these circumstances, it is believed that a needle shield 
which can expose the needle for filing the hypodermic syringe and then 
locked into a needle shielding position and which can later be unlocked to 
expose the needle for injection into the patient is a desirable feature 
because the needle will be protected from contamination and damage between 
the time the syringe is filled and the time the injection is administered. 
It is also desirable that the unlocking of the needle shield be a 
one-handed operation which does not place the user's hand in proximity to 
the bare cannula. 
Although the prior art provides many improved needle shield devices, there 
is still a need for a self-contained needle shield assembly wherein the 
needle shield can be positioned in a needle shielding position or a needle 
exposing position using a one-handed procedure. There is also a need for a 
self-contained needle shield assembly which automatically locks the needle 
shield when it is positioned in the needle protecting position, but allows 
subsequent single-handed unlocking of the shield to move it to a needle 
exposing position. 
SUMMARY OF THE INVENTION 
A needle shield assembly having a releasable lock of the present invention 
includes a needle cannula having a proximal end, a distal end and a lumen 
therethrough, and a hub having a proximal end for connecting to a medical 
instrument and a distal end connected to the proximal end of the needle 
cannula. A base member is connected to or formed integrally with the hub 
and includes a deflectable locking arm having a latch surface. An elongate 
needle shield is hingedly connected to the base member so that the needle 
shield can rotate about an axis which is transverse to the longitudinal 
axis of the needle cannula. The needle shield includes a longitudinal 
opening therein and is capable of rotating back and forth between a first 
needle protecting position wherein the needle cannula is within the 
longitudinal opening of the needle shield to a second position exposing at 
least the distal end of the needle cannula. The needle shield includes a 
latch surface positioned to engage the latch surface of the base member 
when the needle shield is in the first needle protecting position for 
locking the needle shield in the first position. The needle shield 
includes an activating member movably connected to the needle shield 
having an outwardly facing finger pad and a tip portion. The activating 
member is positioned so that digital pressure applied to the finger pad 
causes the tip portion of the activating member to push against the 
locking arm of the base member and deflect the locking arm so that the 
latch surface of the locking arm disengages the latch surface of the 
needle shield and so that continued digital pressure on the finger pad 
causes the needle shield to rotate toward the side of the needle shield 
containing the finger pad from the first needle shielding position to the 
second needle exposing position. The deflectable locking arm and the 
needle shield are configured so that rotation of the needle shield from 
the second position to the first position causes the latch surface of the 
locking arm and the latch surface of the needle shield to engage to lock 
the needle shield in the first position.

DETAILED DESCRIPTION 
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. 
Adverting to FIGS. 1-14, a needle shield assembly having a releasable lock 
such, as needle shield assembly 20, includes a needle cannula 21 having a 
proximal end 22, a distal end 23 and a lumen 25 therethrough defining a 
longitudinal axis 24. In this embodiment, the distal end of the needle 
cannula includes sharpened tip 26. It is within the purview of the present 
invention to include blunt cannula which are cannula without sharp tips. 
Blunt cannula are known in the art and are usually used to inject liquid 
into an I.V. set or other fluid flow path having an access port with a 
pre-slit septum. The blunt cannula is forced through the slit in the 
septum and into fluid communication with the fluid flow path. Upon removal 
of the blunt cannula the slit portion of the septum automatically seals 
itself. 
A hub 28 includes a proximal end 29 and a distal end 31 connected to 
proximal end 22 of the needle cannula. A base member 32 is connected to 
the hub. There are many ways to join the base member to the hub such as 
through an interference fit, adhesives, ultrasonic welding and the like. 
It is within the purview of the present invention to include a hub and 
base member which are a unitary one-piece structure. The one-piece 
structure may be accomplished by many methods including injection molding 
the hub and base member as a one-piece unit thereby eliminating the need 
to assemble the base member to the hub during the manufacturing process. 
