Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1990-12-21
1991-08-06
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604218, A61M 500
Patent
active
050373943
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates generally to medical engineering and, more specifically, to disposable injection syringes.
World-wide diffusion of the epidemic of AIDS, injection syringes and needles being one of the principal ways of infection, poses a problem how to develop reliable constructions of disposable syringes, primary emphasis being placed on objective avoiding a possibility of reusing a disposable syringe.
PRIOR ART
Known in the art are disposable injection syringes, comprising a cylindrical body, a piston with a rod accommodated in said body, a hole in the rear face of the body for the piston rod to pass, and a needle fixing device in the front face of the body (cf., e.g., disposable syringes available from Trumo Europe Co., Belgium). The syringes discussed above differ practically in nothing from disposable syringes now in widespread use in medical practice, the sole exception being the fact that they are made of a cheaper material (that is, polymer) and are not therefore subject to sterilization. This means that the construction of the known disposable syringes enables them to be reused many times, which might occur on account of an inattentive or unscrupulous action of medical staff, or when injections are made by those who are in narcotic or alcoholic intoxication. All stated above proves to be of importance, since such cases are fraught with a danger of infection with the virus of AIDS, with that of infectious hepatitis, and of some other diseases.
One more prior art disposable syringe is known to comprise a cylindrical body accommodating a piston with a rod, a hole in the rear face of the body for the piston rod to pass, and a needle fixing device in the body front face (EP, A, 0282097).
In the syringe in question the needle is fixed in a washer located in the front portion of syringe body and capable of reciprocating along the syringe axis. The piston situated past the washer in the syringe body and rigidly coupled to the rod is not engaged with the washer but is provided with catches adapted for the piston to engage the washer when both of them interact with each other through their end faces. At the end of the injection when the piston and the washer get in contact with each other through their end faces, the piston becomes engaged rigidly, by means of the catches, with the washer, wherein the needly is fixed, with the result that any attempt to repeatedly draw a fresh portion of an injection substance in the syringe, the washer together with the needle is entrained by the piston into the syringe body. As soon as the needle gets inside cylindrical body of the syringe, it is offset with respect to the body axis so that any attempt to perform an injection will result in breakage of the injection needle.
However, such a construction leaves room for reusage of the syringe under consideration, since the piston is brought in engagement with the washer only when in its fully extended position in the front portion of the body. This causes the needle to be retracted into the body, whereby the syringe gets unfit for further use. Sould however the piston be not brought to the fully extended position during injection, the syringe can be applied for making an unlimited number of injections involving almost complete utilization of the syringe body holding capacity.
DISCLOSURE OF THE INVENTION
It is a primary and essential object of the invention to develop such a construction of a disposable injection syringe that would make impossible reusage of the syringe.
Said object is accomplished due to the fact that in a disposable injection syringe, comprising a cylindrical body accommodating a piston with a rod, a hole in the rear body face adapted for the rod to pass outside, and an injection needle fixing device located in the front body face, according to the invention, the rod is of a shaped design and is composed of a plurality of cone frustums arranged consecutively along the rod length and having their greater and lesser bases respectively equal to one another, said cone frustums faci
REFERENCES:
patent: 4367738 (1983-01-01), Legendre et al.
patent: 4731068 (1988-03-01), Hesse
patent: 4906231 (1990-03-01), Young
Mazurik Sergei M.
Sokolov Andrei N.
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