Note: Descriptions are shown in the official language in which they were submitted.
CA 02696951 2010-02-19
PCT/AU2008/001210
Received 22 June 2009
c:%documenl3l11oba1 mcdisafc12U290 amanded.doc
SAFETY SYRINGE WITH PLUNGER LOCKING MEANS
Technical Field
This invention relates to a safety syringe having a retractable needle for use
in the
medical or dental profession or in pcrsonal drug administration so that the
physician,
s surgeon or other nccdle operator might be protected from injur y by the
needle after its
use. In particular it relates to locking means for retaining the plungcr to
which the
needle is attached, and hence the needle, in the retracted position.
B ackrround
The danger of injury and possible infection from the H1V or hepatitis B virus
to medical
io practitioners using needles in the normal course of their business is well
documented.
Further, persons who are in the habit of administering drugs to themselves run
a sevcrc
risk of contacting either of the specified viruses, or indeed contacting other
viruscs if a
needlc, once used, is reused in an unsterilised form.
There have been many proposals airried at reducing the number of so-called
needle-stick
15 injuries and various attempts have been made to providc a safe system for
disposal of
such needles once used, but such prior proposals have had deficiencies.
Many solutions to the foregoing problems provide for retractable needles. One
of the
major disadvantages in many previous proposals is that the syringe although
rendered
initially safe by having the needle retracted, does not usually provide means
for
20 preventing further access to the needle. In other words, the plunger may be
dcpressed.
again causing the needle to re-emerge from the barrel of the syringe, or in
some other
instances may be withdrawn altogether form the barrel of the syringe thereby
gaining
access to the needle.
Object of the Invention
25 It is an object of the present invention to provide a syringe which to some
extent solves
or at least ameliorates some or all of the foregoing disadvantages by
employing a
retractable surgical needle, and for permanently storing that surgical needle,
once used,
in a substantially safe manner. In particular, the present invention provides
for a
positive locking facility to prevent the plunger, to which the withdrawn
needle is
Amended Sheet
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Received 22 June 2009
c:ldocumentslglobal medisafe120290 amended.doc
attached, from being reactivated or withdrawn altogether, once the syringe is
rendered
safe by having the needle retractcd. At the very least the invention provides
an alternate
means for accommodating the needle of a used syringe to protmt against
accidental
injury arising from unwanted contact with the exposed needle once the syringe
has been
used. '
Although the following description generally rcfers to a syringe of
conventional size, no
such limitation is intended thereby, and reference to a syringe is meant to
encompass
any other needle/syringe combination or needle alone including slimline
syringes,
where, by suitable adaptation, the invention may also be usefully applied.
lo Disclosure of the Invention
According to the present invention there is provided a safety syringe having a
retractable needle facility incorporated therein, the syringe comprising a
barrel and
plunger and needle assembly, wherein the needle is caused to retract into the
barrel of
the syringc upon completion of injection once it has been used, by means of
engagement
is between the needlc assembly and the end of the plunger, and wherein locking
means is
provided in the body of the syringe in the form of a full circle ring or bush
to engage the
plunger once it is retracted after use, so that the syringe is rendered
incapable of being
used further in that the plunger can neither be pushed down again to reactive
the needle,
nor can it be removed altogether from the barrel of the syringe to gain access
to the
20 necdlc; and wherein fitment of the ring or bush to the plunger is
facilitated by a plunger
comprising two portions, namely a stem portion and a cap portion, which are
joined
after the ring or bush is fitted thereto.
Preferably a region of weakness is provided in the plunger, located on the
shaft of the
plunger in the vicinity of whcrc it extends from the end of the syringe body
when fully
zs withdrawn, so that after the needle is retracted into the body of the
syringe, and the
plunger is engaged with the locking means, the plunger is broken off so that
it cannot be
depressed again, or readily removed by gripping it and excrting force, thereby
further
assisting in rendering the syringe incapable of being used again.
