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Introduction

Hydrogen peroxide plasma sterilisation is referred to in AS 5369:2023 as low temperature vaporised hydrogen peroxide (VH2O2) sterilisation. Some systems include a gas plasma phase. This paper sets out the process, cycle time, material and packaging limits, cost per cycle, monitoring requirements and selection criteria for dental, dermatology, ophthalmology, day surgery and endoscopy clinics in Australia.

Overview of Sterilisation Methods in Clinics

Process selection: AS 5369:2023 requires critical devices to be sterilised by moist heat after cleaning, with a low temperature process used only where the device is heat or moisture sensitive. Semi-critical devices that cannot withstand moist heat may be processed by low temperature sterilisation, thermal disinfection or high-level disinfection. Non-critical devices are cleaned, and disinfected where the IFU or facility policy requires it. Select the process from the device instructions for use (IFU).

Steam: AS 5369:2023 sets minimum holding times of 15 min at 121 deg C [250 deg F] and 3 min at 134 deg C [273 deg F]. With air removal, heat-up and drying, a wrapped load in a pre-vacuum steriliser takes an indicative 30 to 60 min. Steam leaves no chemical residue and has the lowest cost per cycle, but excludes heat or moisture sensitive devices.

Ethylene oxide (EO): AS 5369:2023 lists common ranges of 400 to 800 mg/L EO, 37 to 55 deg C [99 to 131 deg F] and 50 % to 90 % relative humidity. EO penetrates long lumens and most materials, but is toxic, carcinogenic and flammable, and requires aeration to the residual limits of ISO 10993-7. An indicative total including aeration is 10 to 17 h, and AS 5369:2023 requires a biological indicator (BI) in every load.

VH2O2: Runs at an indicative 40 to 55 deg C [104 to 131 deg F] with cycles of 25 to 75 min, needs no aeration, and returns dry packaged items. It excludes cellulose, liquids and powders, and is limited to the lumen dimensions claimed for each cycle.

Other processes: Liquid chemical sterilisation, e.g. peracetic acid, processes unwrapped devices that must be used immediately. Low temperature steam and formaldehyde and dry heat have narrow clinic applications.

Comparison of Sterilisation Methods

How Hydrogen Peroxide Sterilisation Works

Process: The chamber is evacuated, concentrated aqueous hydrogen peroxide is vaporised and diffuses through the load, and the peroxide oxidises proteins, lipids and nucleic acids. Most cycles repeat the injection and diffusion phases. Some systems apply a gas plasma phase that dissociates residual peroxide. Residual peroxide decomposes to water and oxygen, so items leave the chamber dry and need no aeration.

Lumens: Penetration of lumens is limited by diffusion and by peroxide adsorption and decomposition on the lumen wall. Each cycle carries a lumen claim stated as a maximum length and minimum internal diameter, with separate claims for metal and polymer lumens. An indicative claim for a single-channel stainless steel lumen is 1 mm [0.04"] internal diameter by 500 mm [20"] length, a length to diameter ratio of 500 to 1. Measure each lumened device and confirm it falls within the claim for the selected cycle.

Requirements: AS 5369:2023 requires VH2O2 systems to be tested for efficacy to ISO 22441 and supplied with comprehensive IFU, and equipment to conform to ISO 22441 and ISO/TS 22421. AS 5369:2023 also requires a specification for the sterilising agent at acquisition, covering identity, active ingredient, shelf life, storage conditions and any reuse requirements.

Routine monitoring: Check the cycle record after every cycle, including temperature, pressure, sterilant concentration and time. Place an external chemical indicator on each pack and use BIs as specified in the IFU. Release requires a compliant cycle record, correct BI and external chemical indicator results, intact packs with no visible moisture, and correct process challenge device results where used.

Cycle Time and Throughput Considerations

Turnaround: VH2O2 returns dry, packaged, near-ambient items at cycle end. Shorter cycles are available on some systems for small non-lumened loads. Confirm the validated load, mass and lumen claim for each cycle in the IFU, as shorter cycles carry narrower claims.

Capacity: Throughput equals items per cycle multiplied by cycles per day. A unit with a 50 min cycle and 10 min of loading and unloading completes 8 cycles in an 8 h day. Compact chambers hold few trays, so size the steriliser from the daily count of low temperature items, not from cycle time alone. Where one unit cannot meet peak demand or a breakdown would stop procedures, install a second unit or arrange contingency processing.

Immediate use: VH2O2 sterilises packaged items that can be stored. AS 5369:2023 prohibits routine immediate-use sterilisation where insufficient devices are available or as a cost-saving measure, so size inventory and steriliser capacity to avoid it.

