White Paper

Validation Protocols for Low-Temperature Sterilisation in Dental and Day Surgery Clinics

August 2025

Disclaimer

This content is provided for information only. The authors make no representation or warranty regarding the accuracy, completeness or currency of the content. No information in this whitepaper should be construed as medical advice. Readers should seek appropriate professional guidance before acting on any information contained in this document. The authors expressly disclaim all liability for any direct or indirect loss or damage arising from the use of or reliance on this information.

Introduction

Effective sterilisation of medical instruments is critical for patient safety in dental practices and day surgery clinics. Low-temperature sterilisation technologies are used for heat- and moisture-sensitive instruments that cannot withstand steam autoclaving. This whitepaper focuses on three common low-temperature methods, hydrogen peroxide gas plasma, ethylene oxide (EO), and ozone-based sterilisation systems, outlining how to validate and monitor these processes in accordance with Australian standards. Australian Standard AS 5369:2023 which replaced AS/NZS 4187:2014 provides the overarching framework for reprocessing reusable medical devices in both hospital and office-based healthcare settings. Where specific local guidance is lacking, relevant international standards such as ISO 14937, ISO 11135, and ISO 22441 are referenced for best practices. The target audience for this document is clinical managers and sterilisation technicians, and the guidance herein addresses both technical and clinical aspects of sterilisation validation.

Scope

We cover comprehensive validation protocols including Installation Qualification (IQ), Operational Qualification (OQ), and Performance Qualification (PQ) for each low-temperature steriliser. We also detail routine performance indicators for ongoing validation, recommended maintenance schedules, and best practices to ensure continued compliance and sterilisation efficacy. Throughout, narrative guidance and operational insights are provided, and key points are summarised as checklist-style items for practical use.

Overview of Low-Temperature Sterilisation Technologies

Hydrogen Peroxide Gas Plasma Sterilisation

Hydrogen peroxide gas plasma (HPGP) sterilisation uses vaporised hydrogen peroxide (H2O2) excited by radiofrequency energy to create a plasma state that kills microorganisms at low temperatures typically ~50°C. The process leaves no toxic residues, as H2O2 breaks down into water and oxygen. HPGP cycles are relatively fast often ~45 to 75 minutes and are suitable for heat-sensitive instruments including plastic or electronic devices. However, there are important material and packaging considerations: cellulose-based materials such as paper and cotton that cannot be processed, because cellulose absorbs peroxide and can condense it back to liquid form. Paper products e.g. standard autoclave paper/plastic pouches and cotton textiles are contraindicated for HPGP; they will impair the process and may leave caustic peroxide residues. Instead, special pouches or wraps (medical-grade synthetic material) must be used for packaging, as they are permeable to hydrogen peroxide vapour but non-absorptive. Instruments must be thoroughly dried after cleaning, since any residual moisture can interfere with the plasma sterilant. HPGP sterilisation is gentle on most medical devices, but it cannot penetrate long narrow lumens unless specifically validated and devices with fine long lumens may require alternative methods or special adaptors.

From a clinical perspective, HPGP offers rapid turnaround with no post-sterilisation aeration required, making it convenient for day clinics. Staff safety is high because the sterilant is contained and converted to harmless substances by the end of the cycle. Nevertheless, strict adherence to manufacturer’s instructions is required for loading configuration and compatible materials. Any visible moisture or liquid left on instruments or in packs after a cycle indicates a problem, it could be residual hydrogen peroxide, which must be avoided due to risk of chemical burns on skin or mucosa. Thus, part of routine protocol is to inspect each package for dryness and integrity before releasing items for use.

Ethylene Oxide Sterilisation

Ethylene oxide sterilisation is a well-established low-temperature sterilisation method that employs EO gas, commonly at 37 to 55 °C to alkylate microbial DNA, resulting in death of all microorganisms including spores. EO has high penetrating ability, making it suitable for complex devices with long lumens, multi-layered packaging, or delicate components that steam or H O2 cannot effectively reach. It is often considered the “method of last resort” for heat-sensitive items that cannot be sterilised by other means. In practice, modern EO steriliser units for healthcare use a sealed chamber where air is evacuated, humidity may be added to enhance EO efficacy, and a measured dose of EO gas as pure or EO blended with CO2 or other diluent is introduced. After exposure, an essential aeration phase is included, either within the steriliser or in a separate aeration cabinet to allow EO gas desorption from the materials. Aeration can take many hours and is critical because EO is toxic and irritant; any residual gas or its by-products e.g. ethylene glycol if EO contacts water must be reduced to safe levels before instruments are used on patients. Australian guidelines emphasise that only sterilisers registered on the Australian Register of Therapeutic Goods should be used, and older uncertified EO units should be retired. EO sterilisation in clinic settings often requires dedicated infrastructure such as ventilation systems for exhaust gas, abators or scrubbers to remove EO from emissions, gas leak detectors, etc. due to occupational health regulations. It is generally less common in dental offices or small day clinics, used only if absolutely necessary, because of its cost, cycle time, and safety requirements. Some day surgery centers opt to outsource EO sterilisation or use it sparingly for items that cannot withstand any other process.

From a clinical and operational standpoint, EO sterilisation demands careful handling and documentation. Staff must be trained in EO safety, for example, wearing appropriate PPE when changing gas cartridges or when unloading items that may off-gas. Devices must be cleaned and fully dried before EO sterilisation as any water or moisture can react with EO to form harmful residues. After sterilisation, items often need prolonged aeration e.g. 8 to 12 hours or per manufacturer specifications to reduce EO residuals to acceptable levels typically per ISO 10993-7 limits. The steriliser load configuration should avoid sealing EO-impermeable materials inside containment that would hinder gas penetration or exhaust. In summary, EO is a powerful sterilant for complex tasks, but it requires stringent validation and monitoring to ensure effectiveness and safety.

Ozone-Based Sterilisation Systems

Ozone (O3) gas is a strong oxidising agent that can be used for low-temperature sterilisation. Ozone-based sterilisation systems such as the TSO3 125L system, among others, typically generate ozone from medical-grade oxygen within a sealed chamber. The cycle usually operates at ~30 to 40 °C. A typical ozone sterilisation cycle includes an initial vacuum and humidification since moisture enhances ozone’s microbial kill, injection of ozone gas, exposure phase, and then conversion of ozone back into oxygen at cycle end. Like H2O2, ozone sterilisation leaves no harmful residue, ozone naturally decomposes to oxygen. This makes it attractive from an environmental and safety perspective due to no handling of toxic chemicals post-cycle. Ozone is effective against a broad spectrum of microorganisms. Its microbicidal efficacy in a validated process can achieve a sterility assurance level of 10^−6 (SAL 6) by demonstrating lethality against highly resistant spores such as Geobacillus stearothermophilus, per ISO 14937 requirements. Ozone sterilisation is generally suitable for many plastics, metals, and rubbers that are compatible with oxidation. However, like other oxidative methods, it may have material limitations: certain polymers or coatings could degrade after repeated ozone exposure, and natural rubber or latex may become brittle. Manufacturers of ozone sterilisers provide compatibility data, and it is essential to ensure that instruments and packaging are validated for ozone exposure. Packaging for ozone sterilisation must allow gas penetration, usually oxygen-permeable wrappers or containers are used. Some systems may recommend plastic pouches or specially approved packaging similar to HPGP requirements, since ozone, like peroxide, should not be excessively absorbed by cellulose-based materials which could inhibit effective concentration of the gas. Users should consult the steriliser manufacturer for approved packaging materials and load methods e.g. some ozone units use special instrument trays to maximize gas circulation.

