Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1990-10-03
1993-06-29
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
052229424
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a syringe, specifically for use in medicine, in accordance with the characterizing clause of claim 1.
Such syringes are commonly known in biomedical engineering, e.g. from the British Patent GB-A-20 15 883 or the Australian Patent AU-A-16 859. The syringe according to the Patent GB-A-20 15 883 substantially corresponds to the design according to the German Patent DE-B-29 09 992. As a matter of fact, these known syringes are destined for a single application only, to which end the inner wall of the cylinder includes at least one annular groove or undercut disposed normal to the cylinder axis for latching engagement of at least one radially outwardly urged plunger element such that it can no longer be retracted upon completion of the injection, with the plunger having reached its extreme ejection position within the cylinder. In order to prevent a multiple use of this injection syringe it is therefore definitely required that the plunger be pushed into and latched in its extreme ejection position. With a skilled manipulation of the plunger rod a multiple use of the known syringe is easily possible. The user has merely to see to it that the plunger will not be pushed forward up to its foremost position. Such an attempt merely requires the disposition of an annular spacer around the plunger rod outside of the cylinder between the latter and the operating element provided at the free end of the plunger rod. Thus this known injection syringe does not guarantee either the prevention of multiple use. In view of the ever-increasing risk of an AIDS infection due to the multiple use of injection syringes, in particular in less developed countries, the known syringe structures are not appropriate.
In the design according to the Patent AU-A-16 859 the charged volume of the syringe can be administered only in pre-dosed portions. It is moreover not obvious from that document that this known design allows for an initial displacement for aspiration. The process of charging the cylinder of the syringe appears to be hardly realizable in practice and seems to be also extremely exposed to the risk of contamination. To this adds an extremely doubtful sealing between the plunger and the plunger rod of that known design so that there is the risk of contamination also through this seal. For these reasons the design according to the Patent AU-A-16 859 is not very suitable for application in practice. It was not accepted in medical practice either even though this design has been known already since 1934.
The present invention is now based on the problem of improving a syringe of the type described by way of introduction to the effect that once the syringe has been used a continued use thereof will be reliably precluded, and that in particular any manipulation to render the syringe re-usable again will be prevented.
This problem is solved by the characterizing features of patent claim 1. Preferred structural details of the inventive design are defined in the dependent claims.
The essential aspect of the present invention thus resides in the provision of separate locking means in the form of a stopping collar through which the plunger rod passes, with said stopping collar cooperating with the plunger rod in a way that the volume of the syringe can be administered only administered only once, even when the plunger rod will be displaced in several partial strokes. Due to the separation of plunger, plunger rod, on the one hand, and locking means, on the other hand, the sealing and contamination problems explained in the foregoing with relation to the design according to the document AU-A-166 859 will not occur.
The features defined in claim 12 and the following claims offer an improved safety in the prevention of multiple use. These features result in a destruction of the syringe function so that a multiple use of the syringe is precluded even with application of force.
The injection needle is preferably fixedly linked up with the syringe cylinder so that in this way, too, a multiple use of
REFERENCES:
patent: 3890936 (1975-06-01), McInerney et al.
patent: 4731068 (1988-03-01), Hesse
patent: 4820272 (1989-04-01), Palmer
patent: 4854381 (1989-08-01), Mikula
patent: 5000737 (1991-03-01), Free et al.
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