SAFETY SHIELD SYSTEM FOR SYRINGES
CROSS REFERENCE TO RELATED APPLICATIONS
[00001] This application is a continuation application of Serial
No. 09/885,815 filed June 20, 2001 and Serial No. 09/876,710 filed June 7, 2001, which applications were continuation-in-part applications of Serial No. 09/838,032 filed April 19, 2001, which application was a continuation-in-part application of Serial No. 09/290,786 filed April 12, 1999, now U.S. Patent No. 6,319,233, which application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Serial No. 60/082,221 filed April 17, 1998.
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
[00002] The field of the invention relates to shield systems for protecting
against needle sticks, and syringes including such systems.
BRIEF DESCRIPTION OF THE RELATED ART
[00003] Syringes are well known medical devices for administering
medicaments, drugs and vaccines to patients. Prefilled syringes are generally considered
as those which are filled with a selected dosage of medicament, drug or vaccine by a
pharmaceutical manufacturer for distribution to the end user. They are generally
comprised of a glass barrel which contains the medicament, drug or vaccine, and a stopper
slidably mounted within the barrel. The distal end of the barrel includes a needle cannula
or the like affixed thereto or a connector for a needle cannula assembly such as a Luer
fitting. The proximal end of the syringe includes an integral flange and is open to allow
the insertion of a stopper of a plunger assembly. The plunger and stopper assembly allows
the user to apply manual force to the plunger, causing the medicament, drug or vaccine to
be delivered through the needle cannula or other piercing element. The healthcare worker
or patient grips the flange and applies pressure to the plunger generally with the thumb.
[00004] The use of a sharp-pointed piercing element entails the risk of an
accidental needle stick. To avoid such accidents, many prior art hypodermic syringes have
included rigid cylindrical safety shields telescoped over the syringe barrel. These shields
can be moved between a retracted position, where the needle is exposed for use, to an
extended position where the needle is surrounded by the shield. U. S. Patent Nos.
4,425,120, 4,573,976, 4,850,994 and 4,923,447 disclose various shield systems for
hypodermic syringes. The latter two patents disclose shields which may be spring-
actuated. It is ordinarily desirable to lock the needle shields in the protected positions, and
a number of prior art designs provide for such locking. Some systems, such as those
disclosed in U. S. Patent Nos. 5,201,708, 5,242,240 and 5,318,538 are designed to allow
the shields to be retracted from their locked, extended positions.
[00005] A shield system for protecting the piercing element of a prefilled
syringe is also disclosed in European Publication No. EP 0 740 942 Al. The disclosed
system includes a holder which is coupled to the flange of the syringe barrel, and a shield
which is telescopically mounted to the holder. Two hands are required to operate this
system.
SUMMARY OF THE INVENTION
[00006] This invention relates to a safety shield system for a syringe,
medical cartridge or the like and such a system as used in combination with an assembly
capable of functioning as a syringe, accordance with the preferred embodiment of the
system, the user is able to cause the shielding of a needle cannula by simply applying
additional pressure to the plunger rod of the syringe following injection of the contents of
the syringe barrel. The shield may accordingly be deployed automatically through the use
of only one hand. As there is no need to place the hand near the needle for any purpose,
the risk of needle stick injury is further reduced.
[00007] h accordance with the objects of the invention, a medical device is provided which includes an automatically operable shield system mounted to a syringe barrel. The system includes a tubular holder which defines an enclosure. A tubular needle shield is slidably attached to the holder and preferably telescopically received within the holder. The syringe barrel is received within the holder and shield assembly, preferably within the tubular shield, and the shield is extendable from a retracted position, wherein the needle cannula is exposed to an extended position, wherein the shield encloses the
needle cannula following injection. A compressed spring is located within the holder and shield assembly which biases the shield axially toward the extended position. The shield is releaseably retained to the holder, such that upon application of force to the stopper following injection, the shield is released from the retracted position and the spring drives the shield to the extended position, hi the disclosed embodiment, the shield includes a stop member adjacent its distal end and the holder includes a stop member adjacent its distal end which releaseably retains the shield in its retracted position. In the preferred embodiment, the stop member on the holder is an annular internal groove adjacent the distal end of the holder and the stop member on the shield is a radially outwardly extending annular rib. h the most preferred embodiment, the shield includes a further stop member in the form of a second radial rib adjacent the proximal end of the shield which engages the stop member on the holder when the shield is extended to its extended position. The force of the compressed spring by itself is insufficient to disengage the stop member adjacent the distal end of the shield and the stop member on the holder. However, axial movement of the syringe following injection, disengages the stop members and releases the shield. It is intended to cover the needle tip when in the extended position.
