GB2397227A

GB2397227A - Method and apparatus for decontaminating a medical instrument

Info

Publication number: GB2397227A
Application number: GB0301254A
Authority: GB
Inventors: Lawrence Ralph Dawson
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-01-20
Filing date: 2003-01-20
Publication date: 2004-07-21
Also published as: GB0301254D0

Abstract

A decontaminating apparatus 1 comprises an ultrasonic decontamination tank 2 housed in a sump in the base of a cabinet type washer. Deluge sprayers 6 are located above the tank. A carousel 8 rotatable about a horizontal shaft 10 in the space between the tank 2 and deluge sprayers 6 includes a plurality of baskets 14 connected by spokes 12 to shaft 10. In use, instruments to be decontaminated are loaded into a basket 14 at position A. The carousel 8 rotates clockwise, moving basket 14 to position B where instruments in the basket undergo ultrasonic cleaning. Fluid passes along a pipe 20 from shaft 10 to the interior of the instruments. Carousel 8 continues to rotate, moving basket 14 out of the reservoir 2 to position C, in which ultrasonic decontamination no longer occurs. As the basket moves from position C back to position A, the instruments move through the path of decontamination fluid emitted by deluge sprayers 6. As the basket returns to position B, fluid flows to the interior of the instruments along pipe 20 again, flushing debris loosened by the ultrasonic decontamination out of the instruments into the reservoir 3.

Description

- 1 2397227

METHOD AND APPARATUS FOR DECONTAMINATING A MEDICAL

INSTRUMENT

The present invention relates to a method and apparatus for decontaminating a medical instrument. The invention is particularly relevant to the decontamination of cannulated medical or surgical instruments, but may also be used in the decontamination of noncannulated instruments or other medical and surgical equipment or components.

Although the instruments will typically be constructed to be nondisposable, the present invention may also be used to decontaminate disposable instruments, which in many cases are too expensive to be disposed of after a single use. In decontaminating re- usable instruments, it is important that all external surfaces, and any internal surfaces of the instruments are thoroughly cleaned to remove any body fluids, proteins, tissue or bone fragments. It is often desirable to disinfect the instruments during the decontamination process to reduce the risk of transmitting infection between patients. After decontamination, instruments may undergo sterilization.

Traditionally, medical instruments have been decontaminated by forcing pressurised water or a cleaning fluid over the instruments to achieve cleaning.

Disinfection may also be carried out in this way using water or a decontaminating fluid at an elevated temperature. This so-called "deluge decontamination" is usually carried out in large deluge washer machines which spray the fluid over the instruments in a similar way to a dishwasher machine. The machines may include special flushing attachments to which cannulated instruments can be attached to permit decontamination of internal surfaces. - 2 -

Although deluge decontamination may allow large volumes of instruments to be processed relatively rapidly, it is generally accepted that this type of process does not always provide adequate decontamination of either inside or outside surfaces of instruments, particularly of more complex instruments.

Another technique for decontaminating medical instruments involves the use of ultrasonic waves. In an ultrasonic decontamination process, the instrument is immersed in a bath of decontamination fluid. Ultrasonic transducers are used to excite the fluid in the bath, causing ultrasonic waves to propagate through the fluid.

The ultrasonic waves cause small, high pressure bubbles to form and collapse in the fluid at high frequency.

This "cavitation" effect gives rise to pressure waves in the fluid, which act to "scrub" the surfaces of the immersed instrument. In this way, any debris attached to surfaces of the instrument may be loosened. However, unless further steps are taken, the dislodged debris will tend to remain on the surfaces of the instrument, and particularly inside any cannula.

To provide thorough decontamination of both internal and external surfaces of an instrument, it is desirable to carry out both deluge washing and ultrasonic decontamination.

A combined ultrasonic decontaminating and deluge washing machine is known. In this machine, an ultrasonic reservoir is situated in the base of the washer chamber, with deluge sprayers arranged above the reservoir. The instruments are inserted into the chamber in baskets arranged at various levels, with the lowermost baskets immersed in the ultrasonic reservoir.

Ultrasonic decontamination of the immersed instruments may then be carried out. The bath is then drained, exposing the ultrasonically decontaminated instruments, and the deluge sprayers operated to provide deluge decontamination of the ultrasonically decontaminated - 3 - instruments, and also those instruments situated in the upper parts of the decontamination chamber.

This machine suffers from a number of drawbacks.

The need to repeatedly fill and drain the ultrasonic bath is inefficient in terms of energy and time, and limits throughput. Furthermore, only the instruments which are immersed in the reservoir undergo ultrasonic decontamination in addition to deluge decontamination.

