WO1992019291A1

WO1992019291A1 - Apparatus and method for the destruction of sharps

Info

Publication number: WO1992019291A1
Application number: PCT/AU1992/000207
Authority: WO
Inventors: Malcolm Campbell Mcintyre
Original assignee: Malcolm Campbell Mcintyre
Priority date: 1991-05-07
Filing date: 1992-05-07
Publication date: 1992-11-12

Abstract

An apparatus (10) for the destruction of sharps such as metallic syringe needles and catheters, the apparatus comprising first (12) and second (14) spaced, substantially horizontally aligned electrodes arranged to be connected to a power supply, the electrodes (12, 14) being disposed relative to each other so as to allow a portion of the shaft (67) of a sharp to be placed therebetween to complete an electrical circuit so as to destroy the portion, and to allow successive portions of the shaft (67) to be placed between the electrodes (12, 14) for destruction until all of the shaft is destroyed. The apparatus may also include means (24) for suppressing sparks produced in the destruction of sharps.

Description

TITLE APPARATUS AND METHOD FOR THE DESTRUCTION OF SHARPS

DESCRIPTION The present invention relates to an apparatus and method for the destruction of sharps such as metallic syringe needles and catheters.

FIELD OF THE INVENTION Sharps used in medical applications frequently come into contact with fluids which may contain highly pathogenic bacteria and viruses. This presents a danger to medical personnel using the sharps where accidental needle stick injuries or other transfer of the fluids to the personnel may occur. The recognition of the dangers posed by sharps has lead to various proposals for the destruction of such devices. Many devices have been proposed, particularly mechanical shearing devices such as are exemplified by US Patents 4275628 (Greenhouse), 4315448 (Ball) and 4404881 (Hanifl) . Shearing techniques, whilst they do ensure that the sharp may not be reused, do not eliminate the possibility of injuries occurring through the sheared parts remaining sharp, similarly, the possibility of contamination from liquids held in the sharp also remains after shearing. The inadequacies of shearing devices has been addressed by the development of devices for the destruction of sharps based on electrical resistance techniques. Syringe needles and catheters have a low volume to surface area ratio and the passage of a high electric current through the needle causes heating of the needle. A sufficiently large current will cause the needle point to fuse thus destroying the needle point and also effectively sterilizing the needle. However, the devices of this type that have been proposed to date have suffered from numerous shortcomings. In particular, the devices have only fused a portion of the needle shaft leaving a stub on the body of the syringe which then has to be removed mechanically. For example, Australian Patent No. 553479 (Ch'ing Lung) destroys a portion of the needle by passing a syringe needle between two spaced electrodes and passing current between the electrodes and the syringe needle. The section of the syringe needle between the electrodes is thus heated to destruction. However, this device is not capable of destroying the needle head close to the body of the needle and to ensure that the entire needle is destroyed the device uses a needle head detaching device in the form of an inclined slotted track. The stub removed in this manner is open and potentially sharpened at the stub of the needle. The residue has a section of undestroyed needle in it which may contain contaminated fluids and potentially may have a sharp end. Removal of the needle head in this manner has no sterilizing effect on the contents of the needle head and the needle therefore presents a continuing danger to the user. Thus, this device includes many of the defects of the earlier shearing devices.

Another device has been proposed in US Patent No. 4877934, to Spinello, which discloses a hypodermic needle destroying device which operates again on the electrical resistance heating principle. In this proposal, vertically spaced converging electrodes are provided which enable incinerating currents to travel first throughout the entire length of the contaminated needle and thereafter over progressively shorter lengths until the needle is destroyed. However, apart from the remarkably complex construction of this device, it suffers from various other disadvantages. Firstly, the needle must be drawn along a track at the top of the device, thus leading to the dangers of aerial contamination if a needle is accidentally disengaged from the head of the syringe prior to destruction. In such a case, electrical contact will also fail and destruction of the needle will be incomplete. Secondly, there must always be a vertical spacing between the two converging electrodes, it follows that a needle stub will always be left at the end of the destruction process. This is admitted in the specification where it is stated that the remaining needle stub can be mechanically removed while in its heated state by impacting it against a deforming barrier. This process is unsatisfactory as a portion of the needle will remain unsterilised. Clumsy disengagement also presents the risk of aerial contamination if the needle is accidentally pulled out of its track. Thirdly, a risk, in the Spinello proposal is that undue pressure caused by clumsy use or weakness in the needle shaft will lead to failure of the needle before incineration. In such a case, the needle will not be destroyed and will still represent a serious health hazard. It should be noted that neither of the above devices are suitable for use in the destruction of catheters. Catheters have a different body shape and can have significantly larger needle diameters which aggravate the above listed problems. It is evident from the above discussion that the electrical resistance destruction devices proposed in the prior art are not suitable for the destruction of a significant proportion of medical sharps. Furthermore, it is evident that the devices presently available do not enable complete destruction and sterilisation of the sharp. Hence, while the prior methods proposed offer some of the advantages of an electrical destruction device, they also present many of the disadvantages of the mechanical methods, i.e., incomplete destruction, incomplete sterilisation and aerial contamination.