2
Amended Sheet
IPEA/AU
CA 02696951 2010-02-19
PCT/AU2008/00 1 2 10
Received 22 June 2009
c:klncumantslglobal medl8afe120290 amended.doc
It will be understood that whilst the invention is arguably improved by the
ability to
break off the plunger as well, it should be appreciated that this is an extra
step and one
that some users might iimore.. Therefore the present invention provides for
the locking
means to be of sufficient resistance to prevent the plunger from being
depressed or
removed so that it does not matter that the plunger is broken off. In other
words, even
before the plunger is broken off, the present invention envisages that the
syringe will be
rendered ineffective against ether deliberate or even accidental re-use as
might occur if
the syringe were knocked as it was being placed on a table for example.
Fitment of the ring or bush to the plunger is achieved by having a two part
plunger, the
two parts of which are fitted after the ring or bush is fitted about the shank
of the
plunger. Various means by which this may be achieved include having the shank
of the
plunger in two portions so that thcy can be fitted together after the ring or
bush is
located on one part, or having the end portion of the plunger which is the
thumb tab
separate until the ring or bush is fitted.
The ring or bush may utilise any one of a variety of methods to engage the
plunger once
it has engaged the needle and caused it to be withdrawn into the barrel of the
syringe,
including, but not necessarily limited to twi`ting or pulling the plunger
through or into
the ring or bush as the case may be. In those rings or bushes where a twisting
motion is
required, the ring. or bush may be a twist-lock bush or a threaded bush or may
be a l uer-
lock bush. Alternatively in embodiments where a pull motion is rcquired, the
ring or
bush may be a pull-lock bush or snap-lock bush. Examples of thcsc bushes are
iIlustrated in the aceompanying drawings and discussed below in relation to
the
description of the respective drawings.
Thus in the foregoing embodiments, the ring or bush is pressed into the barrel
when the
plunger is inserted during manufacture. A variety of locking options are also
available
to retain the ring or bush in the barrel, once it thus insertcd. Any
combination of
locking mcchanism to retain the plunger in the locking ring or bush may be
coupled
3
Amended Sheet
ft1C A/ A T T
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Received 22 June 2009
c:ldocumaotslglobal medlsaFe\20290 amended.dog
with any one of the such means by which the ring or bush itself is retained in
the barrel
of the syringe.
It will be appreciated that there are many different means available by which
the ring or
bush can be used to lock the plunger and these are contemplated as being
within the
s scope of the invention.
It is-also preferrcd that a vertical or lorigitudinal protrusion within the
end of the barrel
where the ring or bush is inserted, is provided whereby the ring or bush may
be
prevented from turning, particularly in those cases where a split bush is
utilised or
where a twisting action is rcquired to lock the plunger in the ring or bush.
io The plunger itself is provided with a flange about its distal end to
prevent it from being
pulled right through the locking means. In this way the syringe will not only
be
rendered ineffective against the plunger being depressed again, but also
rendered safe in
that the plunger cannot be removed altogether. Thus, once the plunger locks
into the
ring or bush, neither the plungcr nor the ring or bush itself may he withdrawn
to
15 otherwise gain acccss to the needle located within the barrel after it has
been withdrawn
into the barrel.
Thus, locking of the plunger in the ring or bush is preferably provided by a
flange
located on the plunger, preferably located just above the piston rcgion of the
plunger,
allowing the plunger to bc thus locked against the bottom of the ring or bush,
and
20 preventing the plunger from being entirely withdrawn.
By providing a break point in the plunger, as discussed above, it will also
prevent or at
least minimise the possibility of further tampering, especially preventing
acccss.to the
plunger in a way which allow it to be forced back into the ban-el or gripped
for removal
by excessive force..
25 Thus for example one preferred embodiment utilises a twist lock feahtre
including
corresponding threaded regions in the barrel of the syringe and on the
plungcr, so that
after an injection the plunger is withdrawn and locked in position by twisting
the
plunger to engage the corresponding threaded portions.
