Syringe needle abstract
A safety syringe of the type having a needle shield that is slidable
between a needle exposing retracted position and a needle protecting
extended position and wherein the needle shield is rotatable in
the extended position to a locked and extended position. The safety
syringe includes a collar mounted on the distal end of the syringe
and a plurality of elongate keys on the interior surface of the
needle shield. The keys are slidably received in various protrusions
and slots on the collar to releasably retain the needle shield in
the retracted and extended positions and to retain the needle shield
in the locked and extended position. A needle sheath is also removably
mounted on the distal end of the needle shield to cover the needle
of the syringe when the needle shield is in the initial retracted
position.
Syringe needle claims
What is claimed is:
1. A needle shielding device for use with a barrel, wherein a needle
is attached to the forward end of the barrel, the improvement comprising:
a separate shield retaining means mounted on said barrel and including
at least one locking slot on its outer surface,
an elongated needle shield having distal and proximal ends wherein
said shield is movable over said barrel and retaining means between
a retracted position in which the needle is exposed and an extended
position in which said shield protects said needle, said shield
including at least one elongated key on its interior surface, said
key adapted to slide in a path outside said locking slot and being
rotatable into said locking slot when said shield is in its extended
position; and
an elongate needle protecting needle sheath having an open proximal
end and a closed distal end wherein said need sheath is removably
mounted on said distal end of said shield and said shield is movable
between said retracted and extended positions with said needle sheath
mounted thereon.
2. The needle shielding device according to claim 1 wherein said
locking slot comprises a pair of opposed walls at least one of which
includes a ramp-shaped surface over which said key can ride when
said needle shield is rotated, and a protrusion positioned proximally
of said locking slot for preventing said shield from being movable
to the retracted position after said key has been rotated into said
locking slot.
3. The needle shielding device according to claim 2 wherein each
of said opposed walls includes a ramp-shaped surface so that said
key on said needle shield may be rotated in either direction into
one of said locking slots.
4. The needle shielding device according to claim 1 wherein said
shield includes an inwardly extending detent on its interior surface
and said shield retaining means includes a surface adapted to abut
against said detent to releasably retain said sleeve in the retracted
position.
5. The needle shielding device according to claim 1 wherein said
shield retaining means includes at least one detent extending from
its outer surface adapted to abut against said key when said shield
is in the extended position.
6. The needle shielding device according to claim 1 wherein said
proximal end of said shield includes an inwardly extending rim adapted
to abut against said proximal end of said shield retaining means
to limit the forward movement of said shield.
7. The needle shielding device according to claim 6 further including
a means for preventing rotation of said shield when said shield
is in the retracted position.
8. The needle shielding device according to claim 3 wherein said
means for preventing rotation comprises radially extending projections
on the exterior surface of said shield retaining means.
9. The needle shielding device according to claim 7 wherein said
means for preventing rotation of said needle shield also prevents
said rotation of said needle shield as said needle shield is moved
between the retracted and extended positions.
10. The needle shielding device according to claim 1 wherein said
shield retaining means is separate from said barrel and wherein
there is provided an interlocking means on said shield retaining
means and barrel for preventing rotation of said shield retaining
means about said barrel.
11. The needle shielding device according to claim 1 wherein said
needle shield includes a radially extending finger flange on the
exterior surface thereof.
12. A medical device comprising:
a syringe including an elongate barrel having distal and proximal
ends, a plunger slidable within said barrel, and a needle having
a distal needle point thereon wherein said needle is attached to
said distal end of said barrel,
a collar operatively associated with said distal end of said barrel
and including a plurality of locking slots on the outer surface
of said collar, each of said locking slots being formed by a pair
of opposed walls on said collar,
an elongated needle shield movable over said barrel and said collar
between a retracted position wherein said needle point is exposed
and an extended position wherein said needle point is protected,
said shield including a plurality of elongated keys on its interior
surface, each of said keys being adapted to slide in a keyway displaced
circumferentially from said locking slots on said collar and wherein
at least one of said keys being rotatable into one of said locking
slots when said shield is in its extended position, and
a needle sheath having a closed distal end and an open proximal
end wherein said open proximal end is mounted on said needle shield
to protect said needle point when said shield is in the retracted
position and wherein said shield and needle sheath are movable between
said retracted and extended positions with said needle sheath protecting
said needle when said shield is in said retracted position.
13. The combination according to claim 12 wherein each of said
opposed walls includes a ramp-shaped surface so that said keys can
be rotated in either direction into said locking slots.
14. The combination according to claim 12 wherein a retaining means
is located on said collar and said shield for releasably retaining
said shield in said retracted position.
15. The combination according to claim 12 wherein said collar includes
at least one detent on its outer surface adapted to abut against
one of said keys when said shield is in said extended position.
16. The combination according to claim 12 wherein said shield includes
end walls at its distal and proximal ends to prevent the movement
of said shield beyond said retracted and extended positions.
17. The combination according to claim 12 wherein said shield includes
a radially outwardly extending finger flange thereon to facilitate
the operative movement of said shield between said retracted and
extended positions.
18. The combination according to claim 12 wherein said collar further
includes a plurality of protrusion extending radially outwardly
therefrom and wherein said protrusions are spaced apart to form
keypads therebetween to enable said keys to slide therethrough.