Load preparation: Clean and fully dry every item. Residual water evaporates under vacuum, prevents the chamber reaching the required pressure and cancels the cycle.

Material Compatibility and Packaging Requirements

Assessment: AS 5369:2023 requires the sterilising agent to be compatible with the device and the equipment, assessed from the device IFU and documented. Process a device by VH2O2 only where its IFU lists a VH2O2 process and cycle.

Compatible: Most metals, many polymers, electronics, optics and battery-containing devices, because the process is dry and runs at less than 60 deg C [140 deg F].

Excluded or limited:

• Cellulose, e.g. paper, cotton, linen and wood. Cellulose absorbs and decomposes peroxide, causing cycle cancellation or under-dosing.
• Liquids and powders.
• Copper and brass, which catalyse peroxide decomposition and lower the delivered concentration.
• Lumens outside the length and diameter claim for the cycle.
• Some elastomers and coatings, which embrittle under repeated oxidation. Track device condition against any IFU cycle limit.

Packaging: Use cellulose-free packaging validated for the steriliser, e.g. polypropylene nonwoven wrap and spunbonded polyolefin pouches, with process-specific chemical indicators to ISO 11140-1. Label each pack with its intended process at packaging.

Indicators: Use BIs to the applicable part of ISO 11138. VH2O2 BIs commonly use Geobacillus stearothermophilus spores. Steam indicators do not respond correctly to VH2O2, and the reverse also applies.

Single-use devices: Reprocessing a device labelled for single use is a manufacturing activity regulated by the Therapeutic Goods Administration and is outside AS 5369:2023. Do not use VH2O2 to reprocess single-use devices.

Equipment Costs and Economic Considerations

Cost per cycle: Calculate cost per cycle as capital recovery plus maintenance, divided by annual cycles, plus sterilant per cycle. The following figures are illustrative: purchase price A$80,000 over 10 years at a 5 % real discount rate (A$10,360 per year), maintenance and requalification A$4,000 per year, and sterilant A$12 per cycle. Obtain quotations for each.

Utilisation: At low utilisation, capital recovery, not sterilant, sets the cost per cycle. Compare the cost per cycle at the forecast cycle count with the cost of the alternatives: an external provider's fee per item plus transport and additional sets, or a single-use equivalent device where one exists.

Additional costs: Include cellulose-free packaging, process-specific indicators and BIs, sterilant storage, operator training and installation. VH2O2 units typically need only an electrical supply. Confirm the services required in the IFU.

Device life: Where a device IFU permits both steam and VH2O2, record repairs and replacements by process. Device cost per use equals purchase price divided by uses to replacement, plus repair cost per use. Include any difference in the comparison.

Clinical Outcomes and Safety Implications

Sterility assurance: A validated VH2O2 process is designed to deliver a sterility assurance level (SAL) of one in a million, the probability of one viable microorganism remaining on a device. The SAL holds only where cleaning, drying, packaging, load mass and lumen dimensions match the validated cycle. Oxidising sterilants are consumed by organic soil, so cleaning efficacy sets the process margin.

Prions: AS 5369:2023 excludes reprocessing of devices potentially contaminated with transmissible spongiform encephalopathies and defers to the national Creutzfeldt-Jakob disease (CJD) infection prevention and control guideline. That guideline provides no low temperature process for prion inactivation. Do not treat an SAL as evidence of prion inactivation.

Residues: Residual peroxide decomposes to water and oxygen. Detergent residue on intraocular instruments is associated with toxic anterior segment syndrome (TASS), so rinse to the AS 5369:2023 final rinse water limits before any sterilisation process.

Staff safety: Concentrated sterilant is an oxidiser and corrosive to skin and eyes. Store and handle cassettes per the safety data sheet (SDS). After a cancelled cycle, handle the load per the IFU with the PPE specified in the SDS, as the load can retain peroxide. AS 5369:2023 requires an SDS for each sterilising agent, handling and disposal procedures, a spill kit reviewed against the SDS and staff training. Airborne exposure must not exceed the Safe Work Australia exposure limit, set out in the Workplace exposure limits for airborne contaminants from 1 December 2026, subject to adoption in each jurisdiction.

Traceability: AS 5369:2023 requires critical devices to be traceable at least to the individual cycle of a specified steriliser. For hospitals and day procedure services, NSQHS Standards Action 3.17 requires traceability of critical and semi-critical devices to the patient and procedure.