Clinically, ozone sterilisation is an emerging technology. It offers an alternative for low-temperature processing without toxic residues, but adoption in Australian clinics has been limited. Where used, it must be accompanied by robust validation because it is a newer modality. Turnaround times are moderate (some cycles ~4 to 6 hours including built-in aeration phases, so operational planning is needed to ensure instrument availability. Staff using ozone systems must be trained on specific safety features, while ozone in-cycle is contained, any leaks could be harmful as ozone is a respiratory irritant. Typically, ozone sterilisers include catalytic converters that destroy ozone to oxygen before chamber opening; periodic maintenance of these converters is crucial to safe operation. Overall, ozone technology can be safe and efficacious if validated and maintained properly, serving as a complementary option to H2O2 and EO for sensitive equipment.

Standards and Compliance Framework in Australia

Australian sterilisation standards provide the foundation for validation protocols. The primary standard is AS 5369:2023, reprocessing of reusable medical devices and other devices in health and non-health-related facilities, which updated and replaced the older AS/NZS 4187:2014. AS 5369 harmonises requirements across hospitals, day surgeries, and office-based practices, superseding the separate AS/NZS 4815 that previously applied to office-based clinics. This standard outlines the expected practices for cleaning, disinfection, sterilisation, and maintenance of the reprocessing environment, with specific clauses for different sterilisation methods. It emphasizes the need for a validated process for any sterilisation method used, meaning the process must be proven to consistently achieve the requisite sterility assurance level and be properly controlled and monitored.

For low-temperature sterilisation modalities: AS/NZS 4187:2014 and by extension AS 5369:2023 aligned with international benchmarks. For example, the standard referenced ISO 11135 for ethylene oxide process validation and acknowledged ISO 14937 as the general standard for validating new sterilisation processes applicable to hydrogen peroxide, ozone, and other novel methods. ISO 14937:2009 is often used when no method-specific standard exists; it provides a framework for demonstrating that a sterilisation process reliably achieves a 10^−6 SAL, identifies the most-resistant organism, and defines process parameters and routine control requirements. In fact, manufacturers of hydrogen peroxide plasma sterilisers have incorporated ISO 14937 requirements into their validation, ensuring that biological and chemical indicators for HPGP are appropriately resistant and effective.

When Australian standards do not spell out detailed protocols for a specific technology for instance, ozone sterilisation is relatively new and may not have a dedicated local standard, international standards can be used for guidance. ISO 22441:2022, for example, provides requirements for development, validation, and routine control of vapour hydrogen peroxide sterilisation processes, and ISO 11135:2014 provides analogous guidance for ethylene oxide processes. These standards are recognised in Australia and can be referenced to satisfy validation best practices. It is important to note that local regulatory bodies e.g. the TGA and state health workplace safety regulators also impose requirements: EO sterilisers and certain ozone or plasma devices must be registered medical devices, and installation might require compliance with gas safety regulations. However, the focus of this document is on clinical and technical validation rather than regulatory approval. Clinical managers should ensure that their sterilisation equipment is certified and that reprocessing policies follow the Australian Guidelines for the Prevention and Control of Infection in Healthcare as well as AS 5369 standards. In summary, Australian standards demand thorough validation and routine monitoring of all sterilisation processes to assure patient safety, with international standards providing additional detail where necessary.

Qualification Testing: Installation, Operational, and Performance Qualification

Validating a steriliser in a clinic begins with formal qualification testing to prove that the equipment will perform to the required standard in its actual use setting. This is usually divided into three stages:

Installation Qualification (IQ): Verifies that the steriliser and its supporting systems are correctly installed in accordance with manufacturer specifications and relevant codes.

Operational Qualification (OQ): Confirms that the steriliser operates properly through its intended range of functions and achieves the predefined operating parameters under test conditions.

Performance Qualification (PQ): Demonstrates that the sterilisation process effectively sterilises instruments in real-world conditions, consistently achieving the required performance typically SAL 10^−6 in actual loads.

Each stage should be documented with test results and evidence. Below we detail the protocols and considerations for each qualification phase, specifically tailored to hydrogen peroxide plasma, EO, and ozone sterilisers.

Installation Qualification (IQ)

IQ involves obtaining and recording evidence that the steriliser’s installation meets design and safety requirements. This starts with the site preparation: the steriliser must be located in a suitable environment e.g. adequate ventilation, appropriate room size and layout, and necessary utility connections. For EO sterilisers, IQ is particularly critical, one must verify that ventilation/exhaust systems are in place and functional for example, an EO unit should be vented to the outside or connected to an approved abatement system to manage toxic emissions. The electrical supply, compressed air, or water supply if required for humidity generation or vacuum pumps should be checked against the manufacturer’s specs such as correct voltage, pressure, flow rates, etc. It is also important to ensure any ancillary devices like gas cylinder hookups for EO or drains for condensate in certain systems are installed correctly. Safety features are checked at installation: for instance, door interlock mechanisms, emergency stop functions, and alarms like an EO leak detector should be verified. Documentation to gather during IQ includes the steriliser’s model and serial number, calibration certificates for its sensors if provided, and that the Australian Register of Therapeutic Goods (ARTG) registration is in place for the model as Australian regulations require using only ARTG-listed sterilisers in practice. Additionally, IQ should confirm that all required operational manuals, diagrams, and maintenance schedules have been supplied, and that staff training on basic operation and safety has been completed.

Checklist for Installation Qualification (IQ):

  • Site and Utility Verification: Ensure the steriliser is installed in accordance with manufacturer’s site requirements: correct power supply (voltage/amperage), ventilation ducts or room exhaust especially for EO, gas supply connections for EO or ozone generators if external oxygen is needed, and environmental conditions such as temperature/humidity of room within acceptable range.
  • Physical Installation Check: Verify the unit is level, anchored if required, and that door seals and gaskets are properly in place. Confirm any required water supply or drainage is connected and functioning as some ozone or plasma units require water for humidity or vacuum pump seal.
  • Safety Systems: Test that alarms and interlocks function. For example, attempt a cycle start with the door open to confirm the steriliser does not start; trigger any emergency stop to ensure the cycle aborts safely. If an EO monitor or ambient sensor is installed, test its operation.
  • Documentation and Training: Record the steriliser identification details and ARTG listing. Ensure the operator’s manual, validation protocols, and maintenance instructions are available on-site. Document that personnel have been briefed on basic operation and safety precautions especially handling of sterilant cartridges for H2O2 or EO.
  • IQ Sign-off: The installation should be reviewed by a qualified technician or engineer, and a formal sign-off obtained to indicate that the steriliser is correctly installed and ready for operational testing.