19. A medical device comprising:
a syringe having distal and proximal ends and including a tubular
barrel section, a plunger slidable within said barrel section, and
a needle having a distal needle point thereon wherein said needle
is attached to said distal end of said syringe,
a collar having distal and proximal ends operatively associated
with said distal end of said syringe, said distal end of said collar
including a plurality of locking slots thereon and a plurality of
protrusions along said collar wherein said protrusions are spaced
apart on said collar to form a plurality of keyways therebetween,
an elongated needle shield having distal and proximal ends movable
over said barrel section and said collar between a retracted position
in which said needle point is exposed and an extended position wherein
said needle point is protected, said shield including a plurality
of elongated keys on its interior surface, said keys being adapted
to slide in said keyways formed between said protrusions on said
collar wherein each of said keys are rotatable into one of said
locking slots when said shield is in said extended position, and
a needle sheath having an open proximal end and a closed distal
end wherein said open proximal end is removably mounted to said
distal end of said shield and said shield is movable between said
retracted and extended positions with said needle sheath mounted
thereon.
20. The combination according to claim 19 wherein said collar and
said shield include means thereon for releasably retaining said
shield in said retracted position.
21. In combination,
a syringe having distal and proximal ends including a barrel section
therebetween, and a needle having a distal needle point wherein
said needle is attached to the distal end of said syringe,
collar means operatively associated with said syringe,
an elongated needle shield having distal and proximal ends movable
over said barrel section and said collar between a retracted position
wherein said needle point is exposed and an extended position wherein
said needle point is protected,
means for orienting said shield in slidable alignment along said
collar means wherein rotation of said shield about said barrel section
is prevented as said shield is moved between said retracted and
extended positions,
locking means on one of said collar means or said shield to lock
said shield in said extended position when said shield is in said
extended position and rotated about said barrel section, and
a needle sheath having an open proximal end and a closed distal
end wherein said open proximal end is mountable on said distal end
of said shield and said shield is movable between said retracted
and extended positions with said sheath mounted thereon.
22. A method of using a safety syringe including an elongate barrel
having distal and proximal ends with a needle mounted on the distal
end thereof and an elongate and tubular needle shield having distal
and proximal ends slidably mounted about said barrel and including
a needle sheath mounted on the distal end of the needle shield,
the method including the steps of:
sliding the needle shield and needle sheath from a retracted position
wherein the needle extends distally beyond the needle shield and
the needle sheath protects the needle to an extended position wherein
the needle shield protects the needle,
removing a needle sheath from the distal end of the needle shield,
filling the syringe with a desired medication, and
moving the needle shield proximally along the barrel to an extended
position wherein the needle shield protects the needle of the syringe.
23. The method of claim 22 further including the step of removing
the needle sheath from the distal end of the needle shield when
the needle shield is in a releasable and extended position and moving
the needle shield to a retracted position wherein the needle is
exposed to enable the user to fill the syringe and inject the medication
into the patient.
24. The method of claim 23 further including the steps of:
moving the needle shield to the extended needle protecting position
after injecting the medication into the patient,
rotating the needle shield about the barrel to move the needle
shield to a locked and extended position, and
placing the needle sheath on the distal end of the needle shield
while the needle shield is in the locked and extended position.
25. A method of using a safety syringe having an elongate barrel
member including distal and proximal ends with a needle mounted
on the distal end thereof and an elongate needle shield having distal
and proximal ends slidably mounted about said barrel member and
including a needle sheath mounted thereon, the method including
the steps of:
sliding the needle shield and needle sheath from an initial retracted
position wherein the needle extends distally beyond the distal end
of the needle shield and is protected by the needle sheath to an
extended position wherein the needle is protected by the needle
shield,
removing a needle protecting needle sheath from the distal end
of the needle shield,
filling the safety syringe with a desired medication,
injecting the patient with the desired medication,
sliding the needle shield along the barrel to an extended position
wherein the needle is protected by the needle shield, and
rotating the needle shield about the barrel to place the needle
shield in a locked and extended position.
Syringe needle description
This invention relates to syringes and, in particular, to a hypodermic
syringe having a retractable needle guard primarily for the purpose
of preventing accidental needle sticks.
Most syringes used today for medical or laboratory purposes are
sold as disposable items intended to be used only once. Disposal
of such syringes has posed a safety hazard for the individuals who
use the syringes as well as for those who dispose of them. With
the onset of AIDS, the concern for infection due to accidental needle
sticks from used syringes has increased and a number of different
devices have been proposed to minimize the possibility of spreading
infectious disease due to accidents of this type.
One approach to this problem is to provide a retractable shield
which, after the syringe has been used, can be pulled to an extended
position where it covers the needle, making it difficult for an
individual to accidentally contact the needle. A common feature
of such constructions is that when the shield is pulled to its extended
position, it is locked so that it cannot be retracted (thus exposing
the needle) except by application of extraordinary force.
A number of such constructions have been proposed to satisfy the
general requirement that the needle be permanently covered after
the syringe has been used. Some of these constructions involve twist-to-lock
mechanisms and, in others, locking occurs automatically when the
shield is fully extended. These known devices satisfy many of the
functional requirements of a needle shield but require, in most
cases, modification of the standard syringe construction. This is
highly undesirable for some manufacturers because of the sizable
investment they may have already made in their existing molding
equipment for producing the syringes.
Moreover, certain operational problems arise when a shield is incorporated
into a syringe. For example, since the shield, when it is retracted,
essentially covers the barrel of the syringe, it is desirable to
be able to insert and remove a needle while holding onto the shield
alone. This involves twisting and pushing (or pulling) the needle
to place it on (or remove it from) the luer and can be awkward with
some known constructions.
Further, constructions have been proposed which include an opening
or slot in the side of the shield. This is undesirable because the
needle can extend through the opening if the shield is deflected
in the extended position.
Those devices which lock in response to axial movement 25 to the
extended position, (i.e., without any rotation) have certain inherent
drawbacks that result primarily from the requirement that substantial
force be exerted axially to lock the shield in its extended position.
