Washer Disinfectors Health Technical Memorandum 2030 |
Washer Disinfectors Health Technical Memorandum 2030OPERATIONAL MANAGEMENT 10.0 Washer-disinfectors for thermo-labile endoscopes Introduction10.1 This type of WD is used to process endoscopes which are thermo-labile and cannot withstand thermal disinfection. They are typically of the flexible fibre-optic or video-endoscope type. (Rigid endoscopes capable of withstanding a thermal disinfection process may be decontaminated in WDs for instruments and utensils equipped with an appropriate load carrier designed to provide flushing of the lumen) 10.2 Disinfection is achieved by direct contact of the load with a chemical disinfectant solution at a specified concentration for a specified time either at a specified temperature or within a previously validated temperature range. 10.3 The disinfection facility may be provided as part of the automatic process or as a separate machine intended to disinfect items which have been cleaned. For this reason equipment for chemical disinfection is considered separately (See Chapter 12). Product Compatibility 10.4 Endoscopes may be harmed by some chemical additives or the use of an inappropriate operating cycle in the WD. The reprocessing instructions supplied by the manufacturer of the endoscope should be followed carefully. Load handling/presentation 10.5 Few, if any WDs for thermo-labile endoscopes are capable of cleaning the endoscope without any pre-treatment. As soon as the endoscope is removed from the patient, the channels should be flushed in accordance with the endoscope manufacturers instructions. The outside of the instrument should then be wiped with a swab soaked in an aqueous solution of a suitable detergent. Instrument/biopsy channels should be brushed through several times with a cleaning brush designed for the instrument in accordance with the endoscope manufacturer`s instructions. 10.6 The use of a load carrier specifically intended for the endoscope(s) to be processed is essential. 10.7 The channels of the endoscope should be connected to the appropriate nozzle on the load carrier to ensure the free passage of fluids through the lumens during processing. Selection of cycle variables 10.8 The cleaning stage should terminate with a rinse stage to remove any chemical agents used in cleaning which may be incompatible with the disinfectant to be subsequently used. 10.9 The automatic process should include means to ensure the removal of residual water which might dilute disinfectants Cycle monitoring 10.10 The WD should be equipped with means to provide independent monitoring of all critical cycle variables (see paragraph 9.25) 10.11 This should include means to verify that all channels to be irrigated with cleaning solution are not blocked. Product release 10.12 Before a product is released for use or further processing it should be visually inspected for cleanliness and dryness. When the process includes a chemical disinfection stage the attainment of the required conditions should be verified. OPERATIONAL MANAGEMENT 12.0 Liquid Chemical Disinfectors Introduction 12.1 Machines for the automatic disinfection of items by liquid chemical disinfectants are intended for use only on items previously subjected to a cleaning process. 12.2 The guidance offered in this chapter is equally applicable when the disinfection process is included in a single machine with the cleaning process. Safety precautions 12.3 Chemical disinfectants are potentially hazardous. Depending on the formulation they may cause irritation to the skin, eyes, respiratory tract and mucous membranes and may be volatile, flammable and corrosive. A risk assessment should be undertaken in accordance with the COSHH Regulations (see paragraph 3.14) 12.4 Staff training should include specific instruction on the procedures to be adopted in the event of equipment malfunction. Product compatibility 12.5 The compatibility of all materials and items to be processed should be established by reference to the manufacturer's instructions, or when necessary by appropriate training. 12.6 Factors to be considered in determining the compatibility of the load to the WD process include, but are no necessarily limited to: a. whether or not it can be immersed in aqueous solutions; b. the availability of an appropriate load carrier providing the necessary connection to all channels which require disinfection; c. the maximum operating temperature d. the internal pressure to which channels may be subjected e. the compatibility with the chemical disinfectants used. Load handling/presentation 12.7 Items to be processed should be: a. clean, to ensure that all internal channels are clear and that the activity of the disinfectant is not compromised by residual soiling; b. free from process residues from the cleaning process, eg detergent, which may inactivate the disinfectant; c. dry or free from significant surface moisture which would cause dilution of the disinfectant solution; d. verified as undamaged, eg by means of a leak test; e. disassembled to the extent necessary, eg with valves opened or demounted as recommended by the manufacturer; f. protected with any necessary closure to prevent the ingress of aqueous solutions into the wrong part of the equipment, eg videoscopes which are only immersible if the protective cap is in place; g. connected to the disinfector so as to ensure the passage of disinfectant through all channels. Selection of cycle variables and chemical agents 12.8 The activity of chemical disinfectants is time and temperature dependent. The temperature of the disinfectant should, therefore, be either thermostatically controlled or monitored during each cycle to ensure that it is within the temperature range validated during commissioning. 