Although a deeper reservoir may be used to permit ultrasonic decontamination of a greater number of instruments, this undesirably increases cycle time and running costs. The effectiveness with which ultrasonic waves may propagate also tends to decrease as the volume of the reservoir increases.

The Applicant has realised that there remains a need for a more efficient way to provide both deluge and ultrasonic decontamination of medical instruments in a single machine.

According to the present invention, there is thus provided: an apparatus for decontaminating a medical instrument; the apparatus comprising: deluge decontaminating means; a reservoir; means for applying ultrasonic waves to a fluid contained in said reservoir in use; and a mechanism for moving instruments to be decontaminated between the reservoir and deluge decontaminating means, so that, in an automated decontamination cycle of the apparatus, instruments can undergo both ultrasonic and deluge decontamination.

In accordance with the present invention, the apparatus thus includes means for moving a instrument to be decontaminated between a region in which ultrasonic waves may be applied to the instrument, and a region in which deluge decontamination may be carried out. In this way, the instrument may be thoroughly - 4 - decontaminated both externally, and, if appropriate, internally, with the ultrasonic decontamination acting to loosen debris, and the deluge decontamination to wash debris from surfaces. The instruments are moved between the different regions, and the need always to fill and drain the ultrasonic reservoir to permit both types of decontamination to be carried out is avoided, allowing decontamination to be carried out efficiently and with a higher throughput.

The present invention also extends to method for decontaminating a medical instrument, and thus according to a second aspect of the invention there is provided: a method for decontaminating medical instruments; comprising automatically moving instruments to be decontaminated between a reservoir to which ultrasonic waves are applied and a deluge decontaminating region, to provide automated ultrasonic and deluge decontamination of the instruments.

Ultrasonic waves are preferably applied to fluid in the reservoir by means of one or more transducers which may be located adjacent an edge or base of the reservoir, and preferably on the outside of the reservoir. The transducers are preferably provided with an ultrasonic frequency signal from a frequency generator.

The frequency of the ultrasonic waves is preferably greater than about 15 kHz more preferably greater than about 20 kHz, and ideally between about 25 and 40 kHz.

The ultrasonic waves may be applied only when an instrument to be decontaminated is immersed in the reservoir, but more preferably are applied at all times.

In this way, the ultrasonic waves will be ready to act on an instrument as soon as it enters the reservoir.

The deluge decontaminating region may be of any conventional form and generally comprises spraying means for providing jets of pressurized fluid. The pressure of the jets required to achieve decontamination may be - 5 selected as appropriate and, will depend upon factors such as the length of decontamination cycle, size of the apparatus, nature of decontamination fluid etc. The decontaminating fluid may simply be water, but preferably contains cleaning and/or disinfecting agents.

The decontaminating fluid which is emitted by the deluge decontamination means is preferably the same as the fluid contained in the reservoir. Although separate fluid supplies may be provided to the reservoir and the deluge decontamination means, preferably fluid from the reservoir is supplied to pump means for supplying the deluge decontaminating region. For example, fluid from the reservoir and fluid emitted by the deluge decontamination means may drain to a common sump. In this way, the decontamination fluid may be recycled continually between the deluge and ultrasonic decontamination regions.

In a particularly simple arrangement, the reservoir may be arranged to collect decontaminating fluid emitted by the deluge decontaminating means. However, the Applicant has found that if fluid emitted by the deluge decontaminating means is allowed to fall into the reservoir, the fluid in the reservoir may be disturbed, impeding the propagation of ultrasonic waves.

Preferably the apparatus thus comprises a region separated from the reservoir for collecting fluid emitted by the deluge decontaminating means. The collection region may then be arranged to drain e.g. to a sump. Preferably the deluge decontaminating means is arranged such that the emitted fluid falls generally in the collection region. Preferably deflecting means is provided to direct fluid emitted by the deluge decontaminating means away from the reservoir.

In a preferred arrangement, the ultrasonic decontaminating reservoir is located below the deluge decontaminating region in the lower part of the apparatus. For example, the reservoir may occupy the - 6 sump area of a cabinet type washer. In this preferred embodiment, a collection region may advantageously be defined by a wall of the reservoir. The wall may then act as a weir, allowing the collection region to also collect any overflow from the reservoir.

Preferably the means for moving the instruments comprises a movable carriage. Most preferably the carriage is a basket in which the instruments to be decontaminated are placed. In this way, the external surface area of the instruments exposed to the decontamination fluid may be increased. For example, the basket may prevent instruments from contacting the bottom or sides of the ultrasonic reservoir.

