Cartridge Syringe And Crimped Needle Assembly

Abstract

The invention provides a double-ended hypodermic injection needle comprising a double-ended cannula having mounted along the length thereof holding means comprising a body part engaging therewith and dividing it into two parts, namely an injection part and a cartridge part, the body member being provided with a skirt extending around the cartridge-piercing part of the cannula and at least a part of the outer surface of the skirt being provided with suitably longitudinally extending ribs, for engaging an internal screw thread in the body of a syringe in screw-thread relationship. The rim of the skirt preferably extends beyond the end of the cartridge-piercing part of the cannula and the injection part of the cannula may be protected by an elongated cap. The present invention is concerned with improvements in and relating to needles for hypodermic syringes and more particularly the invention is concerned with disposable needles for hypodermic syringes of the cartridge type. Hypodermic syringes of the cartridge type generally comprise a hollow barrel for receiving a cartridge containing the liquid to be injected, a plunger sliding within the barrel and engageable with a slideable plug member in the cartridge and means for holding a needle. The cartridges for use in such syringes are generally in the form of glass tubes, one end of which is sealed by a puncturable diaphragm, which is commonly of rubber, liquid being held in the cartridge by the slideable plug member referred to above. Disposable needles for use in such syringes are generally of the double ended type; that is, they comprise a cannular hypodermic needle having mounted along its length holding means for engaging with the syringe to hold the needle in position in the syringe, one part of the needle, hereinafter referred to as the injection part, being provided with a suitable shaped point for injection into tissue and the other part of the needle extending from the holding means, hereinafter referred to as the cartridge-piercing part, being provided with a point suitable for puncturing the diaphragm of a cartridge. In practice, the cartridge-piercing part of the needle is generally shorter than the injection part of the needle. One important problem encountered with disposable needles is that of maintaining the chain of sterility. Thus, before distribution or sale, the needles are commonly packed in suitable protective packaging and then sterilised, for example by the action of gamma radiation. In order to maintain the chain of sterility it is necessary that neither the injection part nor the cartridge-piercing part of the needle should come into contact with anything that may affect their sterility; that is, the injection part of the needle should not come into contact with anything but the tissue and the cartridge-piercing part of the needle should not come into contact with anything but the puncturable diaphragm of the cartridge, which itself will be sterile or sterilized before use. The injection part of the needle may be protected by a relatively rigid elongated cap formed of, for example, plastics material, the cap being a push-fit onto a part of the holding means of the needle. At first sight, it would appear that similar means could be adapted to protect the cartridge-piercing part of the needle and, in fact, it has been the practice to protect the cartridge-piercing part of the needle in this manner. However, this method of protecting the cartridge-piercing part of the needle suffers from the disadvantage that in order to insert the needle into the syringe it is first necessary to remove the protective cap from the cartridge-piercing part of the needle and then to introduce this into a hole in the syringe and finally bring it into contact with the puncturable diaphragm of the cartridge already contained within the syringe. During this operation it is very easy to bring the tip of the cartridge-piercing part of the needle into contact with the body of the syringe and hence to endanger the sterility of the needle. It is an object of the present invention to provide an improved disposable hypodermic needle in which the risk of contamination of the cartridge-piercing end of the needle is minimized and which needle is readily and easily inserted into a hypodermic syringe. According to the present invention there is provided a double-ended, disposable needle comprising a double-ended cannular having mounted along the length thereof holding means comprising a body part engaging therewith and dividing it into two parts, namely an injection part and a cartridge-piercing part, the body member being provided with a skirt extending around the cartridge-piercing part of the needle, the rim of the skirt preferably extending beyond the end of the cartridge-piercing part, and at least a part of the outer surface of the skirt being provided with means for engaging an internal screw thread in the body of a syringe in a screw-thread relationship. The means, located on the outer suface of the skirt, for engaging with the barrel of the syringe in screw-thread relationship may comprise screw-threads formed in the whole or a part of the surface of the skirt which will be of generally annular cross-section. However, the skirt will preferably be made of plastics material and the barrel of the syringe of metal and hence, in accordance with a preferred embodiment of the invention, the skirt will be provided with longitudinally extending ribs which, upon screwing of the needle into the barrel of the syringe will form a type of self-tapping screw. In other words, the screw threads on the inside of the barrel of the syringe will act as a die to cut screw threads in the ribs on the outer surface of the skirt. Screwing the needle into the syringe has the effect of closing the plastics skirt, when this is sufficiently deformable as is preferred, against the wall of the cartridge and after administering the injections the needle and cartridge are removed from the syringe as one unit. This will tend to reduce the likelihood of the cartridge or the needle being reused with a corresponding reduction in the possibility of cross-infection. For sale and transport, both parts of the needle of the invention should be provided with protective packaging and, conveniently, the injection part will be protected by an elongated cap of the type referred to above. This elongated cap preferably has internal longitudinal members engaging with longitudinal members or ribs on the holding means of the needle so that the cap may be used to rotate the needle i.e. when introducing it into or removing it from a syringe. In order to protect the cartridge-piercing part of the needle, the open end of the skirt may be provided with a rupturable membrane or, alternatively, with a protective cap. Alternatively, the whole of the assembly may be contained in a suitable packaging such as an envelope, satchet or bubble pack. In general, the needle will be sterilised in its packaging; for example by the use of gamma radiation. In order to assist in the introduction of the needle of the invention into the barrel of the syringe a part of the body of the holding means may be knurled but it is preferred, as stated above, that the protective cap over the injection part of the needle locks with the holding part of the needle for introduction or removal of the needle. If such a cap is provided and the body of the holding means is not provided with any knurling it will be essential to replace the cap in order to remove the needle from a syringe. This has the advantage that the injection part of the needle is protected and thus the person removing the needle is protected against accidental injury and, if the needle and cap are disposed of as one unit, so is any other person who may have occasion to handle the needle.

