Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1992-01-10
1994-06-07
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604195, A61M 500
Patent
active
053185366
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a disposable hypodermic syringe wherein after use the needle can be fully retracted into the barrel to prevent accidental stabbing, and consequential risk of infection from contaminated needles, which has now become an even more important issue, with the advent of communicable diseases such as AIDS and Hepatitis.
An object of the present invention is to provide a fool-proof disposable hypodermic syringe in which a needle is conveniently and completely retracted (after use) into the syringe barrel safely out of harms way, without a significant increase in the cost of the manufacture of the syringe.
Many attempts have been made to improve syringes for these reasons and a number of disposable hypodermic syringes with retractable needles are known.
In particular, reference is made to U.S. Pat. No 4790822 in which the barrel or body of the syringe receives a needle holder therein with a needle fixed thereon. The holder is positioned within the barrel to enable the needle to extend therefrom for injection purposes or to retract within the barrel. The needle is loaded from the opposite end of the body to that from which the needle projects in use. U.S. Pat. Nos. 4,767,413 and 4,258,713 as well as International published application No WO 89/00435 disclose the use of an axial compression spring located in the barrel surrounding the needle to retract the needle into the respective barrel upon completion of an injection. U.S. Pat. No. 4,790,827 discloses a vacuum tube phlebotomy (instead of a piston and plunger) with the tube slidable in a barrel carrying the needle as well as an outer shield slidable on the barrel protecting the needle rather than a retractable needle. Finally, U.S. Pat. No. 4,692,156 to Haller shows a syringe barrel having a bore at one end for supporting a needle and needle holder introduced into the barrel through the end opposite to that having the bore and a seal bonded to the needle which is sufficiently resilient to pull through the bore when a piston rod engages the innermost end of the needle and allow retraction of the whole needle into the syringe.
However, none of these devices provide a relatively simple, cheap, efficiently operable syringe barrel to which is attachable any one of a number of separate needles of various sizes.
According to the invention there is provided a disposable hypodermic syringe comprising a syringe body, a separately attachable hub mountable upon the body at one end thereof, and a piston means mountable in the body and being slidable along the body from a distal end thereof remote from the said one end, the hub including a needle holder arranged to support a hypodermic needle therein, characterised in that the needle holder is attached to the hub by frangible means so that the piston means interengages with the needle holder when the piston means is substantially fully displaced toward the needle holder, whereby in response to retraction of the piston means the frangible means is broken, the needle holder is disengageable from the hub, and the needle holder and needle are completely withdrawn into the syringe.
Preferably, the needle means comprises a support member and a needle mounted on the support member. Moreover, the piston means may comprise a piston and a piston rod. Conveniently, when the needle and needle holder are to be retracted into the syringe the piston rod is movable relative to the piston, the engagable means being located on the piston rod.
Preferably, the frangible means comprises weakened integral moulding. Conveniently, the weakened integral moulding is enhanced by Gamma Irradiation or any other electron beam radiation sterilisation process.
Embodiments of a syringe will now be described by way of example with reference to the accompanying drawings in which:
FIG. 1 is an external view of an assembled syringe.
FIG. 2 is an internal part sectional view of a syringe barrel sub-assembly and needle holder sub-assembly of the syringe of FIG. 1 prior to assembly,
FIG. 3 is a sectional view of the assembled syringe of FIG.
REFERENCES:
patent: 4026287 (1977-05-01), Haller
patent: 4507117 (1989-06-01), Vining et al.
patent: 4692156 (1989-09-01), Haller
patent: 4710170 (1987-12-01), Haber et al.
patent: 4747830 (1988-05-01), Gloyer et al.
patent: 4767413 (1988-08-01), Haber et al.
patent: 4838870 (1989-06-01), Haber et al.
patent: 5000738 (1991-03-01), LaVallo et al.
patent: 5053010 (1991-10-01), McGary et al.
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