4
Amended Sheet
TPRA/ATT
CA 02696951 2010-02-19
PCT/AU2008/00 1 2 10
Received 22 June 2009
c:ldocuments5 Iobal medisafe120280 ernandad.doe
Alternativcly the locking means is provided by a twist lock feature including
a twist
lock bush having helix grooves therein located in the barrel of the syringe
and
corresponding lugs located on the plunger for engagement in thc helix grooves,
so that
after an injection, the plunger is withdrawn and locked in position by
twisting the
s plunger to cngage the lugs in the corresponding helix grooves.
Again, as an alternative, the locking means may be provided by a twist lock
feature
including a twist lock bush having hclix grooves therein located in the barrel
of the
syringe and lugs located on the plunger for engagement in the helix grooves,
so that
after an injection the plunger is withdrawn and locked in position by twisting
the
to plunger to cause the lugs to move through the corresponding helix grooves
and pass
eompletely through the bush.
In this embodiment, a permanent lock facility is provided in the form of a
ramp or other
protrusion to prevent the lugs from returning through the grooves of the bush
and hence
preventing the plunger from passing back through the bush into the barrel of
the syringe.
i s More preferably however, it has been found that a locking bush with a
simple flange
arrangement is both easy to produce and eff'ective. ln this arrangement a
flange around
the intcrnal perimeter of t.he bush allows a corresponding flange on the
plunger to pass
in one direction, but by virtue of the shape of the flanges prevents its
return. In
combination with an additional flange on the plunger as described above, the
plunger is
20 prevented from being drawn right through the bush providing an efI'ective
lock against
movement in either direction,
Instead of a flange around the entire internal perimeter of the bush, it has
been found
that a pair of fingers function just as efficiently. Movement of the fingers
to allow the
first flange of the plunger to pass can be achieved by shaping the internal
region of the
25 barrel to allow the fingers to bend back as the flange of the plunger
passes, snapping
back by virtue of the resilience once the first flange has passed.
Although much of the following description refers to a particular safety
syringe having a
retractable needle with certain features, it will be understood that the twist
locking
Amended Sheet .
fPRA/AI1
CA 02696951 2010-02-19
PCT/AU2008/001210
Received 22 June 2009
c:ldocumentslgbbe) m6dISafe\20290 amended.doe
mechanism may be utilised with any syringe having any form of retractable
needlc
faf-ility.
The invention finds application for example in one broad embodiment which
providcs a
syringe having a retractable needle facility incorporated therein, so that in
a first storage
position prior to use, the needle is safcly enclosed within the body of the
syringe and in
a second in use position, thc needle is caused to extend from the body of the
tiyringe so
as to function as a useful necdle and syringe combination in known fashion,
and
wherein the needle is then caused to retract again into the body of the
syringe, once it
has becn used, so as to return it to thc first storage position; the syringe
comprising a
+o body and plunger, wherein the plunger has means associated with the end
thereof
contained within the body of the syringe to releasably engage a boss of the
needle
located in the syringe body so as to retain the necdle within the syringe body
in the first
storage position, and wherein the body of the syringe has means located at the
end
thereof opposite to where the plunger extends from the body for releasably
retaining the
ts needle boss in the second in use position so that the necdle extends from
the syringe
body, the plunger being used to bring the needle boss into engagement with the
end of
the syringe body; the plunger then being able to be disengaged from the needle
boss so
as to enable the plunger to be withdrawn and thereby take in fluid into the
syringe and
then to be used to inject same into a patient in known fashion; and when upon
20 completion of injection, and the needle having been withdrawn from the
patient, the
plunger is once again brought into engagement with the needle boss and
withdrawn so
as to cause the needle boss to be released from the end of the syringe body so
that the
needle is once again retracted into the body of the syringe, the needle
remaining
attached to the end of the plunger; and wherein locking means is provided in
the body of
25 the syringe in the form of a ring or bush to engage the plunger once it is
retracted after
use, so that the syringe is rendered incapable of being used fitrther in that
the plunger
can neither be pushed down again to reactive the needle, nor can it be removcd
altogether fiom the barrel of the syringe to gain acccss to the needle; and
wherein
fitment of the ring or bush to the plunger is facilitated by a plunger
comprising two
so portions which are joined after the ring or bush is fitted thereto.
