GB2239805A

GB2239805A - Hypodermic needle assemblies

Info

Publication number: GB2239805A
Application number: GB9100659A
Authority: GB
Inventors: Malcolm Melville Davies
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-01-12
Filing date: 1991-01-11
Publication date: 1991-07-17
Also published as: GB9100659D0; GB9000761D0; WO1991010462A1

Abstract

A hypodermic needle assembly to reduce the risk of infection from needlestick injury comprises a support housing (2) to hold the needle (1) with one end portion projecting for use, while being operable independently of a related syringe (15) or other clinical apparatus to release the needle for retraction into the housing following use. A common screw/wedge mechanism (5, 6, 8, 9, 10) can be used to hold and release the needle by respectively opposite operations. Also the housing can incorporate a compression spring (12) operable independently of the related apparatus to retract the needle when released.

Description

HYPODERMIC NEEDLE ASSEMBLIES This invention relates to hypodermic needle assemblies and more particularly such assemblies for use with clinical apparatus, such as a syringe or catheter, which has a passageway for transfer of fluid to or from a patient and which is applied by way of a skin puncture effected by the needle of the assembly to communicate the passageway with the patient.

There is a growing concern over the risk of cross-infection from patients to medical and other personnel by way of needlestick injuries which occur in the handling of the assemblies following use.

The invention addresses this concern and seeks to reduce the risk in question by the provision of an assembly with a facility whereby the needle can, following use, be retracted to a relatively safe position which effectively precludes the possibility of subsequent needlestick action.

To this end the present invention provides a hypodermic needle assembly comprising: a needle support housing; and a hypodermic needle supported by said housing; said housing having means to hold said needle assembly in a use position with one end portion projecting in exposed manner from the housing to effect a skin puncture, and means operable independently of a related clinical apparatus to release the holding means and allow retraction of the needle one end portion into the housing.

In one form of assembly according to the invention, the housing terminates remotely from the needle one end portion in a connector formation, suitably of conventional female tapered type, for connection with a syringe or other apparatus used in serial communication with the needle for fluid transfer relative to a patient. With this form of assembly, the needle is conveniently retracted into the syringe or other apparatus for safe collective disposal following use.

In another form of the assembly, the housing terminates adjacent the needle one end portion in a connector formation, suitably of conventional male tapered type, for use with a catheter or other apparatus, used in parallel with the needle by disposition therearound for purposes of apparatus location in a patient. In this case the housing terminates remotely from the needle one end portion in a chamber into which the needle is retracted for safe separate disposal of the assembly following use.

In either of these forms of assembly, it can also incorporate means for retracting the needle independently of related apparatus. Such a means is of benefit in allowing use with conventional forms of apparatus having no special facility for needle retraction. A further benefit is that retraction can be effected at any desired stage of apparatus operation, such as following administration of only part of a medicament change in a syringe.

In a preferred form, this retracting means comprises a stressed spring member connected to act between the housing and needle of the assembly.

Notwithstanding the benefits of needle retraction independently of a related apparatus, this independence is not essential and the assembly can comprise means cooperable with the apparatus to effect retraction by appropriate operation of the latter. In a preferred form the cooperating means comprises an extension of the other end portion of the needle, which extension projects from the housing in exposed manner. When used in connection with a syringe, the extension of such an assembly can be engaged by frictional penetration or otherwise with the plunger of the syringe for retraction therewith.

It is, in any case, preferred that the holding and releasing means comprises a common screw mechanism operable in mutually opposite senses respectively to open and close the same around the needle or a longitudinal extension thereof.

Also it is preferred that the holding means comprise a friction member operable to engage and thereby hold the needle or a longitudinal extension thereof. It is further preferred that this engagement is of circumscribing form to effect a seal.

In order to clarify the invention further, the same will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 diagrammatically illustrates, in cross section, one embodiment of an assembly according to the invention, and Figures 1 and 2 similarly illustrate, in partial cross section, respective further embodiments of assemblies according to the invention.