Operational Qualification (OQ)

OQ is the process of testing the steriliser to confirm it operates within its intended limits and controls in the empty or test-load condition. In this phase, the steriliser is run through its cycles under controlled conditions while measuring performance parameters. Initially, calibration of the unit’s sensors such as temperature probes, pressure transducers, gas concentration monitors, humidity sensors, etc. is verified, this may be done by the manufacturer’s service engineer using calibrated test instruments. Australian guidance stresses that all steriliser monitoring instruments must be accurate; routine maintenance includes calibration checks because reliable readings are fundamental to assurance of sterility.

During OQ, one would typically execute a series of test cycles, such as:

  • Empty Chamber Cycles: Run the steriliser empty through a complete cycle or each cycle type, if multiple programs to observe that it achieves the set parameters e.g. target pressure levels, exposure time, gas injection volume. Independent data loggers or wired thermocouples and pressure gauges can be placed to verify chamber conditions if required. The steriliser’s own printout should be checked for each cycle to confirm that all phases such as evacuation, sterilant injection, exposure, aeration, etc. reach the expected values.
  • Loaded Test Cycles (Operational Tests): It may be useful to run cycles with a typical load or a maximum load without biological indicators at this stage to see that the steriliser can handle a full load. For instance, a H2O2 plasma steriliser might be tested with a load that approaches its maximum recommended weight or density to ensure the plasma is still generated properly and no cycle aborts. For EO, a test load might include a lot of packaging to simulate a worst-case for outgassing, ensuring the aeration phase is sufficient.

Key OQ tests also include challenging the controls and fail-safes: for example, intentionally set a cycle parameter slightly out of spec to see if the machine aborts or alarms, this might be done by the manufacturer’s technician in a controlled way. OQ should confirm that the steriliser’s software and sensors detect faults like failure to reach vacuum level, or too low gas concentration and respond appropriately e.g. alarm and cancel the cycle.

All outcomes are recorded. If any parameter falls outside the specified range, adjustments or repairs are needed before proceeding to performance qualification. It’s recommended to involve the steriliser supplier or a validation expert during OQ, as they have the tools to adjust sensor calibrations or cycle parameters if needed. By the end of OQ, you should have evidence that the machine consistently achieves the operational parameters it is supposed to, under normal and some stress conditions. As an example, the OQ for a hydrogen peroxide plasma unit might show that in 3 consecutive empty cycles, the chamber pressure, vaporisation of peroxide, plasma phase, and endpoint vacuum all meet the manufacturer’s cycle specifications with printouts saved as proof. OQ also covers verifying that monitoring devices are in place, e.g. the printer or electronic record system is working and capturing data each cycle, since this is critical for ongoing monitoring.

Checklist for Operational Qualification (OQ):

  • Calibration Check: Verify all measuring instruments such as temperature, pressure, gas concentration read accurately. If not recently calibrated, have a technician perform calibration. Document the date and results.
  • Empty Cycle Tests: Run at least one full cycle for each program to ensure the cycle completes successfully and hits all set-points. Review the cycle printout data or digital logs for compliance with the cycle recipe e.g. for EO: did the chamber reach the target 600 mbar vacuum and hold for the correct dwell, was the correct EO exposure time maintained, etc..
  • Challenge Conditions: Simulate power failure or emergency stop to see that the steriliser handles it safely e.g. aborts cycle and alarms. If possible, test the high/low limits for instance, if the steriliser has a temperature range, confirm it alarms if temperature deviates beyond allowed range.
  • Partial Load Test (if applicable): Some validation protocols include testing a minimal load and a maximal load to ensure the sterilisation cycle can accommodate both extremes. If manufacturer guidance exists for a test pack or validation load, use it during OQ this overlaps with PQ but can start in OQ phase to troubleshoot any issues early.
  • Record Outputs: Ensure the cycle monitoring devices such as printer or USB data logger correctly record each cycle’s details. Check that alarm signals (visible/audible) function and that any electronic integration e.g. cycle data to a computer system is working.
  • OQ Acceptance: Define the acceptance criteria, often given by the steriliser manufacturer or standards and verify all criteria are met. For example: “Vacuum level shall reach at least 20 kPa within X minutes” and check the data against this. Once all criteria are satisfied in consecutive tests, document OQ completion.

Performance Qualification (PQ)

Performance Qualification provides the ultimate proof that instruments as processed will be sterile consistently. It involves challenging the steriliser with actual instrument loads, especially worst-case loads using biological and chemical indicators to verify effective sterilisation. PQ should be done after successful IQ and OQ, and typically consists of multiple cycles to ensure repeatability.

A common approach to PQ is the use of process challenge devices (PCDs) or worst-case test packs that simulate the most difficult item to sterilise in routine loads. For example:

  • In a hydrogen peroxide plasma steriliser, a PCD might be a long narrow lumen device or a specially designed helix test device containing a biological indicator at the end, which tests the plasma’s ability to penetrate a long channel. Use of a helix PCD for HPGP is generally optional and guided by the manufacturer. If the clinic will be processing lumen instruments near the limits of the steriliser’s claimed capability, a lumen PCD is highly recommended during PQ to validate that such items can be sterilised reliably.
  • For EO sterilisation, a typical worst-case load could be a full chamber of instruments with one or more biological indicator test packs placed in the load. Often, a BI test pack for EO might consist of a bacterial spore strip or self-contained BI placed inside a folded surgical towel or within a plastic cassette, wrapped to represent a challenging location for gas penetration. According to AS/NZS 4187, every EO cycle is supposed to include a biological indicator to monitor success, during PQ this is strictly followed and multiple BIs are used.
  • For ozone, one would similarly include biological indicators at hard-to-sterilise locations in the load for instance, inside the lumens of any instruments if applicable, or in the centre of dense sets. Because ozone sterilisation efficacy is dose-dependent, PQ helps confirm that the required ozone dose (concentration × time) reaches all parts of the load.

Biological indicators (BIs) used should be those specified for the process, typically Geobacillus stearothermophilus spores for hydrogen peroxide, ozone, and steam processes since these spores are very resistant to these modalities, and Bacillus atrophaeus spores for EO as they are EO-resistant. It is essential to use BIs labeled for the specific process and do not use steam BI strips to test a plasma load, for example. Also use chemical indicators (CIs) inside packs to verify exposure; for PQ, class 4 to 6 multivariable CIs or integrators can be placed alongside the BIs to give an immediate readout of conditions until the BI results are available.

During PQ, run the steriliser with the instrument load and indicators in place. Upon cycle completion, you will examine the chemical indicators for proper color change and incubate the biological indicators or use rapid-read BIs if available to detect any growth. A successful PQ typically requires no growth in any biological indicators across a series of test cycles, demonstrating at least a 10^−6 sterility assurance level. Many validation protocols call for three consecutive successful cycles with full test loads to confirm consistency. All cycle physical data should be recorded as well to ensure the printouts show that each cycle met time, temperature, and other parameter targets. If any cycle in PQ yields a BI failure (growth), or a critical parameter was out of tolerance, the cause must be investigated and the issue resolved, then PQ trials repeated. Possible adjustments could include altering load configuration, extending exposure time if allowable, servicing the machine, etc. but any change would likely require re-running IQ/OQ or manufacturer involvement if the preset cycle cannot be altered by users.