The present invention provides an apparatus and method for the destruction of sharps which alleviates one or more of the above disadvantages.

SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided an apparatus for the destruction of sharps having shafts of fusible conductive material, characterised in that the apparatus comprises first and second spaced substantially horizontally aligned electrodes arranged to be connected to a power supply, the electrodes being disposed relative to each other so as to allow a portion of the shaft of a sharp to be placed therebetween to complete an electrical circuit so as to destroy the portion, and to allow successive portions of the shaft to be placed between the electrodes for destruction until all of the shaft is destroyed.

According to a second aspect of the present invention there is provided a method for the destruction of sharps, a method for the destruction of sharps, having a shaft of fusible conductive material, characterised in that said method comprises passing an electric current through a selected portion of the shaft extending from the tip thereof, the current being of a level to destruct that portion, and applying said current to one or more successive portions of the shaft as each portion is destroyed until all of the shaft is destroyed. Preferably, the apparatus of the present invention further comprises a spark suppression means located adjacent to the electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a sectional side view of a device in accordance with the present invention;

Figure 2 is an expanded view of a removable electrode component of the device of Figure 1; Figure 3 is an expanded view of a spark suppression chamber of the device of Figure 1;

Figure 4 a,b and c illustrate in detail the electrode component of the device of Figure 1 during the destruction of a' sharp. Figure 5 is a sectional view of a second embodiment of the present invention;

Figure 6 is a sectional view of a third embodiment of the present invention.

DESCRIPTION OF THE INVENTION In Figure 1 there is shown a device for the destruction and disposal of sharps 10 comprising first and second horizontally aligned electrodes 12,14, each electrode 12, 14 being connected to a mains power supply via a transformer 16. The electrodes 12,14 and transformer 16 are all contained within a housing 18. A barrier wall 20 extends across the housing 18 and separates the transformer 16 from the electrodes 12,14.

The electrodes 12,14 are attached to an electrode housing 22 and are located beneath a spark suppression assembly 24. The electrode housing 22 can be seen in greater detail in Figure 2.

The electrode housing 22 comprises a block 26 which contains a central slotted aperture 28. A pair of channels 29 extend parallel to the aperture 28 and on each side thereof. The block 26 is formed of thermally and electrically insulating material and is mounted to the barrier wall 20 by means of a pair of screws 27 located in the channels 29 as can be seen in Figure 1. The electrodes 12,14 are located in the aperture 28 at opposing ends secured in position by respective brackets 30,32 positioned below the electrodes 12,14.

The first electrode 12 is wedge shaped in cross section and has an inner face 33 inclined towards the second electrode 14. A helical compression spring 34 is positioned between an outer face 36 of the electrode 12 and the aperture 28. The compression spring 34 resiliently biases the electrode 12 into position. The bracket 30 is attached to the block 26 by screws on either side of the aperture 28 and electrode 12. Thus, the electrode 12 is able to move in the aperture 28 by forcing the electrode 12 against the spring 34. When pressure on the spring 34 is released, the spring 34 biases the electrode 12 back into position. A contact 38 extends from the outer face 36 of the electrode 12 and is passed over a screw 27 to connect to a first high current lead 40a attached to the transformer 16. The second electrode 14 comprises a body 42 and a wedge shaped projection 44 directed inwardly from the body 42. The projection 44 has an inner face 45 inclined towards the first electrode 12. Upper edges of the electrodes 12,14 are horizontally aligned.

