GB2500866A - Method for decontamination of medical instruments - Google Patents

Abstract

An automated method for the decontamination of medical instruments such as endoscopes, comprises placing 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 performing a disinfectant phase which comprises the application of a disinfectant to the instrument and following the disinfectant phase immediately performing a drying phase with no rinse stage such that disinfectant is allowed to dry on the surface of the instrument. The disinfectant may be hypochlorous acid. The immediate drying phase allows hypochlorous acid to dry on the surface of the instrument such that at least those parts of the instrument intended for internal contact with a patient are substantially coated with a dried layer of hypochlorous acid which is retained during storage and until use of the instrument. An automated decontamination apparatus for the decontamination of medical instruments comprising a housing defining a cleaning chamber, clean means, disinfecting means and controller.

Description

A METHOD FOR THE DECONtAMINATION OF MEDICAL INSI'RUMENIS The present invention relates to a method for the decontamination of medical insUmments, 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 t.o visual internal examination of a patient. Endoscopes are routinely exsed to mucus and other gastrointestinal secretions, blood, saliva, faeces, bile, and somctimes pus, and therefore require unique consideration with respect to decontamination. In addition to the external surface of endoscopes, (heir internal channels for air, water, aspiration and accessories are exposed to body fluids and other contaminants. Rigid endoscopes are commonly steriliscd using an autoclave which subjects the endoscpes to high pressure saturated steam at 121 °C for around 15-20 nhinuLes. However, in contrast to rigid endoscopes and most reusable accessories, flexible [5 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-usc wire brushes, and exposure of all external and accessible internal components t.o a low-foaming eniymatic detergent known to he compatible with the endoscope; h) automatic disinfection using an Automated Endoscope Reprocessor (AER).

According to the Society of (]astroentero]ogy, AER machines should he used for all endoseope decontamination foflowi ng manual pre-cleaning. A] R machines are recommended both because they reliably expose all external and internal components of the endoscope t.o thorough disinfection and rinsing, and because they help prevent atmospheric pollution by the disinfectant, and manual disinfection is no longer considered

acceptable.

I

Cuffently all of the Automatic Endoscope Reprocessors (AER) have three broad phases of operation: I) 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 hiocide to eliminate micrn organisms; and 3) Rinse phase -thc cndoscopc is rinscd with watcr to rcmovc all uaccs of the disinfectant hiocide to avoid hann to the patient caused by any residue.

In ordcr to preserve the sterility of the cndoscopc it is csscntial that thc 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 t5 sysl.enis the ability to consistently achieve bacteria free rinse water is problematical and it.

is necessary for the final rinse water to he 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 hushing of any residues, therefore significantly increasing the sterilization cycle time and limiting the number of endoscopes which can he proccsscd within a givcn timc period.

It is therefore desirable to provide an improved method br the decontaiiination ob medical instruments such as endoscopes which addresses the above described problems andlor 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; conimencing a cleaning phase for the removal of contaminated material froni 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 permit ted to dry on the surface of an endoscope or other medical instrument that hypochiorous acid is sale for ingestion by a hunian and therefore suhscqucnt rinsing of the hypochiorous acid is unnecessmy. 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 arc ohviated.

t5 The automated decontamination device comprises a controller configured o 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 conUol temperature and flow rat.e of the Iluids concerned with each stage.

The decontamination process is terminated following the dmying 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 Rllowing the disin1ectan stage ii is ensured that the hypoehlorous 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. Ibis 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 he 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 carhoxylie acid, wherein the carhoxylic acid is in solution in an alcoholic solvent. which comprises ethanol, the alcoholic solvent optionally also containing water. ftc hypochlorite is preferably in aqueous solution.

The carhoxylie acid may he a mono-, di-or tn-functional, saturated alkanoic acid optionally having one or more substit.uenis which are substantially inert in (he presence of a chlorine [5 donor. The acid is a solid when in pure isolated fonn 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 he in the form of a sealed or closed pack containing the hypochlorite in aqueous solution at an alkaline p1-I. 7. the second supply may he in the form of a further sealed or closed pack containing the earboxylic 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 cndoscopcs, the device comprising a housing defining a cleaning chamber for receiving an instrument for decontamination; cleaning means conligured to apply a cleaning fluid t.o the instrument when located within the cleaning chamber; disinfecting means configured to apply a disinfectant to the instrument; and a controllcr for controlling the cleaning means and disinfectant means, the controller being configured to initiate a cleaning phase in which the cleaning means is operat.ed 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 diying 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 hypoehlorous 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 invenLion will now he 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 [5 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 t.o and sealing the chamber. A plurality of trays is located within the housing defining load carriers for rcc.eiving the endoscopcs. Thc trays preferably comprise a wire frame sbiicturc arranged to optimise access to the endoscopes by cleaning fluids. A plurality of nozzles is located within the cleaning chanther, each nozzle being arranged to he 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 tluids 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 t.o the endoscopes in use. Ihe Al iR 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 endoseope is first subjected to an initial manual cleaning stage to remove the hulk of external contaminants. I bllowing 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 t.he correct, cleaning and disinfect.ing cycle is conducted every time by removing the option for variation by the operator.

