Syringe needle guard

A syringe needle guard is adaptable to the common syringe to provide for protection against accidental needle sticks. The adaptable needle guard provides a safety sleeve for use over any standard syringe without any modification to the syringe itself. A sleeve arm is provided on the sleeve and projects upward to lie substantially at the same level as the syringe's plunger. This allows the arm to be pushed down to cover the needle with only one hand. The sleeve temporarily locks in place to secure the sleeve in either an extended protective position or in a withdrawn needle exposing position. In an alternate embodiment of the present invention the syringe can be modified at the time of manufacture to contain the safety sleeve and plunger.

FIELD OF INVENTION 
This invention relates generally to needle guards for syringes, and more 
particularly to an improved syringe needle guard, which is adaptable to 
fit over standard unmodified syringes, and enables the user to protect and 
shield the needle by using only one hand. 
BACKGROUND OF THE INVENTION 
Various apparatuses, such as hypodermic syringes and intravenous needles 
are utilized for injecting a substance into humans and animals. 
Apparatuses of this type typically comprise a body adapted to have the 
substance to be injected passed therethrough and a needle mounted on the 
body. The substance to be injected can be forced through the needle in 
various ways, such as by a plunger carried by the body or by external 
means, such as a pump or gravitational flow. 
Apparatuses of this type are typically disposable and are discarded after 
use. One problem presented by the disposal of these apparatuses is in 
shielding the sharp end of the needle so that those handling it will not 
be accidentally stuck. This is particularly important because, following 
the injection, the needle may be contaminated and spread blood-transmitted 
diseases, such as hepatitis or acquired immune deficiency syndrome (AIDS). 
AIDS is presently one of the most dangerous diseases to contract, because 
it causes a breakdown of the immune system that renders individuals 
vulnerable to a variety of serious opportunistic diseases. 
The need has arisen for a needle guard for a hypodermic syringe which can 
be manipulated by using only one hand and which can be installed on any 
common syringe, especially those of the disposable type. It follows that 
any syringe needle guard with these abilities will present a unique 
advancement in the art. 
DESCRIPTION OF THE RELATED ART 
The broad concept of providing a protective sheath or sleeve around needles 
is generally known. Prior art mechanisms have generally attached the 
sleeve to the syringe body while allowing for axial movement of the 
sleeve. U.S. Pat. No. 4,723,943 issued to Spencer discloses a syringe with 
a body and a needle at one end and an injection plunger movable into the 
body at the opposite end. A sheath is positioned over the syringe body 
with a longitudinal groove that engages a guide lug fixed on the syringe 
body near the needle end. A disadvantage to this device is that the 
protective sleeve cannot be used on a normal unmodified syringe, typically 
of the disposable type. A further disadvantage is that two hands are 
required to place the sleeve in the protective position. 
U.S. Pat. No. 4,767,413 issued to Haber et al. discloses a disposable 
dental syringe with a protective sleeve. Upon completing an injection, the 
ampule is released from the distal position and moved proximally through 
the cylinder, so that the distal end of the needle is automatically 
retracted within the cylinder. While this mechanism provides for one 
handed needle shielding, it does not provide any means to be adaptable to 
a normal unmodified syringe. 
U.S. Pat. No. 4,573,976 issued to Sampson et al. discloses a syringe with a 
needle guard which is mounted on the syringe cylinder. When the needle 
guard is extended it obstructs access to the point of the needle, and when 
retracted it does not materially obstruct access to the point of the 
needle. While this device provides anti-stick protection, no means are 
provided for one hand actuation of the needle guard, use of the device on 
an unmodified, normal syringe, or means to separate the needle from the 
syringe body while shielding the needle to protect against needle sticks. 
None of the above listed patents are seen to disclose the specific 
arrangement of concepts disclosed by the present invention. 
SUMMARY OF THE INVENTION 
By the present invention, an improved syringe needle guard which can be 
adapted to any common syringe is provided. The syringe needle guard is 
more appropriately called an adapter, in that it can be adapted to fit 
most common disposable and non-disposable syringes. In many medical 
applications it is desirable to use needles and syringes of different 
sizes. An adapter, preferably utilizing Luer-Lok type connections, is 
required as an intermediary between the needle and syringe. 
The present invention is particularly advantageous with arterial blood gas 
syringes. An arterial blood gas syringe is used to withdraw blood from a 
patient. After the blood is withdrawn, the needle is discarded and the 
blood is stored in the syringe cylinder. The contents of the syringe 
cylinder can then be tested. The present invention allows the needle to be 
discarded while covered by a protective sleeve. This prevents the 
occurrence of an accidental needle stick after the blood withdrawal. 
In the present invention the adapter is modified to allow a protective 
sleeve to slide over it. A nub or ridge is placed on the adapter and 
slides within a groove in the protective sleeve. Alternatively, the nub or 
ridge could be placed on the inside of the protective sleeve while the 
groove or channel can be on the adapter or syringe body. A sleeve arm can 
be present on the protective sleeve to facilitate manipulation of the 
sleeve. In operation of the device the protective sleeve is kept in the 
retracted position, substantially covering the syringe body. A temporary 
friction lock retains the protective sleeve in this position. After an 
injection or aspiration is made the sleeve arm is pushed down, thereby 
axially moving the protective sleeve along the syringe until the needle is 
covered. When the protective sleeve is in the extended position, a higher 
resistance friction lock maintains the protective sleeve over the needle. 
