Safety syringe abstract
A safety syringe adapter (4) has a hollow body (26) sized to house
a cartridge-needle unit (6) to which a carrier (24) is fixed. The
cartridge-needle unit and carrier therewith are movable from a use
position, with the needle tip (58) exposed, to a safe disposal position,
with the needle tip within the body. A stem assembly (28) has an
elongate stem (60) and a coaxial tubular stem extension (64) and
is movable to a post-injection position, at which the stem extension
becomes secured to the carrier. Pulling the stem assembly proximally
causes the cartridge-needle unit to move to its safe-disposal position
so the needle tip is within the body for safe disposal.
Safety syringe claims
What is claimed is:
1. A safety syringe adapter comprising:
a cartridge-needle unit comprising a barrel, a piston housed within
the barrel and a needle assembly at a distal end of the barrel,
the needle assembly including a hollow needle having a tip
a hollow body having open proximal and distal ends and having an
interior sized to house the cartridge-needle unit therein;
a carrier, removably secured to the cartridge-needle unit to create
a cartridge-needle unit assembly, the carrier being movable between
a distal position, with the tip of the hollow needle exterior of
the body, and a proximal position, with the tip of the hollow needle
within the body;
a stem assembly having a stem engageable with the piston and a
stem extension extending generally parallel to the stem, the stem
extension integral with the stem and having a distal end housed
within the interior of the hollow body between the hollow body and
the barrel, the stem assembly movable in a distal direction from
a pre-use position to a post-injection position and then in a proximal
direction to a safe-disposal position;
means for coupling the distal end of the stem extension to the
cartridge-needle unit assembly when the stem assembly is at the
post-injection position so that moving the stem assembly to the
safe-disposal position moves the carrier to its proximal position
so the tip of the needle of the cartridge-needle unit is moved to
be within the body; and
means for locking the carrier at its proximal position for safe
disposal.
2. The safety syringe adapter of claim 1 wherein the body has finger
ledges at the proximal end thereof.
3. The safety syringe adapter of claim 1 further comprising means
for preventing complete removal of the stem assembly from the interior
of the body.
4. The safety syringe adapter of claim 3 wherein the removal preventing
means includes a locking region defined by the stem assembly and
spring tabs carried by the body having teeth sized and positioned
to engage the locking region upon attempted complete removal of
the stem assembly from the body.
5. The safety syringe adapter of claim 4 wherein the stem extension
is a tubular member and the locking region is a recessed region
formed in the tubular member, the recessed region partially defined
by a generally radially extending shoulder.
6. The safety syringe adapter of claim 1 wherein the carrier is
threadably securable to the needle assembly of the cartridge-needle
unit.
7. The safety syringe adapter of claim 1 wherein the coupling means
includes complementary mating tapering surfaces on the carrier and
the stem extension to provide frictional coupling therebetween.
8. The safety syringe adapter of claim 1 wherein the carrier locking
means includes a guide element on the carrier which engages an axially
extending slot in the body, the slot having a distal retaining region
and a proximal locking region, the guide element and the proximal
locking region sized and configured so that when the guide element
is housed within the proximal locking region, the guide element
is effectively locked therein.
9. The safety syringe adapter of claim 1 wherein the stem extension
is a tubular member made of transparent material.
10. The safety syringe adapter of claim 1 wherein the stem extension
is tubular.
11. A safety syringe comprising:
a cartridge-needle unit including a barrel, a piston housed within
the barrel and a needle assembly at a distal end of the barrel,
the needle assembly including a hollow needle having a tip;
a hollow body having open proximal and distal ends, an interior
sized to house the cartridge-needle unit therein and finger ledges
at the proximal end thereof;
a carrier, secured to the cartridge-needle unit and movable between
a distal position, with the tip of the hollow needle exterior of
the body, and a proximal position, with the tip of the hollow needle
within the body;
a stem assembly having a stem engageable with the piston and a
tubular stem extension integral, circumscribing and coaxial with
the stem, the stem assembly movable in a distal direction from a
pre-use position to a post-injection position and then in a proximal
direction to a safe-disposal position;
the stem extension and the carrier including complementary engagement
surfaces which mate and become secured to one another only when
the stem assembly is at the post-injection injection position so
that moving the stem assembly to the safe-disposal position moves
the carrier to its proximal position so the tip of the needle of
the cartridge-needle unit is moved to be within the body;
means for locking the carrier at its proximal position for safe
disposal; and
means for preventing complete removal of the stem assembly from
the interior of the body, the removal preventing means includes
a locking region defined by the stem assembly and spring tabs carried
by the body having teeth sized and positioned to engage the locking
region upon attempted complete removal of the stem assembly from
the body.