In the first place, the likelihood of unintentional and irreversible
locking is greater with such devices than with those devices which
require rotation to lock. Also, it is difficult to verify that the
shield is locked upon such forcible extension without attempting
to retract the shield, which increases the possibility of unintended
exposure of the needle. Finally, if the user's hand should slip
from the shield while exerting the force necessary to extend the
shield to the locked position, the user's hand may reflexively rebound
back onto the needle point if the shield does not actually lock.
Other proposed devices have included open ended shields which would
not block access to the needle point by small fingers.
Accordingly, it is an object of this invention to provide a protective
shield of the type described which can be added at minimal expense
to standard syringes.
Another object of the invention is to provide a relatively inexpensive
protective shield which satisfies the functional requirements of
a needle shield and includes none of the drawbacks mentioned above.
Another object is to provide an extendable needle shield for a
syringe which performs all of the necessary functions of such a
shield and which is particularly well suited to an automated process
of manufacture.
A further object of the invention is to provide an extendable needle
shield for a standard syringe which is improved both from the points
of view of functional utility and cost of manufacture.
A still further object is to provide an inexpensive method of assembling
a protective shield and syringe.
SUMMARY OF THE INVENTION
In accordance with the invention, a needle shield is mounted coaxially
on a syringe barrel. The shield includes one or more elongated keys
on its inner surface. A collar is provided on the forward end of
the barrel. The collar may be a separate part or it may be integrally
formed with the barrel and includes on its outer surface at least
one locking slot. The key slides in a path outside of the locking
slot and can be rotated into the locking slot when the shield is
extended. Both the collar and shield can be molded from plastic
materials so that the cost of the shield is relatively low.
In a preferred embodiment, the shield includes a plurality of elongated
locking keys and the collar includes a plurality of locking slots.
Each locking slot is defined by opposing walls, at least one of
which includes a ramp over which the keys can ride when the shield
is pulled to its extended position and rotated.
In the preferred embodiment, when the keys are rotated into the
locking slots, rearward movement of the shield to its retracted
position is prevented by a surface on the collar at the back of
each locking slot. In accordance with a further feature of the invention,
protrusions on the collar and the forward portions of the keys are
shaped such that during assembly the keys are directed into keyways
formed between the locking slots as the collar is moved relative
to the shield. Thus, the construction is well suited to an automated
process in which the collar and shield are secured to the syringe
by machine.
Other benefits of the invention are set forth below in the detailed
description which follows:
IN THE DRAWINGS
FIG. 1 is a side elevational view, partly in section, showing a
needle shield and collar in accordance with a preferred embodiment
of the invention secured to a conventional syringe with the shield
in its retracted position;
FIG. 2 is an enlarged sectional view with the shield in cross-section
in its extended position;
FIG. 3 is a further enlarged partial side sectional view showing
details of the collar and shield;
FIG. 4 is a sectional view along the line 4--4 of FIG. 2 with the
shield pulled to its extended position but before rotation;
FIG. 5 is a sectional view along the line 4--4 of FIG. 2 showing
the shield rotated into its locked position;
FIGS. 6 and 7 are perspective views of a preferred embodiment of
the collar;
FIG. 8 is a side sectional view showing a collar construction for
use with a large diameter barrel; and
FIG. 9 is an enlarged side sectional view showing a shield in its
extended position relative to the collar of FIG. 8.
FIG. 10 is an elevated perspective view of an alternate embodiment
of the present invention showing the needle shield and needle sheath
of the alternate embodiment in the retracted position;
FIG. 11 is a side view partially in cross-section, showing the
needle shield, collar and needle sheath of the embodiment shown
in FIG. 10 in the retracted position and mounted on a syringe;
FIG. 12 is a side view partially in cross-section, showing the
needle shield of the embodiment shown in FIG. 10 in the extended
position:
FIG. 13 is a cross-sectional view of the needle shield and needle
sheath of the embodiment shown in FIG. 10 taken generally along
lines 13--13 of FIG. 10;
FIG. 14 is an elevated perspective view of the collar of the alternate
embodiment as shown in FIG. 11;
FIG. 15 is a cross-sectional view of the collar shown in FIG. 14
showing a cross-sectional view through the protrusions and locking
slots of the collar;
FIG. 16 is a cross-sectional view taken generally along lines 16--16
of FIG. 12 showing the collar and needle shield of the present embodiment
in the extended and unlocked position; and
FIG. 17 is a cross-sectional view taken generally along lines 16--16
of FIG. 12 showing the collar and needle shield of the present embodiment
with the needle shield in the locked and extended position.
DETAILED DESCRIPTION
In its preferred embodiment, the invention is intended to be used
in conjunction with a conventional syringe; however, a protective
shield in accordance with the invention can be used for any medical
or laboratory device having a needle, such as a blood collection
tube holder with a double ended needle. Accordingly, as used herein,
the term "syringe" is intended to include any medical
or scientific device including a needle wherein it is desired to
protect a user from accidental needle sticks.
In describing the invention, the "distal end" of a part
refers to the end of the part closest to the needle point. The "proximal
end" of a part refers to the end furthest from the needle point.
FIGS. 1-6 show a conventional syringe comprising a tubular barrel
10 having a finger flange 11 a plunger 12 slidable within the barrel
10 and a needle assembly through which the contents of the barrel
are dispensed when the plunger 12 is depressed. The barrel 10 may
be tapered very slightly (not shown) from a larger diameter proximal
end to a smaller diameter distal end for molding purposes. The needle
assembly comprises a needle 14 and a hub 16 at the proximal end
of the needle. As is standard, a conically shaped luer tip 17 and
luer lock skirt 18 are integrally formed at the distal end of barrel
10 with luer lock skirt 18 encircling luer tip 17. As shown in FIG.