The syringe barrel is operably coupled to the shield such that sufficient axial movement of the syringe barrel causes axial displacement of the shield sufficient to cause disengagement of the stop members. Such movement of the barrel is ordinarily caused by pressure on the plunger rod of the syringe, driving the stopper against the end of the barrel following complete injection of the contents of the barrel. Upon disengagement of the first and second stop members, the spring causes the shield to move to the extended position.
[00008] The proximal end of the holder is preferably adapted to engage and retain the syringe flange upon receipt of the syringe barrel through the proximal end of the
holder. The axial or distal movement of the shield is preferably limited by a second abutment surface or rib adjacent the proximal end of the shield which engages a radially inwardly projecting distal end portion of the holder. Such movement could alternatively be limited by a tether connecting the holder and shield. The shield is preferably positioned within the holder such that the spring engages a stop member extending radially outwardly from the shield. The opposite end of the spring can bear against any suitable surface, operably connected to the holder, preferably a flange on the end fitting.
[00009] The shield system according to the invention is comprised of a holder, a shield, a spring and an end fitting which receives the spring and which isolates the syringe from the holder, reducing damage to the syringe flange. The tubular shield is adapted for receiving a syringe. The shield is slidably mounted to the holder, and is movable between a retracted position, wherein the shield needle cannula is exposed and an extended position wherein the needle cannula is enclosed. A spring urges the shield towards the extended position. The holder includes a stop member which is engageable with a first stop member of the shield to maintain it in the retracted position. Sufficient axial movement of the syringe barrel causes disengagement of the stop members, allowing the spring to move the shield to the extended position. The holder is engageable with a
second portion of the shield axially-spaced from the first portion to prevent decoupling of the shield and holder when the shield moves to the extended position. An end fitting is incorporated in the system to maintain the position of the spring prior to insertion of a syringe into the holder, prevent direct contact of the spring and the syringe flange and isolate the syringe flange from the holder during extension of the shield, preventing damage to the syringe flange.
[00010] The tubular holder includes an inwardly opening annular channel or chamber adjacent the open proximal end which receives the flanges of the syringe and an end fitting. The chamber includes opposed first and second abutment surfaces to retain the flanges. The fitting is located within the holder and includes a tubular portion surrounding the proximal end of the shield and a flange portion located within the housing chamber between the flange of the syringe barrel and the first abutment surface spaced distally from the proximal abutment surface. In the disclosed embodiment, the flange portion of the fitting includes a radially outwardly extending portion and a radially inwardly extending portion. In the preferred embodiment, the radially outwardly extending portion includes at least one and preferably a plurality of resiliently deformable projections extending toward the first abutment surface which isolates the flange of the barrel from the housing and damps impact of the syringe barrel against the first abutment surface, significantly reducing the likelihood of damage such as cracking of the flange of a glass syringe barrel when the shield is extended to the extended position by the spring. In the most preferred embodiment, the resiliently deformable projections are diamond-shaped having a pointed end opposite the first abutment surface and the projections are integral with the fitting preferably formed of a resilient polymer. The radially inwardly projecting portion of the fitting flange portion receives the spring, which is preferably a coil spring biased between
the radially inwardly projecting portion of the fitting and a radially outwardly extending rib on the shield which also serves as the second stop.