12. A safety syringe adapter comprising:
a cartridge-needle unit comprising a barrel, a piston housed within
the barrel and a needle assembly at a distal end of the barrel,
the needle assembly including a hollow needle cannula having a tip;
a body defining a hollow interior sized to house the cartridge-needle
unit therein and an axis, the body having open proximal and distal
ends and a sidewall with an axially extending slot formed in the
sidewall, the slot having a distal retaining region and a proximal
locking region;
a carrier mounted within the hollow interior, the carrier having
a guide element sized to fit within and be guided by the slot as
the carrier moves between a distal position, with the guide element
removably retained within the retaining region, and a proximal position,
with the guide element effectively locked within the locking region;
the carrier including an attachment element configured to permit
the carrier and the cartridge-needle unit to be secured to one another
so that the cartridge-needle unit moves between a use position,
when the carrier is at the distal position with the tip of the needle
cannula exterior of the body, and a safe disposal position, when
the carrier is at the proximal position with the tip of the needle
within the body;
a stem assembly including an elongate stem having a distal end
engageable with the piston and a proximal end extending past the
open proximal end of the body, the stem assembly movable in a distal
direction from a pre-use position to a post-injection position;
and
the stem assembly also including a tubular stem extension extending
from the proximal end of the stem and surrounding at least a portion
of the stem, the stem extension including a distal end having a
carrier engaging portion configured to become secured to the carrier
when the stem assembly is at the post-injection position so that
movement of the stem assembly from the post-injection position in
the proximal direction to a safe-disposal position causes the cartridge-needle
unit and carrier therewith to move to the safe disposal position
and the tip of the needle to be positioned within the body.
13. A safety syringe adapter comprising:
a cartridge-needle unit comprising a barrel, a piston housed within
the barrel and a needle assembly at a distal end of the barrel,
the needle assembly including a hollow needle having a tip;
a hollow body having open proximal and distal ends and having an
interior sized to house the cartridge-needle unit therein;
a carrier, removably secured to the cartridge-needle unit to create
a cartridge-needle unit assembly, the carrier being movable between
a distal position, with the tip of the hollow needle exterior of
the body, and a proximal position, with the tip of the hollow needle
within the body;
a stem assembly having a stem engageable with the piston and a
tubular stem extension extending generally parallel to the stem,
the tubular stem extension being coupled to the stem and the hollow
body, the stem assembly movable in a distal direction from a pre-use
position to a post-injection position and then in a proximal direction
to a safe-disposal position;
means for coupling the stem extension to the cartridge-needle unit
assembly when the stem assembly is at the post-injection position
so that moving the stem assembly to the safe-disposal position moves
the carrier to its proximal position so the tip of the needle of
the cartridge-needle unit is moved to be within the body; and
means for locking the carrier at its proximal position for safe
disposal, the locking means comprising a guide element on the carrier
which engages an axially extending slot in the body, the slot having
a distal retaining region, a proximal locking region and an intermediate
region therebetween, the guide element, the intermediate region
and the proximal locking region being sized and configured so that
when a sufficient proximal axial force is applied to the guide element,
the guide element slides through the intermediate region into the
proximal locking region and is effectively locked therein.
14. The safety syringe adapter of claim 13 wherein the intermediate
region has opposing walls that taper towards each other from the
distal retaining region to the proximal locking region, the guide
element being sized to laterally deflect the opposing walls as the
guide element slides through the intermediate region.