8 (directed to a different collar construction and described in
detail below), the interior surface of the luer lock skirt 18 includes
an internal thread 18A adapted to threadably engage complementary
locking ears 16A on the needle hub 16. The exterior surface of luer
lock skirt 18 includes a multiplicity of ribs 19 parallel to the
central axis of the barrel. The needle and luer arrangement of FIG.
8 is the same as that of FIGS. 1-6.
A needle sheath 20 covers needle 14 as a protective 5 device. Sheath
20 frictionally engages hub 16 and can be used to disconnect the
needle assembly from the luer lock skirt 18 in conventional fashion.
The construction as so far described is that of a standard disposable
syringe and forms no part of the invention.
The collar employed in accordance with the preferred embodiment
of the invention is shown generally at 22 (FIGS. 2 6 and 8). As
mentioned above, although collar 22 is shown as a separate piece,
the collar (or its functional equivalent) may be integrally formed
as a part of the barrel 10. It includes six equally spaced and integrally
formed identical triangular protrusions 24 with the apex of each
protrusion extending away from the needle. Keyways 25 are formed
between each adjacent pair of protrusions 24.
The triangular protrusions 24 each include angled 20 surfaces 24A
and 24B, side surfaces 25C, a slot 26 and a surface 27 which is
generally circumferential and functions as a stop as explained below.
The slot 26 includes a sloped distal surface 26A. It is not necessary
that protrusions 24 be triangular in shape and other configurations
can be used to provide a stop 27 for the keys and the angled surfaces
25A and 25B necessary to guide the keys into the keyways during
the assembly process as described below. The slot 26 is formed in
protrusion 24 and extends proximally to the point of the protrusion
24 to expose the detenting surface 26A and facilitate the entry
of the detent 50 into the slot 26 during assembly, and also to facilitate
efficient molding of the collar. At the forward end of each protrusion,
two walls 28 and 30 extend toward the needle. A rectangular locking
slot 31 is formed between each pair of walls 28 and 30 which are
ramp shaped in cross section as shown most clearly in FIGS. 4 5
and 6. As shown in FIGS. 3 4 5 and 6 the surface of locking slot
31 is slightly elevated relative to the level of the keyways 25
i.e., the collar diameter at the locking slots 31 is slightly greater
than the collar diameter at the keyways. The slight increase in
the collar diameter at the locking slots removes some of the slack
between the needle shield (described below) and the collar 22 resulting
from the slight taper of the barrel 10 in the preferred embodiment.
This prevents or at least minimizes the wobble or play of the shield
about the collar 22 when it is locked in the extended position.
A circular detent 32 is positioned between each pair of triangular
protrusions 24 with the forward points of detents 32 lying just
in front of the bases of triangular projections 24.
As shown most clearly in FIG. 3 the rear end of collar 22 includes
a peripheral rigid tooth 34 adapted to engage the ribs 19 in the
luer lock skirt 18 to retain the collar 22 on the syringe. Collar
22 is molded of a rigid plastic material such as polycarbonate resin
so that when the collar is pushed over the luer lock skirt 18 the
angled surface of the rigid tooth 34 allows the tooth to move over
the ribs 19 until the proximal end of the collar is seated toward
the distal end of the barrel with the rigid tooth 34 deforming the
ribs 19 of the luer lock skirt 18 to permanently retain the collar
in place on the syringe barrel 10. As an alternative, a circumferential
groove may be formed in collar 22 to receive the peripheral tooth
34. This is unnecessary in the preferred embodiment in which the
yieldable ribs 19 cold flow into the configuration shown in FIG.
3 but may be desirable in the case of syringes which do not include
ribs molded on the exterior surface of the luer lock skirt. Instead
of mechanically interlocking the collar 22 and barrel 10 other
fastening means such as sonic welding or adhesives may be used within
the scope of the invention, although such techniques are generally
disadvantageous because of the additional steps involved and other
problems which may arise with the preferred assembly techniques.
The diameter of collar 22 as measured in the area of the keyways
25 is greater than the outer diameter of the syringe barrel 10 adjacent
the collar.
Locking lip 34 will bite sufficiently into the outer surface of
the luer skirt 18 to prevent axial movement of collar 22 but in
some cases slight rotation or rocking of the collar may occur. To
prevent this, the tooth 34 may be formed with gaps (not shown) so
that not all of the ribs 19 on the outside of the luer lock skirt
18 will be deformed. The non-deformed ribs 19 falling into the gaps
resist rotation or rocking of the collar 22 relative to barrel 10.
Alternatively, as shown in FIGS. 3 and 7 the inner surface of collar
22 may be provided with lugs 35 molded on the inside of the collar
and adapted to fit between the ribs 19 on the outside of the luer
lock skirt 18 to prevent positively any rotational movement with
the meshed ribs 19.
The needle shield comprises an elongated plastic cylinder 40 (e.g.,
made of polypropylene) having three keys 42 integrally formed on
its interior surface. An end rim 44 is formed at the proximal end
of shield 40. As shown in FIG. 2 end rim 44 is adapted to abut
against the proximal end of collar 22 to limit the forward movement
of the shield. Each of the keys 42 includes a distal triangular
point 46 and extends from the distal end of the shield to a point
just short of the distal point of the triangular protrusions 24
on collar 22 when the shield is in its extended position as shown
in FIG. 2. End rim 44 includes three cutout sections 45 which align
with each of the keys 42. Cutout sections 45 facilitate the process
for molding keys 42 but serve no functional purpose after the device
has been assembled. At their rear ends, the keys 42 terminate in
flat surfaces 48. With the three keys 42 in the keyways 25 in the
retracted position (FIG. 1), rotational movement of the shield 40
is prevented by abutment of the edges of keys 42 against the side
surfaces 24C of protrusions 24; therefore, torque can be applied
to the needle while holding shield 40 to thread (or unthread) needles
onto (or from) the syringe. This cannot be done with constructions
in which a shield rotates freely with respect to the syringe.