12.9 The exposure time should be controlled to ensure that the predetermined minimum exposure time has been attained. 12.10 As various disinfectant formulations differ considerably in their properties, the choice of disinfectant should be made in consultation with the manufacturers of the equipment to be disinfected, the disinfector and the disinfectant. Guidance on the properties of commonly used disinfectants is given in ‘Sterilization, disinfection and cleaning of medical equipment, guidance on decontamination from the microbiology Advisory Committee to the Department of Health Medical Devices Agency'. 12.11 The operating cycle must provide adequate rinsing after the chemical disinfection stage to ensure residues of the disinfectant have been reduced to a level at which they do not present a hazard to patients. 12.12 The quality of the final rinse water, especially microbial quality, and the means of ensuring that quality are important characteristics of the process if recontamination of disinfected items is to be avoided. The manufacturers instructions should be followed precisely. Cycle monitoring 12.13 For disinfectant solutions that are formulated for multiple or prolonged use the date of preparation and/or activation and the number of operating cycles run should be recorded. Whenever practicable the concentration of disinfectants intended for re-use should be monitored on a daily basis. 12.14 The WD should be equipped with means to provide independent monitoring of all cycle variables. 12.15 This should include means to verify that all channels to be irrigated with disinfectant solution are not blocked. 12.16 The disinfectant temperature and exposure time should be monitored for each cycle. 12.17 The means employed to maintain the quality of the final rinse water should be monitored in accordance with the manufacturer's instructions. Product release 12.18 Before a product is released for use or further processing it should be verified that the chemical disinfection stage was within the limits previously determined during commissioning. DESIGN CONSIDERATIONS 12.0 Washer-disinfectors for endoscopes Introduction 12.1 This chapter discusses specifications for WDs intended for cleaning and disinfection of flexible endoscopes (fibre-optic or video) and rigid endoscopes and their accessories. 12.2 The guidance given here assumes that the WD is to be used to decontaminate medical devices and that the essential requirements of the EU directives discussed in Chapter 1 must be met. 12.3 WDs for flexible fibre-optic endoscopes are all Type 1 machines; the form of the chamber is often complex and sculpted to provide appropriate support to the endoscope(s) being processed. WDs for rigid endoscopes may be Type 1 or Type 2 machines. 12.4 Disinfection may be achieved:
12.5 Automated WDs for endoscopes are preferred to manual cleaning, whether followed by a manual or automated disinfection procedure. This is both for the safety of the user and also because it provides a more consistent, validated process with a higher level of assurance of attaining the required standards than can be achieved with manual cleaning. Standard specifications 12.6 WDs for rigid endoscopes which can withstand thermal disinfection and steam sterilisation are similar to WDs for surgical instruments and associated equipment and should conform to the specifications in BS 2745: Part 1: 1993 and BS 2745: Part 3: 1993 and the safety specifications in BS EN 61010: Part 1. 12.7 An EU standard is in preparation for WDs for surgical instruments and associated equipment and for specific safety requirements for WDs. 12.8 There are currently no British Standards for WDs intended for use with thermo-labile endoscopes. An EU standard for WDs for thermo-labile equipment including fibre-optic endoscopes and videoscopes is in preparation. Additional specifications 12.9 WDs for endoscopes which employ a thermal disinfection stage should meet all the requirements specified for WDs for surgical instruments (see Chapter 10). WDs with a chemical disinfection stage 12.10 The WD should be an enclosed system. It should be a requirement for the lid to be locked before it is possible to start a cycle, and it should not be possible for the operator to interrupt a cycle before completion. 12.11 The control system should permit regulation of pump pressure and inlet pressure to the various connections to allow the WD to be adjusted for particular types of instrument. It is desirable that this should be a programmable option on the instrument controller. 12.12 The WD should discharge solutions of cleaning agents to drain after each operating cycle unless the WD is equipped with means to verify the concentration of the chemical additive which remains active in the solution. (For some cleaning agents this may be achieved by continuous monitoring of in-use concentration using an appropriate ion selective electrode (ISE). 12.13 The disinfectant solution should be used once and discarded. Alternatively, systems which re-use the disinfectant solutions for a number of cycles should incorporate a means to ensure the automatic cycle will not start when the disinfectant concentration has fallen to, or below, either the minimum recommended by the manufacturer or established independent testing – eg for a 2% solution of glutaraldehyde a limiting concentration of 1.5% would be recommended (Babb et al 1992). 12.14 The rinsing stage should be carried out with water of a suitable quality that does not lead to recontamination of the endoscope with micro-organisms coming from the incoming water supply reservoirs, including pipework within the machine. 