An elongate needle shield 35 includes proximal end 37 hingedly connected to 
base member 32. In this embodiment, the hinge connection is accomplished 
by hinge holes 38 in parallel spaced arms 33 of the needle shield which 
engage opposed circular hinge pins 33 on base member 32 to allow the 
needle shield to rotate about an axis which is preferably transverse to 
the longitudinal axis of the needle cannula. Needle shield 35 also 
includes distal end 40 and longitudinal opening 41 which ends at the 
distal end of the needle shield at end wall 44. 
Needle shield 35 is capable of rotating back and forth between a first 
needle protecting position, as illustrated in FIG. 1 wherein needle 
cannula 21 is within longitudinal opening 41 of the needle shield, to a 
second position, such as the positions illustrated in FIGS. 3 and 4, 
exposing at least distal end 23 of the needle cannula. 
Base member 32 includes a deflectable locking arm 34 having a latch surface 
45. Also, needle shield 35 includes a latch surface 46 positioned to 
engage latch surface 45 on the base member when the needle shield is in a 
first needle protecting position for locking the needle shield in the 
first position. It is an important feature of the present invention that 
when the needle shield is rotated from the second position to the first 
position, latch surfaces 45 and 46 engage to lock the needle shield in the 
first position. Thus, the needle shield is not frictionally held in the 
first position but locked therein so that the needle shield cannot be 
rotated to expose the needle under normal operating conditions unless the 
latching surfaces are intentionally unlocked as will be explained in more 
detail hereinafter. In the preferred embodiment, surfaces 47 on the 
deflectable arm and surfaces 49 on the needle shield are configured so 
that rotation of the needle shield from the second position to the first 
position causes the latch surfaces of the latch arm and the locking 
surfaces of the needle shield to engage and lock the needle shield in the 
first position. 
Needle shield 35 further includes an activating member 50 movably connected 
to the needle shield having an outwardly facing finger pad 51 and a tip 
portion 52 preferably located on the opposite side of the needle cannula 
from the finger pad when the needle shield is in the first needle 
protecting position. The activating member is positioned so that digital 
pressure applied to the finger pad causes the tip portion of the 
activating member to push against locking arm at contact surface 53 of the 
locking arm, and deflect the locking arm, as illustrated in FIG. 6, so 
that latch surface 45 of the locking arm disengages latch surface 46 of 
the needle shield and so that continued digital pressure on the finger pad 
causes the needle to rotate toward the side of the needle shield 
containing the finger pad from the first needle shielding position to the 
second needle exposing position, as illustrated in FIGS. 2, 3, 4 and 7. 
This is an important feature of the present invention since the user can 
unlock the needle shield and rotate it from the first needle protecting 
position with a single-handed procedure comprising applying digital 
pressure to finger pad 51 of activating member 50. The unlocking and 
rotation of the needle shield is accomplished in one step with one finger 
motion. Without intentional deflection of the activating member the needle 
will remain safely locked within the needle shield, not to be re-exposed, 
under normal use, without the intentional act of the user. The needle 
shield is safely locked in a shielded position to prevent accidental 
inadvertent re-exposure of the needle cannula. The act of unlocking and 
rotating the needle shield out of the needle protecting position takes 
place by applying digital pressure on the opposite side of the needle from 
the longitudinal slot keeping the user's fingers on the opposite side of 
the needle from the slot helps prevent incidental contact with the needle 
during the procedure of exposing the needle cannula. The increased safety 
of having a securely locked needle shield and the ability to unlock and 
rotate the needle shield from a remote location away from the open side of 
the needle shield are important features that overcomes many of the 
shortcomings of the prior art. 
The movable relationship between the activating member and the needle 
shield can be accomplished by many structures including various shapes and 
configurations of structure or mechanism connecting the elements such as 
linkages, concentric sliding structure, living hinges, separate hinges, 
and the like. In this embodiment, the movable relationship is a rotational 
relationship between the needle shield and the activating member which is 
achieved through a proximally directed cantilever arm 55 connected to the 
needle shield at location 57 so that it pivots therefrom as a cantilever 
beam. Free end 58 of cantilever arm 55 connects directly to activating 
member 50 so that when digital pressure is applied to the finger pad 51, 
cantilever arm 55 pivots or deflects toward deflectable locking arm 34 of 
the base member causing tip portion 52 to press against contact surface 53 
on the locking arm to disengage latch surface 45 and latch surfaces 46. 
