Needle Shield

Abstract

A needle shield employing a tubular member closed at one end which is adapted to be positioned in surrounding relationship with respect to a needle so as to normally maintain the needle sealed from the atmosphere. An automatic valve is on the member in normally closed position and adapted to be automatically opened when subjected to predetermined pressure. In this manner, communication is provided between the atmosphere and the interior of the member which permits fluid to pass through the opening. The valve automatically returns to the normally closed position when the predetermined pressure is relieved to reseal the enclosed needle from the atmosphere.

Description

BACKGROUND OF THE INVENTION

Often preassembled syringes are subjected to sterilization procedures. The gases produced during conventional sterilization operations often cause substantial pressure differentials between the interior and exterior of the needle shield. In fact the change in pressure is often very abrupt. When this occurs, conventional shields have a tendency to displace from the proper mounted position which naturally ultimately affects the condition of the product at completion of the procedure in regard to sterility.

It is important that the portion of the assembly protected by the shield be retained in a condition which maintains the integrity of the protected object such as a needle both before and after sterilization procedures. However, it should also be kept in mind that it is advantageous to admit small quantities of gases to aid the sterilization procedure as well as to relieve any excess build-up of pressure within the shield during sterilization.

Sterilization procedures are particularly effective when high vacuum cycles are utilized with regard to gas or steam sterilization procedures. However with known needle shields, an excessive internal build-up of pressure occurs and the shield either partially moves from its proper position on the needle or entirely falls off or pops off the needle during sterilization. Naturally, this is quite undesirable as the ultimate integrity of the product is disturbed and, consequently, sterilization procedures must be carefully controlled to avoid the undesirable result.

SUMMARY OF THE INVENTION

With the above background in mind, it is among the primary objectives of the present invention to provide a needle shield which has an automatic valve structure built in so that the valve is responsive to predetermined pressure differentials during sterilization procedures to relieve built-up gases from within the shield and also to admit small quantities of gases for aid in the sterilization procedure. The shield is designed so that the valve structure will automatically close upon relief of the predetermined pressures thereby providing an end product with the proper interrelationship of elements and a needle which is protected in regard to sterility and in the provision of a microbial barrier. The valving structure built into the member will permit the assembled product to be exposed to sterilization methods that utilize high vacuum cycles without any detrimental effects on the product thereby increasing the efficiency of sterilization procedures and reducing product costs. Furthermore, the resultant shelf life of the product will not be affected.

In summary, a needle shield is provided which includes a tubular member closed at one end. The tubular member is adapted to be positioned in surrounding relationship with respect to a needle so as to normally maintain the needle sealed from the atmosphere. An automatic valve is on the member normally closed and adapted to be automatically opened when subjected to predetermined pressure. In this manner, communication is provided between the atmosphere and the interior of the member permitting fluid to pass through the opening. The valve automatically returns to the normally closed position when the predetermined pressure is relieved to reseal the enclosed needle from the atmosphere.

With the above objectives, among others, in mind, reference is had to the attached drawing.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 is a partially sectional side elevation view of a syringe assembly having a needle shield of the invention mounted thereon;

FIG. 2 is an enlarged partially sectional view of the needle shield of the invention;

FIG. 3 is a fragmentary elevation view thereof showing the needle shield in sealed position; and

FIG. 4 is a fragmentary elevation view thereof showing the needle shield in open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a conventional syringe assembly 10 with the needle shield 20 of the present invention mounted thereon. The syringe assembly includes the conventional disposable glass hollow syringe barrel 12 with a reciprocally movable plunger and stopper assembly 14 positioned therein. Conventional materials for the plunger assembly 14 are employed such as plastic for the plunger rod and rubber for the attached stopper.

Syringe barrel 12 terminates in a reduced forward end portion 18 which has a cannula 16 mounted therein in a conventional fashion so that the bore of cannula 16 communicates with the interior of syringe barrel 12. In this manner, a continuous passageway is provided from the forward tip of cannula 16 to the rear open end of syringe barrel 12.

To protect cannula 16 and maintain it in a sterile condition subsequent to assembly and prior to use, a needle shield 20 is positioned so as to be in surrounding relationship with cannula 16 and mounted on the base of the exposed portion of the cannula or as shown on reduced portion 18 of syringe barrel 12.

Needle shield 20 is of a resilient self-sealing material such as natural rubber and is in the general configuration of a tubular member 22 with a closed forward end and an open rear end. Tubular member 22 is hollow to form an interior chamber 24 for reception of cannula 16. As shown, the chamber 24 has an enlarged rear chamber portion 26 to conform with the reduced forward portion 18 of the syringe to facilitate sealing engagement therewith and seal cannula 16 from the atmosphere when needle shield 20 is positioned on the syringe assembly.

Spaced from the enlarged rear chamber portion 26 is a slit 28 through the wall of tubular member 22. The spacing removes the slit from being located in the portion of tubular member 22 which engages with the syringe. The self-sealing nature of tubular member 22 causes slit 28 to be normally closed as the edges 30 engage in the wall of tubular member 22.

Diametrically opposed to slit 28 in tubular member 22 is a second smaller slit 32 in the wall of tubular member 22 which due to the normal resilient self-sealing nature of tubular member 22 is normally in the closed position maintaining the integrity of the interior of the tubular member with respect to the atmosphere. When subjected to sufficient pressure from either the interior or exterior of tubular member 22, the edges 30 while seal slit 28 will be forced away from one another thereby providing an opening between the interior chamber 24 and the atmosphere. In a similar manner, slit 32 may also be opened. FIG. 3 depicts the shield 20 in the normally closed or sealed condition and FIG. 4 depicts the shield under the predetermined pressure so that slit 28 is opened and the pressure can be relieved. Once the pressure is relieved, the surfaces 30 forming the slit will return into engagement with one another thereby closing slit 28 and similarly slit 32 will be closed thereby resealing the interior of member 22 from the atmosphere.

