IMPROVEMENTS IN OR RELATING TO CRYOGENIC PROBES

Abstract: A cryogenic probe comprises a probe body (30) and a tip (10), the body and the tip having co-operating screw threads for releasably securing the tip to the body. The probe tip is largely formed of plastics material, whilst the head portion (14) of the tip as used for surgery is formed from brass. When a cryosurgical operation has been completed the tip (10) may be removed from the probe body and, due to the constructional materials used, the tip is rendered disposable. A new tip (10) can be used for any subsequent operation, thus obviating the risk of cross-contamination without the need for sterilisation procedures.

Description: Iwprovewents in or Relating to Cryogenic Probes This invention relates to cryosurgical apparatus, and concerns in particular portable cryogenic probes such as are used by general practitioners and other doctors for out-patient treatment of skin lesions such as warts, moles and the like. Such devices may be contact probes, where a super-cooled tip is applied directly to the surgical site, or may be spray devices where a spray of cryogen is directed on to the relevant site. In this Specification, the term "probe" is to be understood as referring to both types of device. Known probes are attached to a cryogenic supply apparatus and comprise a probe body and tip which are made of brass. The disadvantage of such a probe is that brass is expensive and the tips have to be sterilised before each use. It is an objection of the invention to obviate and/or mitigate these and other disadvantages. According to one aspect of the invention, there is provided a probe tip for a cryogenic probe, the tip being adapted to be removably secured to a probe body. According to another aspect of the invention, there is provided a cryogenic probe comprising a probe tip and a probe body, the tip being adapted to be removably secured to the probe body. Preferably, the probe tip comprises securing means to secure the probe tip to the probe body. The securing means may comprise cooperating formations provided on the tip and the body adapted to cooperate with each other. Preferably, the securing means comprise screw threads on the tip adapted to engage corresponding screw threads on the probe body. The threads on the probe tip may be internal and the threads on the body may be external. In the preferred embodiment, the probe tip compr¬ ises a main portion and a head portion, the head portion extending from the main portion. The main portion may be formed of a suitable plastics material, for example acetal, and the head portion may be formed of a suitable material for use in contacting the body tissue at super¬ cooled temperatures. The head portion may be formed of a metallic material, for example brass. The probe body may comprise an extending portion upon which the threads are formed. Exhaust means may be provided to exhaust evapora¬ ted cryogen from the probe. Preferably, the exhaust means comprises an exhaust tube projecting from the probe body. An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings:- Fig. 1 is a sectional view of a probe tip; Fig. 2 is a view along the lines 11—11 in Fig. 1; Fig. 3 is a sectional view of a probe body; and Fig. 4 is a view along the lines IV-IV in Fig. 3. Referring to Figs. 1 and 2, a probe tip 10 is shown which comprises a main portion 12 and a head portion 14. The main portion 12 has a bore 16 extending from one end 18 to the head portion 14. The main portion 12 comprises internal threads 20 which extend from the end region 18 towards the head portion 14. The main portion 12 is formed of a suitable plas¬ tics material for example acetal and the head portion 14 is formed of a suitable metallic material, for example brass. By forming the main portion 12 from an inexpensive plastics material the probe tip 10 is rendered dispos¬ able. Thus, a new tip can be used for each separate cryosurgical treatment. This possibility ensures high standards of hygiene and obviates the risk of cross-contamination between successive patients. Fig. 3 shows a probe body 30 which has a bore 32 extending therethrough. A portion 34 extending from one end of the body 30 is provided with external threads 36 which can threadably engage the threads 20 on the main portion 12 of the probe tip 10, thereby securing the probe tip 10 to the body 30. The other end of the probe body 30 is provided with a further threaded portion 42 which is adapted to engage suitable cryogenic supply apparatus (not shown) which is well known in the art. The probe body 30 is also provided with an exhaust tube 38 having a bore 40 extending therethrough, in communication with the bore 32. In operation, the probe tip 10 is threadably attached to the extending portion 34 of the body 30 to secure the tip 10 to the body 30 with the respective bores 16, 32 in register. The further threaded portion 42 is then threadably attached to suitable cryogenic supply apparatus (not shown). A cryogen (for example, liquid nitrogen) is then passed from the cryogenic supply apparatus through the bore 32, into the bore 16 where, upon contact with the head portion 14, it evaporates. Thus, the head portion 14 is supercooled. The evaporated cryogen is then exhausted via the bore 40 of the exhaust tube 38. The supercooled head portion 14 can then be applied to lesions on the skin for surgical removal. Modifications may be made to the probe without departing from the scope of the invention. For example, the threads securing the probe tip to the probe body could be reversed such that the internal threads are on the probe body and the external threads are on the probe tip. The probe tip and body portions may be configured differently from those described and shown. Whilst endeavouring in the foregoing Specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims: Claims:- 1. A cryogenic probe comprising a probe tip and a probe body, the tip being adapted to be removably secured to the probe body. 2. A probe according to Claim 1 wherein the tip includes securing means comprising screw threads adapted to engage corresponding screw threads on the probe body. 3. A probe according to Claim 1 or Claim 2 wherein the probe tip comprises a main portion and a head por¬ tion, the head portion extending from the main portion. 4. A probe according to Claim 3 wherein the main portion is formed of a plastics material. 5. A probe according to Claim 4 wherein the main portion is formed of acetal and the head portion is formed of brass. 6. A probe according to any of the preceding Claims and further comprising exhaust means to exhaust evaporated cryogen from the probe. 7. A probe substantially as hereinbefore described with reference to the accompanying drawings. 8. Any novel subject matter or combination including novel subject matter disclosed, whether or not within the scope of or relating to the same invention as any of the preceding Claims.

Inventors: CLARKE BRIAN KEVIN RODERICK, CLARKE, BRIAN, KEVIN, RODERICK
Applicants: CRYOGENIC TECHNOLOGY LTD, CRYOGENIC TECHNOLOGY LIMITED
Application year: 1992
Main classification: A61B17
IPC codes: A61B17, A61B18, A61F7, A61M11