Three detents 50 are also formed on the inner surface of the shield
40 toward its forward end. The detents 50 may be equally spaced
and are adapted to be received within the slots 26 in the triangular
protrusions 24 to retain the shield 40 in its retracted position
(FIG. 1). In the preferred embodiment, as shown in the drawings,
the detents 50 are each spaced thirty degrees from an adjacent key
42. It is not necessary that the detents be equally spaced. Each
of the detents includes a sloped distal surface 50A and a proximal
surface 50B more gradually sloped than slope 50A.
In the retracted position, the distal end of shield 40 terminates
at the same point as the distal end of collar 22. An end cap 52
(see FIG. 2) is placed on the forward end of the shield 40. Cap
52 is molded from a resilient plastic material (such as polyallomer)
and includes a side wall 53 and an end wall 54 which is adapted
to be positioned between the distal end of collar 22 and the proximal
end of the needle sheath 20 (FIG. 1) for substantially closing the
distal end of shield 40. Side wall 53 is shaped as shown so that
end cap 52 can be retained on shield 40 by the interlocking mechanical
engagement of the side wall 53 and a complementary projection 55
at the forward end of shield 40. Cap 52 need not be a separate part
and can, instead, be formed as an integral part of shield 40.
The end wall 54 includes a central needle aperture which is made
small enough that the end of shield 40 is closed to the maximum
extent while allowing the locking ears 16A of needle hub 16 to be
extended through the aperture to permit needles to be mounted and
removed while the shield 40 is in its retracted position (FIG. 8).
The aperture is not, however, large enough to allow the proximal
end of the sheath to pass through it. The minimum needle aperture
reduces the likelihood that a child or person with small fingers
may accidentally contact the needle point. End cap 52 also makes
the distal end of shield 40 more rigid and resistive to deformation
when dropped or otherwise impacted upon a hard surface.
In addition, the rim 54 and its position between the 5 proximal
end of needle sheath 20 and the distal end of barrel serves a functional
purpose when removing or installing needles on the luer tip 17 (FIG.
8), for example, when the filling and injection needles are different.
When a needle is to be mounted on a syringe, the syringe is held
by shield 40 with the shield in its retracted position. Needle hub
16 projecting from the proximal end of the protective sheath 20
is inserted through the aperture in the end wall 54 and the hub
telescoped onto the luer tip 17. Using the conventional cooperative
wrenching tabs (not numbered) of the sheath and needle, the needle
hub 16 is rotated by twisting and pushing with the sheath to thread
the locking tabs 16A within the internal threads 18A in the luer
skirt 18 until needle 14 is mounted on the syringe. As hub 16 is
threaded onto the luer tip 17 the needles move axially relative
to sheath 20. The shield 40 is prevented from rotating by abutment
of keys 42 against surfaces 24C of protrusions 26 while the rim
54 provides a surface against which the needle sheath can be forced.
Without this feature, the user could not grasp the shield alone
when installing and removing the needle since the force exerted
by the needle hub on the syringe luer tip would push the syringe
out of the shield. This would mean that the user would have to remember
to grasp the barrel and not the shield when removing or attaching
the needle.
The end wall 54 is particularly important when the invention is
used in conjunction with large diameter barrels. Such a construction
is shown in FIGS. 8 and 9 wherein like numerals are used to identify
parts identical to those shown in the embodiment of FIGS. 1-6. In
FIGS. as is the luer tip 17 and the luer lock skirt 18. In this
case, however, the collar 122 includes two concentric hubs or sleeves
124 and 126 supported by an annular strut 128 preferably forming
an I-beam in cross-section as shown in FIG. 9. The cross-sectional
shape is not critical, however, and those skilled in the art will
readily understand that the cross-section could be cup- or channel
shaped, with a web extending either distally or proximally between
the concentric hubs or sleeves. The end cap 152 includes side wall
153 and end wall 154 which, as shown, covers a substantial portion
of the barrel opening and thus greatly reduces the risk of accidental
needle stick when the shield is in its extended position.
The device may be assembled as follows. Shield 40 is inserted on
the forward end of the barrel 10 of an assembled syringe to its
retracted position shown in FIG. 1 (prior to installation of the
needle 14 and sheath 20 on the syringe). With the shield 40 held
in position, the collar 22 is then placed over the luer lock skirt
18 inside of the shield 40. Engagement of the triangular protrusions
24 on collar 22 with the triangular points 46 at the end of keys
42 on shield 40 as the collar 22 is pushed onto the luer lock skirt
18 causes the shield 40 to rotate until the keys 42 are positioned
in the keyways over detents 32 between adjacent triangular protrusions
24. The collar 22 is pushed inwardly until the proximal end of the
collar butts up against the face 56 on the syringe barrel 10. In
this position, as shown in FIG. 3 the three detents 50 are seated
in the slots 26 of three of the protrusions 24. After the shield
40 and collar 22 have been assembled on the syringe, end cap 52
is placed on the shield 40. The needle 14 with its sheath 20 may
then be attached to the luer tip to complete the assembly.
Alternatively, collar 22 may be positioned within shield 40 with
the keys 42 positioned in the appropriate keyways 25. The shield
and collar may then be telescoped together over the syringe barrel
with the collar being forced onto the luer lock skirt as the shield
is moved to the retracted position in which the proximal end of
the collar abuts against the distal face of the syringe barrel.
This procedure, with appropriate tooling, may be used with the end
cap 52 in place on the shield which means that this assembly process
could be used with a shield having end wall 54 integrally formed
as a portion of the shield as mentioned above. Conversely, this
alternative assembly method can be used with an open shield in which
case end cap 52 can be placed on the shield after assembly.