Preferably a plurality of carriages is provided which are movable sequentially between the reservoir and deluge decontaminating region. This arrangement enhances throughput of the apparatus. The carriages may move linearly, but more preferably are rotatably movable between the reservoir and the deluge decontamination region, and may be guided in any suitable manner, e.g. using rails or chains.

Alternatively, the movable carriage or carriages may be in the form of e. g. a rotatable drum. The instruments could then be placed in the drum, or in segments of the drum, to transfer them between the reservoir and deluge decontamination regions.

Preferably the apparatus comprises means for sequentially immersing a plurality of carriages in a fluid contained in the reservoir for ultrasonic decontamination and moving the carriages out of the reservoir and into the deluge decontamination region for deluge decontamination. Preferably the means for sequentially immersing and moving the carriages comprises at least one rotatable arm. In this way, instruments placed in the carriages may be moved cyclically between regions of the apparatus, undergoing both ultrasonic and deluge decontamination. In a particularly preferred embodiment, a plurality of carriages are mounted on respective arms of a rotatable frame. For example, the carriages may be mounted on spokes of a wheel or carousel, rotatable about a central axis. Such an assembly may then be fitted into the central cavity of a conventional cabinet washer, allowing the present invention to be implemented as a simple modification of the equipment.

From a third aspect the present invention provides: an apparatus for decontaminating medical instruments, the apparatus comprising: a reservoir and means for applying ultrasonic waves to a fluid contained in said reservoir, deluge decontamination means situated above said reservoir; and means for moving instruments to be decontaminated between said reservoir and said deluge decontamination means; wherein said means comprises a movable carriage or carriages which sequentially immerse said instruments in a fluid contained in said reservoir for ultrasonic decontamination of the instruments, and move the instruments out of said reservoir into the space above the reservoir for deluge decontamination of the instruments.

Preferably the instrument to be decontaminated is moved through the reservoir as ultrasound is applied to the decontamination fluid. The Applicant has found that by moving the instrument in this way, the effectiveness of the ultrasound decontamination is enhanced. It is thought that this is because the relative motion between the instrument and the fluid reduces the effect of standing waves. Standing waves can be thought of as layers of high power within the fluid, and may lead to an non-uniform decontamination effect arising across a reservoir. - 8 -

Previously the problem caused by standing waves has been addressed by varying the frequency of the ultrasonic waves propagating in the fluid. However, if the frequency is varied in this way, the ultrasonic waves cannot be applied to the fluid at an optimum frequency at all times. In contrast, by moving the instrument through the fluid in accordance with the present invention, all surfaces of an instrument may receive a more uniform decontaminating action, at a frequency optimised for effective decontamination.

It is believed that this method is advantageous in its own right, and thus in accordance with a fourth aspect of the invention there is provided: a method for decontaminating a medical instrument, the method comprising: providing a reservoir of decontaminating fluid; and automatically moving an instrument to be decontaminated through the reservoir while applying ultrasonic waves to the fluid.

The speed at which the instrument is moved through the fluid will depend upon factors such as the nature of the instrument and the frequency of the ultrasonic waves, and should not so great as to interfere with the cavitation effect occurring in the fluid. For example, the speed may advantageously be selected to match the cycle length of a conventional washer to allow simple modification of the washer in accordance with the present invention. Such cycles vary in length from as little as 30 seconds in length to as great as 45 minutes.

The instrument to be decontaminated may be any medical or surgical equipment or an element thereof.

However, preferably, the instrument is a cannulated instrument having a hollow tubular element or cavity, which may be regular or irregular. Preferably the instrument is single-walled. For example, the instrument may be a laparoscopic instrument or similar 9 - having an internal passageway through which e.g. surgical implements, fluids or catheters may be introduced.

Preferably the apparatus thus comprises means for supplying fluid to an internal surface of an instrument.

Preferably the fluid is supplied at least in the ultrasonic decontamination region. By filling the inside of the instrument with fluid in this way, ultrasonic decontamination of the internal surface may be obtained, as ultrasonic waves will propagate through the fluid. It is also advantageous to instead, or preferably additionally supply fluid to the internal surface at other times, e.g. in the deluge spraying region to provide more thorough decontaminating and removal of debris from the instrument.

