Universal safety syringe

Details Universal safety syringe Universal safety syringe

1999-08-10

2001-09-11

Kennedy, Sharon (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S195000, C604S198000

Reexamination Certificate

active

06287279

ABSTRACT:

BACKGROUND OF INVENTION
1. Field of Invention
The invention relates to a universal safety syringe according to the preamble of the main claim.
2. Description of Prior Art
In the case of a number of safety syringes, as are disclosed, for example, in German Patent Specification 43 40 082, the injection cannulas are moved back into the cylinder, after use, in order to remain there permanently and safely, without there being any risk of injury, during further handling of the syringe. However, as in the abovementioned document, a new material is also usually proposed, in this case an elastomeric material for example, or it is no longer possible to use the conventional needles with Luer cone.
In other embodiments, for example the version described in U.S. Pat. No. 5,336,198, even separate means are proposed for the purpose of tilting the cannula laterally in the cylinder in order that it cannot be pushed out again. Unfortunately, all these proposals have in common a not inconsiderable degree of complexity, which makes these safety syringes appear expensive and suitable only for special applications.
Unfortunately, however, there is such a great demand for safety syringes within the medical profession today that safety syringes really have to be in constant use. Up until now, the complex geometries with which the cannulas and/or syringes have been provided has meant that this has not been possible.
In order, however, for it to be possible for safety syringes with a retractable cannula to be established for general usage, a necessary precondition is so-called “downward” compatibility with material which has been used up until now, so that it is also possible to fit the wide variety of cannulas which have been available up until now. Otherwise, it would be necessary for novel cannulas of all sizes to be provided immediately for all conceivable purposes and at all use locations, in order to avoid the two systems coexisting over a transition period—with myriad possibilities of confusion, and problems with storage of double stocks and differing handling methods at the same time.
However, since hitherto known safety syringes require their own cannulas and cannula bases in each case, although it has frequently not been possible to provide or reproach [sic] the desired variety of these, it is essential for it to be possible to continue using the cannulas which have been used up until now.
If, however, use is made of a universal safety syringe with retractable cannula, careless handling of the plunger may cause the latter to be pushed forwards in the cylinder, where it comes into contact with the cannula base before the syringe is actually used. This can take place, for example, as the cannula is pushed on. It goes without saying, however, that it is absolutely essential for this to be avoided because, even during further filling of the syringe, the cannula base is drawn back (too early) into the cylinder - and it is precisely in emergency situations that this may initially go unnoticed.
In the case of hitherto known safety syringes, for example those in DE 38 44 150, this has been avoided by safety elements which were removed prior to injection, in order for it to be possible for the plunger to be pushed right in. For universal usage, however, separate safety elements are highly undesirable since they not only increase the costs of the syringes, but also render handling of the syringes for hitherto conventional usage more complex.
SUMMARY OF THE INVENTION
According to the invention, then, the disadvantages of the prior art are eliminated by a universal safety syringe having the features of the main claim. Advantageous embodiments of the invention can be gathered from the subclaims.
It is advantageous, in particular, that, in contrast to conventional syringes, the safety syringe does not have any additional part, and it is thus not only the case that the novel safety syringe constitutes the most cost-effective safety syringe solution, but also that the movements involved in handling it are exactly the same as those for handling the conventional syringe. All conventional cannulas can be fitted by way of the outer Luer standard cone provided. Since the principle does not require a prefitted cannula, it is also possible, however, for appropriate (safety) cannulas on their cannula bases to be selected and inserted just prior to use.
The safety syringe described thus corresponds both to DIN 13098 and to ISO 7886. It is advantageous, in particular, that, in a preferred embodiment, a premature pushing-down action, which could render the syringe unusable, is not possible. In the case of an eccentric cone arrangement, a guide groove or, as proposed, two guide grooves located opposite one another can make it possible to use, for this case as well, the principle according to the invention, which, moreover, is suitable not only for all syringe sizes, but also for two-part and three-part syringes with an additional elastic plunger seal at the end of the plunger.
The universal safety syringe according to the invention is distinguished by a cannula base which is pushed firmly against a stop in the protective cap, and also [lacuna] a protective cap which can be pushed externally onto a cone, corresponding to a Luer cone, of the cylinder, there being provided on the inside of the cap, in front of a recess designed for receiving the cannula base, a narrowed section which delimits the push-on travel.
The recess which receives the cannula base [lacuna] provided with an undercut which prevents the cannula base from being removed in the forward direction, and with an undercut of which the effect can be overcome by the cone being widened from the inside and which is provided for safeguarding the cannula base against being pushed in unintentionally during insertion of the syringe, this latter undercut being widened by a cylindrical end of the plunger during the final advancement stage, while a preferably mushroomshaped plunger head is pushed into an essentially cylindrical cavity with border elements engaging behind the mushroom-shaped head.
A further advantageous configuration is distinguished by lugs which are provided at the actuating end of the plunger, are prestressed outwards and, prior to the filling operation, are retained, by corresponding lug supports on the plunger, in a position in which they are aligned essentially along the syringe axis, in order thus to prevent the plunger from being pushed into the cylinder.
Said lugs are designed, for example, as two spreader lugs which are located essentially opposite one another, are fastened at the actuating end of the plunger by film hinges, are oriented towards the cylinder and are initially clamped in a recess, provided at the introduction opening for the plunger, in the cylinder opening for the introduction of the plunger.
Even in the case of an eccentric arrangement of the cone and of the plunger head which grips the cannula holder, the invention can be applied in that the plunger is additionally guided by way of projecting edges in corresponding guide grooves on the inside of the plunger [sic].


REFERENCES:
patent: 3370588 (1968-02-01), Burke
patent: 3881484 (1975-05-01), Gidcomb et al.
patent: 5152750 (1992-10-01), Haining
patent: 5328475 (1994-07-01), Chen
patent: 5344403 (1994-09-01), Lee
patent: 5401246 (1995-03-01), Mazur et al.
patent: 5569203 (1996-10-01), Chen
patent: 5578015 (1996-11-01), Robb

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