The use of the syringe may be conventional. Needle sheath 20 is
removed and medication drawn into barrel 10 by withdrawal of plunger
12 with the shield in its retracted position shown in FIG. 1. After
the contents of the syringe have been injected into a patient, the
shield 40 is pulled forward into the extended position shown in
FIG. 2. When this happens, the keys 42 slide in the keyways 25 over
detents 32 between the adjacent protrusions 24 on collar 22 (FIG.
4) and the distal surfaces 50A of detents 50 slide over surfaces
26A (FIG. 2) of slots 26. The user can feel the rear edges 48 of
keys 42 clearing detents 32 which signals that the shield 40 is
fully extended.
To lock the shield in place, the user rotates shield 40 causing
the keys 42 to move over the adjacent ramps 28 (or 30) until the
keys fall into the locking slots 31 formed between each pair of
ramps 28 and 30 (see FIG. 5). Because of the arrangement of the
ramps 28 and 30 the shield can be locked by rotating it either
clockwise or counterclockwise. When the keys 42 are positioned in
the locking slots 31 the rear edge 48 of each key abuts against
the squared off surface 27 of one of the triangular protrusions
24 so that the shield cannot be returned to its retracted position
without application of excessive force. Because of the interlocking
relationship of the square key and locking slots, shield 40 can
no longer be rotated and, accordingly, the shield is permanently
locked in place.
There are circumstances where it may be desirable to extend the
shield 40 to the position shown in FIG. 2 without locking it in
place. For example, if a syringe is to be filled at a location remote
from the patient, rather than replacing the sheath 20 after the
syringe is filled, it is preferable to extend shield 40 so that
it functions as a temporary protective element while the syringe
is carried to the patient. Use of the protective shield 40 in this
fashion is facilitated by the detents 32 on collar 22. These detents
32 are positioned in each of the keyways 25 between the triangular
protrusions 24 so that when the shield 40 is pulled to its extended
position (FIG. 2), the flat end 48 of each of the keys 42 abut against
one of the detents 32. This prevents the shield 40 when it is in
its extended position, from being retracted unless sufficient force
is applied to move the keys 42 over the detents 32. Hence, in this
situation, the shield is first extended as a temporary sheath for
the needle, returned to its retracted position for the patient's
injection, and then finally again extended and locked by rotation
so that the shield cannot be retracted. If it is desired to return
the shield 40 to its retracted position rather than locking the
shield in its extended position, because of the gradual slope of
surface 50B of detent 50 the detent can be pushed over the squared
off surface 27.
FIGS. 10-17 illustrate a further embodiment of the present invention
wherein the collar and shield are modified for use on a syringe
having a needle integrally molded on the distal end thereof. As
described hereinafter, this embodiment of the present invention
is particularly useful with relatively small diameter syringes such
as a 1 cc insulin syringe.
The collar employed in accordance with the present embodiment is
shown generally at 222. As mentioned previously, although the collar
222 is shown as a separate piece, the collar (or its functional
equivalent) may be integrally formed as part of the distal end of
the syringe barrel 210. The collar 222 includes four equally spaced
and integrally formed triangular protrusions 224 with the apex
of each protrusion 224 extending proximally away from the needle.
Keyways 225 are formed as recesses between each adjacent pair of
protrusions 224.
The triangular protrusions 224 on the outer surface of the collar
222 each include angled surfaces 224A and 224B, side surfaces 225C,
a slot 226 and a surface 227 which is generally circumferential
and functions as a stop for the proximal end of the key 224 as explained
hereinafter. The slots 226 on the protrusions 224 includes a sloped
distal surface 226A. Although it is not necessary that the protrusions
224 be triangular in shape, it is anticipated that other configurations
may be used to provide a stop surface 227 for the keys 242 (as described
hereinafter) and the angled surfaces 225A and 225B may be modified
as necessary to guide the keys 242 through the keyways 225 as described
hereinafter. The slot 226 is formed in each protrusion 224 and extends
proximally from an angled detenting surface 226A to the triangular
point of the protrusion 224. At the forward or distal end of each
protrusion 224 two ramp shaped wall members 228 and 230 extend
longitudinally along the outer surface of the collar 222 toward
the needle. A rectangular locking slot 231 is formed between each
pair of wall members 228 and 230 as shown most clearly in FIG. 14.
The surface of the locking slot 231 is slightly elevated relative
to the level of the keyways 225 i.e. the collar diameter at the
locking slots 231 is slightly greater than the collar diameter at
the keyways 225. This slight increase in the collar diameter at
the locking slots 231 removes some of the slack between the needle
shield 240 and the collar 222 caused by the slight taper of the
distal end of the barrel 210. This prevents or at least minimizes
the wobble or play of the shield 242 when it is locked in the extended
position as described hereinafter. A raised spherical detent 232
is positioned between each pair of triangular protrusions 224 with
the distal portion of the spherical detent 232 being located slightly
distal to the stop surface 227 of the triangular protrusion 224
and the proximal portion of the spherical detent 232 being located
between the side surfaces 225C of the protrusions 224.