Following act.ivat.ion the controller causes conunencement. of a cleaning phase in which a cleaning solution, which is preferably an enzymatic cleaning solution is externally directed to thc endoseopes by the cleaning means. In addition, the nozzles connected to the endoseope 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 [5 which time it. is discontinued by the controller. A short rinse phase is then preferably activated by the eontmller to rinse the enzymatic solution from the endoseope using filtered water. IJnlike the final rinse phase of the prior art systems, bacteria free water is not. required for this intermediat.e rinse phase as any bacteria which may he present. is destroyed by the following disinfectant phase. As such, the expensive and time consuming proccsses 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 thy to prevent dilution of the subsequently applied disinfectant. During the drying phase air is blown through the tubes of the endoseope by [he nozzles to facilitate drying of these channels.

When the intermediate drying stage is complete the controller activates the final disinfectant stage. In the disinfectant. st.age the cleaning means are used to direct. a how of disinfectant fluid at t.he endoseope. The disinfectant used is a hypoehlorous acid.

Hypoehlorous acid (1-IOCI) is a mixture of active elements derived from salt by electrolysis through a proprietary eleetroehernieal cell. EleeU'olysed saline produces a rapidly active hiocide in the form of hypochlorous acid that is effective against, vegetative bacteria, myeohaeteria, spores.,ycasts and vimses..Ihe hypoehlorous acid is applied to the endoscopes by the cleaning means both externally and internally to the tubes by the nozzles. These may he the same deaning means as used for applying the enzymatic solution or separate fluid delivery means.

The applicant has surprisingly found that hypoehlorous acid may he 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. hypoehlorous 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 he safely retained on the surface of endoseope, but. such retention should he encouraged as it provides an actively anti-bacterial surface coating to the endoseope which continues to maintain the sterility of the endoseope following reprocessing. The preferred hypoehiorous acid is a hypochiorous acid marketed by the applicant as TrioSafe, and as described in UK Patent Number 0B2477597. [5

ftc controller of the present invention is configured to commence a drying phasc following the disinfectant phase in which the hypochlorous acid is allowed to dry on the surface of the endoscope. In the drying phase the endoseope is retained within the cleaning chamber and permitted to dry. Commencement of the drying phase may comprise the ccssation of the disinfectant stage alone and the absence of a further rinse phase. Initiation of the drying phase may also comprise the coniroller initiating a timer to regulate the drying period and notily the operaLor when the drying period is complete. l'his 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 elficacy of drying process. Air may he blown onto the external surface and/or through the channels of the endoseope tubes. Following drying thc disinfectant process is terminated by the controller. [he reproccssor is controlled such that no further rinsing takes place to ensure that. the hypoehlorous acid is pernnt.ted t.o dry on the surface of the endoscope is t.o ensure that it. is retained on the surface of t.he endoseope following drying and during subsequent storage.

The drying st.age is coniplet.e when the hypoehlorous acid in contact with the endosco has substantially transitioned from the Uquid phase with a solid phase residue remaining as a coating on the endoseope. IL will however be appreciated that while the residue is preferred thc drying phase may comprise only the removal of the liquid phase hypochiorous acid, or other suitable disinfectant from the endoscope through evaporation with no residue remaining as such a process still ohviaes the requiremen( 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. PenniLting the hypochlorous acid (.o dry on (he endoscope and (he absence of a final rinse stage distinguishes the pmcess of the present invention from the systems of the prior art and provides previously unohservcd technical advantages. The hypochlorous acid is pennit(ed to dry on the surface (internal and external) of (he endoscope such that the surlace is substantially coated with a residue layer of dried hypochlorous acid. No further rinsing is performed at any stage up until the cndoscopc is used. Following reprocessing the endoscopc is stored in a sterile environment with the hypochlorous residue retained and is (aken directly from storage (o the poin( of use without any fur(her processing of any t5 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 (o a sterile clean room such tha( the disinfected cndoscopcs are removed in sterile environment in which they are then stored. In the pass-thixugh embodiment the cleaning chamber comprises two access doors.

with the contaminated endoscopes being loaded in the non-sterile morn through a first.

access door and removed in tFe clean rom through the second door. Alternatively the AER may he a single entry unit which the cndoscopes arc inserted and removed from the unit through the same access.

Whilst cndeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should he understood that the Applicant claims protection in respect of any patentable feature or combination of feaLures hereinhefore referred to and/or shown in the drawings whether or not. particular emphasis has been placed thereon.

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