Acceptance criteria should be predefined. For example: “In three PQ cycles with the maximum intended load, all biological indicators must be inactivated (no growth), all class 5 integrating chemical indicators must show a pass result, and all physical cycle parameters must remain within the validated range. Packaging integrity must remain intact with no evidence of wetness or chemical residual.” These criteria ensure not only microbial kill but also that the items are safe to use with no toxic remnants. In the case of EO, PQ might also include checking that residual gas levels fall below certain thresholds after aeration as some validation protocols in manufacturing measure EO residue on or in devices. In a clinic setting, one might simply note that there is no strong EO odor after aeration and rely on the established cycle aeration time validated by the manufacturer for residual removal.

All findings of the PQ should be documented in a validation report. This report should be approved by a qualified person e.g. sterilising department manager or a validation specialist before the steriliser is released for routine use. The validation documentation is typically retained for the life of the equipment and is critical in audits or if any issues arise later.

Checklist for Performance Qualification (PQ):

  • Worst-Case Load Identification: Determine the most challenging items or fullest load that will be processed. Include items that represent maximum load density, longest lumens, or heavy bioburden scenarios if applicable. Assemble test loads that simulate these challenges.
  • Biological Indicators Placement: Place BIs in the hardest-to-sterilise locations e.g. inside lumens, inside the center of wrapped sets, or in corners of the chamber if indicated). Use process-appropriate Geobacillus or Bacillus spore indicators with a high population , up to 10^6 spores per unit is standard. For EO, ensure at least one BI is included in every cycle during PQ mirroring routine requirements.
  • Chemical Indicators and PCDs: Distribute CIs e.g. internal chemical indicator strips inside packs next to BIs. Use external chemical indicator tape or labels on every pack to verify it has been exposed to the process. If using any PCD, e.g. lumen test device or challenge pack, include it in the load as well, as per manufacturer recommendations.
  • Number of Cycles: Run at least three consecutive test cycles for each type of load being qualified. Do not alter the load or cycle parameters between these runs. This repetition verifies consistency.
  • Post-Cycle Assessment: After each cycle, check that the printout shows all phases executed correctly with no errors or deviations. Examine all chemical indicators, external indicators should have changed color uniformly; internal integrators or multi-parameter CIs should indicate that sterilising conditions were met inside packs.
  • Biological Indicator Results: Incubate the BIs according to the supplier’s instructions e.g. 24 to 48 hours for spore strips, or use a rapid fluorescence readout if available. All BIs must show no growth (sterile result). If any BI shows growth, consider the cycle a failure and investigate causes such as insufficient exposure, operator error in loading, malfunctions, etc. Resolve issues and repeat PQ.
  • Ancillary Checks: Especially for EO, verify that items are dry and free of EO odor after the cycle plus aeration. For H2O2, ensure no condensing residue on items as they should be dry and not have hydrogen peroxide odor. For ozone, ensure the converter is effectively removing ozone with no ozone smell when opening the chamber. Package integrity should be intact with no burst pouches or melted materials.
  • Documentation: Record the details of each cycle including the date, cycle number, load description, BI lot numbers, CI types, operator name. Compile results of physical monitoring, BI, and CI in a report. Have a supervisor or validator review and sign off that PQ is successful. Retain this documentation.
  • Requalification Triggers: Note in the validation plan that requalification (repeating some or all of these tests) will be done if certain events occur, for instance, after major repair, software updates, relocation of the steriliser, or on a scheduled basis. Some facilities choose to revalidate annually or biennially to ensure ongoing compliance.

Performance Indicators for Ongoing Validation

Once a sterilisation process is validated and in routine use, continuous monitoring and periodic re-validation are essential to maintain confidence that the process remains effective. Australian standards require routine monitoring of each steriliser cycle and regular testing as part of ongoing validation. This section outlines the key performance indicators (PIs) and monitoring practices for ongoing validation of low-temperature sterilisers, from daily cycle checks to periodic challenges.