A major advantage to this type of sleeve and arm type mechanism is that 
the needle can be covered and uncovered with only one hand. This allows 
the other hand to be free to apply pressure to the artery or vein of a 
patient. 
Given the problems and challenges of proper syringe and needle manipulation 
and disposal, it is an object of the present invention to provide a 
syringe with an integral sheath to facilitate user protection from 
inadvertent needle sticks. 
Another object of the present invention is to provide a syringe needle 
guard that can easily be manipulated by using only one hand. 
An additional object of the present invention is to provide a syringe 
needle guard that can be adapted to fit a large number of standard or 
modified disposable and non-disposable needles and syringes. 
A further object of the present invention is to provide a syringe needle 
guard that includes an arm attached to the needle guard and which lies 
substantially near the injection plunger of the syringe. 
Yet another object of the present invention is to provide a syringe needle 
guard which can be temporarily locked in either the retracted or extended 
position, while still being able to be manipulated by one hand. 
A still further object of the present invention is to provide a syringe 
needle guard which allows the user to remove and discard the needle, 
protective sleeve and adapter together, while separately removing the 
syringe cylinder to test the withdrawn blood sample. 
With these and other objects in view which will more readily appear as the 
nature of the invention is better understood, the invention consists in 
the novel combination and assembly of parts hereinafter more fully 
described, illustrated and claimed with reference being made to the 
attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, particularly FIG. 1, the present invention 
will be understood to relate to an improved syringe needle guard which can 
be adapted to fit a variety of syringe bodies and needles. The needle 
guard 100 includes adapter 10, protective sleeve 12 and sleeve arm 14. The 
needle guard 100 can be retrofitted over a normal syringe 16. The adapter 
10 includes connectors for fluid connection to the syringe and needle. 
There are typically a male end connector 18 and female end connector 20, 
preferably but not limited to the Leur-Lok type. The adapter 10 provides 
for free flow of fluid from the male end 18 to the female end 20. A 
locking nub 22 is also attached to the adapter 10. The locking nub 22 fits 
into longitudinal channel 24 in protective sleeve 12. 
Two friction locks are present in the protective sleeve 12. Lock 26 is a 
low friction temporary lock to keep the protective sleeve 12 in a 
withdrawn, needle exposing position. Lock 28 is a higher friction lock, 
more resistant to movement, to keep the protective sleeve 12 in an 
extended, needle covering position. The sleeve arm 14 is formed integrally 
with the protective sleeve 12 and is used to position the protective 
sleeve 12 in either the needle exposing position, as shown in FIG. 1, or 
in the needle covering position, as shown in FIG. 2. The thumb rest 30 of 
the injection plunger 32 can be at approximately the same level as the 
thumb rest 34 of sleeve arm 14. This allows easy access to both of the 
thumb rests 30 and 34 with the hand that is holding the syringe 16 and 
needle guard 100. 
Alternative structures for the locking mechanism could place the locking 
nubs or circumferential ridge on the inside of the protective sleeve, 
while the groove or channel could be placed on the adapter 10 or syringe 
body. A nub on the inside of the protective sleeve could fit into axially 
extending ridges on the adapter or syringe body. The locking mechanisms 
can utilize multiple locks with equal coefficients of friction, or, 
multiple locks with unequal coefficients of friction. 
In FIG. 3 an alternate embodiment of the present invention is shown. This 
embodiment illustrates a syringe modified at the time of manufacture. 
Syringe 300 includes protective sleeve 302 with sleeve arm 304. In this 
embodiment a circumferential locking ring 306 can replace the locking nub 
22. Locks 308 and 310 function identically to locks 26 and 28 
respectively. When the sleeve arm 304 is pushed towards the distal end of 
syringe 312, the locking ring 306 will disengage from lock 308 and the 
protective sleeve 302 will move axially along syringe 312 to cover needle 
314. The protective sleeve will entirely cover needle 314 when locking 
ring 306 engages with lock 310. 
In FIG. 4 a similar embodiment of the present invention as in FIG. 3 is 
shown. In this embodiment the syringe and needle guard are formed 
integrally at the time of manufacture. Syringe 402 contains a 
circumferential locking ring 404 about its outer diameter. The protective 
sleeve 406 contains lock 408, channel 410 and lock 412. An adapter 414 is 
shown attached to syringe 402 and needle 416. The protective sleeve 406 is 
of a longer length than the protective sleeve 302 to accommodate the 
attachment of adapter 414. 
In operation of the device 100, referring to FIGS. 1 and 2, the device 100 
is particularly useful in arterial blood gas syringes. Prior to inserting 
the needle 36 into a patient, the protective sleeve 12 can be covering the 
needle 36 as shown in FIG. 2. This will protect against accidental needle 
sticks to the patient and/or medical staff. To make the injection or 
aspiration, the sleeve arm 14 is pulled back towards the injection plunger 
32 with the thumb of the hand that is holding the syringe 16. The needle 
36 will now be exposed and the injection or aspiration can be made. After 
the injection or aspiration is accomplished the needle is removed from the 
patient, and pressure must be applied to the injection site. The person 
making the injection must hold the syringe with one hand and apply 
pressure with the other. With the sleeve arm of the present invention the 
person who made the injection can use one hand to push the protective 
sleeve 12 over needle 36. By these means the needle 36 can always be 
protected or covered by protective sleeve 12 immediately prior and 
subsequent to injection by the use of the same hand which is holding the 
syringe 16. 
It is to be understood that the present invention is not limited to the 
embodiments described above, but encompasses any and all embodiments 
within the scope of the following claims.