[00011] The shield system facilitates the safe use of prefilled syringes,
although it can be adapted for other sharp-pointed injection devices, such as syringes filled just before use and other injection devices. When employed with a syringe, the system allows the contents of the syringe to be expressed in a conventional manner. Continued, and preferably increased pressure on the plunger rod following injection causes the syringe
barrel to move axially, thereby axially displacing the shield. Such displacement causes release of the stop members, and the spring to move the shield over the needle of the syringe. Protection against needle sticks is accordingly provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[00012] Fig. 1 is a top perspective view of a preferred embodiment of the medical device according to the invention as assembled;
[00013] Figure 2 is an exploded, perspective view thereof;
[00014] Fig. 3 is a sectional elevation view thereof;
[00015] Fig. 4 is a sectional view thereof following actuation of the shield
system of the device;
[00016] Fig. 5 is an enlarged sectional view of the proximal portion of the device prior to actuation of the shield system;
[00017] Fig. 6 is an enlarged sectional view showing a portion of the device, including the distal portion of a syringe holder of the device, prior to actuation of the shield system;
[00018] Fig. 7 is an enlarged sectional view showing a portion of the device including the distal portion of the syringe holder following actuation of the shield system;
[00019] Fig. 8 is an enlarged sectional view of the proximal portion of the
device immediately following actuation of the shield system;
[00020] Figure 9 is an end view of the end fitting; and
[00021] Figure 10 is a side, partially cross-sectioned view of the fitting
shown in Figure 9.
DETAILED DESCRIPTION OF THE INVENTION
[00022] An injection device 10 for injecting a medicament, drug or vaccine
into a patient is shown in Figures 1-8. The device comprises a prefilled or prefillable
syringe 12 and a shield assembly coupled to the syringe.
[00023] Syringes are ordinarily comprised of a tubular, generally cylindrical
portion 16, known as a barrel, a needle cannula 18 or other piercing element or a
connecting element secured to one end of the barrel, and a piston or stopper 20 slidably
positioned within the barrel. The needle cannula may be removably secured to the barrel,
but is more likely to be permanently secured to the barrel when the barrel is comprised of
glass. Glass barrels are commonly used in prefillable syringes, and ordinarily contain a
single dose of medication. Prefilled syringes made from plastic are also known to the art.
Referring to Fig. 2, the shield system disclosed herein is employed in conjunction with a
prefillable syringe 12 including a barrel 16, a cannula such as a needle 18 permanently
secured to the barrel, a stopper 20 slidably positioned with the barrel, and a plunger rod.22
engageable with the stopper. The syringe barrel 16 includes a radially outwardly extending
integral flange 24, which is normally grasped by the healthcare worker or patient but is
used to couple the syringe to the shield system of this invention.
[00024] The shield system 14 according to this invention includes a tubular
holder 26, a tubular shield 28 coupled to the holder, a coil spring 30 and an end fitting 32
which engages one end of the spring. With the exception of the spring 30 and the fitting
32, all of the components of the shield system may be made from a semi-rigid plastic material, such as polypropylene. The spring is preferably a metal coil spring. The fitting is preferably formed of a resilient polymer, such as a thermoplastic elastomer, rubber, synthetic rubber or a rubber blend.
[00025] The holder 26 is preferably comprised of an elongate, generally cylindrical tubular body 34 which defines a generally cylindrical enclosure. The holder has proximal and distal open ends 35 and 37, respectively, which provide access to the enclosure. A flange 38 extends radially outwardly from the holder body near the proximal open end 35 thereof. The flange and body of the holder are designed for easy handling as an injection is made. Only one hand should be required for injection.
[00026] The inner surface of the holder enclosure includes a frustoconical surface 40 adjoining the proximal open end 35 as shown in Figures 3 and 5. A first
abutment surface 44 is formed by the holder body in opposing spaced relation to the second abutment surface 42. A second abutment surface 42 is formed at the inner end of this surface, as shown in Figures 4 and 5. As shown in Figures 5 and 8, the abutment surfaces 42 and 44 and the outer wall 43 form an annular channel or chamber for receipt of the syringe flange 24. The inner diameter of the holder, measured at the abutment surfaces 42 and 44, is smaller than the distance between the edges or major diameter of the syringe flange 24. Accordingly, once the syringe is inserted far enough into the holder such that the flange 24 is located between abutment surfaces 42, 44, it is slidably coupled to the holder. The frustoconical surface 40 facilitates this insertion. The spring 30 urges the syringe flange 24 towards engagement with the second abutment surface 42 as shown in Figure 5. The gap formed between the abutment surfaces 42 and 44 is preferably greater than the thickness of the syringe flange 24 to allow large tolerances in height to ease
clipping (particularly at high speed) and absorb flange thickness variations and system
built up to tolerances.