Specialty Clinic Perspectives and Recommendations

For every clinic type, list each reusable device with its Spaulding classification and the processes its IFU permits. Assign steam to every device whose IFU permits it. A VH2O2 steriliser is justified only where enough remaining devices are critical or semi-critical, heat or moisture sensitive, and list VH2O2 in their IFU.

Dental Clinics

Current practice: Dental instruments are predominantly steam-tolerant and are processed in small steam sterilisers to EN 13060. Process wrapped, porous and hollow loads, e.g. handpieces, in a Type B cycle. The Dental Board of Australia retired its infection control guidelines on 1 July 2022 and expects practitioners to use evidence-based guidance, and AS 5369:2023 is the national standard for reprocessing.

VH2O2 role: Limited to heat-sensitive critical or semi-critical items whose IFU lists VH2O2, e.g. some laser or electrosurgical handpieces and attachments. Process handpieces by the method in their IFU, which is normally steam.

Recommendation: Retain steam as the primary process. Consider VH2O2 only where the device audit identifies enough eligible items to justify the cost per cycle. Otherwise outsource those items or use single-use equivalents.

Dermatology and Skin Clinics

Current practice: Surgical instruments that breach the skin are critical and are steam sterilised or single-use. Devices that contact only intact skin, e.g. dermatoscopes and many laser or light-based applicators, are non-critical and are cleaned and disinfected per their IFU.

VH2O2 role: Limited to reusable heat-sensitive devices that breach or contact non-intact skin, e.g. some microneedling or radiofrequency tips, where the IFU lists VH2O2. Many such items are single-use.

Recommendation: A standalone dermatology clinic rarely has the item volume to justify a VH2O2 unit. Share a unit within a multidisciplinary facility or outsource, and document the process for each device in the clinic's reprocessing procedures.

Ophthalmology Clinics and Eye Surgery Centres

Current practice: Most intraocular instruments are steam-tolerant titanium or stainless steel. Some microsurgical instruments, optics and powered handpieces are heat sensitive.

VH2O2 role: Heat-sensitive intraocular and ocular surface devices whose IFU lists VH2O2. Confirm lumen dimensions for cannulated devices against the cycle claim.

Recommendation: Keep steam for standard sets. Use VH2O2 for IFU-listed heat-sensitive items. Rinse intraocular instruments to the final rinse water limits and follow the IFU cleaning process to control TASS risk. Validate loads that represent the clinic's eye sets.

Day Surgery, Surgical Specialty Clinics, and Endoscopy Centres

Day surgery: Rigid scopes, camera heads, light cables and powered instruments are the main VH2O2 load where their IFU lists it. Size VH2O2 capacity for the number of heat-sensitive sets used per list, and provide a second unit or contingency where a single unit would stop procedures.

Flexible endoscopes: Flexible endoscopes are semi-critical heat-labile devices, processed by high-level disinfection in a washer-disinfector to ISO 15883-4 and stored in a controlled environment storage cabinet to EN 16442. Sterilise a flexible endoscope by VH2O2 only where its IFU lists a VH2O2 cycle and its channels fall within that cycle's lumen claim.

Recommendation: Keep steam for standard trays. Maintain a list of devices assigned to VH2O2, label their packs, and train staff in drying, cellulose exclusion and loading limits.

Conclusion

VH2O2 sterilisation fills the gap between steam and EO for heat and moisture sensitive critical and semi-critical devices. It runs in 25 to 75 min, needs no aeration and leaves no toxic residue, but excludes cellulose, liquids and powders and is limited by the lumen claim for each cycle. Steam remains the primary process for every device whose IFU permits it. Justify a VH2O2 unit from a device audit and a cost per cycle at the forecast utilisation, and operate it to AS 5369:2023 with ISO 22441 equipment, IFU-specified monitoring, release criteria and traceability.

Sources

1. Standards Australia. AS 5369:2023 Reprocessing of reusable medical devices and other devices in health and non-health related facilities.
2. ISO 22441 Sterilization of health care products, Low temperature vaporized hydrogen peroxide.
3. ISO 11138 series Sterilization of health care products, Biological indicators. ISO 11140-1 Chemical indicators.
4. ISO 10993-7 Biological evaluation of medical devices, Part 7: Ethylene oxide sterilization residuals.
5. Communicable Diseases Network Australia. Creutzfeldt-Jakob disease infection prevention and control recommendations for health care settings, 2013.
6. Australian Commission on Safety and Quality in Health Care. National Safety and Quality Health Service Standards, Action 3.17.
7. Safe Work Australia. Workplace exposure limits for airborne contaminants, applying from 1 December 2026.
8. Dental Board of Australia. Infection prevention and control, frequently asked questions.