In the assembly of Figure 1 the hypodermic needle and support housing are denoted at 1 and 2.

The housing has two main constituent parts 3 and 4.

Part 3 is of a form involving two generally tubular portions 5 and 6 disposed in coaxial manner with one portion 5 located within the other 6. The portions 5 and 6 are joined at one pair of corresponding ends to a tapered annular nose portion 7, but are otherwise mutually spaced. The radially inner surface of portion 6 is formed with a thread 8.

The part 4 also involves a generally tubular portion 9 dimensioned to engage, remotely from nose portion 7, the space between portions 5 and 6. The radially outer surface of portion 9 is formed with a thread 10 complementary with thread 8 whereby the engagement just mentioned involves screw connection between portions 9 and 6 with operation of this connection in mutually opposite senses serving to cause relative movement of portion 9 respectively into and out of its engagement. Moreover, the radially inner surface of portion 9 is tapered whereby this movement causes portion 5 to contract or expand in a radial sense by wedging action together with increasing and decreasing engagement, respectively, of the screw connection.

The needle 1 is normally supported by the housing 2 to extend coaxially through the nose portion 7. One end portion of the needle projects outwardly from the nose portion for use to effect a skin puncture. The other end portion passes into the remainder of the housing and is there fixably connected with a sleeve 11 which itself passes through the free end of portion 5.

A helical spring 12 is mounted around the needle and is normally held under compression between the nose portion 7 of the housing and the needle sleeve, this portion and sleeve being recessed to seat the spring ends for this purpose.

This normal arrangement is sustained by engaging the screw connection sufficiently to contract the portion 5 around the sleeve to hold the latter, and with it the needle, by friction.

This action can be enhanced by the provision of a ring member 13 around the free end of portion 5 which member is of friction material effective also to form a seal around the sleeve.

Assembly entails mounting of the spring over the needle one end portion, passing of this portion through the housing from the end of the latter remote from the nose portion to locate the needle and compress the spring, and operating the screw connection.

Clearly operation of the screw connection to allow expansion of the portion 5 releases the frictional engagement of this portion on the needle sleeve 11 whereby the spring can expand to retract the needle one end portion into the housing.

The embodiment of Figure 1 is intended for use with clinical apparatus such as a syringe. For this purpose housing part 3 is continued from portion 9, remotely from the nose portion 7, into a connector portion 14 suitably of conventional female tapered form for interference connection with the nose of a syringe partially indicated at 15. In any event, following use of the syringe the screw mechanism is to be operated to effect needle retraction. This preferably results in passage of the needle into the syringe barrel, the syringe plunger being withdrawn if appropriate beforehand for this purpose, whereby the needle support housing need not be unduly long. This clearly entails appropriate dimensioning of the needle, spring and sleeve relative to the syringe nose opening, but this is not problematical with the routinely used forms of syringe. Also, it is preferable, but not essential, that the needle sleeve projects into the connector portion to enter, in use, the syringe nose opening and ensure alignment for the desired retraction.

The housing parts 3 and 4 can be formed from any suitable material or combination of such materials, but are preferably of polypropylene, polystyrene, polycarbonate or other polymeric materials. The choice of material can take account of compatibility with the medicaments, body fluids or other substances to be used in the syringe. The needle sleeve 11 can be made as a separate part of polymeric or metallic material and connected with the needle by cementing or shrink-fitting or, alternatively, made in one piece with the needle. Ring member 13 can also be selected having due regard to the medicaments or other fluids to be used in the syringe, but will be of rubber, neoprene or other elastomeric material of appropriate frictional properties and resilience for its purposes.The spring can be metal or polymeric and the needle itself can be of standard dimensions and type.

The embodiment of Figure 2 can be largely of the same form of Figure 1 and so is shown predominantly in outline. The difference in Figure 2 is that housing part 3 is continued from portion 9 into a closed chamber 16 of sufficient length, at least in combination with the remainder of the housing to accommodate the needle and its sleeve when retracted.

