Maintenance and testing
All steam sterilisers must be commissioned on installation and verified throughout the lifecycle of the device. Operators and contracted technicians will be required to test and document the performance at regular interval.
Verification of the sterilisation process
In order to ensure appropriate sterilisation, validation of the sterilisation process is undertaken to ensure the desired performance is being achieved. This validation process involves the following steps:
- Commissioning — installation qualification (IQ) and operational qualification (OQ).
- A commissioning report includes installation documents and operation verification. This work is performed by the service technician when a new or repaired steriliser [e.g., after a major or critical component has been replaced/repaired] is installed in the practice.
- Performance qualification (PQ).
- Physical qualification (by a qualified instrument technician or manufacturer’s technician).
- Calibration report — this addresses the accuracy of thermocouples used to measure temperature (undertaken annually).
- Penetration report — this checks the physical attributes of the steriliser. This record is obtained after major repairs or when pack contents, packaging materials, or loading methods change significantly.
- Microbiological report to confirm functioning of the steriliser using a biological indicator (also known as a spore test).
- The validation report summarises satisfactory completion of commissioning, operational, and performance qualification. It provides validation of the total process. Further information on validation can be found in the ADA’s Practical Guide to Infection Control.
Monitoring of cycles
Sterilisation can’t be assumed to have been achieved without appropriate testing and load checking. For steam sterilisation, time, temperature, and pressure must be measured with continuous, automatic, permanent monitoring (e.g., use of a process recorder, data printer, or data logger). Where an older steam steriliser with no recording device is used, it must, where possible, be fitted with mechanisms to electronically record sterilising parameters. Otherwise, the parameters must be read from the relevant gauges and then documented at intervals of 10 seconds. Alternatively, a biological indicator (spore test) or chemical indicator (Class 4 or greater) can be used for each load.
The processed chemical indicator must achieve all sterilisation parameters applicable to the indicator used, and that information must be recorded. Hard copy prints that are checked and signed off provide a valuable record of the cycle parameters. Given their importance, each practice should develop a protocol around handling the situation where the printer has malfunctioned or has no paper (e.g. including Class 6 chemical indicators inside each pouch or package). If data from the steriliser is recorded onto a memory card or sent to a file server, there must be a process for reviewing this data — ideally for each cycle at the time, but at least once every day.
The everyday performance of a steam steriliser must be monitored by periodic testing, including daily and weekly tests. The details of these tests are presented in AS/NZS 4815 and AS/NZS 4187 and are described in the ADA’s Practical Guide to Infection Control under the topic of monitoring of steriliser cycles. The sections below discuss the use of chemical indicators and the process of validation.
Operating the steam steriliser
Clinical support staff must be trained in the correct operation of a steam steriliser. An operator’s manual must be available for each steam steriliser, and the unit must be used according to the manufacturer’s instructions.
Before steam sterilising an instrument, the operator must verify the item is suitable for the process. For example, some items are made of low melting point plastic and cannot withstand the process. Likewise, there must not be any attempt to steam sterilise disposable single-use items.