The electrodes 12, 14 are arranged such that the inclined faces 33,45 are arranged in the form of a V-shape, the electrodes 12,14 progressing towards each other. This arrangement has the effect of guiding the sharp into position in use.

A contact 46 extends from the bracket 32 and is attached to a screw 27 in a channel 29 to connect the second electrode 14 to a second high current lead 40b and thence to the transformer 16.

The electrodes 12,14 may conveniently be made of metals, carbon, carbon composites or any other suitable conductive materials. Further, each electrode may be formed of different material. For example, the first electrode 12 may be formed of copper and the second electrode 14 of a carbon composite.

The electrode housing 22 including electrodes 12,14 is designed to be readily removable from the device 10 by manually removing the screws 27. No tools are required to effect this operation. Thus, when the electrodes 12,14 require maintenance or replacement this may be readily achieved and any period where the device 10 is not available for use will be minimised.

The spark suppression assembly 24 is located directly abov the electrode housing 22 and is seen more clearly in Figur 3.

The assembly 24 consists of a sleeve 48 mounted vertically in an aperture in the housing 18. An insertion guide 50 is positioned within the sleeve 48 and is vertically slidable within the sleeve 48. A helical compression spring 52 resiliently biases the guide 50 into position. The spring 52 rests on a perforated plate 54 which is held in position by a ring 56. The guide 50 has a centrally located aperture 58 which is dimensioned to allow a syringe and needle or catheter to be placed therein.

A stainless steel disposal drawer 60 is located below the electrode housing 22 on the floor of the housing 18. Both the electrode housing 22 and the disposal drawer 60 may be accessed through a lockable door in the housing 18. The device 10 is operated through an on/off switch 62 which is also connected to a circuit breaker 64 to ensure safe operation of the device. In use, the device 10 is connected to a mains supply through a connection socket 65 and activated by the switch 62. A sharp such as a hypodermic needle attached to a syringe body or a catheter comprising a metallic shaft passing through a plastic sleeve, is inserted into the aperture 58 and pressure is exerted on the guide 50. This action depresses the guide 50 and spring 52 moving the guide 50 towards the plate 54. Figures 4a, b and c show in detail the destruction of a sharp by the electrodes. For clarity only the electrode housing 22 and associated parts are shown. Shown in the figures is a hypodermic syringe 66 comprising a hollow, metallic, hypodermic needle shaft 67 attached to a syringe body 68 by a hub 69. The shaft 67 is inserted into the spark suppression assembly 24 (not shown in the figures) as described above. The needle shaft 67 is guided into the region between the electrodes 12,14. The tip of the needle shaft 67 comes into contact with the first electrode 12. The second electrode 14 also contacts with the shaft 67. An electrical circuit is thus completed by a portion 67a of the shaft 67 extending between the electrodes 12,14. The portion 67a is rapidly heated to incandescence and fuses. The fused material falls through the gap between the electrodes 12,14 and into the disposal drawer 60. Continued downward pressure on the syringe 66 enables successive portions of the shaft 67 to contact the electrodes 12,14 until it is destroyed.

Figure 4b illustrates the position with the destruction of the needle shaft 67 partially effected and in Figure 4c the needle shaft is virtually entirely destroyed. To ensure that complete destruction of the shaft (67) particularly of the portion of the shaft close to the syringe body (68), the electrode (12) is maintaining close proximity to the electrode (14) by the bias of the spring (34).

A range of different needles may be destroyed by the apparatus 10 by virtue of the spring action accommodating various thicknesses of needle diameter. The circuit is finally disconnected when the electrodes 12,14 come into contact with the non electrically conductive material surrounding the shaft 67. Heat from the destruction of the needle shaft 67 will often be sufficient to seal the hub 69.

The heat generated during the destruction also has a sterilizing effect on the hub 69 and lower syringe body 68 surrounding the shaft 67. The spark suppression assembly 24 prevents any sparks which may be produced during the destruction process from escaping and also acts as a guide to ensure that the needle is correctly positioned against the electrodes 12,14.

