SHEATH FORTHE NEEDLE OF AHYPODERMIC SYRINGE
This invention concerns a sheath for the needle of a hypodermic syringe.
Hypodermic syringe assemblies are usually provided with a protective sheath covering the needle for its protection until the syringe is required for use.
It is a common, though by no means universal, practice to change the needle of a syringe after filling and before administration of the injection because of a perception that the original needle may become blunted, bent or subjected to loss of needle lubricant during the filling operation, for example by insertion through the rubber cap of the vial, contaminated with a foreign substance, for example latex from such a cap or rendered unsterile.
It is an object of the invention to provide means eliminating any need for the changing of needles as aforesaid.
According to the present invention, there is provided a sheath which sealably connects over the needle of a hypodermic syringe and which is capable of penetrating the rubber cap of a vial and which has apertures therein to enable the passage of liquid to its interior for extraction by the needle of the syringe.
The sheath may have a pointed end.
The sheath may have at least one aperture through its wall above the pointed end.
The sheath may have an aperture at its pointed end. The sheath may be protected before use by a removable guard.
The guard may be in the form of a part cylindrical wall.
The guard may be integral with the sheath and removable at a frangible connection.
The sheath may be attached to the syringe by a simple push-on/pull-off friction fit.
The sheath may be attached to the syringe by a threaded connection.
The sheath may be attached to the syringe by a bayonet connection.
The sheath may be formed from a plastics material.
The invention will be further apparent from the following description with reference to the several figures of the accompanying drawing which show, by way of example only, one form of sheath embodying same.
Of the drawing:-
Figure 1 shows a cross-section through the sheath;
Figure 2 shows a cross-section through the sheath of Figure 1 in position over the needle of a hypodermic syringe; and
Figure 3 shows a perspective view of the sheath of Figures 1 and 2. Referring now to the drawing, it will be seen that the sheath generally indicated at 10 and which is formed from a plastics material has a socket 11 at its rear end which engages the end cap E of a hypodermic syringe having a needle N, barrel B and plunger P with a push-on/pull-off friction fit. An annular seal 12 is provided on the end of the sheath 10 which abuts the forward face of an annular flange F at the rearward end of the cap E.
The sheath 10 has a hollow interior 14 which accommodates the needle N of the syringe.
The sheath 10 has a pointed forward end 15 capable of penetrating the rubber cap of a vial or being inserted into an ampoule whose cap has been broken therefrom.
Behind the end 15 are a pair of diametrically opposed radial apertures 16.
A guard 17 in the form of a part cylindrical wall is formed integrally with the sheath 10 and is removable from the sheath at a frangible connection 18. The guard protects the sheath and prevents its pointed end from damaging and thereby compromising the sterility of primary packaging in which the syringe is supplied. The slot 19 in the wall enables the guard to be broken away without damaging the sheath which passes through the slot 19 during this operation.
In use, the syringe is removed from its primary packaging and the barrel B of the syringe filled in known manner after insertion of the forward end of the sheath through the rubber cap of a vial or insertion of the forward end into an ampoule whose cap has been broken therefrom, by retraction of the plunger P. The sheath 10 is then removed and discarded to enable administration of the injection in known manner.
It sometimes happens that medical staff use a filling needle of larger bore than the injection needle for the purposes of filling the syringe - particularly when the bore of the injection needle is particularly fine. The possibility of removing the sheath 10 and original needle before replacing the sheath 10 and using it as a filling needle should not be overlooked.
It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to one skilled in the art, being possible, without departing from the scope thereof.
Thus, for example, the pointed end of the sheath may have a single forwardly facing aperture instead of the radial apertures described above.
Again, for example, the guard may comprise a complete cylindrical wall, though more care is then required in its removal.