6
Amended Sheet
IPEA/AU
CA 02696951 2010-02-19
PCT/AU2008/001210
Received 22 June 2009
c:ldocumentslglobal medisafe120290 8men4ep.ACe
Aiternatively, the needle assembly may be such that in the initial position,
the needle is
already extended, ready for use, or may be gland arrangement to which a
replaceable
needle may be fitted, the necdlc in either case being protected by a suitable
sheath or
cover prior to use, so that the end of the plunger only corncs into contact
with the needle
assembly or gland as the case may be at the end of the injection, at which
point
engagement between the plunger and the assembly or gland is achieved, so that
the
assembly or gland is withdrawn together with the ncedle itself into the barrel
upon
retraction of the plunger. The plunger is then causcd to engage with the
locking bush and preferably snapped off
io at the break point to render the syringe safe and inetTective against
further use.
The invention is thus of particular benefit in that the z>,eedle is not only
safely retracted
after use, but is locked in that position by means of the locking bush.
Snapping off the plunger (if provided) also renders the syringc both
ineffective for
subsequent use as well as providing additional safety in that there is no
means by which
the needle can be caused to re-emerge or caused to extend from the syringe
body,
whether accidentally or through deliberate tampering.
Brief Description of the Drawinas
The invention may be better understood frorn the following non-limiting
description of
preferred embodiments, in which:
2o Figures 1. is a cross sectional view of one embodiment of the invention
utilising a
locking bush according to one aspect of the invention in which a snap.lock
bush is
utilised to retain thc plunger after use;
Figure 2 is a cross sectional view of the plunger utilised in the embodiment
of Figure 1,
showing a thumb tab fitted to the shank of the plunger in the form of a cap,
Figure 3 is a c,=ross sectional view of the shank of the plunger and the thumb
tab
separated,
Figure 4 is a cross sectional view of the end of the barrel of Figure 3 to
which a locking
bush is to be fitted,
7
Amended Sheet
IPEA/AU
CA 02696951 2010-02-19
PCT/AU2008/001210
Received 22 June 2009
e:ldooumentslglobal medieafa120290 amended.doc
Figure 5 is a cross sectional view of a preferred embodiment of a locking bush
for use
with the syringe and its cornponents as illus-trated in Figures 1 to 4,
Figure 6 is a plan view of the locking bush of Figure 5,
Figures 7 and 8 show from two perspectives the bush of Fig 5,
s Figure 9 is a cross sectional view of the end of the plunger and the bush of
the previous
figures, after engagement has taken place,
Detailed Descrintion of the Drawings
Referring generally to the Figures, there is shown a syringe according to one
aspect of
the invention generally referenced 11, which comprises a syringe body or
barrel 12, a
zo plunger 13 slidcable therein and a nccdlc 14. The needle 14 is provided
with a hub 15.
The plunger 13 is shown separately in Figures 2 and 3 for greater clarity.
The needle hub 15 is located by interference fit in a gland 16, fitted inside
the end of the
barrel 12. The needle assembly comprising the needle and hub 14/15 and gland
l6 may
be replaced or exchanged (or indeed fitted) prior to use of the syringe so to
providc
15 flexibility of choice with respect to nccdlc gauge for example.
Thc needle an d hub 14/15 may be utilised directly in the end of the barrel 12
in integral
arrangement, without a gland 16, in other cmbodiments of the invention, where
there is
no need to exchange the needle 14.
The needle 14 is protected by a cover 21 prior to use.
zo Plunger 13 is provided with clip means 22 located on a stem 23 at the end
of the plunger
13. The clip engages with the inner region 25 of the needle hub 15 when the
plunger 13
is brought into ccintact with the needle hub 15 at the end of the injection.
Plunger 13 is also provided with a piston region 26 about its lower periphery
which
seals against the inside of the syringe body 12, when inserted therein.
Plunger 13 has a
25 thumb tab 24.which is fitted on to the plunger stem like a cap.
