Safety syringe abstract
A disposable safety syringe has a needle shuttle slidably located
within a main syringe barrel. The shuttle has a pair of outwardly
extending guide tabs which engage a guide slot formed in the barrel
wall. The upper end of the needle shuttle is configured to accept
a Wyeth needle cartridge having a needle attached to an ampoule
by a carrier. A bushing and rod assembly are mounted in the barrel
below the ampoule. After use, the needle shuttle is maneuvered downwardly
by the guide tabs to a locking position in which the needle attached
to the ampoule is housed within the barrel for safe disposal.
Safety syringe claims
What is claimed is:
1. A combination disposable syringe and cartridge assembly, the
cartridge assembly including an ampoule and a needle carrier secured
to the ampoule, the ampoule having a main body portion, a dispensing
end and an opposite end, a piston housed within the main body for
expelling the contents of the ampoule, said combination comprising:
a main housing having a wall portion with an interior volume, said
wall portion having a guide slot with a tab support portion and
a tab lock portion;
a needle shuttle having a needle carrier attachment portion and
a guide tab engageable in said guide slot;
said needle shuttle supporting an attached needle assembly in a
first extended position when the needle shuttle guide tab is located
in the tab support portion of said guide slot and maintaining an
attached needle assembly within said interior volume of said main
housing when the needle shuttle guide tab is located in the tab
lock portion of said guide slot, the needle shuttle guide tab including:
a pair of axially extending, circumferentially flexible leg portions;
and
a laterally spaced, radially extending tab portion formed on each
of said flexible leg portions;
a bushing and rod assembly insertable in said interior volume of
said main housing and including:
means for translating the ampoule piston towards the dispensing
end of the ampoule to expel the contents; and
a rod member having an end portion engageable with the ampoule
piston;
said bushing and rod assembly including a rod-member-guiding bushing
member having a longitudinally extending bore, an outer wall surface
of a first diameter and a peripheral portion of a second diameter,
said first diameter being smaller than the inner diameter of said
interior volume, said second diameter being larger than said inner
diameter of said interior volume; and
said bushing member being provided with a longitudinally extending
cut-away for enabling said rod member to be laterally press-fitted
into said bore.
2. The invention of claim 1 wherein said needle carrier attachment
portion of said needle shuttle includes an internally threaded end
portion.
3. The invention of claim 2 wherein the cartridge assembly comprises
a needle carrier having an externally threaded portion; and wherein
said internally threaded end portion of said needle shuttle is formed
with threads matched to the externally threaded portion of said
needle carrier.
4. The invention of claim 1 wherein said guide slot includes an
inwardly tapering wall portion, adjacent the tab lock portion, engageable
with the circumferentially flexible leg portions.
5. The invention of claim 1 wherein the ampoule piston has a threaded
portion; and wherein said rod member end is threadably engageable
with said threaded portion.
Safety syringe description
BACKGROUND OF THE INVENTION
This invention relates to a relatively low cost, disposable syringe
designed to reduce or eliminate accidental needle strikes by enabling
selective position control of a cartridge mounted needle from an
injecting position to a retracted and locked position.
Hypodermic syringes are used for a variety of injection procedures
including the delivery of medicinal drugs and anesthetics to a patient.
Once the injection procedure is completed, problems can arise if
the syringe is not disposed of properly and adequately. Healthcare
workers are susceptible to accidental and potentially infectious
needle strikes if the needle is carelessly handled or broken during
disposal of the syringe after use. If an accidental needle strike
does occur, a blood test is typically required to determine whether
the worker has been infected. The cost of performing such tests
and the loss of personnel time attendant upon such tests can be
particularly damaging to a healthcare facility striving for economy
and efficiency.
There are several known syringes designed to provide retraction
of a syringe needle after use. In some such designs, the apparatus
is designed such that the needle is retracted within the same ampoule
which initially housed the medication dispensed with the syringe.
In other known devices, the retraction mechanism is designed to
retract the used needle within the syringe housing and lock the
needle in the retracted position.