As shown most clearly in FIGS. 11 and 12 the proximal portion
of the interior surface of the collar 222 includes an inwardly extending
annular rigid tooth 234 which is adapted to engage the ribs 219
on the distal end of the syringe to retain the collar 222 on the
syringe. Additionally, a plurality of longitudinally oriented stop
ribs 235 are located on the interior proximal portion of the collar
222 between the rigid tooth 234 and the proximal end of the collar
222. The collar 222 is molded of a rigid plastic material such as
a polycarbonate resin so that when the collar is pushed over the
distal end of the syringe, the angled surface of the rigid tooth
234 allows the tooth 234 to move over the ribs 219 until the proximal
end of the collar 222 is securely seated against the distal end
of the barrel 210 with the rigid tooth 134 slightly deforming the
ribs 219 of the distal end of the syringe to permanently retain
the collar 222 in place on the syringe. As described above, the
rigid tooth 234 will bite sufficiently into the outer surface of
the distal end of the syringe to prevent axial movement of the collar
222 along the syringe. In some cases slight rotation of the collar
222 may occur and therefore, a plurality of stop ribs 235 are formed
on the interior surface of the proximal end of the collar 222 so
that the ribs 219 on the distal end of the syringe will fall into
gaps between the stop ribs 235 to resist rotation of the collar
222 relative to the barrel 210. The combination of the rigid tooth
234 and the stop ribs 235 provides an adequate mechanical interlocking
of the collar 222 onto the distal end of the syringe. It is anticipated
that other fastening means such as sonic welding or adhesives may
be used within the scope of the present invention, although such
techniques are generally disadvantageous because of the additional
steps involved and other problems which may arise during assembly
of the present embodiment.
The needle shield 240 of the present embodiment preferably comprises
an elongated plastic cylinder made of a semirigid material such
as polypropylene. As shown in the drawings, the needle shield of
this embodiment preferably has two longitudinally oriented keys
242 integrally formed along its interior surface. A proximal end
rim 244 is formed at the proximal end of the shield 240. As shown
in FIG. 12 the proximal end rim 244 is adapted to abut against
the proximal end of the collar 222 to prevent the forward or distal
movement of the shield 240 beyond the extended position as described
hereinafter. Each key 242 includes a triangularly shaped distal
end 246 and extends longitudinally along the shield 240 from a location
adjacent to the distal end of the shield 240 to a proximal end 248
located adjacent to the distal point of the triangular protrusions
224 on the collar 222 when the shield 240 is in its extended position
as shown in FIG. 12. The proximal end rim 244 includes a pair of
cut-out sections which are aligned with each of the keys 242 to
facilitate the process for molding the keys 242 on the interior
surface of the needle shield 240. As shown in phantom in FIG. 11
the proximal end 248 of the keys 242 terminate in slightly rounded
surfaces. The keys 242 also include a slightly recessed longitudinal
groove 249 which extends substantially along the keys 242 between
the triangular distal end 246 (FIG. 12) and the rounded proximal
end 248 of the keys 242 to facilitate the sliding movement of the
spherical detent 232 therein as the needle shield 240 is moved between
the retracted and extended positions. With the two keys 242 in the
keyways 225 on the collar 222 rotational movement of the shield
240 is prevented by the abutment of the edges of the keys 242 against
the side surfaces 225C of the protrusion 224 so that the needle
shield 240 will not rotate about the syringe barrel 210 as the needle
shield 240 is moved between the retracted and extended positions.
As shown in FIGS. 12 and 13 a pair of longitudinal detents 250
are formed on the inner surface of the needle shield 240 near the
distal end of the needle shield 240 and keys 242. These longitudinal
detents 250 are radially spaced apart from the keys 242 and are
adapted to be received within the slots 226 on the protrusions 224
to prevent the needle shield 240 from freely sliding along the collar
222 when the needle shield 240 is in the retracted position. In
the present embodiment, the longitudinal detents 250 are each spaced
approximately 45. from an adjacent key 242 and are positioned to
be received in the slots 226 of the protrusions 224 when the needle
shield 240 is in the retracted position as described above. The
longitudinal detents 250 each include a sloped distal end 250A and
a proximal end 250B which has a more gradually sloped surface than
the surface of the distal end 250A. When the needle shield 240 is
in the retracted position, as shown in FIG. 11 the distal end 250A
of each detent 250 contacts the angled detenting surface 226A at
the distal end of the slots 226 on the collar 222. The contact between
the distal end 250A of the detent 250 and the angled detenting surface
226A creates a slight resistance to the movement of the needle shield
240 from the retracted position to the extended position. The contact
between the gradual slope of the proximal end 250B of the detent
250 and the angled detenting surface 226A provides a gradual increase
in resistance as the needle shield 240 is moved from the extended
position to the retracted position. This contact provides a distinct
click or release of tension as the detent 250 passes through the
locking slot 231 and over the distal portion of the protrusion 224
and into slot 226 as the needle shield 240 reaches the fully retracted
position. As shown in FIG. 11 a distal end cap 252 is formed on
the distal end of the needle shield 240 by inwardly folding a portion
of the distal end of the needle shield 240. The distal end cap 252
limits the proximal travel of the needle shield 240 along the barrel
210 so that the distal end of the needle shield 240 is adjacent
to the distal end of the collar 222 when the needle shield 240 is
in the retracted position.
As shown in FIG. 10 the outer surface of the needle shield 240
includes a radially extending finger flange 260. In the preferred
form of the present embodiment, the finger flange 260 is spaced
from the distal end of the needle shield 240 approximately 1/5 of
the length of the needle shield 240. Because the prevent embodiment
is designed primarily for use on relatively small diameter syringes,
the finger flange 260 adds further protection for the user by providing
a radially extending surface which may be grasped by the user to
move the needle shield 240 between the extended and retracted positions
without having the user's hands unnecessarily close to the needle.
The outer surface of the distal end of the needle shield 240 also
includes four equally spaced and longitudinally aligned ridge members
262 (FIG. 13). These ridge members 262 extend between the distal
end of the needle shield 240 and the finger flange 260 to provide
a contact surface for the interior of the needle sheath 264 as described
hereinafter.
