Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1993-06-21
1996-07-02
Rosenbaum, C. Fred
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604110, 604240, A61M 532
Patent
active
055317057
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
THIS INVENTION relates to syringes and more particularly to a syringe unit having a needle which is retractable into a protective position after use.
BACKGROUND ART
It is well known that infectious diseases such as Hepatitis and AIDS can be transmitted through syringe needles which have become contaminated during use. Such diseases can be transmitted to health-care workers who are accidentally punctured by used syringe needles. In an endeavour the problem of accidental needle strikes, there have been various proposals for withdrawing the syringe needle into a protective position within the confines of the syringe after use of the syringe. In this way, the syringe needle is no longer exposed and the syringe can be disposed of safely. Such a syringe typically comprises a syringe barrel and a piston in reciprocal sealing engagement with the interior of the barrel. The syringe includes a retractable needle portion which normally extends from one end of the barrel. Means are provided selectively engaging the piston with the needle portion such that the needle portion can move in unison with the piston into a position in which it is wholly contained within the barrel of the syringe. Examples of such proposals are given in U.S. Pat. Nos. 4,026,287, 4,507,117 and 4,747,830.
With such syringes, the means by which the piston selectively engages the needle portion may take various forms. In many cases, however, the engaging means have not proved altogether satisfactory in that they do not perform properly or are not cost-effective in manufacture. A simple solution would appear to be an engaging means comprising a socket provided in the needle portion for receiving a spigot on the piston to provide operative engagement between the needle portion and the piston. The difficulty with this proposed solution is that injection fluid would be trapped between the socket and spigot as they move into mating relationship and so prevent effective engagement between them.
DISCLOSURE OF INVENTION
The present invention seeks to overcome the above-mentioned difficulty and to provide a novel and useful syringe unit in which the needle is retractable into a protective position.
In one form the invention resides in a syringe unit comprising a barrel substantially closed at one end by an end wall and open at the other end, a piston receivable in the barrel and movable therealong, a fluid chamber defined within the barrel between said piston and said end wall, a base for supporting a cannula, securing means for releasably securing the base of the needle portion to the barrel with the cannula extending outwardly from the barrel and the bore of the cannula communicating with said fluid chamber, said securing means being arranged to effect release of said base from the barrel upon rotation of the base relative to the barrel, and engaging means for releasably engaging the piston with said base whereby when so engaged with the base the piston can be rotated to effect release of the base from the barrel and then retracted to move the cannula into a protective position within the barrel, said engaging means comprises a cavity provided on the base and a projection provided on the piston for reception in the cavity and engagement therewith, said cavity providing for fluid communication between the barrel and the cannula, and means defining a fluid flow passage between the cavity and the projection when the projection is fully engaged in the cavity, said fluid flow passage contributing to provision of fluid communication between the fluid chamber and the bore of the cannula.
A syringe unit according to the invention may comprise a complete syringe or a cartridge-needle unit which is adapted for connection to an injection unit. Additionally, the base may comprise portion of a syringe needle or may be adapted to support a syringe needle.
Preferably, said fluid flow passage is defined by at least one channel in the projection.
Preferably, said projection is in the form of a spigot which tapers inwardly towards the free end there
REFERENCES:
patent: 4233975 (1980-11-01), Yerman
patent: 4747830 (1988-05-01), Gloyer et al.
patent: 4932939 (1990-06-01), Magre et al.
patent: 4935015 (1990-06-01), Hall
patent: 4936315 (1990-06-01), Lineback
patent: 4955869 (1990-09-01), Bin
patent: 4955870 (1990-09-01), Ridderheim et al.
patent: 5019043 (1991-05-01), Segui Pastor et al.
patent: 5112316 (1992-05-01), Venturini
Alter Konrad G.
Herbert Newton J.
Alexander J.
Nujenko Pty Ltd
Rosenbaum C. Fred
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