Cleaning and liquid contact with solids – Processes – Including application of electrical radiant or wave energy...
Patent
1997-12-29
1999-11-16
Coe, Philip R.
Cleaning and liquid contact with solids
Processes
Including application of electrical radiant or wave energy...
134 2218, 134169R, 134170, B08B 312
Patent
active
059850388
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method and apparatus for cleaning hollow elements. In particular, the invention relates to the cleaning of medical and surgical instruments having hollow tubular elements which may be regular or irregular. However, the invention may also be used in the cleaning of other instruments or equipment having hollow or tubular bores or cavities. Examples are pipes, bores or valve blocks which are used to carry gas or fluid such as hydraulic fluid.
Many instruments used in the medical field, such as cannulae, comprise internal passageways through which, for example, surgical implements, fluids or catheters may be passed. An example of these are surgical instruments used to access internal parts of the body, such as laproscopic instruments, which may comprise a long tubular locating/gripping sleeve with a scissor-grip at one end which is connected inside the sleeve to a surgical tool, such as a cutter or grip, at the other end.
The cannulated instruments described above may either be constructed to be disposable or non-disposable, and the present invention is designed for cleaning either type. The non-disposable instruments, and in many cases even the disposable instruments, are often too expensive to be disposed of after only one use. Therefore, it is important that all internal and external surfaces of these instruments are thoroughly cleaned and disinfected in order to prevent the risk of passing on infection to other patients. Quite often, body fluid, tissue, or even pieces of bone can become lodged in the cannula of the instrument, which must be completely removed before the instrument is reused.
Traditionally, cannulae have been cleaned by hand by passing a brush along the passageway to dislodge any debris. Pressurised fluid is then passed through the cannula to wash out the loosened debris. Clearly, this is a time-consuming manual process, which requires the instrument to be dismantled, and it is quite possible that not all the debris will be removed, increasing the risk of cross-infection. Also, due to the construction of some instruments, it is not always possible to clean the cannulae by hand.
Another method of cleaning cannulated instruments is to use ultrasonic waves. The instruments are placed in a bath of cleaning fluid and the fluid is also pumped into the cannula. Ultrasonic transducers are then used to excite the fluid outside the instrument, and the excitation propagates through the instrument to the fluid in the cannula. The ultrasonic waves produce an effect in the fluid known as cavitation, in which tiny high pressure bubbles form and collapse at a high frequency. The effect of the expansion and collapse of these high pressure bubbles causes pressure waves which create a scrubbing action on the surfaces of the instrument, thereby dislodging any debris both inside and outside the instrument and cleaning all surfaces. The instrument is then removed from the cleaning fluid and is sterilised, which may be carried out by placing the instrument in an autoclave.
However, the application of ultrasonics to the cleaning fluid in the cavities does not provide a particularly efficient process because the debris remains inside the cannula once it has been dislodged by the cavitation. Debris or residue can then still be present in the cannula after the sterilisation stage. When an autoclave is used to sterilise the instrument, the debris or residue can even be "baked" back on to the surface of the instrument. This increases the risk of infection being passed to the next patient.
To overcome this problem, the applicants have developed a system in which the cleaning fluid is continuously pumped through the cannula of the instrument to be cleaned, while the ultrasonic waves are applied to the fluid. In this method, the instruments do not need to be dismantled as the fluid is pumped into the cannula through a specially provided opening. By providing a continuous moving stream of cleaning fluid, the debris removed by the ultrasonic excitation is flushed out in the cleaning fluid stream
REFERENCES:
patent: 4064886 (1977-12-01), Heckele
patent: 5147464 (1992-09-01), Skovron
patent: 5295497 (1994-03-01), Skovron
Informal translation of the abstract and claims of foreign patent TW 236579 A.
Translation of Japanese Publication No. JP 6-63012.
Translation of Japanese Publication No. JP 6-343607.
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