Most preferably the apparatus comprises means for supplying a flow of fluid to the interior of the instrument. By irrigating the surface using a pressurised stream in this way, debris loosened by the ultrasonic waves may be more effectively flushed out of the instrument. Most preferably the flow is a pulsed flow, such that the flow includes still and moving pockets of fluid, rather than being of a constant pressure. The frequency of the pulses of fluid may vary depending upon the particular application. However, a frequency of less than 300Hz has been found to provide a good decontamination effect, and most preferably the frequency is around 25100 Hz. A suitable pulsed flow may be obtained using a piston pump or valve system.

Preferably the fluid flow is intermittently operated, at least while the instrument is in the reservoir. By operating the flow only intermittently in this way, there will be periods during which the fluid within an instrument is substantially at rest, allowing ultrasonic waves to more easily penetrate the fluid along the length of the instrument and loosen debris from the interior surfaces. -

The frequency and time for which the flow is operated will depend upon the particular application.

However, it has been found that good results may be obtained by operating the flow for around 15 seconds, and then switching it off for around 45 seconds while the instrument is in the reservoir. If desired, the ultrasonic waves may be switched off during the irrigation part of each cycle, but for ease of operation, the ultrasonic waves are preferably applied continuously.

From a fifth aspect the present invention provides a method for decontaminating a hollow medical instrument; the method comprising supplying an intermittent, pulsed flow of fluid to the interior of the instrument to be decontaminated whilst immersed in a reservoir of decontaminating fluid, and applying ultrasonic waves to the fluid in the reservoir while the instrument is immersed at least during the periods in which said flow is not in operation.

By "intermittent pulsed flow", it is meant that the flow is a pulsed flow which is switched off for certain periods while the instrument is immersed in the reservoir i.e. a flow is supplied to the interior of the instrument at intervals separated by periods of deadtime. The flow is pulsed in that it contains still and moving pockets of fluid, rather than being of constant pressure. Preferably, the frequency of the pulses is less than about 300 Hz, and most preferably in the range of from around 25 to 100 Hz.

The most suitable length of operation of the flow per cycle will depend e. g. upon cycle length, size of apparatus, and the nature of the instruments to be decontaminated. In general, a longer period of down time per cycle will result in fluid within the instrument being still for a greater length of time, allowing more effective ultrasonic decontamination of the interior of the instrument. During flushing periods, ultrasonic - 11 decontamination will in general be less effective, as the moving fluid within the instruments will tend to interfere with the propagation of bubbles in the fluid, which are responsible for decontamination of surfaces through cavitation. Preferably the pulsed flow is operated for around one third of the time that the instrument is immersed in the reservoir. Preferably the intermittent flow is operated in a cycle containing around 15s of flow followed by 45s of deadtime.

It will be appreciated that this aspect of the invention may be used with, or independently of, the preceding aspects of the invention. If it is to be incorporated into a combined deluge/ultrasonic decontaminating apparatus and method of the above main aspect, then fluid may be supplied to the interior of the instrument in any suitable manner. For example, each carriage may be provided with a conduit to which an instrument may be connected for supplying fluid to an interior surface of the instrument. If the carriage is to contain more than one instrument, further conduits, or suitable adaptors may be provide to allow connection of each instrument to a fluid supply.

Preferably, the apparatus comprises means for supplying pressurized fluid to each of a plurality of carriages so that the interior of each instrument may, if desired, be flushed out during decontamination. The carriages may be supplied from independent sources of fluid, but preferably a plurality of supply conduits are associated with respective carriages and connected to a manifold. In a preferred embodiment the carriages are mounted on arms which rotate about a central axis. In this arrangement the manifold is preferably situated in the central axis, whereby fluid may be supplied to each carriage by means of conduits associated with each arm.

The fluid supply to the carriages may be controlled using e.g. electronically controlled valve or mechanical pump arrangements, or a combination thereof. Preferably - 12 means are provided for controlling the supply of fluid to each carriage. Most preferably, independently operable control means is provided associated with each carriage. For example, pumps or valves may be used to provide an intermittent and/or pulsed flow as desired, or a flow to only those carriages located in a certain part of the apparatus. Alternatively, a simple indexing arrangement may be used, whereby fluid is supplied to a carriage when it moves into a predetermined position.

For example, fluid may be supplied when a conduit associated with a carriage moves into registration with a port connected to a fluid supply. In the preferred embodiment the port is provided in a central axis about which the carriages rotate. In other arrangements, the carriages may move on rails supported by a plurality of axles. Ports may then be provided in some or all of the plurality of axles.

Preferably, means are provided to control the quantity and pressure of fluid supplied to each carriage. For example, the quantity and pressure of the flow may be controlled using valves or more preferably using a suitably sized and calibrated conduit associated with each carriage.