In this case the assembly is for use with apparatus such as a catheter 17. The tapered external surface of the housing nose portion is formed to serve as a male connector complementary with the connector 18 located proximally of the catheter. In use the catheter is located, as shown, over the needle one end portion with the free end tip of the latter exposed and the respective connectors engaged. The catheter is applied to a patient, by way of skin puncture with the needle tip, typically to a vein, with suitable location being indicated by blood flow through the needle. This flow is visually detected, for which purpose the chamber, and the sleeve if it is not closed or plugged at its free end, are to be suitably transparent. In any event, once located, the needle is withdrawn and retracted while the catheter remains in place for connection with a fluid line.

The embodiment of Figure 3 can also be largely of the same form as Figure 1 and so is shown predominantly in outline. The difference in Figure 3 is that the free end of the needle sleeve, or a continuation of the needle therethrough, is formed to penetrate the forward end membrane of an ampoule 19 in a syringe 20 such as used in dentistry, for example, and the piston plug 21 of the ampoule. Operation of the syringe 20 can be conventional except that, given a facilIty for plug withdrawal following use as by the provision of a plunger 22 releasably connectable with the plug, the needle can be retracted into the ampoule during such withdrawal. This retraction may be effected simply by the frictional connection of the sleeve in the plug which results from penetration, there being little or no force to overcome this once the housing hold is released.However, it may be preferred to provide the sleeve free end with a barbed or other formation 23 and, in addition, a thin wall portion 24 in the plug to be pierced thereby and so increase the resistance to separation during retraction.

While the invention has been described with more particular reference to the illustrated embodiments, it is open to variation within the scope of the appended claims. For example, the screw mechanism can be replaced by a cam or other releasable holding means. Similarly the compression spring retraction arrangement may be replaced by a manually operable one such as by provision of a side arm connected with the needle sleeve, which arm is arranged to traverse a longitudinal slot in the wall of a unitary needle support housing. In this case the needle may be held by releasably locating the arm in engagement with an undercut or lateral extension of the slot.

Also the forms of clinical apparatus to which the assembly is applicable is not intended to be limited to those specifically mentioned above. Additionally, in some cases, such as a syringe, the assembly can be permanently connected with the apparatus for disposal therewith following use.

Claims

1. For use with clinical apparatus operably applied to a patient by way of a skin puncture and having a passageway for transfer of fluid material relative to that patient, a hypodermic needle assembly comprising: a needle support housing; and a hypodermic needle supported by said housing; said housing having means to hold said needle releasably in a use position with one end portion projecting from said housing in exposed manner to effect said skin puncture, and means operable independently of said apparatus to release said holding means and allow retraction of said needle one said portion into said housing.

2. An assembly according to Claim 1 wherein said housing terminates remotely from said needle one end portion in a connector formation for connection with said apparatus to communicate the same serially with said needle.

3. An assembly according to Claim 1 wherein said housing terminates adjacent to said needle one end portion in a connector formation for connection with said apparatus in parallel disposition around said needle, and said housing terminating remotely from said needle one end portion in a chamber to receive said needle when retracted.

4. An assembly according to Claim 1,2 or 3 comprising means operable independently of said apparatus to retract said needle following operation of said releasing means.

5. An assembly according to Claim 4 wherein said retracting means comprise a stressed spring member connected to act between said housing and needle.

6. An assembly according to Claim 2 comprising means cooperable with said apparatus to retract said needle following operation of said releasing means.

7. An assembly according to Claim 6 wherein said cooperating means comprise an extension of the other end portion of said needle, which extension projects from said housing in exposed manner.

8. An assembly according to any preceding claim wherein said holding and releasing means comprise a common screw mechanism operable in mutually opposite senses respectively to open and close the same around said needle or a longitudinal extension thereof.

9. An assembly according to any preceding claim wherein said holding means comprise a friction member operable to engage said needle or a longitudinal extension thereof and thereby hold the same.

10. An assembly according to Claim 9 wherein said friction member circumscribes said needle or longitudinal extension in sealing engagement therewith.