While such known designs have been found suitable in a wide variety
of applications, none is compatible with a syringe using the Wyeth
needle cartridge. In the Wyeth design, a single ended needle is
bonded to a plastic carrier member, which in turn is secured to
the ampoule containing a liquid medication. The needle passageway
is in fluid communication with the interior of the ampoule, and
a pliant needle cover, usually fabricated from rubber, is removably
attached to the needle carrier member to seal the needle from ambient
until the medication is ready to be dispensed. The needle carrier
is provided with externally formed threads or ridges. Since the
Wyeth needle cartridge provides a convenient supply of a variety
of medications at relatively low cost, such cartridges have found
wide use. However, after the medication has been dispensed from
a Wyeth needle cartridge, the needle is exposed and poses a safety
threat requiring special disposal procedures. Consequently, the
need exists for an economical disposable syringe which is compatible
with the Wyeth type of needle cartridge, and which provides safe
handling and disposal for such needle cartridges after use.
SUMMARY OF THE INVENTION
The invention comprises a disposable safety syringe which is designed
for use with the Wyeth standard needle cartridge, is relatively
simple in design and use, and provides retractable locking for the
cartridge after use, with the needle being positioned safely within
the syringe barrel.
In the preferred embodiment, the invention includes a main housing
having a wall portion with an interior volume, the wall portion
having a guide slot with a tab support portion and a tab lock portion.
A needle shuttle dimensioned to be insertable within the interior
volume of the main housing has a needle carrier attachment portion
and a guide tab locatable in the main housing guide slot. The needle
carrier attachment portion is designed to secure an attachable needle
and cartridge assembly, preferably a Wyeth type needle and cartridge
assembly, and includes an internally threaded end portion preferably
formed with threads engageable with an externally threaded portion
of the needle carrier.
The needle shuttle guide tab enables manipulation of the needle
shuttle between an injection position in which the guide tab is
located in the tab support portion of the guide slot and a lock
position in which the guide tab is located in the tab lock portion
of the guide slot. In the tab support position, the needle shuttle
supports an attached needle and cartridge assembly in an extended
position: in the tab lock position, the needle shuttle maintains
an attached needle and cartridge assembly in a retracted position
in which the needle is located within the interior volume of the
main housing so that the needle is safety locked in a totally retracted
position.
The needle shuttle preferably includes a longitudinally extending
wall member terminating in a pair of laterally spaced leg portions
each having a guide tab. To facilitate insertion of the needle shuttle
within the interior of the main housing, the leg portions are inwardly
flexible.
A bushing and rod assembly is dimensioned to be inserted partially
within the interior volume of the main housing. The bushing and
rod assembly includes means engageable with a slidable piston located
within the ampoule for translating the piston towards the dispensing
end of the ampoule to expel the contents thereof. The bushing and
rod assembly preferably includes a bushing member having a longitudinally
extending bore, an outer wall surface of a first diameter and a
peripheral portion of a second diameter. The first diameter is smaller
than the inner diameter of the interior volume of the main housing,
and the second diameter is larger than the inner diameter of the
interior volume. The bushing and rod assembly further preferably
includes a rod member having an end portion engageable with the
ampoule piston. The end portion of the rod member is preferably
threaded to engage a threaded portion of the ampoule piston. The
bushing member is preferably provided with a longitudinally extending
cut-away for enabling the rod member to be press fitted into the
bore.
The invention can be configured for shipment with or without the
needle and cartridge assembly. When configured for shipment with
the needle and cartridge assembly, the assembly is attached to the
needle shuttle, and the needle shuttle is positioned by manipulation
of the guide tabs to the tab support position in which the needle
is extended from the main housing but covered with a removable needle
cover. The bushing and rod assembly is installed in the bottom of
the main housing, with the rod attached to the ampoule piston. When
configured for shipment without the needle and cartridge assembly,
the needle shuttle is typically installed in the main housing, and
the busing and rod assembly is included with the package.