Preferably, fluid is pumped from the reservoir to supply the carriages. In this way, fluid may be recycled, returning through the interior of the instruments to the reservoir.

The instruments may undergo one or more cycles of ultrasound and deluge decontamination as required. If only one cycle is used, the instruments are preferably moved from the ultrasound decontaminating region to the deluge decontaminating region. By carrying out deluge decontamination after ultrasound decontamination, loosened debris may be more effectively washed from surfaces of the instrument. However, the instruments are preferably returned to the ultrasound decontaminating region after deluge spraying for further / - 13 decontamination. For example, a number of cycles may be carried out using decontaminating fluid at different temperatures, and/or including different decontaminating agents to achieve effective cleaning and, if desired, disinfecting of instruments.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a vertical cross-sectional view of an apparatus in accordance with a first embodiment of the present invention; Figure 2 is a cross-sectional view along the line 2-2 in Figure 1, showing a basket in an aligned position in more detail.

Figure 3 is a vertical cross-sectional view of an apparatus in accordance with a second embodiment of the present invention.

The decontaminating apparatus 1 comprises a tank 2 containing decontamination fluid 3. Ultrasonic transducers 4 are provided adjacent to the tank 2 to supply ultrasonic excitation to the fluid 3. The transducers 4 are driven by a frequency generator (not shown).

The tank 2 is housed in the sump in the base of a cabinet type washer 1. Deluge sprayers 6 are located above the tank 2. A carousel 8 is rotatable about a horizontal shaft 10 in the space between the tank 2 and the deluge sprayer 6. The carousel 8 is in the form of a circular frame 13 connected by a plurality of spokes 12 to a sleeve 22 which is rotatable about shaft 10. A pipe 20 runs through each spoke 12 and through the sleeve 22 for reasons discussed in more detail below.

The pipe 20 is illustrated by way of example for one of the baskets 14 in figure 1. A basket 14 is mounted on the end of each spoke 12 furthest from the central shaft.

Decontamination fluid 3 is supplied to the hollow / - 14 interior 16 of shaft 10 and to the deluge sprayers 6 from the reservoir 2 using a suitable arrangement of pipes and pumps. A port 24 is located in the shaft 10 above the reservoir 2 for purposes to be discussed in more detail below. The connection of the fluid supplies to these parts of the apparatus is illustrated schematically in Figure 1.

The connection of the baskets 14 to the shaft 10 will now be described in more detail with reference to Figure 2. A pipe 20 runs through the sleeve 22 and along the inside of each spoke 12 from the shaft 10 to the basket 14. The shaft 10 includes a port 24 connecting its inner and outer surfaces 26 and 28 respectively. The passageway 24 defines an indexing point I, such that when a pipe 20 is arranged in alignment with the passageway 24, fluid may pass from the interior 16 of the shaft 10 through the passageway 24 and to the pipe 20 to basket 14.

The decontamination process will be described with reference to one of the baskets 14. The process will be the same for the other baskets associated with the remaining spokes 12 which move sequentially through the areas of the washer 1 as the carousel >3 rotates.

Instruments are loaded into basket 14 at position A. The basket includes an attachment device (not shown) such that hollow instruments may be attached to the end of the pipe 20, allowing flow of decontamination fluid from the hollow interior 16 of the shaft 10 to the interior of the instruments in the basket when the basket is in the aligned position shown in Figure 2.

Each basket may of course contain suitable attachments for connecting more than one instrument to the pipe 20 to allow simultaneous decontamination of a plurality of instruments. The internal dimensions of the pipe 20 are selected appropriately to provide a desired fluid flow or back pressure to each basket, and hence through each instrument or group of instruments connected to it. - 15

In position A, the pipe 20 associated with spoke 12 is not in alignment with the fluid passageway 24 defining the indexing point I of the shaft 10, and no fluid flows along the pipe 20 to the interior of the instruments in basket 14. The carousel 8 rotates clockwise, with sleeve 22 rotating about shaft 10 to move the basket 14 into the tank 2 of decontamination fluid. The speed of rotation of carousel 8 will depend upon the cycle length required. For example, the period of rotation may be between 30 seconds and 45 minutes.

The speed may suitably be selected to match that of an existing washer in which the carousel is installed to implement the present invention.

As the basket 14 moves through the reservoir 3 towards position B. the instruments in the basket are immersed in the decontamination fluid, and ultrasonic waves applied by the ultrasonic frequency generator to the tank 2 propagate through the fluid 3 to provide ultrasonic decontamination of the exterior surfaces of instruments. The frequency of the ultrasonic waves is between about 20 and 40 kHz.