It has been found that with a conventional needle shield, a slit of approximately one-eight inch in length will operate satisfactorily for larger slit 28. Opposing small slit 32 is generally of a very small length such as one-sixty-fourth of an inch. A purpose of the opposing slits is to insure that during manufacture of the shield 20, the piercing member will pass entirely through the wall of tubular member 22 to provide complete communication between chamber 24 and the atmosphere. By passing the piercing member through the wall and then through the opposing wall and thereby transfixing tubular member on the piercing device, communication between the interior and exterior of shield 20 is assured. Once the piercing member has been removed, the self-sealing nature of tubular member 22 will cause slits 28 and 32 to be sealed.

With shield 20 in position on syringe 10 sterilization of the assembly is facilitated. In fact, sterilization methods utilizing high vacuum cycles can be utilized without any detrimental effects on the product. This is true for both gas and steam sterilization procedures. When subjected to sterilization and there is an internal build-up of pressure in chamber 24, the valve formed by slit 28 will open and permit the shield to vent and thereby relieving the pressure. Once the pressure has been relieved, the slit 28 will reseal as discussed above. During a vacuum sterilization cycle an internal build-up of pressure resulting in possible movement of the shield is prevented.

Surfaces 30 and slit 28 form a partial one-way valve that closes as soon as the internal pressure is relieved to thus present a microbial barrier and retention of sterility. Design parameters have been found effective which will provide a material and slit size so that the valve will remain closed at very low differential pressures such as below five inches of mercury. In this manner, recontamination of the needle within the shield is prevented under all normally expected storage conditions. Additionally, at higher pressures such as ten to fifteen psi, the aperture will admit small quantities of gases which will aid in sterilization.

Shield 20 is a particular advantage during large volume high speed sterilization procedures of preassembled syringes. There is no danger of internal pressure causing shield 20 to disassemble from the remainder of syringe assemble 10 thereby requiring resterilization of the product.

It should also be noted that the forward end portion of member 22 is thicker so that it engages with the forward end of cannula 16 and seals the open tip of the cannula from the remainder of chamber 24. This avoids the problem of entrapment of air within the cannula.

It is also contemplated that the present system could be adapted for use with rigid shield such as plastic shields by inclusion of a valve on the plastic shield. The valve would be of the type which is responsive to pressure to open and close and operate in a similar manner as the depicted embodiment.

Thus, the above discussed objectives, among others, are effectively attained.

Claims

I claim:

1. A needle shield comprising; a tubular member of self-sealing resilient rubber closed at one end and adapted to be positioned in surrounding relationship with respect to a needle so as to normally maintain the needle sealed from the atmosphere, and surfaces in the wall of the tubular member forming an aperture normally closed by the surrounding self-sealing resilient surfaces and the surfaces being adapted to be automatically separated to open the aperture when subjected to predetermined pressure thereby providing communication between the atmosphere and the interior of the member and permitting fluid to pass through the opening and to automatically return to the normally closed position when the predetermined pressure is relieved to reseal the enclosed needle from the atmosphere, the opening being in the form of a slit passing through one side wall of the tubular member intermediate the ends thereof, the needle being mounted to a supporting surface so as to form a needle assembly and the needle shield having its open end mounted on the supporting surface in sealing engagement therewith, the slit being spaced from the portion of the tubular member mounted on the supporting surface so as to form a one-piece combined needle shield and valve structure.

2. The invention in accordance with claim 1 wherein the tubular member is adapted to sealingly engage the forward tip portion of a needle adjacent the end thereof at a point between the forward tip of the needle and the aperture in the member so as to isolate the opening forward tip of the needle from the aperture.

3. The invention in accordance with claim 1 wherein a second smaller slit extends through the side wall of the tubular member intermediate the ends thereof at a point diametrically opposed to the larger slit.

4. The invention in accordance with claim 1 wherein the needle is mounted on a syringe to form a syringe assembly and the needle shield has its open end mounted on the syringe in sealing engagement therewith.

5. The invention in accordance with claim 1 wherein the aperture will remain in the normally closed position at differential pressures between the interior and exterior of the member under five inches of mercury.

6. The invention in accordance with claim 1 wherein when subjected to a pressure between ten and fifteen psi, the member will cause the aperture to open and admit small quantities of gases to facilitate sterilization of the needle.

7. A needle shield comprising; a tubular member of self-sealing resilient material closed at one end and adapted to be positioned in surrounding relationship with respect to a needle so as to normally maintain the needle sealed from the atmosphere, and surfaces in the wall of the tubular member forming an aperture normally closed by the surrounding self-sealing resilient surfaces and the surfaces being adapted to be automatically separated to open the aperture when subjected to predetermined pressure thereby providing communication between the atmosphere and the interior of the member and permitting fluid to pass through the opening and to automatically return to the normally closed position when the predetermined pressure is relieved to reseal the enclosed needle from the atmosphere, the opening being in the form of a slit passing through one side wall of the tubular member intermediate the ends thereof, a second smaller slit extending through the side wall of the tubular member intermediate the ends thereof at a point diametrically opposed to the larger slit, and the larger slit being approximately one-eighth of an inch in length and the second smaller slit being approximately one-sixty-fourth of an inch in length.