HTM01-05 is a wide-ranging document which attempts to cover all aspects of infection control, and it can

present challenges to the dental practice when attempting to implement all of its recommended procedures.

It is the intention of this article to outline some of the more important testing and validation that should be carried out to ensure decontamination equipment is functioning properly, can conform to the required standards and that the required data can be properly recorded by dental teams.

Technology also plays its part in monitoring the performance of dental equipment through

the integration of intelligent microprocessors that can ‘self-monitor’ certain units. However, whilst these off er advantages, they can still be prone to failure, putting patients and staff at risk of infection. It is therefore recommended that a series of routine tests be carried out by the operator to ensure that the equipment performs safely and eff ectively. Table 1

shows an example of such a routine, with daily, weekly, monthly and annual tests for a SciCan Hydrim C51WD instrument washer disinfector.

EQUIpMENT TESTSAutoclaves are common to every practice and are subjected to rigorous use. It is essential that

Carmel Maher is a fully-trained infection control advisor and has worked with dental practice teams for over seven years. She has a wealth of knowledge covering virtually all aspects of infection control and runs courses on behalf of Optident.

Carmel Maher’s series on infection control for the dental team turns to testing and validation of decontamination equipment in the practice

INfECTION CONTROLTESTING AND VALIDATION REQUIREMENTS

TEAMfOCUS

ppD January 2012 95

TABLE 1: RECOMMENDED ROUTINE MAINTENANCE pROTOCOL – C51WD & M2 INLINE WITH MANUfACTURER RECOMMENDATIONS

DailyCheck door locks

Clean strainers and mesh fi lters Check rotation of wash arms Check door seal Load carrier check Visual examination of load items

WeeklyIncluding daily checks, plus:Residual protein test

MonthlyIncluding weekly checks, plusResidual soil test

AnnuallyIncluding monthly checks, plus Annual service Annual calibration check Annual revalidation

CP(D): Competent person (Decontamination)

i. Ensure a cycle cannot be started with the door openii. Ensure the door cannot be opened during operationi. Remove strainer and mesh fi lter. Wash under cold tapi. Check upper and lower wash arms move freelyi. Check door seals for leaks during operationi. Check alignment of load carriersi. Visual examination of load under magnifi cation

i. Using a suitable protein test method

i. Using a suitable soil test method

i. Replace parts as per SciCan annual service recommendationsi. Calibration check of time and temperaturei. Automatic control testii. Chemical dosing testiii. Residual protein testiv. Cleaning effi cacy test v. Thermometric test – disinfection cycle vi. Safety checks

User / Operator

User / Operator User / Operator User / Operator User / Operator User / Operator

User / Operator

User / Operator

CP(D)/Service engineerCP(D)/Service engineerCP(D)/Service engineer

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certain checks be made to ensure their function is correct and consistent.

The steam penetration test was developed to test the steam penetration capability of sterilisers designed to reprocess hollow loads (B and S types), and should be performed at the start of each working day.

Certain test methods may be specific to individual units and HTM01-05 does not explain that different manufacturers may vary in their advice to both servicing and testing. It is vital, therefore, for users of equipment to become familiar with appropriate recommendations from the relevant manufacturers.

An example of a specific steam penetration test as recommended by a manufacturer can be shown for the SciCan Statim G4 2000 and G4 5000 autoclave (Figure 1). The manufacturer specifically recommends that this be carried out with a helix device known as SciCan S Class Process Challenge Device (PCD), and it further states that no other steam penetration test is compatible with these units.

An alternative test method for steam penetration, which can be applied to some other manufacturers’ autoclaves, is the Bowie Dick pack. It is made up from layered sheets, in the centre of which will be found a test emulator. The test will be considered successful if, after completion of the appropriate test cycle, the test emulator has completely changed colour. This is particularly useful for sterilisers that are used to reprocess porous loads.

Air leakage test (user/operator), is a method of testing the rate at which air leaks into the steriliser chamber during the vacuum phase

of a sterilising cycle. It can only be made if the equipment concerned is fitted with an appropriate test cycle. On completing the appropriate test cycle the unit will indicate a pass or fail result.

AUTOMATIC CONTROL TESTIt is vital with any decontamination equipment that records are made and checked regularly, to ensure that the values shown on the unit display, or recorded by any printer or data-logger fitted to the equipment, are within known limits. At certain intervals during the critical phase of an operating cycle (sterilising, washing, disinfecting phases); a record should be made of the elapsed time, temperature and pressure (where applicable). These recorded values should be compared on a regular basis against values which have already been established as giving satisfactory result, either by the equipment manufacturer or previous validation tests.

RESIDUAL pROTEIN TESTThis test is one of the most critical and is intended for a washer-disinfector (such as shown in Figure 2) and ultrasonic cleaners. In this test, instrument swabs are used to test for traces of proteins that may not be visible to the naked eye.

On completion of a normal operating cycle, one of the load items should be selected for testing. The instrument swab is rubbed over an area and placed in a vial that contains a special reagent. It is then incubated

for a set time at a set temperature. Following incubation the swab will develop in colour indicating a pass or fail result.

RESIDUAL SOIL TESTThis test will determine cleaning efficacy. It is a method of checking that the washer-disinfector or ultrasonic cleaner is effectively removing soils. This test is not listed in HTM01-05 as a user/operator test. Many manufacturers do, however, recommend that the user/operator does this test and thus, reduce the need for quarterly engineer visits.

There are various tests available, but usually consist of a holder, designed to replicate a process challenge into which a test slide is placed. The slide will contain traces of replica soils, and after following a normal operating cycle the test slide should be removed from the holder and visually checked for any traces of soil. If all traces of soil are removed, this will indicate a successful test.

ULTRASONIC ACTIVITY TESTThis test is designed to test the ultrasonic

96 January 2012 ppD

Figure 1: SciCan G4 Statim autoclave Figure 2: SciCan C51WD washer-disinfector

Figure 3: Optident infection control manual

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ppd

To ask a question or comment on this article please send an email to: comments@ppdentistry.com

Contact Optident on:Tel: 01943 605050www.optident.co.uk

TEAMfOCUS

activity of an ultrasonic cleaner and ensure that it produces consistent results. Although not listed in HTM01-05 as a user/operator test, some manufacturers may recommend the user/operator perform this test, to reduce the need for quarterly engineer visits. Two common methods for testing ultrasonic activity are the use of aluminium test foil or an ultrasonic activity meter.

Aluminium test foil is prepared and distributed in predetermined areas of the ultrasonic chamber and allowed to run through a normal operating cycle. Following the test cycle the foils are removed, dried and the erosion pattern that has developed is compared to other foils used to perform the test. A uniform pattern throughout all the test foils indicates a pass result.

The same principle also applies to the use

of an ultrasonic activity meter; in that each reading that is taken from a predetermined position within the chamber is logged and compared to each other for consistency.

pERIODIC TESTING AND SERVICINGUsers must be aware of the need to carry out periodic validation tests, and these should be carried out by a suitably trained test person or service engineer.

Manufacturers and suppliers can prove to be invaluable when seeking advice as to the differing requirements for decontamination equipment, and wherever possible equipment service intervals should be strictly adhered to.

Those staff involved in the use, testing, validation and recording of test data relative to autoclaves, washer-disinfectors and ultrasonic cleaners will also find much

practical advice and guidance by referring to Optident’s comprehensive infection control manual (Figure 3).

Next month: handpiece care and maintainance

ppD January 2012 97

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