15. The safety syringe adapter of claim 14 wherein the slot further
includes an axial extension proximal the proximal locking region
to facilitate the lateral deflection of the opposing walls of the
intermediate region.
Safety syringe description
BACKGROUND OF THE INVENTION
Various medications are often supplied using cartridge-needle units
and a syringe adapter. The cartridge-needle units include a barrel
having a piston at one end and a needle assembly at the other with
the pharmaceutical to be injected housed within the syringe barrel
between the piston and the needle assembly. The adapter typically
includes a hollow body sized to hold the barrel of the cartridge-needle
unit and a stem designed to engage the piston. The cartridge-needle
unit is mounted within the adapter body and the injection is given.
After use, the cartridge-needle unit is disposed of while the body
and stem of the adapter can be reused.
One of the problems with health care delivery is risk of infectious
diseases being spread through accidents, especially needle sticks,
with used syringes. There have been many attempts to create safety
syringes in which the needle is either manually or automatically
drawn into the barrel or other housing of the syringe after use.
However, these designs have not fully addressed the problems associated
with the safe disposal of conventional cartridge-needle units after
use.
SUMMARY OF THE INVENTION
The present invention is directed to a safety syringe adapter for
use with a conventional cartridge-needle unit which has few parts,
is inexpensive to produce and is easy to use.
The safety syringe adapter is designed for use with a cartridge-needle
unit of the type having a barrel housing a piston and a needle assembly
at the distal end of the barrel. The adapter includes a hollow body
having open proximal and distal ends and is sized to house the cartridge-needle
unit therein. A carrier is securable to the distal end of the cartridge-needle
unit and is movable, together with the cartridge-needle unit, within
the body from a distal position, with the tip of the needle exterior
of the body, to a proximal position, with the needle tip positioned
within the body.
A stem assembly includes an elongate stem, which engages the piston,
and a stem extension, which extends parallel to the stem. The stem
assembly is movable in a distal direction from a pre-use position,
prior to an injection, to a post-injection position, after an injection,
at which point the stem extension becomes secured to the carrier.
Pulling the stem assembly in a proximal direction causes the carrier
and cartridge-needle unit therewith to move in a proximal direction
as well until the stem assembly reaches a safe disposal position.
At this point the tip of the needle is positioned within the body
and the carrier becomes secured to the body at the proximal position.
Further proximal movement of the stem extension can be prevented,
such as by engagement of radially inwardly extending teeth carried
by the body with a locking region on the stem extension. The used
syringe can now be disposed of safely.
One of the primary advantages of the invention is that it is adapted
for use with conventional cartridge-needle units, such as that made
by Wyeth Labs, Inc. of Philadelphia, Pa. No specially designed ampules
or cartridge-needle units need be used. Also, the user needs to
simply pull on the stem assembly after the injection has been given
to pull the needle into the hollow body and lock the syringe into
its safe disposal condition. No twisting or separate manipulation
of buttons or latches needs to be accomplished. A further advantage
of the invention is that it can be made using only three parts,
in addition to the cartridge-needle unit. It can thus be relatively
inexpensive to produce and suitable for use as a disposable adapter.
Other features and advantages of the invention will appear from
the following descriptions in which the preferred embodiment has
been set forth in detail in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of a safety syringe made according
to the invention in its pre-use or as-shipped condition;
FIG. 2 is an exploded isometric view of the syringe of FIG. 1;
FIG. 3 is a cross-sectional view of the syringe of FIG. 1 in the
pre-use or as-shipped condition, with the cartridge-needle unit
in its use position, the stem assembly in its pre-use position and
the carrier in its distal position, the cutting plane passing axially
along the slot in the hollow body and then rotating 90.degree. near
the proximal end of the slot to pass through the finger ledges and
spring tabs;
FIG. 4 is an enlarged view of the carrier of FIG. 2 with a section
broken away to show the interior;
FIG. 5 is an enlarged cross-sectional view of a portion of the
syringe of FIG. 3;
FIG. 6 is an enlarged view of the distal portion of the syringe
of FIG. 3 but with the stem assembly in its post-injection position
and engaged with the carrier; and
FIG. 7 is an enlarged view of a portion of the syringe of FIG.
