The present invention relates to a method for the decontamination of medical instruments, and in particular a method for the decontamination of endoscopes.

Endoscopes are complex reusable medical instruments consisting of a long, thin, flexible (or rigid) tube used to visual internal examination of a patient. Endoscopes are routinely exposed to mucus and other gastrointestinal secretions, blood, saliva, faeces, bile, and sometimes pus, and therefore require unique consideration with respect to

decontamination. In addition to the external surface of endoscopes, their internal channels for air, water, aspiration and accessories are exposed to body fluids and other

contaminants. Rigid endoscopes are commonly sterilised using an autoclave which subjects the endoscpes to high pressure saturated steam at 121 °C for around 15-20 minutes. However, in contrast to rigid endoscopes and most reusable accessories, flexible endoscopes are heat labile and cannot be autoclaved.

The current process of decontamination for flexible endoscopes comprises two basic stages: a) manual cleaning, which includes brushing with single-use wire brushes, and

exposure of all external and accessible internal components to a low-foaming enzymatic detergent known to be compatible with the endoscope; b) automatic disinfection using an Automated Endoscope Reprocessor (AER).

According to the Society of Gastroenterology, AER machines should be used for all endoscope decontamination following manual pre-cleaning. AER machines are recommended both because they reliably expose all external and internal components of the endoscope to thorough disinfection and rinsing, and because they help prevent atmospheric pollution by the disinfectant, and manual disinfection is no longer considered acceptable. Currently all of the Automatic Endoscope Reprocessors (AER) have three broad phases of operation:

1) Cleaning phase - endoscope is washed with a detergent to remove gross c

contaminants;

2) Disinfectant phase - a disinfectant which is applied to the endoscope which

conventionally uses an aggressive biocide to eliminate micro organisms; and

3) Rinse phase - the endoscope is rinsed with water to remove all traces of the disinfectant biocide to avoid harm to the patient caused by any residue.

In order to preserve the sterility of the endoscope it is essential that the rinse water is bacteria free. This requires expensive reverse osmosis or filtration systems to produce the bacteria free water which are both costly to purchase and maintain. Even with such systems the ability to consistently achieve bacteria free rinse water is problematical and it is necessary for the final rinse water to be sampled from the automatic reprocessor and tested for its microbiological quality at least weekly. In addition, the rinse phase takes some 6 or more minutes to achieve complete flushing of any residues, therefore significantly increasing the sterilization cycle time and limiting the number of endoscopes which can be processed within a given time period.

It is therefore desirable to provide an improved method for the decontamination of medical instruments such as endoscopes which addresses the above described problems and/or which offers improvements generally.

According to the present invention there is provided a method for the decontamination of medical instruments such as endoscopes as described in the accompanying claims. In addition there is provided an automated decontamination apparatus as described in the accompanying claims.

In an embodiment of the invention there is provided an automated method for the decontamination of medical instruments such as endoscopes, the method comprising placing the instrument within a cleaning chamber of an automated decontamination device; commencing a cleaning phase for the removal of contaminated material from the device; subsequent to the cleaning phase commencing a disinfectant phase comprising the application of a disinfectant to the instrument; and following the disinfectant phase commencing a drying phase in which the hypochlorous acid is allowed to dry on the surface of the instrument.

The disinfectant is preferably a hypochlorous acid. It has been found that when permitted to dry on the surface of an endoscope or other medical instrument that hypochlorous acid is safe for ingestion by a human and therefore subsequent rinsing of the hypochlorous acid is unnecessary. By applying a drying phase following the disinfectant phase, removing the final rinse phase altogether, and allowing the hypochlorous acid to dry on the endoscope, the time consuming and expensive processes required to produce bacteria free rinse water, and the time associated with the rinse cycle are obviated. The automated decontamination device comprises a controller configured to cause the commencement of the cleaning, disinfectant and drying phases. The controller ensures that each phase is operated for the optimum period and may also control temperature and flow rate of the fluids concerned with each stage. The decontamination process is terminated following the drying phase and the instrument is not rinsed following the disinfectant process either prior to or following the drying phase. By completely removing the rinse phase following the disinfectant stage it is ensured that the hypochlorous acid is permitted to dry on the endoscope and that a residue is retained thereon.

The drying phase preferably comprises generating a forced airflow and applying said airflow to the instrument to increase drying efficiency.

