Disposable self-shielding unit dose syringe guard

Details Disposable self-shielding unit dose syringe guard Disposable self-shielding unit dose syringe guard

2000-08-08

2002-02-05

Hayes, Michael J (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S110000, C604S197000

Reexamination Certificate

active

06344032

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to syringes, and more particularly to an improved syringe guard for a unit dose cartridge or pre-filled syringe and including a shield for covering the needle thereof after medication is dispensed from the syringe.
BACKGROUND
Medication is often dispensed using a unit dose medical cartridge, such as an ampule, vial or syringe, and a syringe holder, injector or adapter. The cartridge typically has a barrel with a needle at one end and a plunger at the other end. Such cartridges are often referred to as “pre-filled syringes” because they contain a specific dosage or volume of medication when they are initially provided, as compared to conventional syringes which are furnished empty and filled by the user prior to use. Alternatively, the medical cartridge may include a rubber stopper instead of a needle, or may include a piston rather than a plunger on the other end. The syringe adapter is typically a hollow body adapted to hold the cartridge, including a plunger to engage and move the piston in the cartridge.
Because of the threat of communicable diseases, a number of syringes and adapters have been developed to prevent accidental needle sticks or inadvertent reuse of needle devices. Many of these devices, however, are not easy to use or are complicated to manufacture, resulting in less effective disposable syringe devices.
For example, U.S. Pat. No. 5,569,211 discloses a syringe that allows the needle of the syringe to be withdrawn into the barrel of the syringe after medication is dispensed from it. This device, however, is a specially designed substitute for a conventional syringe, and cannot be used to hold commercially available pre-filled syringes.
U.S. Pat. No. 5,522,812 discloses a complicated syringe shield device for holding a conventional cartridge not having its own needle. The device has a number of complicated parts, including a cylindrical body, a double needle assembly, a cylindrical shield, a special collar piece allowing the shield to be drawn over the needle and locked, and a plunger assembly, resulting in a device that is potentially difficult and expensive to manufacture. The device also requires two hands to operate, one to hold the body, and one to rotate the shield into the locked position, which may be inconvenient to the medical professional using the device.
Another consideration with unit dose cartridges and pre-filled syringes is that they are often made from glass, particularly for holding certain vaccines or biotech drugs where concern about micro-organisms or other contaminants is most critical. Glass cartridges and pre-filled syringes are very fragile and often break during transportation or use. Some existing adapters may not adequately protect the syringe contained therein from such risks. Others provide greater protection for the cartridge, but may obstruct the professional's view of the syringe when the device is being used, hampering monitoring of the medication being delivered.
Therefore, there is a need for an improved safety syringe which is inexpensive and simple to manufacture.
In addition, there is a need for a safety syringe guarding mechanism which provides improved protection for the cartridge or pre-filled syringe therein, but allows effective observation of the syringe and the medication being dispensed.
SUMMARY OF THE INVENTION
The present invention is directed to a guard or adapter for a medical cartridge, such as a unit dose cartridge or pre-filled syringe, that is used to inject medication or other drugs into a patient. Generally, the guard comprises two parts, namely a housing or body for receiving and holding the cartridge, and a protective case or shield slidably attached to the body. In addition, for a cartridge provided without its own plunger, an embodiment of the guard includes a finger grip plug that is attached to the body and a plunger connectable to the piston of the cartridge. The various parts are generally molded from a suitable plastic, such as polypropylene, synthetic resinous polymers of butadiene and styrene, or polycarbonate, having a clear finish.
The body generally includes two elongate rails or similar structures defining a substantially rectangular shape, having a cavity therein adapted to receive a medical cartridge or a pre-filled syringe. The body has an open proximal end communicating with the cavity, a distal end with an opening through it, and possibly a collar molded to the distal end. The body may also include a plurality of tabs or ribs extending along a portion of the cavity adapted to engage the barrel of a cartridge received therein.
The protective case or shield is a tubular member adapted to slidably fit on the body, having open proximal and distal ends. One or more elongate windows are formed in the shield, allowing observation of the cartridge or pre-filled syringe held within the body. One or more windows, preferably the same windows used for viewing the cartridge, also cooperate with a stop tab or tabs molded on the body, thereby limiting the relative sliding relationship of the shield and the body. In addition, the shield includes a set of detents, preferably comprising a pair of detent arms and protruding detents molded into the proximal end of the shield. The detents cooperate with one or more sets of detent pockets molded into the body to lock the shield in relation to the body.
The shield is generally provided pre-assembled on the body, preferably by inserting the body into the shield until the stop tabs on the body communicate with the elongate windows on the shield. The shield may then slide in relation to the body between a proximal or unguarded position and a distal or guarded position, defined by the length of the windows in the shield. The guard is generally provided with the shield in the proximal or unguarded position, wherein the stop tabs abut the distal edges of the windows. Alternatively, the proximal travel of the shield may be limited by the detent arms abutting a finger grip on the body. In the unguarded position, the detents on the shield preferably engage a set of proximal detent pockets on the body, holding the shield in relation to the body.
Generally, after the cartridge or pre-filled syringe in the guard has been used to deliver its medication, the shield is moved distally until it reaches the guarded position. In the guarded position, the stop tabs on the body abut the proximal edges of the windows, preventing further distal movement. As the shield is moved, the detents on the shield leave the proximal detent pockets, preferably because of sloping edges on the proximal detent pockets, and slide along the body until they enter a set of distal detent pockets when the shield reaches the guarded position. The distal detent pockets may have blunt or oblique proximal edges, which prevent the shield from being returned proximally, and thereby substantially lock the shield in the guarded position for disposal. Preferably, the proximal edges of the detent pockets are inclined at an angle corresponding substantially to the proximal edges of the detents to maximize bearing surface engagement therebetween.
In a first preferred embodiment, the guard has only two parts, namely a body and a shield, which are pre-assembled in the unguarded position ready to receive a cartridge. In this embodiment, the body includes a finger grip integrally molded onto its proximal end, preferably defining a “T” shape, having locking detents formed on the finger grip. A cartridge, preferably and typically a conventional unit dose pre-filled syringe including a needle and needle cover on its distal end and a plunger and flange on its proximal end, is inserted into the proximal end of the body until it is fully encapsulated within the cavity. Once fully inserted, the proximal end of the pre-filled syringe engages the locking detents on the finger grip, substantially permanently locking the pre-filled syringe into the guard. Once locked into the guard, the needle and its cover on the pre-filled syringe extend at least partially

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