12.15 The rinse water from one process should not be retained and used in subsequent cycles but should be discharged to drain. 12.16 There should be no static water stored within the WD at a temperature above 10C or below 55C for more than four hours if it is intended to come into contact with the load. This should be controlled and monitored by the automatic controller of the WD. 12.17 WDs should be designed and constructed such that they are able to be drained and dried when not in use. 12.18 The available operating cycles on the automatic control system should provide for a WD decontamination cycle to ensure that all pipework, tanks, pumps, water filtration systems and other fittings which are used to carry aqueous solutions intended to come into direct contact with the product are cleaned and disinfected. The decontamination cycle shall be user selectable. 12.19 The automatic controller should control the temperature of the disinfectant solution or monitor the temperature to ensure that it is above a value previously determined during validation studies (see HTM 2030 ‘Validation and verification' for more information). 12.20 The WD should be equipped with a recorder or data logger to record the attainment of the specified value of critical cycle variables throughout the cycle. 12.21 The WD should be equipped with means to contain or vent fumes and gases from the disinfectant solution to ensure that operators are not exposed to hazardous concentrations of the chemicals used. The WD should be provided with means to vent fumes from the chamber before allowing access to the operator. Load Handling Equipment 12.22 The loading system should be appropriate to the range of endoscopes which it is intended to process. 12.23 Some endoscopes are not designed to be completely immersed in liquid and the operating head must remain above the liquid level. 12.24 The load carrier needs to provide connections to the various channels within the endoscope to allow the cleaning and disinfection solutions to flow through the channels and may need to provide holders for disassembled components, valves etc. Compatibility with items to be processed 12.25 Attention is drawn to the need to ensure that for any particular load item that all cleaning and decontamination processes are carried out in strict accordance with the manufacturers instructions. All endoscopes, but particularly those incorporating fibre-optic systems, are easily damaged. 12.26 If the process conditions recommended by the manufacturer, including maximum temperatures, internal pressures, nature of any physical treatment such as ultrasonication, and limitations on the chemical additives which may be used, are ignored serious damage can be caused to these expensive instruments. Disinfection requirements 12.27 The standard of disinfection required should be defined by the user in consultation with the control of infection officer. 12.28 In general: endoscopes which, in use, are passed into sterile body cavities are considered to be invasive and must be sterilized; endoscopes which, in use, come into contact with mucous membranes but do not invade sterile body cavities are non-invasive and can be decontaminated using high-level disinfection. 12.29 The choice of disinfectant should be based on the rigours of the disinfection procedure required, and on the compatibility with the endoscope and WD and the constructional materials of both. Rinse water: quality requirements 12.30 For invasive endoscopes the final rinse water should be sterile and for non-invasive endoscopes it is preferable that it is sterile. 12.31 The most reliable method of providing water of the quality required for the final rinse is to use “bottled” sterile water. 12.32 Alternatively it is possible to produce water of appropriate quality by treatment of the local piped water supply. This may be provided adjacent to or within, the WD. 12.33 The nature and extent of treatment will depend in part on the quality of the local water supply but normally should include at least the following steps:
The operating system should include:
12.34 The design of the pipework, tanks, valves and pumps to avoid dead legs and areas where microbial growth may proliferate is critical to the maintenance of the system from microbial contamination. All fittings and pipe connections should be pharmaceutical grade sanitary fittings. Operating cycle requirements 12.35 The following operating cycle presents a general specification which may need to be adapted for particular instruments. It assumes that immediately after use, and before transfer to decontamination, the insertion tube will have to be wiped clean and that all channels will have been flushed through to remove gross contamination and ensure that they are free from blockages. 12.36 It is also assumed that any manual dismantling required (including removal of single use items, separation of accessories, removal of valves and covers, and disassembly) has taken place before the instruments are placed into the WD. 12.37 The operating cycle should include:
The efficacy of chemical cleaning agents (detergents and enzymic cleaners) is affected by concentration, temperature, contact time and the presence or absence of materials/chemicals which will react with, and therefore inactivate, the chemical cleaning agent. The WD should provide means to control all these factors to the extent necessary to obtain satisfactory and reproducible cleaning. For most rigid endoscopes ultrasonication may be used except for the telescope; ultrasonication generally is not suitable for use with optical of fibre-optic systems. The pressure at which fluids are pumped through the internal channels of the endoscope should be controlled and maintained within the limits specified by the endoscope manufacturer.