As shown in FIGS. 10 and 11 the needle sheath 264 is a generally
closed cylindrical member having an open proximal portion 266; a
tapered intermediate portion 268 and a reduced diameter distal section
270 having a closed end thereon. The interior surface of the proximal
portion 268 of the needle sheath 264 includes an inwardly extending
annular rib 272 which is designed to contact and deform the ridge
members 262 on the exterior surface of the distal end of the needle
shield 240. The needle sheath 264 of the present invention is designed
to be frictionally mounted on the exterior surface of the distal
end of the needle sheath 240. Additionally, the needle sheath 264
may be further heat staked to the distal end of the needle shield
240 to provide further retention of the needle sheath 264 on the
needle shield 240. The assembly of the present embodiment may be
accomplished in the same manner as described above with respect
to the preferred embodiment with the additional steps of attaching
the needle sheath 264 to the needle shield 240 after the needle
shield 240 and collar 222 have been assembled on the syringe and
crimping the distal end of the needle shield 240 to form the distal
end cap 252 on the distal end of the needle shield 240.
The use of the present embodiment provides a further advantage
over the above-described preferred embodiment by enabling the user
to move the needle shield 240 to the extended position prior to
removing the needle sheath 264 from the distal end of the needle
shield 240. This allows the user to remove the needle sheath 264
from the present embodiment while the needle 214 remains protected
by the needle shield 240.
The present embodiment also allows the user to safely resheath
the syringe once the syringe has been filled with the desired medication.
When the user desires to transport the medication-containing syringe
from the filling area to the patient, the needle shield 240 may
be moved to the releasable extended position and the needle sheath
264 may be returned to the distal end of the needle shield 240 to
provide further protection against accidental contact with the needle
214. By allowing the user to position the needle sheath 264 on the
needle shield 240 when the needle shield 240 is in the releasable
extended position, it is not necessary for the user to place their
fingers unacceptably close to the needle 214 during the resheathing
process. Additionally, by resheathing the needle 214 while the needle
shield 240 is in the extended position, the needle point will not
be accidentally damaged by contact with the needle sheath 264. When
the present embodiment is in the retracted position as shown in
FIGS. 10 and 11 the needle shield 240 is generally axially aligned
along the barrel 210 of the syringe and extends approximately one-half
of the distance of the barrel 210. The distal end of the needle
shield 240 is adjacent to the distal end of the collar 222 so that
the distal end cap 252 of the needle shield 240 contacts the distal
end of the collar 222 to prevent further proximal movement of the
needle shield 240 along the barrel 210. In this position, the distal
ends 250A of the longitudinal detents 250 contact the angled detenting
surfaces 226A in the slots 226 on the collar 222. The triangular
distal end 246 of the keys 242 extend slightly beyond the spherical
detents 232 so that the spherical detents 232 are aligned in the
distal portion of the longitudinal groove 249 adjacent to the distal
end 246 of each of the keys 242. The needle sheath 264 extends from
the distal end of the needle shield 240 to protect and entirely
enclose the needle 214 which is permanently attached to the distal
end of the syringe.
As the needle shield 240 is moved from the retracted position to
the extended position, the longitudinal detents 250 on the needle
shield 240 are initially forced over the angled detenting surfaces
226A in the slots 226 on the collar 222 and the keys 242 slide along
the keyways 225 on the collar 222 so that two of the spherical detents
232 on the collar 222 will slide longitudinally in the longitudinal
grooves 249 in the keys 242 and so that the longitudinal detents
250 are released from contact with the collar 222 as the needle
shield 240 is initially moved from the retracted position.
When the needle shield 240 reaches the extended position, the spherical
detents 232 pass from the longitudinal grooves 249 in the keys 242
and into contact with the proximal end 248 of each key 242. The
proximal end 248 of the keys 242 are shaped so that as the proximal
ends 248 of the keys 242 passes beyond the distal surface of the
spherical detents 232 on the collar 222 the user feels and hears
an audible click as the needle shield 240 reaches the fully extended
position. Additionally, in the fully extended position, the proximal
end rim 244 of the needle shield 240 contacts the proximal end of
the collar 222 so that further distal movement of the needle shield
240 is prevented. Next, if the user has not previously done so,
the needle sheath 264 may be removed from the distal end of the
needle shield 240. If the user so desires, they may then return
the needle shield 240 to the retracted position by sliding the needle
shield 240 proximally and linearly along the syringe barrel 210
so that the longitudinal detents 250 pass over the protrusions 224
and into the slots 226 to releaseably retain the needle shield 240
in the retracted position as described above.
Next, when the needle shield 240 is in the retracted position,
the syringe may be used in a conventional manner to draw and inject
a medication into the patient. Alternately, the needle shield 240
may be moved from the retracted position to the releasable extended
position to safely transport the medication containing syringe to
the patient, as described above. Once the needle shield 240 is in
the retracted position and the injection has been completed, the
needle shield 240 may be moved to the extended position so that
the keys 242 slide in the keyways 225 and over the spherical detents
232 between the adjacent protrusions 224 on the collar 222 and so
that the longitudinal detents 250 slide over the protrusions 224
as described above. To lock the needle shield 240 in the extended
position, the user may rotate the needle shield 240 in either direction
about the syringe barrel 210 to cause the proximal ends 248 of the
keys 242 to move over the adjacent wall members 228 or 230 until
the proximal ends 248 of the keys 242 fall into the locking slots
231 formed between the wall members 228 and 230 (FIG. 17). When
the keys 242 are positioned in the locking slots 231 the proximal
end 248 of each key 242 abuts against the squared-off stop surface
227 of one of the triangular protrusions 224 on the collar 222 and
against the perpendicular wall surface of the wall members 228 and
230 so that the needle shield 240 cannot be rotated or returned
to its retracted position without the application of excessive force.
Finally, the user may return the needle sheath 264 to the distal
end of the needle shield 240 as described above to allow for the
safe disposal of the entire assembly. |