In position B. pipe 20 is in alignment with fluid passageway 24 of shaft 10. Fluid passes along the interior of the spoke 12 through pipe 20 and to the interior of the instruments situated in the basket 14.

Ultrasonic waves propagate through the fluid along the length of the hollow interior of the instruments, providing ultrasonic decontamination of the internal surfaces.

Fluid is pumped along the pipe 20 from shaft 10 using a piston pump (not shown). In this way, a pulsed flow of decontamination fluid is supplied to the interior of the instruments when the basket is in position B. The frequency of the pulsed flow provided is around 25-100 Hz. The pulsed flow helps to flush debris loosened by the ultrasonic waves along the instrument, and into the decontamination fluid reservoir - 16 3. Of course, the pulsed flow may be provided using a suitable valve arrangement associated with the fluid passageway 24, rather than using a piston pump.

As the carousel 8 continues to rotate, the pipe 20 moves out of alignment with the fluid passageway 24, and the fluid flow through the instruments in basket 14 stops. However, as the basket 14 moves through the reservoir 3, the hollow interior of the instruments remains filled with fluid through which ultrasonic waves may propagate, and ultrasonic decontamination of both the internal and external surfaces of the instruments continues. The basket 14 then moves out of the reservoir 2 to position C. In this

position, the instruments in the basket 14 are no longer immersed in the decontamination fluid of tank 2, and ultrasonic decontamination does not occur. The basket then moves from position C back to position A through the space above the ultrasonic reservoir 2. In this region the instruments move through the path of the decontamination fluid emitted by the deluge sprayers 6, providing deluge decontamination of the external surfaces of the instruments.

Decontamination fluid emitted by the sprayers 6 falls to the base of the apparatus 1, and collects in the reservoir 3, for recycling to the sprayers or the shaft 10.

As the basket moves towards the index point I associated with position B for the second time, fluid flows to the interior of the instruments once more along pipe 20. This flow provides a flushing effect, forcing debris loosened by the ultrasonic decontamination along the interior of the instruments and out into the reservoir 3. In this way, the instruments undergo flushing once per cycle as the basket 14 moves past position B. The period for which the instruments experience the pulsed flow of fluid through their interior, and the - 17 period for which they undergo ultrasonic decontamination, but with no internal flow of decontamination fluid, will be determined by the relative size, and number of index points provided on the shaft 10 in the region above the ultrasonic bath 2, and the speed of rotation of the carousel 8. The Applicant has found that a period of flow of around a third the length of the time for which the basket is immersed in the reservoir 3 per cycle is suitable. For example, respective lengths of around 15 seconds of flow and 45 seconds of ultrasonics without flow may be appropriate.

Further indexing points may be provided by providing further passageways in the shaft 10, allowing flushing of the instruments in other regions, e. g. in the deluge spraying region if desired. Of course, although the index point arrangement described above is particularly simple, suitable arrangements for valves or pumps may instead be used to supply fluid to the interior of instruments provided in the baskets 14.

Operation for non-cannulated instruments is identical, with the exception that such instruments may simply be placed in the baskets 14, and secured as appropriate, and do not need to be connected to the pipes 20. They will then undergo ultrasonic decontamination as the basket moves through the tank 2, and deluge decontamination in the area above the tank 2.

If only non-cannulated instruments are to be cleaned, the apparatus need not include means for supplying fluid from the shaft along the spokes of the carousel 8, as fluid will not need to be supplied to the interior surfaces of any instruments.

A modified apparatus in accordance with the present will now be described with reference to Figure 3. The apparatus in this embodiment is similar in many respects to that of the first embodiment already described. We will therefore describe in detail only those features - 18 which differ from those of the first embodiment. Parts of the apparatus of the second embodiment corresponding to parts of the apparatus in the first embodiment are shown using corresponding reference numerals, but annotated by a prime sign (').

The decontaminating apparatus 10 includes a tank 2' containing fluid 3' to which ultrasonic waves may be applied by transducers 4' as in the first embodiment.

One wall 32 of tank 2' defines a drainage channel 34 with sloping wall 36 in the base of the apparatus 10.

The drainage channel 34 is connected to a sump (not shown) in the base of the apparatus 10. Any fluid overflowing from the reservoir 2 ' may flow in the direction of arrow F over the wall 32 and into the drainage channel 34. In this way, wall 32 defines a weir separating the reservoir from the drainage channel.