  1. Physical Cycle Monitoring: Every sterilisation cycle should be monitored via the steriliser’s printout or digital cycle record. The critical parameters including time at sterilising exposure, pressure/vacuum levels, temperature (if heated), and for HPGP or ozone the delivered concentration/dose must be reviewed by staff after each run. For example, after each H2O2 gas plasma cycle, the operator should check that the printout confirms the correct number of pulses and pressure set-points were reached, and that no error codes are present. Likewise, each EO cycle printout should be checked to ensure the full exposure time at the correct gas concentration and the completion of the aeration phase. Cycle data review is typically a standard operating procedure: any deviation or alarm indicated on the record should trigger an investigation and the affected load should be quarantined (not released) until resolved. Modern sterilisers usually make this easy by flagging faults, but human verification remains a vital step. Maintaining a log of cycle parameters can help identify trends e.g. if vacuum levels are gradually degrading, indicating a possible leak.
  2. Chemical Indicator Use: Chemical indicators (CIs) are a frontline performance indicator for each load. As mandated in AS/NZS 4187 and reaffirmed in AS 5369, an external chemical indicator typically Class 1 process indicator, like indicator tape or an external strip that changes color when processed should be placed on every package or tray to show it has been exposed to the process. This is a quick visual check upon unloading if an external CI on an item is unchanged, you know that item missed the process and must not be used. Additionally, internal chemical indicators should be used inside packs as appropriate. In steam sterilisation, it’s common to use a Class 4, 5, or 6 internal CI in every pack. For hydrogen peroxide plasma, the standards note that if a full validation has been completed, using an internal CI in every pack is optional. However, many clinics still choose to place at least a multi-parameter CI inside the most challenging pack of each load for extra assurance. For EO loads, it is prudent to include internal CIs in packs as well, given the complexity of EO cycles, some packaging manufacturers provide EO-specific integrator strips. Ozone sterilisation should also use process-specific CIs if available, since ozone is newer, one must obtain indicators validated for ozone use. Some H2O2 indicators also respond to ozone, but it’s best to use what the steriliser maker recommends. All chemical indicators should be checked when the load is opened: any failure to reach the expected endpoint e.g. a color change means potential process failure. The packaging and loading of items should ensure the indicators are placed in areas most difficult for the sterilant to reach, typically deep inside the pack or innermost item.
  3. Biological Indicator (BI) Testing: Biological indicators are the most direct measure of sterilisation efficacy and are used at regular intervals to challenge the process. The frequency and manner of BI use depend on the sterilisation modality and standards of practice:
    For Ethylene Oxide sterilisation, every cycle should include a BI in a test pack or PCD. This stringent requirement is because EO is high-risk and cycle failures might not be immediately evident without a BI. In practical terms, a self-contained BI vial can be placed in the center of a representative pack in each load. After the cycle (and aeration), the BI is incubated. Many facilities will not wait for the BI result for routine loads since incubation can take 48 hours unless a rapid BI is used, but they will have a protocol: if a BI comes back positive (growth), they treat it as a sterilisation failure, investigate, and potentially recall any items from that load if used. Increasingly, rapid-read BIs e.g. fluorescent enzyme-based indicators with ~4 hour readouts are used for EO so that results are known sooner.
    For Hydrogen Peroxide Gas Plasma sterilisation, the norm per AS/NZS 4187 was to use BIs on a weekly basis at minimum if the steriliser prints out all cycle parameters. Most HPGP units have highly automated controls; the rationale is that if the physical conditions are met each time and documented, the risk of undetected failure is low, so a weekly BI provides a periodic check. Many hospitals nonetheless choose to do BIs more frequently e.g. daily in each machine for extra assurance. Best practice is to run a BI in a process challenge pack that simulates a hard-to-sterilise configuration such as the longest lumen instrument regularly processed once per day or per week, and whenever major maintenance has occurred. The BI should be the type specified for H2O2 (Geobacillus stearothermophilus spores, usually on a stainless steel carrier in a small plastic vial). After processing, incubate the BI and look for growth/no-growth. A failed BI (growth positive) in any routine test is a serious red flag, you would immediately remove that steriliser from service, recall items since the last passed BI, and investigate root causes.
    For Ozone sterilisation, because it is analogous to H2O2 in many ways (oxidative chemistry, with automatic cycle control), one can apply a similar approach: perform BI tests at least weekly. If the manufacturer or any relevant guideline suggests a different frequency, that should be followed. Until ozone processes are more standardized, a cautious approach would be to use a BI PCD daily or weekly. Use Geobacillus stearothermophilus spores as the challenge (some ozone steriliser makers provide specific BI kits).
    In all cases, maintain a BI log recording the results. Each BI should be traceable by lot number and dated. If growth is observed, record the incident per the clinic’s incident protocol and initiate corrective actions. Routine BI monitoring is a key performance indicator that provides ongoing validation that the steriliser is truly killing spores as expected over time.
  4. Leak Rate and Air Removal Tests: For vacuum-based systems which include nearly all modern low-temp sterilisers except perhaps some simple EO units, vacuum leak testing is an important performance indicator. In steam sterilisers, a daily vacuum leak test is standard for pre-vacuum autoclaves. For hydrogen peroxide plasma, the standards note that a leak rate test is optional and to be done at intervals recommended by the manufacturer. Many HPGP units perform self-diagnostic leak tests or prompt the user to do so periodically. It’s wise to do a leak test at least monthly if not provided automatically, this usually involves running a special cycle or using a test program that measures pressure rise in an empty chamber under vacuum over a set time, indicating any leaks. An EO steriliser should also be checked for leaks regularly to ensure operator safety as well as cycle integrity; often this can be combined with routine maintenance. Ozone sterilisers similarly may have a vacuum integrity test routine. Passing the leak test ensures that there are no significant air ingress or sterilant egress issues which could compromise sterilant concentration or pose safety hazards.
    Additionally, while Bowie-Dick tests to detect inadequate air removal are not required for these processes as they are specific to steam sterilisers, the concept is analogous: any situation where air could be trapped in loads hindering sterilant penetration should be avoided. Proper loading such as not overpacking or occluding pathways is important and can be considered a performance factor, though not a formal test, staff should be trained to load correctly as part of ongoing quality control.
  5. Cycle Counts and Ongoing Calibration: Keeping track of how many cycles have been run and the time since last maintenance is another indicator relevant to performance. Many sterilisers internally track usage and will alert when service is due e.g. after a certain number of cycles or hours of operation. Technicians should heed these alerts and schedule service, as exceeding recommended use without maintenance could increase risk of failure. Annual calibration checks of sensors are generally advised, for instance, verifying the temperature probe or pressure transducer against a standard annually to adjust any drift. If any calibration shift is detected, it should be corrected and one might run a few BI tests after calibration just to reconfirm performance.
  6. Documentation Review: A less direct but important part of ongoing validation is periodic review of all the above records. Supervisors or an infection control committee should review sterilisation logs, BI/CI results, maintenance records, and any failure incident reports on a scheduled basis e.g. monthly or quarterly. This oversight can identify if, for example, chemical indicator failures are trending upward or if there have been any cycle aborts that were not properly resolved. It is a recommended best practice in quality management to conduct such reviews and also to perform internal audits, effectively a validation that the routine process monitoring itself is being done and recorded correctly.

In summary, the key performance indicators for the ongoing validation of low-temperature sterilisers are: physical parameter compliance each cycle, chemical indicator results each load, biological indicator challenges at defined intervals, and the results of periodic mechanical tests like leak tests. Through diligent monitoring of these indicators, a clinic ensures that its sterilisation process remains within a state of control. If any indicator falls out of expected range e.g. a BI failure, a CI failure, a cycle parameter anomaly, or a failed leak test, it must prompt immediate investigation and corrective action, which may include re-running validation steps, servicing equipment, or retraining staff as needed.

Maintenance Schedules and Best Practices for Compliance

Proper maintenance of low-temperature sterilisers is not only essential for safe operation but is also typically mandated by standards as part of maintaining validation status. A steriliser that is out of calibration or poorly maintained cannot be trusted to sterilise instruments reliably. This section outlines maintenance schedules (daily, periodic, and annual tasks) and best practices, from both technical and clinical perspectives, to ensure continued compliance and optimal performance of hydrogen peroxide, EO, and ozone sterilisation systems.

Daily Pre and Post-Use Checks: Before the first cycle of the day, operators should perform basic checks on the steriliser: confirm that the machine is clean no residues from prior runs, that necessary supplies such as sterilant cartridges, gas cylinders, printer paper or printer connectivity, etc. are in place, and that the machine self-test if it runs one at startup passes. Hydrogen peroxide plasma sterilisers usually have single-use or cassette-based peroxide cartridges; the user should ensure a cartridge with sufficient volume is loaded and not expired. Any filters that are user-accessible like dust filters on intake vents or chamber HEPA filters, if present might be checked or cleaned as recommended. For EO units, check the EO cylinder or cartridge level and the expiration date if applicable and verify that the ventilation system is on and functioning. Some systems have a blower or require the room exhaust to be operational during use. Ensure the aerator if separate is ready. For ozone steriliser units, confirm the oxygen supply from a tank or concentrator is sufficient and that the ozone destruct catalyst isn’t past its hour limit. Basic daily functionality tests may include running a vacuum test or leak test at start-up if the manufacturer advises it. Some sterilisers automatically do a vacuum leak test each day or after a certain number of cycles.

After each cycle or at the end of the day, cleaning and care might be needed: for HPGP, wipe down the chamber and door seal with a damp water or alcohol-dampened cloth to remove any white residues that hydrogen peroxide might leave. Do not use bleach or corrosive cleaners on any steriliser chamber. For EO, if any liquid was added for humidity inside the chamber, drain it if instructed; also, ventilate the area briefly after unloading items to avoid any lingering EO gas; usually the steriliser’s purge should handle this. Ozone steriliser chambers should be dry, if you see water droplets from the humidity phase, you might wipe them. Check that no instruments or packaging have fallen into the chamber or on heaters, etc. A visual inspection of the door gasket for cracks or damage is good practice daily as a compromised gasket can cause leaks.

