Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1992-10-19
1994-11-15
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604195, 604228, A61M 550, A61M 532, A61M 5315
Patent
active
053643593
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a safety assembly for an injection syringe, as defined in the preamble of claim 1.
Such injection syringes are known from EP-A 0 360 313 not published in time. Therein the needle can be fully retracted after use of the syringe, and can be bent if desired, in order to prevent effectively injures by the needle and re-use of the syringe.
It is an object of the invention to improve such syringes still more, in order to allow the injection liquid container to be partially emptied and/or to prevent refilling of this container before coupling the needle foot with the piston rod unit by retracting this unit. Moreover it is an object of the invention to prevent, in the case of such syringes which are to be filled before use with injection liquid by aspiration, that, when expelling air before aspiration, the piston rod unit will be coupled with the needle foot.
To that end the invention provides a safety assembly according to the characterizing portion of claim 1.
For obtaining the first object in injection syringes having an unlatching element which is shiftable outside the liquid container, the assembly according to the invention has the characteristics mentioned in claim 2 or 3.
For obtaining the second object in injection syringes having a piston rod unit which is or can be fixedly coupled with the piston, the assembly according to the invention has the characteristics of claim 4. For obtaining the third object, the assembly according to the invention has the characteristics of claims 5-8.
The invention will be elucidated below by reference to a drawing, showing in:
FIG. 1a a lateral view of a first embodiment of a piston rod unit according to the invention without the corresponding injection syringe;
FIG. 1b a cross-section according to line 1B--1B of FIG. 1a;
FIG. 1c a view corresponding with FIG. 1a of said unit in an other condition;
FIG. 2 a cross-section of an other embodiment of a piston rod unit according to the invention and of the adjacent terminal portion of a corresponding injection syringe;
FIGS. 3a and b a third embodiment of a piston rod unit in two different conditions; and
FIG. 3c an exploded perspective view of a practical embodiment of the unit of FIGS. 3a and b.
In the drawing only those elements have been shown which are required for the description of the piston rod unit according to the invention. For the remaining parts of a corresponding injection syringe, reference can be made to EP-A 0 360 313, and in particular to the Figs. thereof to be mentioned below.
The unit according to the invention shown in FIG. 1 is intended to be used in injection syringes with separate liquid containers (so-called carpules) to be provided in a syringe casing, e.g. as shown in FIGS. 1 and 2 of the EP-application mentioned above.
In these known syringes, the liquid container is provided with a piston, and is closed, at the other extremity, by a plug which will be pierced by the inner end of an injection needle when a needle foot is placed on this extremity. This needle foot is latched in the syringe casing. When the piston is completely pushed into the liquid container by means of a piston rod unit, and the complete contents thereof are driven outwards through the needle, a sleeve which is shiftable around this container and which forms a part of this unit engages the needle foot and latching means thereof, the latter then being released, and the foot will be coupled with this sleeve in order to allow it to be pulled into the casing. Such syringes are used specially by dentists.
If, however, only a part of the contents of the container are to be used for an injection, the remainder thereof should be driven out before the coupling with the needle foot can take place. In order to avoid this objection, the piston rod unit of FIG. 1 can be used.
This unit comprises, to that end, and in the manner known from the EP-application mentioned above, a piston rod 1, e.g. with a cross-shaped cross-section, one extremity thereof joining a disc 2 or the like engaging the piston. At the other extremi
REFERENCES:
patent: 4838870 (1989-06-01), Haber et al.
patent: 4950241 (1990-08-01), Ranford
patent: 5045063 (1991-09-01), Spielberg
patent: 5116319 (1992-05-01), van den Haak
patent: 5226881 (1993-07-01), Pickhard
patent: 5226882 (1993-07-01), Bates
Advanced Protective Injection Systems Medical B.V.
Cermak Adam J.
Yasko John D.
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