The efficacy of chemical disinfectants is affected by concentration, temperature, contact time and the presence or absence of materials/chemicals which will react with, and therefore inactivate, the disinfectant. The WD should provide means to control all these factors to the extent necessary to obtain satisfactory and reproducible disinfection;
Drying stage 12.38 Drying may be achieved by purging with heated dry air; means should be provided to ensure the temperature of the endoscope is not raised above the maximum specified by the endoscope manufacturer. The quality of air used should not contribute to physical, chemical or microbial recontamination of the decontaminated item. 12.39 Drying may also be accomplished by purging the decontaminated item with 70% alcohol and allowing this to evaporate. The quality of the alcohol used should not contribute to physical, chemical or microbial recontamination of the decontaminated item. In particular spore-free alcohol should be used. Decontamination of the washer-disinfector 12.40 Automatic WD's for endoscopes may themselves act as a source of contamination for the decontaminated items. 12.41 The design, installation and operation of the WD, including the quality of connected services, may contribute to the problem. 12.42 The WD should include a flushing stage for the WD pipework after each cleaning cycle to remove dislodged debris, biofilm etc so that these cannot initiate a problem. 12.43 All tanks used for the storage of water or aqueous solutions should be designed and constructed to ensure that they are free draining and cleanable. (The use of hard water, water of inadequate microbiological quality or water stored at ambient temperatures for prolonged periods will promote contamination and the formation of biofilms within the machine) 12.44 The use of soft water can help alleviate this problem but it should be noted that base exchange softeners, and also de-ionisers, may themselves be a source of microbial contamination and can lead to high microbial counts of water borne organisms. These organisms are typically of species adapted to develop biofilms and the extra cellular layers present in these biofilms provide good protection against microbicides. 12.45 Microbial colonisation of pipework may occur if the system is not disinfected regularly or if there is inappropriate cleaning and maintenance of the machine. 12.46 The WD manufacturer should provide information on cleaning and disinfection procedures and compatible chemicals for these purposes. Requirements for the control of disinfection stage 12.47 The chemical disinfection system must:
Instrumentation/recorders 12.48 The extent of necessary monitoring depends on the particular application. As a minimum for the thermal disinfection stage the attainment of the required temperature should be monitored independently of the cycle controller, displayed on a temperature indicator or recorder, and recorded. 12.49 When the WD is to be used to decontaminate medical devices and the technical Standards described in the essential requirements of the EU Directives discussed in Chapter 1 must be met additional monitoring facilities will be required. 12.50 The WD should be equipped with monitoring and recording devices to monitor the pump pressure (or water flow) and temperature at each process stage, the flow or volume admitted of each chemical additive used (or, when applicable, by direct measurement of the concentration), the chemical purity of the final rinse (by measurement of electrical conductivity), and the flow and temperature of the hot air used for drying. Test Connections 12.51 Test connections should be provided to permit the connection of thermocouples to be used during validation and periodic testing. 12.52 When additional monitoring is provided (see above) a separate test connection should be provided for each sensor to permit periodic verification of calibration of the installed system by comparison with a calibrated test sensor. |
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