The method may further include the step of rinsing the endoscope following the cleaning phase and prior to the disinfectant phase. This ensures that the detergent from the cleaning phase is removed so as to prevent spoiling of the hypochlorous acid. The method may further including the step of drying the instrument following rinsing and prior to the disinfectant phase to ensure that the disinfectant is not diluted by any retained cleaning solution. The method may be a method of decontaminating a flexible endoscope.

The disinfectant is preferably a disinfectant combination, which comprises; a first supply of a water-soluble hypochlorite; and a second supply of at least one saturated, water- soluble, physiologically acceptable carboxylic acid, wherein the carboxylic acid is in solution in an alcoholic solvent which comprises ethanol, the alcoholic solvent optionally also containing water. The hypochlorite is preferably in aqueous solution.

The carboxylic acid may be a mono-, di-or tn-functional, saturated alkanoic acid optionally having one or more substituents which are substantially inert in the presence of a chlorine donor. The acid is a solid when in pure isolated form at 20[deg.]C, and is an alkane dioic acid with up to 7 carbon atoms in a saturated chain, or a hydroxyl substituted alkanoic acid.

The alcoholic solvent for the carboxylic acid may comprise 40 to 60% by weight of ethanol, substantially all the balance being water.

The first supply may be in the form of a sealed or closed pack containing the hypochlorite in aqueous solution at an alkaline pH. 7. The second supply may be in the form of a further sealed or closed pack containing the carboxylic acid in solution in said alcoholic solvent. In another aspect of the invention there is provided an automated decontamination apparatus for the decontamination of medical instruments such as endoscopes, the device comprising a housing defining a cleaning chamber for receiving an instrument for decontamination; cleaning means configured to apply a cleaning fluid to the instrument when located within the cleaning chamber; disinfecting means configured to apply a disinfectant to the instrument; and a controller for controlling the cleaning means and disinfectant means, the controller being configured to initiate a cleaning phase in which the cleaning means is operated to clean an instrument, to subsequently initiate a disinfecting phase in which the disinfecting means is operated to apply a disinfectant to the instrument, and to initiate a drying phase subsequent to the disinfecting phase in which the disinfectant is permitted to dry on the instrument.

The disinfecting phase preferably comprises utilising the disinfecting means to apply a hypochlorous acid to the instrument.

The apparatus preferably comprises rinse means for rinsing the medical instrument, the controller being configured to activate said rinsing means following the cleaning phase and prior to the disinfectant phase.

The present invention will now be described by way of example only with reference to the following illustrative figures in which:

Figure 1 is a schematic representation of a method of

decontamination according to the present invention.

An automated endoscopic reprocessor (AER) comprises a housing defining a cleaning chamber for receiving endoscopes for reprocessing and a door for proving access to and sealing the chamber. A plurality of trays is located within the housing defining load carriers for receiving the endoscopes. The trays preferably comprise a wire frame structure arranged to optimise access to the endoscopes by cleaning fluids. A plurality of nozzles is located within the cleaning chamber, each nozzle being arranged to be connected to the tubes or channels of the endoscopes when the endoscopes are located within the load carriers. The plurality of nozzles are configured to channel air and/or cleaning fluids to the endoscope tubes.

The AER comprises means for directing and agitating cleaning fluids to the endoscopes located on the load carriers within the chamber. These may be fixed or rotating nozzles, hoses of any other suitable means for mechanically directing fluid to the endoscopes in use. The AER further includes a controller for controlling and coordinating the cleaning and disinfecting processes occurring within the cleaning chamber. Following use in a medical procedure, an endoscope is first subjected to an initial manual cleaning stage to remove the bulk of external contaminants. Following the initial manual cleaning stage the endoscope is placed on a load carrier within the cleaning chamber. The chamber is closed and sealed and the operator then activates the cleaning cycle. Preferably operation of the cleaning cycle comprises a single activation stage such as operation of a single button or switch, with no further input being required from the operator. This ensures that the correct cleaning and disinfecting cycle is conducted every time by removing the option for variation by the operator. Following activation the controller causes commencement of a cleaning phase in which a cleaning solution, which is preferably an enzymatic cleaning solution is externally directed to the endoscopes by the cleaning means. In addition, the nozzles connected to the endoscope channels direct the cleaning solution internally to the endoscope to flush out and clean these channels. The cleaning phase is operated for approximately 5 minutes after which time it is discontinued by the controller. A short rinse phase is then preferably activated by the controller to rinse the enzymatic solution from the endoscope using filtered water. Unlike the final rinse phase of the prior art systems, bacteria free water is not required for this intermediate rinse phase as any bacteria which may be present is destroyed by the following disinfectant phase. As such, the expensive and time consuming processes associated with such bacteria free rinsing are avoided by the present invention.