3 but with the syringe in its safe-disposal condition with the stem
assembly in its safe disposal position, the carrier in its proximal
position and the needle tip positioned within the hollow body.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1-3 illustrate a safety syringe 2 including a safety syringe
adapter 4 and a cartridge-needle unit 6. Cartridge-needle unit 6
can be a commercially available cartridge-needle unit such as made
by Wyeth Labs, Inc. of Philadelphia, Pa. Cartridge-needle unit 6
includes a barrel 8 having a distal end 10 a proximal end 12 a
needle assembly 14 at distal end 10 and a piston 16 housed within
barrel 8 at proximal end 12. Cartridge-needle unit 6 is filled with
a pharmaceutical or other liquid. In the preferred embodiment, needle
assembly 14 has external threads 8 and a removable safety sheath
20 covering a needle cannula 2.
Adapter 4 includes, in the preferred embodiment, three parts: a
carrier 24 a hollow body 26 and a stem assembly 28. Carrier 24
is generally cylindrical in shape and has internal threads 30 sized
to engage external threads 18 formed on needle assembly 14 to create
a cartridge needle unit assembly. Carrier 24 also includes a radially
outwardly extending boss 32 which acts as a guide element within
body 26 as discussed below.
Body 26 has a generally cylindrical side wall 34 defining a hollow
interior 36 extending from an open distal end 38 to an open proximal
end 40. The initial entry of carrier 24 into interior 36 of side
wall 34 through end 38 is accommodated by a tapering entrance ramp
41 along which boss 32 slides. A pair of finger ledges 42 extend
radially outwardly from body 26 at proximal end 40.
Side wall 34 has an axially extending slot 44 within which boss
32 slides. Slot 44 extends from a distal retaining region 46 which
is defined in part by relatively small retaining shoulders 48 through
a proximal locking region 50 and on to a slot extension 52. Proximal
locking region 50 is defined in part by relatively large locking
shoulders 54 which are created by a narrowing slot portion 56 adjacent
proximal locking region 50. As will be discussed in more detail
below, boss 32 fits within and is normally retained within distal
retaining region 46 when syringe 2 is in its pre-use condition of
FIGS. 1 and 3 by virtue of retaining shoulder 48. However, upon
exertion of a moderate proximally directed force, boss 32 can be
moved proximally (that is towards finger ledges 42) within slot
44 by expanding slot 44. Continued proximal movement causes boss
32 to engage within proximal locking region 50. However, since locking
shoulders 54 are much larger than retaining shoulders 48 distal
movement of carrier 24 is effectively not possible. The lateral
deflection of side wall 34 as boss 32 passes within narrowing slot
portion 56 is accommodated by the provision of slot extension 52.
The configuration of boss 32 and of slot 44 effectively prevents
distal movement of carrier 24 when boss 32 is in distal retaining
region 46 and both distal and proximal movement of carrier 24 when
boss 32 is within proximal locking region 50.
As shown in FIG. 3 cartridge-needle unit 6 is secured to carrier
24 through the engagement of threads 18 30 so that cartridge-needle
unit 6 moves with carrier 24 as carried 24 moves from its distal
position, with boss 32 engaged within region 46 see FIGS. 3 and
5 to its proximal position, with boss 32 engaged within region
50 see FIG. 7. As shown in FIGS. 1 3 and 6 the tip 58 of needle
22 is external of body 26 when carrier 24 is in its distal position
and cartridge-needle unit 6 is in its use position. Tip 58 see
FIG. 7 is positioned within body 26 when boss 32 is in its proximal
position and cartridge-needle unit 6 is in its safe-disposal position.