In this embodiment, the rotating carousel 8 of the first embodiment has been replaced by a rail system for moving baskets of instruments between ultrasonic and deluge decontamination regions. The rail 38 is supported on axles 30, 40, 50, 60 and 70, and is moveable anti-clockwise in the direction of the arrows of Figure 3.

The baskets 14' are mounted on the rails by means of spoke assemblies 42. Each spoke assembly 42 comprises a pipe (not shown) for supplying fluid to instruments in the baskets in a similar manner to pipe of the first embodiment. The deluge sprayers 6' are arranged to emit fluid towards the wall of the apparatus on the right hand side of Figure 3, and towards drainage channel 34. A deflecting shield 80 separates the deluge spraying region 44 from the remainder of the space above the reservoir 2' . Each axle 30, 40, 50, 60, 70 is connected to a fluid supply for supplying fluid to instruments in a basket when the pipe in spoke assembly 42 moves into alignment with a port on the axle (not shown) in a - 19 similar way to the indexing system used in the first embodiment.

In operation, a basket 14' moves past axle 60. As the spoke assembly 42 connecting the basket to the rail 38 passes axle 60, the pipe in the spoke assembly 42 moves into registration with a port (not shown) in the axle 60, allowing fluid to pass through the pipe and fill the interior of the instruments.

The basket 14' then continues to move on rotating rail 38 into the ultrasonic reservoir 2'. Ultrasonic decontamination of the interior surfaces of the instruments may commence immediately as the instruments are filled with fluid. As the spoke assembly 42 moves past the port of axle 70, fluid flows into the interior of the instruments once more, flushing out debris loosened from the internal surfaces of the instruments by the ultrasonic waves.

The basket 14' then moves out of the ultrasonic reservoir 3' and into the path of the fluid emitted by the deluge sprayers 6' in the deluge spraying region 44 in the right hand side of the apparatus. As the rail 38 rotates, the basket 14' moves past axle 30 causing the instruments to be once again filled with fluid. The interior surfaces are then flushed as the spoke assembly 42 moves into registration with the port in axle 40.

The fluid emitted by the deluge sprayers 6' falls to the base of the washer, and flows along sloping wall 36 into the drainage channel 34 in the direction of arrow G to the sump. The deflecting screen 80 and the orientation of the deluge sprayers 6' prevents the emitted fluid falling into the reservoir of fluid 3' and impeding the propagation of ultrasonic waves.

The basket then moves out of the deluge spraying region 44 towards axle 50 where fluid fills the interior of instruments in the basket once more, and then returns to axle 60 to commence a further cycle if desired.

It will be appreciated that the number of axles may # - 20 be varied, depending upon e.g. size and volume of the washer, a greater or lesser number of axles may be used.

Furthermore, although in the embodiment described above, fluid is supplied to the interior of instruments as a basket passes each axle, the number of points at which fluid may be supplied to the interior of instruments in the baskets may be selected as desired. As with the first embodiment, an alternative arrangement using e.g. electronically controlled valves may be used to supply fluid to the instruments, rather than the mechanical indexing system described.

Once a desired number of cycles of deluge and ultrasonic decontamination have been completed in either embodiment, the ultrasonic transducers 4, 4' may be switched off, the tank drained and the instruments removed from the basket 14, 14' to be cleaned and dried.

It will be appreciated that the apparatus of any of the embodiments may be operated under microprocessor control to provide a number of different cycles. For example, factors such as the temperature of the fluid emitted by the deluge sprayers, frequency of the pulsed flow provided to the interior of instruments, duration/location of flushing, nature of the decontaminating fluid, and speed of movement of the baskets through the reservoir etc. may be varied.

Suitable microprocessor controls are known in the context of dishwashers and washing machines.

For example, the instruments may first undergo a pre-cleaning stage, in which the decontaminating fluid used is simply cold water at a temperature of below 35 C. This cycle would act to remove soluble protein residues and gross residues from the instruments. The instruments may then undergo a cleaning stage in which the decontaminating fluid includes a detergent. For example, an alkali at 60 C may be used, or an enzyme at 40 C. The instruments are then rinsed using water to wash away any detergent residues. Finally, the - 21 instruments may be disinfected, using either water at a higher temperature, or a decontaminating fluid including chemical agents. Each stage in the process may involve one or more cycles of the apparatus. After removal from the apparatus, the instruments may undergo a final sterilization process.