Description

In order that the invention may be well understood, reference will now be made to the accompanying drawings in which:

FIG. 1 is a vertical cross-section through a packaged needle according to the invention; and

FIG. 2 is a vertical section through a needle of the invention in position in a cartridge-containing syringe.

Referring now to the drawings a disposable needle according to the invention comprises a body member 1 mounted on a cannula 2 having an injection part 3 and a cartridge-piercing part 4. Body member 1 is conveniently formed, for example by injection moulding of a suitable plastics material such as polyethylene, polypropylene, nylon or a polyester such as polyethylene terephthalate. Cannula 2 will generally be of a material conventionally used for hypodermic needles, such as, for example, stainless steel or carbon steel.

Cylindrical skirt 5 extends upwardly from body member 1 and surrounds the whole of the length of and extends slightly beyond cartridge-piercing part 4 of needle 2. Skirt 5 is provided on its outer surface with ribs 9, and on its inner surface with a projection adapted to engage with cartridge-ends of varying types and dimension in a snap fit.

The injection part 3 of needle 2 is protected by cap 7 which engages in a push fit with the lower part or hub of body member 1 and is suitably formed of a material which may be the same as or different from the plastics material used for body 1. Body member 1 is provided with longitudinal ribs which cooperate with longitudinal ribs in cap 7 so that body member 1 may be rotated by means of cap 7.

The whole assembly of the needle and cap 7 may be contained within an envelope or other container 8 shown in chain-dotted outline in the drawing. This envelope may be of plastics material, of paper, of regenerated cellulose or may be a thin film of a metal such as aluminium foil. Alternatively, the whole assembly of the needle and cap 7 may be contained within other sterilizable packaging means such as a blister or bubble pack.

Referring now to FIG. 2 of the drawings a hypodermic syringe assembly comprising the needle of the invention comprises the needle screwed into a screw-thread in the lower part of the barrel 10 of the hypodermic syringe which is also provided with a piston member 11 operated by handle 12 and engaging a plug in cartridge 14 contained within the syringe barrel 10. Whilst it cannot be seen from the drawings cartridge-piercing part 4 of the needle has penetrated the diaphragm of cartridge 14 so as to bring the contents of the cartridge into communication with cannula 2.

The needle of the invention is used and introduced into a syringe as follows. Firstly, the whole of the sterilised assembly of FIG. 1 is taken from its protective packaging, i.e. in the assembly shown in FIG. 1, envelope 8 is removed therefrom by cutting or tearing one end of the envelope and holding cap 7 while removing the envelope. Whilst still holding cap 7 or any other part of the outer surface of the needle assembly the puncturable diaphragm-bearing end of cartridge 14 (which has previously been sterilized) is introduced into skirt 5 so that cartridge-piercing part 4 of needle 2 ruptures the diaphragm. Suitably, the inner dimensions and shape of skirt 5 will be so selected that the puncturable diaphragm-bearing part of cartridge 14 is a push fit therein allowing for variation in cartridge size and shape. It will be noted that during the whole of this operation the cartridge-piercing part 4 does not come into contact with anything but the sterile puncturable diaphragm of cartridge 14 and the injection part 3 is protected by cap 7.