This movement of carrier 24 and cartridge-needle unit 6 is accomplished
by movement of stem assembly 28. Stem assembly 28 includes a stem
60 extending from a thumb pad 62 and a stem extension 64 also extending
from thumb pad 62 coaxially with and surrounding stem 60. As shown
in FIG. 3 the tip 66 of stem 60 is threaded to a threaded stud
68 extending from piston 16 as is conventional.
Stem extension 64 is generally cylindrical and fits between barrel
8 and side wall 34 so as to stabilize both cartridge-needle unit
6 and stem 60. Stem assembly 28 is moved from its pre-use or as-shipped
position of FIG. 3 to its post-injection position of FIG. 6 by the
user pressing on thumb pad 62 while grasping finger ledges 42 as
is conventional. At the end of this movement, as shown in FIG. 6
an outer tapered surface 70 formed at the distal end of stem extension
64 frictionally engages a complementary inner tapered surface 72
of carrier 24. The frictional engagement between surfaces 70 72
is sufficient so that when the user subsequently pulls on thumb
pad 62 in a proximal direction, the frictional engagement overcomes
the resistance of retaining shoulders 48 thus pulling carrier 24
and cartridge-needle unit 6 therewith in the proximal direction
until boss 32 engages proximal locking region 50. At this point
carrier 24 and cartridge-needle unit 6 are effectively locked within
body 26 with tip 58 sheltered by side wall 34 of the body as shown
in FIG. 7.
To prevent the inadvertent or unauthorized removal of stem assembly
28 from body 26 body 26 has a pair of spring tabs 74 with radially
inwardly directed teeth 76 at open proximal end 40 of body 26. Teeth
76 are positioned to engage a tapered locking region 78 formed in
stem extension 64. Region 78 is defined in part by a radially extending
shoulder 80 which teeth 76 engage in the event of attempted complete
removal of stem assembly 28 from body 26.
In the preferred embodiment, the pre-use and safe-disposal positions
of stem assembly 28 relative to body 26 are the same proximal position
as shown in FIGS. 3 and 7. However, stem assembly 28 could assume
different proximal positions relative to body 26 if desired.
In use, syringe 2 in the pre-use condition in FIGS. 1 and 3 is
selected and safety sheath 20 is removed. The injection is then
given in a conventional manner by pressing on thumb pad 62 while
grasping finger ledges 42. At the end of an injection, stem assembly
28 is in the post injection position of FIG. 6 so that surfaces
70 72 frictionally engage. To prepare for disposal of syringe 2
thumb pad 62 is pulled in the proximal direction until stem assembly
28 is in its safe-disposal position and carrier 24 is in its proximal
position, see FIG. 7 thus placing syringe 2 in its safe-disposal
condition with needle tip 58 positioned within body 26. Used syringe
2 can then be safely disposed of.
In the preferred embodiment, components of safety syringe adapter
4 are made of suitable plastics, such as polycarbonate. It is preferable
that the user be able to see the contents of cartridge-needle unit
6 so that body 26 and stem assembly 64 at least, are preferably
made of transparent or clear material. In the preferred embodiment,
stem assembly 64 is generally cylindrical; however, other elongate
stem extension structures, such as the axially extending rods tied
together at their distal ends with a circular ring, could be used.
The engagement between stem extension 64 and carrier 24 can be other
than a tapered friction fit. For example, detents, barbed elements,
spring fingers or, threaded engagement elements could be used between
stem extension 64 and carrier 24. Also, stem assembly 28 could be
configured to become secured to proximal end 12 of barrel 8 when
at its post-injection position rather than being secured to carrier
24. Locking carrier 24 in its proximal position could be accomplished
using other catch elements; for example a one-way ratchet between
carrier 24 and the inner surface of side wall 26 or an inwardly
biased tooth extending into interior 36 from side wall 26 to catch
on carrier 24 could be used. Carrier 24 could be secured to cartridge
needle unit 6 other than by threads 18 30; for example, carrier
24 could be configured to snap over and engage the shoulder of needle
assembly 14 adjacent distal end 10 of barrel 8.
Other modifications and variations can be made to the disclosed
embodiment without departing from the subject of the invention as
defined in the following claims. |