Periodic Maintenance (Weekly/Monthly): Certain maintenance tasks should be done on a scheduled basis:

  • Biological decontamination: Some sterilisers might require periodic decontamination cycles for instance, an empty cycle with a special program to clean the chamber or neutralize residues. HPGP steriliser manufacturers sometimes recommend running a cleaning cycle or plasma conditioning cycle after a set number of uses.
  • Filter changes: If the unit has filters e.g. an inline filter for air or moisture, or an EO exhaust filter, these might be changed quarterly or as per the manual.
  • Vacuum pump oil: Many large sterilisers especially older EO units or some ozone units have vacuum pumps that use oil. The oil may need checking or changing after a certain runtime. For example, one recommendation for HPGP units is replacing vacuum pump oil on a schedule.
  • Catalyst replacement: Ozone and H2O2 machines contain catalysts often catalytic converters with substances like alumina or platinum to break down O3 or H2O2. These have a finite life. The manufacturer might specify to replace the ozone destruct cartridge or H2O2 absorber catalyst annually or after X cycles. Keeping to this schedule is critical, an expired catalyst could lead to hazardous emissions e.g. ozone leaking into the room.
  • Gasket care: On a weekly basis, clean the door gasket with mild soap and water, and check alignment of the door. Some gaskets may need periodic lubrication or eventually replacement if wear is noted.
  • Instrument care impacting steriliser: Indirectly, ensure that only clean and residue-free instruments go into the steriliser. For instance, residual cleaning chemicals or lubricants on instruments can sometimes damage steriliser chambers or reduce efficacy e.g. oils can coat sensors. So, reinforce proper instrument preparation as a maintenance of the process.

Calibration and Annual Preventive Maintenance: At least once a year, a qualified service technician often from the steriliser’s manufacturer or an authorised service agent should perform comprehensive preventive maintenance and calibration on the unit. Annual maintenance typically includes:

  • Calibration of sensors: verifying chamber temperature readings against a standard thermometer, pressure gauges against calibrated standard, and for plasma/ozone units verifying that injection volumes or concentrations of sterilant are correct, sometimes done by measuring weight of cartridges used or using specialized sensors. Any drift is corrected.
  • Mechanical checks: inspection of valves, tubing, and pumps for wear or blockages. Replace parts subject to wear e.g. vacuum pump seals, valve seals, door gasket if needed. For EO, the door seal and valves are critical to prevent leaks of toxic gas as these are often replaced or overhauled on schedule.
  • Software/firmware updates: ensuring the control software is up to date if updates have been released to fix bugs or improve reliability.
  • Functional tests: The technician will run test cycles, including leak tests, cycle verification tests, and safety checks. They may use external sensors to map the chamber and ensure uniform conditions, particularly done in larger hospital units.
  • Verification of interlocks and alarms: e.g. testing that an EO sensor alarm will trigger at the correct threshold by introducing a test gas, or that the door lock cannot open mid-cycle.
  • Replacement of consumables: beyond what users do, some parts like H2O2 vaporizer components or ozone generators. Some use UV lamps to make ozone, those lamps might need replacement after a certain number of hours would be serviced.

The outcome of annual servicing should be a service report detailing what was done and confirmation that the steriliser is performing to spec. Many standards including ISO 14937 explicitly require annual requalification or calibration for sterilisation equipment. In practice, after a major annual service, the clinic might perform a mini-PQ, for instance, run a BI test pack in the first load to double-check that everything is working. This is a prudent best practice even if not strictly required.

Maintaining Compliance Records: Compliance is demonstrated by documentation. Keep a maintenance log with dates of all service visits, repairs, part replacements, and calibrations. Also document routine upkeep like filter changes. If any unscheduled repair occurs e.g. a valve is replaced because it was leaking, note the event and consider doing a partial revalidation for example, run a few BI challenge cycles before declaring the steriliser fully back in service. Such records may be reviewed by accreditation bodies or health inspectors, and they provide assurance that the steriliser’s validated state is maintained.

Spare Parts and Downtime Planning: A practical operational consideration is to plan for downtime. If a steriliser will be out of service for maintenance especially an EO steriliser, since not many backups may be available due to their cost, coordinate schedules to avoid disruption of surgery schedules. For critical items, have contingency plans e.g. alternative sterilisation at another facility or having enough instrument inventory to wait out maintenance. Keep some essential spare parts on hand if possible like door gasket, some common seals to allow quicker fixes.

Environmental and Staff Safety Checks: Maintenance also ties into safety. Regularly inspect the area around the steriliser: ensure ventilation vents are not blocked, measure and record room ventilation rates if required as some standards require a certain number of air changes per hour in reprocessing areas. For EO, many facilities have an EO gas sensor in the room, check its calibration and battery if portable as per manufacturer (could be quarterly). Staff who perform maintenance tasks should wear appropriate PPE; for example, changing an EO cartridge or filter might require gloves and eye protection, and ensuring no ignition sources as EO is flammable at high concentrations. Properly label and store sterilant supplies such as hydrogen peroxide solution bottles or cassettes must be stored cool and upright, EO cartridges in a secure ventilated cabinet, etc. All chemical sterilants should have Safety Data Sheets accessible in the department.

Best Practice Tips:

  • Always follow the manufacturer’s maintenance schedule to the letter. They have specific intervals for each component which are based on reliability data.
  • Never disable or ignore alarms, if an alarm is sounding repeatedly even if it seems like a nuisance, it indicates something that needs fixing, for instance, an EO abator might alarm if its catalyst is spent. Address the root cause rather than overriding the system.
  • Use only manufacturer-approved replacement parts and compatible consumables. For example, do not substitute a different brand of hydrogen peroxide solution unless it’s recommended; concentration and purity matter for the cycle.
  • Keep the chamber loading area and seals clean. Debris on seals can cause leaks; tape residues or indicator strips left in the chamber can interfere with sensors. Regular cleaning prevents accumulation of such issues.
  • Train staff on what minor maintenance they are allowed to do versus when to call an engineer. User maintenance might include cleaning filters or refilling fluids, but anything beyond should be done by professionals to maintain warranty and safety compliance.
  • If a steriliser is not going to be used for an extended period (weeks), follow shut-down storage procedures. Some EO units require purging with air, and plasma units might prefer you remove cartridges and store them. Upon re-start, consider doing a verification cycle with indicators to ensure all is well.

By adhering to diligent maintenance schedules and practices, a clinic not only extends the life of expensive sterilisation equipment but also ensures that each cycle is as effective as the day the machine was first validated. Compliance with maintenance recommendations is directly tied to patient safety: a poorly maintained steriliser could deliver sub-lethal cycles or expose staff and patients to hazardous residues. Therefore, maintenance is a cornerstone of sterilisation quality assurance, equally as important as the initial validation.

Operational Guidance and Validation Checklists

To translate the above concepts into everyday practice, this section provides operational guidance and concise checklists for validation and ongoing use of low-temperature sterilisers. These checklists serve as a summary for clinical managers and sterilisation technicians to ensure all critical points are covered. The focus is on both technical validation steps and practical, clinical checkpoints before and after running sterilisation cycles. Adopting a checklist-driven approach can help standardise procedures and prevent oversight of important details.