Figure 4 illustrates schematically a portable device 70 in which the transformer is replaced with a rechargeable 12 V lead acid battery 72. The electrode component 22, electrodes 12,14, spark suppression assembly 24 and disposal drawer 60 are all as for the device 10 described above. The portable device 70 may be conveniently transported to any location where it may be desired to use it and where no mains supply is available. Internal circuits are protected by a combined on/off switch 81 containing a circuit breaker. The battery 72 may be connected to a separate recharging unit for recharging. Through a connector 80 LED indicators 73 are fitted to indicate the state of charge of the battery 72. A printed circuit board 83 contains electronic components to monitor internal voltages and control the indicators 73. A carry handle 82 is provided for ease of transporting this unit. Figure 6 illustrates a mobile sharps disposal unit 74. This unit is designed for use in vehicles where a 12 V DC supply voltage is available such as in ambulance or other mobile units. This voltage is connected to high current terminals 76. As with the portable unit 70, the electrode housing 22, electrodes 12,14, spark suppression assembly 24 and disposal drawer 60 are the same as for the device 10. The mobile unit 74 also includes indicators 75 which give information on the operational state of the unit 74. Voltage and current limiting resistors 77 are fitted to reduce and control the voltage and current to the nominal operating voltage. The operation of both the portable unit 70 and mobile unit 74 is as described for the device 10.

Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.

Claims

CLAIMS 1. An apparatus for the destruction of sharps having shafts of fusible conductive material, characterised in that the apparatus comprises first and second spaced substantially horizontally aligned electrodes arranged to be connected to a power supply, the electrodes being disposed relative to each other so as to allow a portion of the shaft of a sharp to be placed therebetween to complete an electrical circuit so as to destroy the portion, and to allow successive portions of the shaft to be placed between the electrodes for destruction until all of the shaft is destroyed.

2. An apparatus for the destruction of sharps according to claim 1, characterised in that at least one of the electrodes has an inner face which is inclined towards the other electrode.

3. An apparatus for the destruction of sharps according to claim 2, characterised in that the first electrode is wedge shaped in cross section adjacent the second electrode and has an inner face inclined towards the second electrode.

4. An apparatus for the destruction of sharps according to claim 2 or 3, characterised in that the first electrode is resiliently biased into position.

5. An apparatus for the destruction of sharps according to any one of claims 2 to 4, further characterised in that the second electrode comprises a body and a wedge shaped projection, the projection having an inner face inclined towards the first electrode.

6. An apparatus for the destruction of sharps according tc any one of claims 2 to 4, characterised in that the apparatus comprises a housing containing the electrodes and an aperture arranged to receive a sharp to be destroyed, and one or both electrodes has an inner face inclined towards the other electrode such that the inner face converges with the electrode as it extends away from the aperture.

7. An apparatus for the destruction of sharps according to claim 6, characterised in that the first and second electrodes are attached to an electrode housing.

8. An apparatus for the destruction of sharps according to claim 7, characterised in that the electrode housing is removably located in the housing.

9. An apparatus for the destruction of sharps according to any one of claims 1 to 8, characterised in that a disposal drawer is located below the electrodes.

10. An apparatus for the destruction of sharps according to any one of claims 1 to 9, characterised in that it further comprises a spark suppression means located adjacent to the electrodes.

11. An apparatus for the destruction of sharps according to claim 10, characterised in that the spark suppression assembly comprises a sleeve arranged to receive a body of the sharp.

12. An Appparatus for the destruction of sharps according to claim 11, characterised in that an apertured, slidable insertion guide is located within the sleeve so as to guide the body of the sharp.

13. An apparatus for the destruction of sharps according to claim 11, in which the sleeve comprises a perforated disc and means is provided for resiliently biasing the insertion guide away from the perforated disc.

14. An apparatus for the destruction of sharps according to any one of claims 1 to 13, characterised in that the power supply may be selected from a mains supply, a vehicl battery or a rechargeable battery pack.

15. An apparatus for the destruction of sharps according to any one of claims 1 to 14 characterised in that the electrodes may be formed of the same or different material selected form the group consisting of carbon, carbon composites, copper, copper alloys.

16. A method for the destruction of sharps, having a shaft of fusible conductive material, characterised in that said method comprises passing an electric current through a selected portion of the shaft extending from the tip thereof, the current being of a level to destruct that portion, and applying said current to one or more successive portions of the shaft as each portion is destroyed until all of the shaft is destroyed.