[00027] A radial groove 48 or stop, best shown in Figs. 6 and 7, is provided on the inside surface of the holder adjacent its distal end 37. The radial groove is provided in an arcuately inwardly projecting distal end portion 50 of the holder, which also serves as
a stop member as described below.
[00028] A pair of opposed detents 52 are provided on the holder which prevent retraction of the shield 28 once extended. Each of these detents 52 is formed on an axially extending arm 54 which is integral with the holder body 34 and pivotable with respect thereto. (See Figs. 2, 6 and 7.) The end surface of each detent 52 faces the distal open end 37 of the holder which is substantially perpendicular to the longitudinal axis of the holder. An inclined end surface 53 is provided on the opposite side of each detent, and faces the proximal open end 37.
[00029] The shield 28 is comprised of a substantially cylindrical tubular body 56. The tubular shield 28 preferably has an outside diameter small enough to be positioned within the holder and an inside diameter large enough to receive the barrel 16 of the syringe. As shown in Figs. 2 and 7, a stop member 58 in the form of a radially outwardly extending collar or rib is formed integrally on the body 56 of the shield near the distal end thereof. A second, radially outwardly extending collar or rib 59 is formed integrally on the shield body 56 towards the proximal end, and defines another stop member 59. The second collar 59 is preferably larger in diameter than the first collar.
[00030] The coil spring 30 has an internal diameter large enough to fit over the proximal end of the shield, such that one end thereof bears against the collar 59. The opposite end of the spring bears against the radially inwardly projecting flange portion 65 of the flange portion or collar 66 of the end fitting 32 as shown in Fig. 5, and the flange
portion 66 is biased against the flange 24 of the syringe barrel as shown in Figure 5, such that the spring 30 is operably biased between the second abutment surface 42 of the holder
22 and the shield 28.
[00031] The spring 30 causes the shield 28 to move axially upon axial
movement of the plunger rod 22 when the stopper 20 is driven against the distal end of the
barrel as shown in Figure 4, with sufficient force to disengage the rib 58 on the shield from
the groove 48 in the holder distal end as described further below. Direct engagement of
the end fitting 32 or syringe flange 24 and shield, as provided in the preferred embodiment,
is not necessary in such an arrangement. The operation of the device can be effected
whether the shield, spring, end fitting and syringe barrel are directly or indirectly engaged,
so long as axial movement of the syringe barrel causes axial movement of the shield.
[00032] The end fitting 32 includes a cylindrical tubular portion 64 which is
inserted within the body 34 of the holder as shown in Figure 8 and surrounds the proximal
end of the shield 28 between the rib 59 and the proximal open end as shown in Figure 5.
As described above, the end fitting also includes a proximal flange portion 66 including a
radially inwardly projecting portion 65 which receives the proximal end of the spring 30
and the flange portion 66 further includes a radially outwardly projecting flange portion 67
which extends into the annular channel or chamber defined by the opposed abutment
surfaces 42 and 44 and the outer wall 43 as shown in Figures 5 and 8 and is located
between the first abutment surface 44 and the flange 24 of the syringe barrel 16. The
radially outwardly extending flange portion 67 has a diameter greater than the internal
diameter of the opposed abutment surfaces 42 and 44 of the chamber adjacent the
proximal open end 35 of the holder, such that the shield 28, spring 30 and fitting 32 are
assembled and inserted through the open end 35 as shown in Figure 5, wherein the radial
outer flange portion 67 is biased against the frustoconical surface 40 as described above.