Checklist: Initial Validation (IQ, OQ, PQ)

Installation Qualification (IQ):

  • Verify installation environment: Adequate ventilation or exhaust in place (particularly for EO), room meets temperature/humidity requirements, and steriliser is level and secured.
  • Confirm all utility connections: Correct electrical supply (voltage, phase), water supply on if needed, gas supply connected (for EO or oxygen for ozone generators), and drains functional.
  • Check safety features: Door lock and seals, emergency stop, alarm systems, EO leak detector if present and test each for proper function.
  • Documentation: Record equipment model/serial and ARTG registration number. Ensure manuals and maintenance schedules are on-site.
  • Staff orientation: Conduct initial operator training on basic operation and emergency procedures.
  • Sign-off: Installer or qualified technician signs IQ report confirming proper setup.

Operational Qualification (OQ):

  • Empty Chamber Test Cycles: Run a cycle or more with no load on each sterilisation program. Review printout data to ensure all set points such as pressure, time, etc. are achieved. No errors should occur.
  • Calibration Verification: Use independent measuring devices if available e.g. thermometer, pressure gauge to spot-check chamber conditions. Adjust or calibrate the steriliser’s sensors if discrepancies are found.
  • Functional Checks: Simulate power failure, door open, or other fault conditions to verify the steriliser aborts cycles and alarms appropriately without compromising safety of course.
  • Loaded Operational Test: If applicable, run a cycle with a typical load. Ensure the machine can reach parameters with the load such as no excessive drying time, etc.
  • Pass/Fail Criteria: All test cycles should complete without alarms, and physical parameters must remain within allowed tolerances. Investigate and resolve any deviations before proceeding.
  • Documentation: Compile OQ results such as cycle printouts, data logger results, observations and have them reviewed. OQ is successful when the steriliser consistently operates as intended under test conditions.

Performance Qualification (PQ):

  • Worst-case Load Prep: Identify the most challenging items to sterilise (long lumens, heavy sets, densely packed trays) that will be processed clinically. Prepare a test load including these items or representations.
  • Biological Indicators (BIs): Place BI spores (10^6) in the hardest locations e.g. inside lumens, center of packs. Use BIs specific to the process (Geobacillus stearothermophilus for H2O2/ozone, Bacillus atrophaeus for EO).
  • Chemical Indicators (CIs): Include internal CIs in each pack near the BI and use external indicator tape on every package. If a manufacturer-supplied process challenge device (PCD) is available e.g. helix test for HPGP, include it as well.
  • Number of Cycles: Run at least 3 consecutive cycles with the test load without changing the load configuration. This checks repeatability.
  • After each cycle, check cycle printout for correct parameters and inspect CIs: all indicators should show acceptable results e.g. color change indicating sterilant penetration. Do not move to the next cycle if a major failure is detected; investigate first.
  • BI Analysis: Incubate BIs immediately after running cycles or use rapid BI readers. All BIs must show “no growth” for the PQ to pass. If any BI grows, consider PQ failed, identify the cause e.g. load too heavy, cold spots, operator error and rectify, then repeat PQ.
  • Acceptance: PQ is successful when each cycle’s physical data meets criteria, all CIs are acceptable, and BIs from all cycles are negative for growth, proving the required sterility assurance level. Document these results in a validation report and have it approved by the responsible authority e.g. CSSD manager or Infection Control.
  • Final Validation Report: Compile IQ, OQ, and PQ documentation into a complete report. Include any deviations and their resolutions. This becomes the baseline reference for the steriliser’s validated state.

Checklist: Routine Monitoring and Ongoing Validation

Before Each Cycle:

  • Inspect instruments for cleanliness and dryness as soil or moisture can impede sterilisation. Verify items are properly packaged in compatible materials e.g. only special pouches for H2O2 plasma; ensure any lumen devices are prepared according to instructions, such as flushing and drying. Do not overload packs or trays and allow space for sterilant circulation.
  • Load the steriliser correctly: avoid overloading the chamber or stacking items in a way that blocks airflow/gas flow. Use any load racks or spacers provided. Ensure any required humidity sensors or load probes (for EO) are placed as directed.
  • Place a chemical indicator on the outside of every pack if not already part of pouch design and ideally an internal CI inside packs or in the center of instrument sets. This is an immediate check for exposure.
  • For EO cycles, include a BI in each load inside a test pack as per recommended practice. For H₂O₂ and ozone, ensure a BI PCD is run at the prescribed frequency, e.g. the first load of the day or one load per week. It can be prudent to include it more often if resources allow.

After Each Cycle:

  • Review the steriliser printout or cycle record immediately. Confirm that all critical parameters such as time, pressure, temperature, dose met the cycle specification. Check for any errors or alarms. If anything is out of range or an alarm occurred, do not release the load, label it as non-sterile and investigate the issue.
  • Examine the external chemical indicators on all packs as they should have changed to the indicated color e.g. stripes on tape turned dark. If any pack’s indicator is unchanged, that pack may not have been exposed to the process from possible loading error or cycle failure, do not use it.
  • Verify internal chemical indicators if used after opening packs as this is often done at point of use or during pack checking. A Class 5 integrator or equivalent should show the pass result. If an internal CI suggests an inadequate process, treat the contents as non-sterile even if the external looked fine, it could indicate an interior area didn’t get sterilant.
  • Check package integrity and dryness: All wraps and pouches should be intact with no tears, seal breaches, or excessive moisture. Particularly for H₂O₂ plasma, no visible moisture or condensate should be present. In an EO load, items should be dry and only have a slight odor if any. A strong EO smell means insufficient aeration, so consider extending aeration or quarantine those items longer.
  • Conduct product release only after the above checks are satisfactory. This means a designated staff member (sometimes called a “Technical Release” person) signs off that the cycle’s physical, chemical and if applicable, biological monitors are all acceptable and that the items appear safe for use.

Periodic Testing and Checks:

  • Biological Indicator Routine: Incubate routine BIs as per schedule. For EO, this is each cycle, so you'll have a continuous rotation of BI results coming in. For HPGP/ozone weekly BIs, pick a consistent day e.g. every Monday first load includes BI PCD. Log results of each BI test. If a BI ever shows growth (positive), immediately stop using the steriliser, pull it from service for evaluation and recall any loads since the last negative BI result. Investigate cause e.g. operator error, sterilant depletion, mechanical issue and perform corrective actions and revalidation if needed before reuse.
  • Leak Tests: Perform a vacuum leak test at the recommended interval. Record the leak rate; if it exceeds the allowable limit often specified in mbar/min or similar, arrange for maintenance before further use. A passed leak test gives confidence in chamber integrity.
  • Alarm Systems: Periodically e.g. monthly, test any safety alarms manually if possible, for instance, ensure an EO area gas sensor will alarm by exposing it to a calibrated test gas ampoule or during professional maintenance. Ensure staff respond appropriately during drills.
  • Requalification: Plan for annual re-validation or after major events. Even if not explicitly required by Australian standards beyond maintenance, many facilities do at least an annual biological performance requalification, for example, running a full chamber BI challenge test to re-verify sterility. Always requalify at least do a robust BI/CI test cycle after any major repair, software update, or relocation of the steriliser. Document these requalification results alongside the original PQ records.

