Biological and physicochemical autoclave controls ensure that every sterilization cycle reaches the required parameters. This guide details the different types of controls, their frequency, and documentation requirements under French regulations.
Sterilization control operates at three complementary levels. Physical indicators are the parameters displayed by the autoclave (temperature, pressure, duration) -- they confirm that the cycle ran according to the selected programme. Chemical indicators (autoclave tape, chemical integrators) change colour when exposed to sterilization conditions. Biological indicators (spore tests) are the most reliable: they confirm that the most resistant micro-organisms have been destroyed.
The Bowie-Dick test (for pre-vacuum autoclaves) or Helix test (for hollow loads) verifies steam penetration into the load. It must be performed daily, before the first load of the day, in an empty autoclave.
A failed Bowie-Dick test indicates a steam penetration problem -- it could be a leak, a vacuum pump issue, or a worn gasket. The autoclave must not be used until the problem is resolved.
Biological indicators contain spores of Geobacillus stearothermophilus, the micro-organism most resistant to saturated steam. If the sterilization cycle destroys them, it will destroy any other micro-organism.
Recommended frequency varies by guidelines: weekly as general best practice, after every new installation or autoclave repair, and whenever there is any doubt about the equipment's performance.
Autoclave tape (Class 1 indicator) is placed on each pouch. It does not guarantee sterilization -- it merely indicates that the pouch has been through the autoclave. Chemical integrators (Class 4, 5, or 6) provide more thorough verification by measuring exposure to temperature, pressure, and time.
The Class 6 chemical integrator is the most reliable chemical indicator: it only changes colour when all critical cycle parameters have been reached.
Every biological and physico-chemical control must be documented: date, type of test, result (pass/fail), and any corrective action taken. These records are an integral part of the sterilization register and must be kept for a minimum of 5 years.
Digital traceability allows control results to be archived automatically and linked to the relevant sterilization cycles, eliminating the risk of loss or oversight. For more details on use-by dates, see the dedicated guide.
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