The syringe barrel 16 is then inserted through the open end 35 or the shield assembly is
assembled on the syringe barrel and inserted into the holder 26 as an assembly.
[00033] It would therefore be desirable to isolate the flange 24 of the syringe
barrel from the holder 26 and damp impact of the syringe flange 24 and the radially
outwardly projecting flange portion 67 against the abutment surface 42. This is
accomplished in the present invention by providing resiliently deformable projections 70
which extend from the radially outwardly extending flange portion 67 of the fitting toward
the first abutment surface 42 as best shown in Figures 5 and 8. These projections 70
isolate the flange 24 of the barrel 16 from the holder and prevent damage to the syringe
flange 24. In the prefeπed embodiment, the flange portion 67 includes a plurality of
spaced resiliently deformable projections 70. However, as will be understood, the object
of the projections can also be fulfilled by a single continuous resiliently deformable
projection. Further, in the prefeπed embodiment, the distal end of the resiliently
deformable projection or projections 70 have a pointed distal end facing the abutment
surface 42 providing improved damping by the projections. In the most prefeπed
embodiment disclosed, the resiliently deformable projections are diamond-shaped as best
shown in Figure 9 providing excellent damping of vibration of the syringe flange 24 as
shown in Figure 8, wherein the shield 28 has just been released and the spring 30 is not yet
fully expanded. As will be understood, the end fitting 32 also avoids direct contact of the
coil spring against the fragile glass syringe flange 24. Further, in the most prefeπed
embodiment, the resiliently deformable projection 70 are integral with the flange portion
66 and the tubular portion 28 for ease of manufacture and assembly. In such
embodiments, the fitting 32 is preferably formed of a resilient polymeric material, such as
a thermoplastic elastomer, rubber, synthetic rubber and blends. The improved end fitting
32 thus reduces damage to the flange 24 of the syringe barrel 16 and isolates the flange
from the housing 22.
[00034] It would therefore be desirable to isolate the flange 24 of the syringe
barrel from the holder 26 and damp impact of the syringe flange 24 and the radially
outwardly projecting flange portion 67 against the abutment surface 42. This is
accomplished in the present invention by providing resiliently deformable projections 70
which extend from the radially outwardly extending flange portion 67 of the fitting toward
the first abutment surface 42 as best shown in Figures 5 and 8. These projections 70
isolate the flange 24 of the barrel 16 from the holder and prevent damage to the syringe
flange 24. In the prefeπed embodiment, the flange portion 67 includes a plurality of
spaced resiliently deformable projections 70. However, as will be understood, the object
of the projections can also be fulfilled by a single continuous resiliently deformable
projection. Further, in the prefeπed embodiment, the distal end of the resiliently
deformable projection or projections 70 have a pointed distal end facing the abutment
surface 42 providing improved damping by the projections. In the most prefeπed
embodiment disclosed, the resiliently deformable projections are diamond-shaped as best
shown in Figure 9 providing excellent damping of vibration of the syringe flange 24 as
shown in Figure 8, wherein the shield 28 has just been released and the spring 30 is not yet
fully expanded. As will be understood, the end fitting 32 also avoids direct contact of the
coil spring against the fragile glass syringe flange 24. Further, in the most preferred
embodiment, the resiliently deformable projection 70 are integral with the flange portion
66 and the tubular portion 28 for ease of manufacture and assembly, hi such
embodiments, the fitting 32 is preferably formed of a resilient polymeric material, such as
a thermoplastic elastomer, rubber, synthetic rubber and blends. The improved end fitting
32 thus reduces damage to the flange 24 of the syringe barrel 16 and isolates the flange
from the housing 22.
[00035] The assembly and use of this prefeπed embodiment of the invention
will now be described. The shield 28 is slidably mounted to the holder 26 by inserting the
shield through the proximal open end 35 thereof until the first stop member or collar 58 is
received in the radial groove or stop member 48 in the holder. The spring is inserted
through the proximal open end 35 of the holder, and over the shield until it abuts the
relative large collar or rib 59. As a final step, prior to providing the shield system to the
end user, the end fitting 32 is slipped over the exposed end of the spring and pushed
through the proximal end 35 of the holder. The spring is substantially compressed during
this step. The shield 28 is resiliently urged towards the distal end 37 of the holder 26
while the end fitting 32 is urged towards the proximal end 35 of the holder 26 by the coil
spring 30. Neither element can move due to the engagement of the stop members 48, 58,
and the annular wall or collar 66 of the end fitting with the abutment surface 42,
respectively. The force of the spring 30 is insufficient to cause the disengagement of the
shield and holder.
