Sterilisation process

Correct loading is critical to:

• ensure steam can reach and sterilise every surface of every item,
• protect sterile barrier systems from damage, and
• allow complete drying of the load.

General principles for loading the steriliser

• Only sterilise instruments and devices that are:
  • compatible with the steriliser’s specifications, and
  • included in the practice’s validated load configuration.
• Do not overload. Each load needs to remain within the validated parameters established at annual validation/performance re-qualification.
• Loads cannot be larger or more difficult to sterilise than the validated “challenge load.”
• Any new load configuration that could exceed the validated challenge load requires re-validation.
• In an emergency situation (where re-validation cannot occur immediately), a Class 5 or 6 chemical indicator may be used until validation can be arranged as soon as possible.

Wrapped and unwrapped items

• Ideally, do not sterilise wrapped and unwrapped items in the same load.
• If unavoidable:
  • never place unwrapped items above trays of wrapped items, as condensate can drip onto packs below.

Equipment used when loading the steriliser

• Only use validated, ARTG-listed sterilisation containers, load separators, perforated metal trays, or cassettes.
• Equipment needs to be designed for, and validated with, the specific steriliser model.
• Obtain accessories directly from the steriliser manufacturer or a medical supply company if not supplied with the steriliser.

Load separators are used to space items, for example identical kidney dishes that would stack closely together, hindering air removal, steam penetration and drying.

Trays used in the steriliser need to be:

• perforated to allow steam penetration and drainage of condensation
• specifically validated for the steriliser model.

Multiple trays may be required if packs are sterilised flat in single layers.

Do not use solid trays: they block steam movement, cause pooling of condensate, and may result in wet packs.

Method of loading

• Follow the loading instructions provided by the manufacturer.
• Follow the manufacturer’s instructions on placement of packs and use of equipment.
• Ensure adequate space between each pack/pouch to facilitate air removal, allow steam penetration and facilitate drying – load trays loosely with a single layer of packs on each tray, within the boundaries of the loading tray.
• Load the steriliser so that no items touch the walls. A square frame insert to achieve this may be supplied with the steriliser.
• Loading of the steriliser follows the same pattern of loading described in the validation protocol.
• Photographs or diagrams of the validated loading pattern and any lesser loading patterns used are useful as a reference.

Table 10.17 Principles of steriliser loading

For sterilisers that produce printouts, the paper position and ink levels need to be checked before running each cycle to ensure the data are recorded.

Processing time

The sterilisation time (and temperature, if more than one option is available) is a critical factor in achieving sterility. Processing time = penetration (equilibration) time + holding time. Table 10.18 outlines the components of processing time.

Table 10.18 Components of processing time

Drying time

The validation process determines the minimum drying time for cycles, based on the challenge load(s).

Heat distribution

Small steam sterilisers (<60 L)

• Heat distribution studies are not required for small benchtop sterilisers.
• Such studies may not reliably identify “cold spots” in small chambers.

Large sterilisers

• A heat distribution study is required to ensure monitoring reflects the temperature in the coolest part of the chamber.
• This study only needs to be performed once.
• Information may be obtained from:
  • the manufacturer,
  • previous validation records, or
  • the service technician performing maintenance.

Routine checks

• Heat distribution can be verified during routine calibration.
• This should not incur additional cost.

Ensure sterile barrier systems, chemical indicators, and cycle printouts are checked properly. Maintain sterility and prevent damage to packs or instruments.

Key steps and rules

• Do not interrupt the cycle: the steriliser door needs to remain closed until the cycle is complete and chamber pressure has returned to zero.
• Remove the load promptly: do not leave packs to cool inside the steriliser.
• Inspect packs and pouches: any that are wet, dropped, torn, damaged, or have broken seals are considered unsterile and need to be fully reprocessed.
• Re-cleaning is only required if instruments have been contaminated.

Any reprocessing needs to be recorded in accordance with practice procedures.

More information: wet packs

• All packs need to be dry before use.
• A wet pack indicates a steriliser malfunction or processing error, which needs to be identified and corrected immediately.
• Wet packs pose a contamination risk:
  • Excess moisture can allow microorganisms to enter the package.
  • Handling wet packs can transfer microorganisms to the contents, compromising sterility.

Table 10.19 Steps for unloading the steriliser

Immediate-use sterilisation is only suitable when a device needs to be used immediately and cannot be kept sterile another way, such as by using sterile packaging.

Immediate-use sterilisation is used when necessary, and the process needs to be clearly defined and tested as part of the practice’s overall sterilisation procedures.

Devices that are sterilised without sterile barrier systems, like packaging, needs to be used straight away. If not, they could become contaminated before being used in a sterile area.

⚠️ Immediate-use sterilisation is not to be used:

• due to insufficient availability of clean devices; or
• as a cost-saving measure.

Devices processed for immediate use need to be transferred with care to minimise exposure to air or other potential sources of contamination.

Such devices are not to be stored for future use or retained for subsequent procedures.