Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1989-12-28
1991-04-30
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604220, A61M 500
Patent
active
050114760
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to syringes and more particularly to medical syringes which can only be used once.
BACKGROUND ART
Medical syringes comprise a cylindrical barrel and a plunger with a cylindrical base made of resilient material located in sealing relation within the barrel and a needle mounted at the base of and in communication with the barrel.
Originally the barrel was made of glass and the syringe was designed for multiple use with either the needle or the whole syringe being subjected to sterilisation between uses. However, for convenience and in order to minimize cross infection, the syringes most used in medicine now are plastic disposables.
Although relatively cheap and disposable, these syringes can be reused and usually are by drug users amongst whom the spread of Acquired Immune Deficiency Syndrome (AIDS) is on the increase because of the sharing of syringes.
Many prior art syringes have been designed in an attempt to prevent reuse. Some use complicated mechanisms to prevent withdrawal of the plunger; these are difficult to manufacture and greatly increase the cost over the plastic disposable. Others use techniques in which the plunger collapses or the seal between the plunger and the barrel is broken, which prevents suction. None of these have proved to be reliable and affordable and although medically desirable have not been successful.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a syringe which is as cheap to manufacture as the standard plastic disposable syringe but which cannot conveniently be reused after it is filled and used once.
This invention comprises a syringe having a cylindrical barrel and inside the barrel a cylindrical plunger with a resilient base in sealing relation with the barrel, the plunger having at least one circumferential groove and the barrel having an inwardly extending circumferential projection at its aperture such that the projection engages the groove to prevent withdrawal of the plunger.
In a preferred form of the syringe of this invention the plunger has one groove located so that engagement with the projection on the barrel occurs when the plunger is pressed home fully and a second groove located between the first groove and the base so that engagement with the projection occurs before the plunger is pressed home fully.
BRIEF DESCRIPTION OF THE DRAWINGS
Following is a description of a preferred embodiment of the invention with reference to the drawings in which FIG. 1 is a perspective view of a syringe with part of the barrel cut away.
BEST MODE FOR CARRYING OUT THE INVENTION
The syringe 1 consists of a barrel 2 having a needle assembly 3, including a non-removable needle 4 at its end 5. The other end 6 of the barrel 2 has an oblong flange 7 serving as a finger support around aperture 8.
Extending through aperture 8 is a cylindrical plunger 9 with a base 10 made of resilient material in air-tight relation with the inner barrel wall 2a such that withdrawal of the plunger 9 will result in the inward suction of liquid through the needle 4. Plunger 9 is provided with two annular grooves 13a and 13b adjacent to its outer end and the inner wall 2a of barrel 2 has an annular barb 11 located adjacent to its outer extremity. Plunger 9 is further provided at its outer end with a flange 20 adapted to sit within a recess 7a of flange 7 when the base 10 bottoms on end 5 of the barrel.
The syringe is supplied to the user with the plunger 9 partially withdrawn so that groove 13b is just outside the barrel 2. The user fills the syringe 1 by withdrawing the plunger 9 to the full extent of the barrel while the needle is inserted in the liquid to be injected.
The barrel has a portion 12a which is additional to the measured dose and greater than the travel of the plunger between grooves 13a 13b . This allows the full measured dose viz. 10 mls to be drawn into the syringe without the groove 13b passing into engagement with the barb 11 of the barrel.
The syringe is asperated by pushing the plunger 9 until the base 10
REFERENCES:
patent: 1863785 (1932-06-01), Dickinson
patent: 2373520 (1945-04-01), Wallin
patent: 3951146 (1976-04-01), Chiquiar-Arias
patent: 3998224 (1976-12-21), Chiquiar-Arias
patent: 4030498 (1977-06-01), Tompkins
patent: 4391272 (1983-07-01), Staempfli
patent: 4731068 (1988-03-01), Hesse
LandOfFree
Single fill and use syringe does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Single fill and use syringe, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Single fill and use syringe will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-637953