8
Amended Sheet
IPF.A/Ai I
CA 02696951 2010-02-19
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Received 22 June 2009
c:ldoCumentelgbbal medlsafe120290 amanded.doc
A break groove or weaker region 27 is providcd at a suitable location on the
plunger 13,
so that it may be broken off after it has retracted the needle 14 into the
barrel of the
syringe 12, that is to say, after use as described below.
A locking bush 28 is located in the upper region of the barrel 12. The bush is
first fitted
to the shaft or stem of the plunger 13 during assembly and the thumb tab 24 is
snapped
onto the shaft and held in place by suitable means, using for example
mechanical means
such as snap lock facility as illustrated or adhesive or welding means.
Details of the locking bush 28 and relevant portions of the syringe 11
pertaining to its
use are illustrated in detail in Figures 4 to 9.
lo Referring to Fig 5 to 8, locking bush 28 has a flange 30 located about its
periphery and a
pair of fingers 31 depend from the bush 28 for mating with a correfponding
circumferential groove region 32 located between circumferential flanges 33
and 34
located near the end region of the plunger 13. The flange 33 and fingers 31
are suitably
ramped on one side to provide easc of passing, but have faces on the other
side which
are effectively parallel with each other, so as to prevent return.
Turning to Fig 4, the profile of the inner region 35 of the end of the barrel.
12 similarly
allows for ease of fitment and retention of the bush 28 therein specifically
by providing
a groove 36 into which flange 30 locates for mating engagement with
appropriate
ramping where required to assist in fitment. In particular'a recess 37 is
provided behind
ao the fingers 31 of,the bush 28 when it is in place (as shown in Figure 1),
so that the
fingers 31 can deform as the end of the plunger 13 engages therewith.
A flange 38 is also located about the periphery of the bush to strengthen it
and assist in
alignmcnt of the bush 28 when being fitted to the barre112.
Specifically, the first flange 33 is able to pass the fingers 31 by pushing
them into the
26 recess 37 as that region of the plunger 13 passes the fingers 31 of the
bush 28. The
second flange 34 is providcd with a greater diameter than that of flange 33 so
as to be
prevented from passing the fingers 31, thereby locking the plunger 13 when the
fingers
31 thus engage in the_ groove 36. The plunger 13 can thc be neither pulled
further
9
Amended Sheet
TARA/ATT
CA 02696951 2010-02-19
PCT/AU2008/001210
Received 22 June 2009
c:ldocumentslglobel medisafe120290 amended.doc
through the bush 28 by virtue of flange 34, nor can it be depressed again by
virtue of
flange 33.
Thus in use, after an injection has been completed, the plunger 13 is pushed
home to
engage with the needle hub 15. The plunger 13 with needle 14 engaged is then
retracted, the needle 14 being thus withdrawn into barrel 12, the plunger 13
being then
drawn fully back so as to engage with the locking bush 28 by means of tlanges
33 and
34 preventing the plunger from moving in either direction once the fingers 31
have
engaged in the groove 361ocated therebetween.
The plunger 13 is then snapped off at break point 27. With the plunger 13
disabled and
lo the needle 14 retracted inside the body 12 of the syringe 11, it is
rendcrcd totally useless
and may then be disposed of safely.
Illustrated in Figs 10 to 12 are three alternate embodiments of the two part
plunger
arrangement. In Fig 10, the stem of the plunger is split into two components
41 and 42,
whereas in Fig 11 and Fig 12 the thumb tab 43 is separate from the stem 44
prior to
assembly, ie prior to the ring or bush being fitted thcrcto.
It will be appreciated by those skilled in the art that many modifications and
variations
may be made to the embodiments described herein without departing from the
spirit or
scope of the invention.
Throughout the specification the word "contprise" and its dcrivatives are
intended to
2o havc an inclusive rather than exclusive meaning unless the context requires
otherwisc.
The invention disclosed herein has utility in that provides an alternate means
for a safety
syringe having a retractable needle facility which can be rendered useless
after an
injection by locking the plunger and breaking it off
Amended Sheet
7DL A/ A T i