This action is best illustrated in FIG. 6. 
For the purpose of illustration needle shield assembly 20 is connected to a 
hypodermic syringe 61 comprising a syringe barrel 62 having a distal end 
63 and a proximal end 64 and a circular side wall 65 therebetween defining 
a chamber 67 for retaining fluid. The distal end of the syringe barrel is 
connected to the hub so that lumen 25 of the needle cannula is in fluid 
communication with chamber 67 of the syringe barrel. In this embodiment, 
distal end 63 of the syringe barrel includes an elongate frusto-conically 
shaped tip having a passageway therethrough which provides the fluid path 
between the cannula and the chamber. The frusto-conically shaped tip of 
the barrel tip frictionally engages a frusto-conically shaped cavity of 
the needle hub. The distal end of the syringe barrel also includes a 
locking luer-type collar 68 concentrically surrounding the tip. The 
luer-collar has an array of internal threads which may engage the needle 
hub to hold it securely to the syringe barrel. For the purpose of drawing 
fluid into and out of chamber 67 the hypodermic syringe includes an 
elongate plunger rod 70 having a distal end 71 and a stopper 73 which is 
in fluid-tight slidable engagement with the interior of the chamber. It is 
important to note that it is within the scope of the present invention to 
include various hub configurations for attaching to a wide variety of 
medical or fluid-handling devices. The hub configuration described 
hereinabove, having a frusto-conically shaped interior cavity, reflects 
one of these many possibilities. Many syringes, fluid handling devices, 
such as stopcocks and adapters, and other fluid handling devices contain 
luer slip and locking luer-type fittings to which a hub having a 
frusto-conically shaped interior cavity will properly engage. 
It is also within the purview of the present invention to provide a needle 
shield assembly wherein the hub is integrally molded with the syringe 
barrel and the base member is attached to the syringe barrel. 
The needle shield assembly of the present invention also includes means for 
releasably retaining the needle shield in the second needle exposing 
position. The second needle exposing position can be any position which 
exposes the distal end of the needle cannula. In FIG. 2 this position is 
illustrated with the needle shield at approximately a 90.degree. angle 
with respect to longitudinal axis 24 of the needle cannula. In FIG. 4 the 
second position is illustrated with the needle shield at approximately 
180.degree. or parallel, with longitudinal axis 24 of the needle cannula. 
In this preferred embodiment the means for releasably retaining includes 
inwardly directed projections 74 on the needle shield and recesses 75 and 
76 in the base member. When the needle shield is at an angle which is 
approximately perpendicular or 90.degree. from the longitudinal axis of 
the needle cannula projection 74 engages recess 75 to releasably retain 
the needle shield in that position. The retention force provided by 
projection 74 and recess 75 can be overcome by applying additional 
rotational force to the needle shield. Also, when the needle shield is 
rotated approximately 180.degree. from the needle cannula, as illustrated 
in FIG. 4, projection 74 engages recess 76 to releasably retain the needle 
shield in that position. Again, the needle shield can be moved back to the 
first needle protecting position by applying sufficient force to overcome 
resistance of projection 74 as it engages recess 76. 
FIGS. 15 and 16 illustrate an alternative embodiment of the present 
invention. This embodiment is substantially similar in function to the 
embodiment of FIGS. 1-14 except for the structure providing the movable 
relationship between the needle shield and the activating member, and the 
shape of the contact surface on the locking arm. In particular, like the 
needle shield assembly of FIGS. 1-14, alternative needle shield assembly 
80 includes a needle cannula 81, a hub 88, a base member 92 and an 
elongate needle shield 95. Needle shield 95 includes an activating member 
110 movably connected to the needle shield having an outwardly facing 
finger pad 111 and a tip portion 112 located on the opposite side of the 
needle cannula from the finger pad when the needle shield is in the first 
needle protecting position as illustrated in FIG. 15. The movable 
relationship between needle shield 95 and activating member 50 is achieved 
through living hinge 81 which is integrally molded at the juncture of the 
activating member and the needle shield which allows the activating member 
to pivot with respect to the needle shield at hinge 81. It is within the 
purview of the instant invention to include any hinge structure, including 
a mechanical hinge, to achieve this relationship. As with the embodiment 
of FIGS. 1-14, the activating member is positioned so that digital 
pressure applied to the finger pad causes the tip portion of the 
activating member to push against a deflectable locking arm 94 of the base 
member and deflect the locking member so that latch surface 106 on the 
needle shield disengages latch surface 105 on the deflectable locking arm. 