Once the rinse phase has been completed an intermediate drying phase is introduced in which the external water is permitted to drip dry to prevent dilution of the subsequently applied disinfectant. During the drying phase air is blown through the tubes of the endoscope by the nozzles to facilitate drying of these channels.

When the intermediate drying stage is complete the controller activates the final disinfectant stage. In the disinfectant stage the cleaning means are used to direct a flow of disinfectant fluid at the endoscope. The disinfectant used is a hypochlorous acid.

Hypochlorous acid (HOCl) is a mixture of active elements derived from salt by electrolysis through a proprietary electrochemical cell. Electrolysed saline produces a rapidly active biocide in the form of hypochlorous acid that is effective against vegetative bacteria, mycobacteria, spores, yeasts and viruses. The hypochlorous acid is applied to the endoscopes by the cleaning means both externally and internally to the tubes by the nozzles. These may be the same cleaning means as used for applying the enzymatic solution or separate fluid delivery means. The applicant has surprisingly found that hypochlorous acid may be retained on the surface of an endoscope and that the remaining residue is non-toxic and may be safely ingested by a human. Furthermore, not it has been found by the applicant that hypochlorous acid retained as a residue on an instrument such an endoscope remains active and continues to kill bacteria. Therefore, the applicant has found that not can a hypochlorous acid residue be safely retained on the surface of endoscope, but such retention should be encouraged as it provides an actively anti-bacterial surface coating to the endoscope which continues to maintain the sterility of the endoscope following reprocessing. The preferred hypochlorous acid is a hypochlorous acid marketed by the applicant as TrioSafe, and as described in UK Patent Number GB2477597.

The controller of the present invention is configured to commence a drying phase following the disinfectant phase in which the hypochlorous acid is allowed to dry on the surface of the endoscope. In the drying phase the endoscope is retained within the cleaning chamber and permitted to dry. Commencement of the drying phase may comprise the cessation of the disinfectant stage alone and the absence of a further rinse phase. Initiation of the drying phase may also comprise the controller initiating a timer to regulate the drying period and notify the operator when the drying period is complete. This may comprise a visual or audible signal and/or the automated unlocking of the access door to permit removal. Preferably the cleaning chamber includes means to force airflow to accelerate and increase the efficacy of drying process. Air may be blown onto the external surface and/or through the channels of the endoscope tubes. Following drying the disinfectant process is terminated by the controller. The reprocessor is controlled such that no further rinsing takes place to ensure that the hypochlorous acid is permitted to dry on the surface of the endoscope is to ensure that it is retained on the surface of the endoscope following drying and during subsequent storage.

The drying stage is complete when the hypochlorous acid in contact with the endoscope has substantially transitioned from the liquid phase with a solid phase residue remaining as a coating on the endoscope. It will however be appreciated that while the residue is preferred the drying phase may comprise only the removal of the liquid phase

hypochlorous acid, or other suitable disinfectant from the endoscope through evaporation with no residue remaining as such a process still obviates the requirement for rinsing. Once the drying stage has been completed and the disinfectant process terminated the cycle is complete and the endoscope is removed from the cleaning chamber without a final rinse stage. Permitting the hypochlorous acid to dry on the endoscope and the absence of a final rinse stage distinguishes the process of the present invention from the systems of the prior art and provides previously unobserved technical advantages. The hypochlorous acid is permitted to dry on the surface (internal and external) of the endoscope such that the surface is substantially coated with a residue layer of dried hypochlorous acid. No further rinsing is performed at any stage up until the endoscope is used. Following reprocessing the endoscope is stored in a sterile environment with the hypochlorous residue retained and is taken directly from storage to the point of use without any further processing of any kind.

In a pass-through AER the AER unit is located with a loading access within a non-sterile room and a corresponding unloaded access opening into to a sterile clean room such that the disinfected endoscopes are removed in sterile environment in which they are then stored. In the pass-through embodiment the cleaning chamber comprises two access doors, with the contaminated endoscopes being loaded in the non-sterile room through a first access door and removed in the clean rom through the second door. Alternatively the AER may be a single entry unit which the endoscopes are inserted and removed from the unit through the same access.

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.

It will be appreciated that in further embodiments various modifications to the specific arrangements described above and shown in the drawings may be made. For example, while the invention is described for use in disinfecting endoscopes, it is not limited to such and may be utilised for cleaning and disinfecting any devices requiring similar cleaning considerations.