[00036] The shield system 14 receives a syringe 12 of appropriate size
through the proximal open end 35 of the holder. The system as shown is designed for
receiving a syringe 12 including a flange 24. The syringe flange 24 engages the conical
surface 40 and is inserted into the shield until the flange 24 snaps behind the second
abutment surface 42 in the holder 26. The end fitting 32 is displaced axially slightly
during this procedure. As the needle of the syringe is ordinarily protected by a needle
cover or cap (not shown) at this time, it may be safely coupled to the shield system.
[00037] The force required to disengage the rib or stop 58 of the shield from
the stop member or internal groove 48 of the holder is greater than the force of the spring
plus the force required to expel the contents of the syringe barrel 16 by compressing the
stopper 20. The plunger rod 22 is employed to move the stopper 20 through the syringe
baπel until the contents of the barrel have been completely expelled. (The needle cover is,
of course, removed prior to injection). The contents of the barrel of a prefilled syringe
ordinarily corresponds to a single dose of the prescribed medicament.
[00038] Following removal of the needle 18 from the patient, the user
applies a greater force to the plunger rod 22 than that applied during injection. Such force
causes axial displacement of the syringe barrel 16, end fitting 32, the spring 30 and the
shield 28 with respect to the holder 26. The distance between the annular wall or collar 66
of the end fitting (or the flange 24) is then sufficient to permit the second stop member rib
58 to move far enough axially to where its retention by the groove 48 is overcome by the
force of the spring. The first stop member 48 may also be displaced radially inwardly as
such sliding occurs if sufficient flexibility of the holder body is provided.
[00039] Once the rib 58 and groove 48 are disengaged, the spring 30
expands rapidly, causing the shield 28 to slide axially or distally with respect to the holder
26 and syringe barrel. The collar or stop member 59 moves past the detents 52, causing
them to deflect radially outwardly and then inwardly to their original positions. The collar
59 then engages the abutment surface 50 as shown in Figure 7. The resiliently deformable
projection or projections 70 on the fitting 32 damps vibration of syringe 12 during
movement the shield 28 reducing damage to the flange 24. Upon such engagement, the
needle cannula 18 is entirely and permanently enclosed and covered by the shield 28, as
shown in Figs. 4 and 7. The shield cannot be retracted sufficiently to expose the needle tip
due to the engagement of the stop member or collar 59 with the detents 52. It cannot be
removed from the holder as the stop member 59 cannot move past the abutment surface 50.
[00040] The above-described procedure is particularly safe as it can be
accomplished using only one hand. No second hand is required to move the shield, push a
button or use any other actuating member to release the shield spring. The risk of
accidental actuation of the shield through inadvertent contact with an actuating button is
also eliminated. Moreover, a one-handed system is simpler for most people to use. It is
readily apparent that the shield system can be adapted for use with syringes of various
shapes and sizes without major modification.
[00041] The deployment of a shield in response to the axial displacement of
a syringe baπel with respect to a holder is a safe and effective way of protecting against
needle sticks. The prefeπed embodiment of the invention, as described above, provides
advantages for the user as well as the manufacturer. The components are relatively easy to
manufacture and assemble. It will be appreciated, however, that modifications can be
made without changing the basic mode of operation of the device. For example, the stop
member 58, of the shield, rather than being in the form of a collar, can simply be the end
of the shield. The dimensions of each component of the medical device are determined by
the specific uses(s) for which it is designed.
[00042] It will be appreciated and understood by those skilled in the art that
further and additional revisions to the invention may be devised without departing from the spirit and scope of the appended claims, the invention not being limited to the specific
embodiment shown.