Record Keeping:

  • Keep a Sterilisation Log Book or digital records: each cycle’s details such as date, load number, operator, cycle parameters, CI results, BI if used and should be recorded and kept for the time period required by policy (often several years). This provides traceability if there is ever a question about an instrument’s sterilisation, you can check the records.
  • Maintain Maintenance Records: document each preventive maintenance visit, repairs, parts replaced, and routine upkeep tasks done such as filter changes, etc. Also file the calibration certificates or service reports provided by technicians.
  • Incident Reports: If any cycle failure or indicator failure occurs, fill out an incident report as per your quality system. This helps ensure proper follow-up and serves as documentation if auditors review how issues are handled.

These routine checklists complement the initial validation. They embed quality assurance into day-to-day operations, which is exactly the goal of standards like AS 5369, “a programmed series of checks and challenges, repeated periodically, carried out according to a documented protocol, to demonstrate the process is reliable and repeatable”. By following these steps, clinical staff can be confident that each sterilisation cycle is effective, and any drift from validated conditions will be caught promptly.

Checklist: Maintenance and Best Practices

  • Daily Care: Clean chamber and door seal daily such as remove any residue, lint, or tape. Verify sterilant levels and replace H2O2 cartridges if low; check EO cartridge weight or pressure. Ensure the printer or USB logger has paper/space. Power up the machine and confirm no error codes.
  • Consumable Checks: Use only in-date, approved consumables such as sterilant refills, chemical indicators, biological indicators. An expired BI or CI can give false results; an expired EO cartridge might deliver insufficient gas. Manage inventory of these supplies diligently.
  • Environmental Conditions: Keep the steriliser room within the temperature range specified (usually air-conditioned to ~20 to 25 °C). Excessive heat or cold can affect cycle performance and personnel comfort when wearing PPE for EO handling. Ensure room ventilation is functioning, for EO, an airflow of at least the minimum air changes per hour per local OHS regulations is maintained.
  • Scheduled Servicing: Adhere to the manufacturer’s service schedule (typically annual). Plan ahead to have an authorised technician service the unit. Do not postpone maintenance, running a steriliser beyond its service due date can risk a breakdown or ineffective sterilisation. Coordinate with clinic schedules so that instrument reprocessing can continue via alternative means during servicing, e.g. borrow capacity from a nearby facility if needed.
  • Parts Replacement: Keep a log of parts with limited life. For example, note the last time the ozone catalyst was changed and when it’s next due. For H2O2 sterilisers, note if there is a shelf-life on the vacuum pump oil or internal filters and track those. Pre-order parts that are coming due to avoid backorder delays.
  • Staff Training: Regularly refresh staff training on steriliser operation and troubleshooting. Hold drills or reviews on emergency procedures, e.g. how to respond to an EO leak alarm (evacuate area, ventilation, etc.), or what to do if a cycle aborts. Training should also cover the rationale behind all these validation and maintenance steps. Staff are more likely to comply if they understand that a lapse in maintenance or monitoring could directly compromise patient safety by risking non-sterile instruments or chemical injuries.
  • Stay Updated: Keep informed about any manufacturer recalls, field notices, or software upgrades for your steriliser model. Manufacturers may periodically release updates improving performance or safety, implementing these in a timely manner is part of best practice. Also, stay abreast of any changes in standards or guidelines. For instance, if research finds a better BI incubation method that speeds up results, consider adopting it to improve your validation program.
  • Continuous Quality Improvement: Use data from your monitoring to improve processes. If you notice frequent wet packs in EO, maybe drying or packing methods need improvement. If a lot of cycles are aborted due to operator error, more training is needed or perhaps a change in workflow. Employ root cause analysis for any failure and genuinely fix the underlying issue, not just the symptom.

Finally, foster a culture of safety and quality in the sterilisation area. Managers should encourage technicians to speak up if they suspect a problem, even if it’s as simple as an unusual smell or a questionable indicator, these could be the first sign of a larger issue. By using these checklists and instilling vigilance, clinics can ensure their low-temperature sterilisation processes remain consistently effective and compliant with Australian standards and international best practices.

Conclusion

Validating and maintaining low-temperature sterilisation technologies in dental and day surgery clinics is a complex but critical undertaking that ensures patient instruments are safe for use. Hydrogen peroxide gas plasma, ethylene oxide, and ozone-based sterilisers each have unique advantages and challenges, but all share the need for rigorous initial qualification (IQ/OQ/PQ) and ongoing validation. By adhering to Australian Standards like AS 5369:2023 and leveraging relevant international guidance when needed, clinical managers and sterilisation technicians can develop robust protocols that cover every aspect of the sterilisation process, from installation and operation to performance verification and routine monitoring.

The technical perspective, covering calibration, cycle parameters, biological kill efficacy, and equipment maintenance must integrate with the clinical perspective, which focuses on practical outcomes like instrument turnaround times, material compatibility, and avoiding patient/staff hazards for example, residual chemical irritants or failed sterility. Both perspectives converge on the same goal: a reliable sterilisation process that consistently achieves sterility (SAL 10^−6) without adverse effects.

In summary, the key pillars of low-temperature steriliser validation in Australian clinics are:

  • Comprehensive Qualification Testing: Meticulous IQ, OQ, PQ procedures to establish a validated baseline for each sterilisation modality, ensuring compliance with proven standards e.g. ISO 11135 for EO, ISO 14937 for novel processes and manufacturer specifications.
  • Routine Performance Monitoring: Use of physical monitors, chemical indicators on every load, and biological indicators at appropriate intervals to verify each cycle’s effectiveness. Immediate corrective action is mandated for any indicator deviations, supported by thorough documentation and investigation of failures.
  • Scheduled Maintenance and Calibration: Strict adherence to maintenance schedules (daily, weekly, annual) as recommended by manufacturers and standards, keeping the equipment in peak condition. This includes replacing consumables such as filters, gaskets, etc. calibrating sensors, and testing safety systems, all documented to demonstrate compliance.
  • Operational Best Practices: Ensuring proper loading, packaging, and handling of instruments specific to each technology e.g. no cellulose in H₂O₂ loads, adequate aeration for EO, correct packaging for ozone, along with ongoing staff training and use of checklists to maintain consistency and readiness for audits or inspections.
  • Continuous Improvement and Revalidation: Recognising that validation is not a one-time event, clinics should periodically revalidate or at least re-challenge their sterilisers, and remain alert to innovations or changes in standards that could enhance safety or efficiency.

By following the guidance and checklists provided in this whitepaper, dental and day surgery clinics can establish a validation program that not only meets regulatory and standards requirements but also instills confidence among staff and patients. The result is a high level of sterility assurance for all reprocessed instruments, reduced risk of infection transmission, and a well-run sterilisation department that stands up to scrutiny. In the critical realm of infection control, such diligence is not optional, it is an ethical and professional imperative grounded in the principle of “do no harm,” ensuring that every instrument that touches a patient is as safe as possible.

Sources

The recommendations in this document are based on Australian standards and authoritative guidelines, including AS 5369:2023 and the superseded AS/NZS 4187:2014, relevant ISO standards, and expert publications on low-temperature sterilisation processes. These sources, cited throughout the text, provide further detail and rationale for the validation protocols and should be consulted for in-depth guidance on specific tests or criteria. Adhering to these evidence-based practices will help ensure compliance, safety, and effectiveness in sterilisation operations across Australia’s dental and day surgery clinics.