In use, with the needle and cartridge assembly supported in the
main housing in the extended position and the rod member attached
to the ampoule piston, the needle cover is removed and the ampoule
contents are expelled by forcing the rod member inwardly of the
main housing.
After the ampoule contents are expelled, the needle and cartridge
assembly are moved to the retracted and locked position by manipulating
the needle shuttle by means of the guide tab toward the locking
position. The needle carrier, which is attached to the needle shuttle,
is automatically withdrawn within the interior of the main housing
and locked in place by means of the locking engagement between the
needle shuttle guide tab and the tab lock portion of the main housing
guide slot.
For a fuller understanding of the nature and advantages of the
invention, reference should be had to the ensuing detailed description
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a preferred embodiment of the invention;
FIG. 2 is a sectional view illustrating the preferred embodiment
of the invention prepared for packaging;
FIG. 3 is a sectional view of the invention during use to expel
the medication; and
FIG. 4 is a sectional view of the invention in condition for disposal
and illustrating the needle in the retracted locked position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings, FIG. 1 is an exploded perspective
view of the preferred embodiment of the invention. As seen in this
Fig., the disposable syringe includes a main body member generally
designated with reference numeral 10 having a barrel portion 12
with oppositely disposed upwardly extending angled finger tabs 13
14 integrally formed at the bottom end thereof, and a beveled nose
portion 15. Extending longitudinally of barrel portion 12 is a guide
slot 16 terminating at the upper end in a laterally extending slot
portion 17. Guide slot 16 also has a pair of mutually facing, inwardly
tapering wall portions 18 terminating in an enlarged, generally
rectangular lock slot portion 20.
A one piece needle shuttle generally designated with reference
numeral 25 has a generally cylindrical upper body section 26 and
a downwardly depending wall member 27 terminating in a pair of flexible
leg portions 28 29. Leg portions 28 29 each include one of a pair
of outwardly extending guide tab 30 31 which are laterally spaced
by an amount which ensures a locking fit in lock slot 20 in the
manner described more fully below.
As best seen in FIGS. 1 and 2 the upper body portion 26 of needle
shuttle 25 has an internally threaded annular wall portion 37 designed
to be threadably engaged with the needle carrier of a standard Wyeth
medication cartridge assembly generally designated with reference
numeral 50.
More particularly, cartridge assembly 50 includes a single ended
needle 51 bonded within a unitary carrier 52. Carrier 52 has a central
nose portion 53 and an internal passageway 54 (see FIG. 2), and
the lower end of needle 51 is bonded within the passageway 54 typically
by means of a suitable adhesive. Needle carrier 52 is normally provided
with an external threaded portion 55 and threads 37 formed in the
needle shuttle 25 are configured to engage this threaded portion
55.
Again with reference to FIG. 1 the assembly 50 comprising needle
51 and carrier 52 is bonded to a standard Wyeth medicine cartridge
or ampoule 58 typically fabricated from glass or pharmaceutically
compatible plastic material. A removable needle cover 56 is removably
arranged over central nose portion 53 of carrier 52. Cover 56 is
typically fabricated from butyl or urethane rubber and seals needle
51 as well as the contents of ampoule 58 from ambient. A sealing
piston 60 is located in the bottom interior of ampoule 58 and seals
the fluid contents within ampoule 58 prior to dispensing. Piston
60 has a centrally located downwardly depending threaded member
62 configured for threadable engagement with an activation rod generally
designated with reference number 65. Rod 65 includes a stem portion
66 with an enlarged upper end 67 having an internally threaded bore
68. The lower end of stem portion 66 terminates in a base portion
69.
A guide bushing generally designated with reference numeral 70
has a generally cylindrical body with an enlarged waist portion
72 and a longitudinally extending central bore 74 dimensioned to
receive stem portion 66 of rod 65. To facilitate assembly, a portion
of bushing body 70 is cut away so that the stem portion 66 can be
pressed into the bore 74. The outer diameter of the body of bushing
70 is dimensioned to provide a close fit in the lower end of the
interior of barrel portion 12 while waist portion 72 limits upward
movement of bushing 70 within the barrel portion 12.
