Splatter prevention mechanism for a syringe

#The present invention relates to a syringe that reduces spray of fluid from the end of a syringe and the needle mounted to the end of the syringe.

#Throughout the world, the re-use of hypodermic syringe products, which are intended for single-use only, is a problem which causes the transfer of contagious diseases. Intravenous drug users who routinely share and re-use syringes are a high-risk group with respect to the AIDS virus. Also, the effects of multiple syringe use are a major concern in some countries where the repeated use of syringe products during mass inoculation programs may be responsible for the spread of many diseases. Syringes are often recycled in developing countries without proper sterilization.

#To alleviate these problems, syringes have been designed with collapsible plunger rods which render the syringe effectively unusable after its intended use. For example, as disclosed in U.S. Pat. No. 6,217,550 (Capes et. al), the entire content of which is incorporated herein by reference, the plunger rod is provided weak points so that when pressed with excessive force at the completion of an injection, the plunger breaks into two unusable parts. Thus, the user expels as much fluid as possible from the barrel of the syringe as would normally be done, and then presses hard upon the plunger thumb press to break the plunger rod. Syringes of this type, which are capable of being used only once, will be referred to herein as single use syringes.

#FIG. 1A is a perspective view of a syringe accordance with a first embodiment;

#FIG. 1B is an exploded perspective view of the syringe shown in FIG. 1 depicting a barrel and a collapsible plunger rod;

#FIG. 2 is a partial perspective view of a distal portion of the syringe barrel depicted in FIG. 1;

#Before describing several exemplary embodiments, it is to be understood that the invention is not limited to the details of construction set forth in the following description and drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Additionally, a convention employed in this application is that the term “proximal” denotes a direction closest to a practitioner, while the term “distal” denotes a direction furthest from the practitioner.

#According to one embodiment depicted in FIGS. 1, 2, 3, 4A and 4B, a syringe 10 includes a barrel 20 having an internal surface 26 defining a fluid chamber 18, a distal end 12, a proximal end 14, and a breakable or collapsible plunger rod 30. The plunger rod 30 can be slidably disposed within the barrel 20. The plunger rod 30 includes a distal portion 34, a proximal portion 36 and a plunger 38 connected to the distal portion 34. In the embodiment shown, the distal portion 34 and the proximal portion 36 are connected to each other via collapsible or breakable connection 40. However, it will be understood that the invention is not limited to syringes including a plunger rod including a collapsible or a breakable connection. The plunger 38 is slidably positioned in fluid-tight engagement with the internal surface 26, and is able to slide distally and proximally along longitudinal centerline 32. The distal end 12 of barrel 20 includes an elongate tip 16, which has a passageway 24 that provides fluid communication with the chamber 18. The distal end 12 also defines a roof 50, which faces the proximal end 14. The roof 50 has an opening 54 that is substantially aligned with the passageway 24, and which provides fluid communication between the passageway 24 and the chamber 18.

#By moving the plunger rod 30 distally, the plunger 38 may force fluids out of passageway 24 in the elongate tip 16. By moving proximally, the plunger 38 may draw fluids through the passageway 24 and into the fluid chamber 18. It will be appreciated by those skilled in the art that the elongate tip 16 of the syringe 10 may be releasably or permanently connected to a needle assembly via a hub, as is known in the art. Such needle assemblies include, but are not limited to, Luer lock type needle assemblies and Luer slip type needle assemblies. It is further within the purview of this invention to include a needle assembly having a one-piece construction wherein the cannula and the hub are formed from a single piece.