Claims

Claims: 1. An apparatus for decontaminating a medical instrument; the

apparatus comprising: deluge decontaminating means; a reservoir; means for applying ultrasonic waves to a fluid contained in said reservoir in use; and a mechanism for moving instruments to be decontaminated between the reservoir and deluge decontamination means, such that, in an automated decontamination cycle of the apparatus, instruments can undergo both ultrasonic and deluge decontamination.
2. The apparatus of any preceding claim further comprising a collection region separated from the reservoir for collecting fluid emitted by the deluge decontaminating means.
3. The apparatus of claim 2 wherein the collection region is defined by a wall of the reservoir.
4. The apparatus of any preceding claim, wherein the ultrasonic decontaminating reservoir is located below the deluge decontaminating region in the lower part of the apparatus.
5. The apparatus of any preceding claim wherein the mechanism for moving the instruments comprises a movable carriage.
6. The apparatus of any preceding claim wherein said mechanism for moving the instruments comprises a plurality of carriages which are movable sequentially between the reservoir and deluge decontaminating region.
7. An apparatus for decontaminating medical instruments, the apparatus comprising: a reservoir and means for applying ultrasonic waves to a fluid contained in said reservoir, deluge decontamination means situated above said reservoir; and means for moving instruments to be decontaminated between said reservoir and said deluge decontamination means; wherein said means comprises a movable carriage or carriages which sequentially immerse said instruments in a fluid contained in said reservoir for ultrasonic decontamination of the instruments, and move the instruments out of said reservoir into the space above the reservoir for deluge decontamination of the instruments.
8. The apparatus of any of claims 5 to 7 wherein the carriage or carriages are rotatably movable between the reservoir and the deluge decontamination region.
9. The apparatus of any of claims 5 to 8 wherein a plurality of carriages are mounted on respective arms of

a rotatable frame.
10. The apparatus of any of claims 5 to 9 comprising means for supplying pressurized fluid to the or each carriage.
11. The apparatus of claim 10 comprising independently operable control means for controlling the supply of fluid to the or each carriage.
12. The apparatus of any one of the preceding claims further comprising means for supplying a flow of fluid to the interior of an instrument to be cleaned.
13. The apparatus of claim 12 wherein the flow is a pulsed flow.
14. The apparatus of claim 13 wherein the frequency of the pulses of fluid is less than 300 Hz.
15. The apparatus of claim 13 or 14 wherein the frequency of the pulses of fluid is from around 25 to around 100 Hz.
16. The apparatus of any of claims 12 to 15 wherein the fluid flow is intermittently operated.
17. A method for decontaminating medical instruments; comprising automatically moving instruments to be decontaminated between a reservoir to which ultrasonic waves are applied and a deluge decontaminating region, to provide automated ultrasonic and deluge decontamination of the instruments.
18. The method of claim 17 further comprising moving the instrument to be decontaminated through the reservoir as ultrasound is applied to the decontamination fluid.
19. The method of claim 17 or 18 further comprising supplying fluid from the reservoir to pump means for supplying the deluge decontaminating region.
20. A method for decontaminating a medical instrument, the method comprising: providing a reservoir of decontaminating fluid; and automatically moving an instrument to be decontaminated through the reservoir while applying ultrasonic waves to the fluid.
21. The method of any of claims 17 to 20 further as comprising supplying a flow of fluid to the interior of an instrument to be cleaned.
22. The method of claim 21 further comprising operating the fluid flow intermittently.
23. The method of claim 21 or 22 wherein the fluid flow is a pulsed flow.
24. A method for decontaminating a hollow medical instrument; the method comprising supplying an intermittent, pulsed flow of fluid to the interior of the instrument to be decontaminated whilst immersed in a reservoir of decontaminating fluid, and applying ultrasonic waves to the fluid in the reservoir while the instrument is immersed at least during the periods in which said flow is not in operation.
25. The method of claim 23 or 24 wherein the frequency of the pulses is less than about 300 Hz.
26. The method of any of claims 23 to 25 wherein the frequency of the pulses is from around 25 to around 100 Hz.
27. The method or apparatus of any preceding claim wherein the frequency of the ultrasonic waves is greater than about 15 kHz.
28. The method or apparatus of any preceding claim wherein the frequency of the ultrasonic waves is greater than about 20 kHz.
29. The method of any of the preceding claims wherein the frequency of the ultrasonic waves is between about and 40 kHz.
30. An apparatus for decontaminating a medical instrument substantially as herein before described with reference to any one of the accompanying drawings.
31. A method for decontaminating a medical instrument substantially as herein before described with reference to any one of the accompanying drawings.