In use, the device is assembled in the following fashion. Needle
shuttle 25 is inserted into the bore of barrel 12 from below and
manipulated upwardly. Leg portions 28 29 are flexed inwardly in
order to permit locking tabs 30 31 to clear the first portion of
the inner wall of barrel 12. Shuttle 25 is manipulated further upwardly
within barrel 12 until the locking tabs 30 31 extend through the
guide slot 16 in barrel 12. Thereafter, shuttle 25 can be manipulated
upwardly by means of the protruding guide tabs 30 31 until the
shuttle 25 is in the uppermost position at which the upper edges
of the guide tabs 30 31 encounter the upper edge of the slot portion
17. Thereafter, shuttle 25 is rotated by means of the guide tabs
30 31 into the slot portion 17 so that the shuttle is supported
by the lower edge of slot portion 17. If the syringe is to be shipped
with the cartridge assembly 50 the assembly 50 is now inserted
via the bottom opening in barrel 12 and maneuvered upwardly therein
until the threaded portion 55 of carrier 52 can be engaged with
the internal threaded portion 37 of shuttle 25. Ampoule 58 is now
supported within barrel 12 in the attitude illustrated in FIG. 2.
The stem portion 66 of rod 65 is pressed fitted into bushing 70
and is threadably attached to piston member 62 by rotating rod 65
in the proper direction. Bushing 70 is fitted into the interior
of barrel portion 12. This shipping configuration for the invention
is illustrated in FIG. 2. In some applications, the end user will
supply the cartridge 50: in such applications, the two subassemblies
comprising the body member 10/shuttle 25 and the rod 65/bushing
70 are shipped in the package to the user.
When the syringe is scheduled to be used for an injection, the
needle cover 56 is first removed. The user then applies an upward
force to rod 65. This causes piston 60 within ampoule 58 to be translated
upwardly and expel the contents of ampoule 58 via passageway 54
and needle 51.
After the contents of ampoule 58 has been expelled by the required
amount, rod 65 is disengaged from piston 60 and rod 65 and bushing
70 are manually withdrawn through the bottom opening in barrel portion
12. Thereafter, needle shuttle 25 is rotated by rotating guide tabs
30 31 to the guide slot 16 and needle shuttle 25 is manipulated
downwardly until the guide tabs 30 31 are engaged in the lock slot
20. As the needle shuttle 25 is manipulated downwardly, the cartridge
assembly 50 follows this motion and needle 51 is withdrawn into
the interior of barrel 12 until the position illustrated in FIG.
4 is achieved. As seen in this FIG., the needle 51 is locked in
place entirely within the barrel 12 illustrated in FIG. 4 and the
spent assembly may now be disposed of in a safe manner.
As will now be apparent, disposable syringes fabricated according
to the teachings of the invention are completely compatible with
standard Wyeth cartridge assemblies, and provide a safe and economical
technique for disposing of used assemblies of this type. In addition,
due to the simplicity of the design of the invention, the ampoule
58 may be readily inserted by the user in those applications in
which it is not desired to transmit the ampoule 58 along with the
syringe supplied to the user.
While the above provides a full and complete disclosure of the
preferred embodiment of the invention, various modifications, alternate
constructions and equivalents may be employed as desired. For example,
although expressly designed for use with Wyeth type cartridge assemblies,
the device can be adapted for use with any other type of standard
or custom designed cartridge in which the needle is bonded to the
ampoule using a carrier capable of interlocking engagement with
a needle shuttle. Further, although needle shuttle 25 has been illustrated
and described as having internal threads 37 designed for threaded
engagement with external threads 55 shuttle 25 may be configured
to provide a snap fit or a friction fit to the needle carrier 52
if desired. Therefore, the above description should not be construed
as limiting the scope of the invention, which is defined by the
appended claims. |