The larger the contact area between latch surface 105 and latch surface 
106, the stronger the locking engagement between the base member and the 
needle shield to lock the needle shield in the first needle protecting 
position. The more the latch surfaces overlap the more the deflectable 
locking wall must be deflected to disengage the locking surfaces to unlock 
the needle shield. To provide additional deflection of the deflectable 
locking arm, the tip portion of the activating member or the contact 
surface on the locking arm which contacts the tip portion can be given a 
cam-like profile to magnify the deflection of the locking arm with respect 
to the movement of the tip portion of the activating member. In this 
embodiment, contact surface 113 is provided with a convexly shaped cam 
surface to magnify the response of the deflectable locking arm with 
respect to the motion of tip portion 112 over cam surface 113. The cam 
surface can also include a concavely shaped portion such as 
semi-circularly shaped portion 100 to hold the tip portion 112 of the 
activating member while the needle shield is in the first locked position. 
This will keep the tip portion 112 from moving away from the cam surface 
during normal use and will give the outwardly facing finger pad a more 
firm feel. 
FIG. 18 illustrates an alternate embodiment of the present invention which 
is similar to the embodiment of FIGS. 1-14 except that hub 128 is 
integrally formed with syringe barrel 162 of hypodermic syringe 161, and 
base member 132 is rotationally connected to hub 128. As in the embodiment 
of FIGS. 1-14, the needle shield assembly of the present embodiment 
includes an elongate needle shield 135 hingedly attached to base member 
132 through the action of hinged pins 133 on the base member and hinge 
holes 138 in the needle shield. Needle cannula 121 is connected to hub 128 
using an adhesive 201, such as epoxy, or by other suitable means. Distal 
end 123 of the needle cannula includes a sharp tip 202 which is sharpened 
to a bevel shape having a bevel surface 205 oriented at angle A. Bevel 
surface 205 faces direction B. Base member 132 is rotationally engaged 
with the hub in a snap-fit arrangement involving the engagement of 
inwardly facing annular rib 203 on the base member and annular recess 204 
on the hub. The hub and the base member are dimensioned so that the base 
member will tightly fit the hub and remain in position but will allow 
rotation of the base member around the hub by applying a rotational force 
sufficient to overcome the frictional fit between the base member and the 
hub. There are numerous structural configurations that can be used to 
provide a rotational connection between the base member of the hub, such 
as tight threads, a ratchet structure, detents and the like. The structure 
described herein to provide for rotational connection between the base 
member and the hub is merely representative of these many possibilities. 
This is an important feature of the present embodiment because when 
injecting medication into a patient's vein it is desirable to have the 
bevel surface of the needle cannula facing upwardly as illustrated in FIG. 
18. This orientation of the needle makes it easier to insert the needle 
into the patient's vein. Accordingly, it is desirable to have bevel 
surface 205 facing the same side of base member 132 as needle shield 135 
when the needle shield is in the second needle exposing position, as best 
illustrated in FIG. 18, so that the needle shield does not interfere with 
positioning the syringe close to the patient's body, for example, the 
patient's arm, when attempting to gain easy access into a vein. The needle 
shield can be positioned on the same side of the syringe as the bevel 
surface by designing the elements so that the assembly of the needle 
shield assembly to the syringe barrel achieves this result or by providing 
adjustable components, such as in the embodiment of FIG. 18, where the 
base member can be rotated to the optimum position with respect to the 
needle cannula.