The cartridge/needle assembly is then introduced into the barrel 10 of the syringe and is screwed home, using cap 7 to give a good purchase, so that the screw threads in the lower part of barrel 10 cut corresponding screw threads in the ribs 9 on the outside surface of skirt 5.

The syringe/cartridge/needle assembly will then assume the condition shown in FIG. 2 of the drawings and will be ready for use by removal of cap 7. Thus, injection part 3 is not exposed to any risk of contamination before it is desired to inject it into the tissue and the cartridge-piercing part 4 is only brought into contact with the sterilized puncturable diaphragm of cartridge 14.

If desired, cannula 2 may be more securely located in holding member 1 by means of a so-called "metal insert", that is a metallic insert surrounding and tightly gripping needle 2 and affording a larger bearing surface to hold holding member 1. Alternatively, in order to securely locate cannula 2 in holding member 1 cannula 2 may be provided with a screw thread where it engages with holding member 1 or an adhesive may be used to bond cannula 2 and holding member 1 together.

In accordance with a modified embodiment, body member 1 is formed as one piece moulding with cap 7, the moulding being provided with a suitably weakened portion so that cap 7 may be snapped or twisted off from body member 1 to expose injection part 3 of needle 2. In this case cannula 2 will generally be provided with a metal insert extending the length of body member 1 in order that the whole of body member 1 and cap 7 may be moulded together in one operation and cannula 2 then inserted into the moulding.

The injection part 3 may be arranged to be off-centre with regard to body member 1 (to facilitate intravenous injection) and, in order that the cartridge-piercing part 4 shall remain concentric with body member 1, cannula 2 may be cranked.

Skirt 5 holds a cartridge firmly in place in the syringe and, hence, one syringe may be used with cartridges of different lengths without the problem of the cartridge slipping or being loosely held in the syringe/cartridge/needle assembly.

Claims

I claim:

1. In combination:

a syringe having a body with an axial passage, one end of said body being open-ended and provided with an internal screw thread;

a pierceable cartridge received in said passage; and

a double-ended needle including

an axially extending, double-ended cannula having an injection part at one end and another end part at the other end piercing said cartridge; and

holding means comprising a hub mounted on said cannula interjacent said cannula parts, provided with an axially projecting skirt extending around, and in radially spaced relation with, said cartridge piercing part, said skirt axially internally receiving an end portion of said cartridge, substantially the entire length of said skirt being threaded and threadedly received by the internal screw thread of said body so that, as said skirt is threadedly received by said internal screw thread, said skirt is crimped against said end portion of said cartridge to grip said end portion and produce in situ in said syringe a cartridge-needle assembly which can be removed as a unit from the syringe.

2. In combination:

a syringe having a body with an axial passage for receiving a pierceable cartridge, one end of said body being open-ended and provided with an internal screw thread; and

a double-ended needle for said syringe including

an axially extending double-ended cannula having an injection part at one end and a cartridge piercing part at the opposite end,

holding means, including a hub mounted on said cannula interjacent said parts, provided with an axially projecting skirt extending around, and in radially spaced relation with, said cartridge piercing part, for internally receiving a pierceable end portion of said cartridge, substantially the entire length of said skirt being threaded and threadedly received by the internal screw thread on said syringe body so that as said skirt is threadedly received by said internal screw thread, said skirt is crimped against the side of said cartridge end portion to grip said end portion and produce in situ in said syringe a cartridge-needle assembly which can be removed as a unit from the syringe.

3. A needle according to claim 1 in which the rim of the skirt extends beyond the end of the cartridge-piercing part of the cannula.

4. A needle according to claim 1 in which the skirt is provided on its inner surface with one or more projections adapted to engage with and hold a cartridge-end.

5. The combination as set forth in claim 1 wherein said skirt comprises deformable plastic material, the dimensions of said skirt, said body and said cartridge being such that said skirt is deformed against the outer cartridge surface when said skirt is threaded in said body.