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.
Sterilization control operates at three complementary levels. Physical indicators are the parameters displayed by the autoclave (temperature, pressure, duration) — they confirm the cycle ran according to the selected program. Chemical indicators (autoclave tape, chemical integrators) change color when exposed to sterilization conditions. Biological indicators (spore tests) are the most reliable: they confirm that the most resistant microorganisms 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, vacuum pump issue, or worn gasket. The autoclave must not be used until the problem is resolved.
Biological indicators contain spores of Geobacillus stearothermophilus, the microorganism most resistant to saturated steam. If the sterilization cycle destroys them, it will destroy any other microorganism.
Recommended frequency varies by standard: weekly according to general best practices, after every new installation or repair, and whenever there is doubt about the autoclave's operation.
Autoclave tape (Class 1 indicator) is placed on each pouch. It does not guarantee sterilization — it only indicates that the pouch passed through the autoclave. Chemical integrators (Class 4, 5, or 6) offer 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 color when all critical cycle parameters are met.
Every biological and physicochemical control must be documented: date, test type, result (pass/fail), corrective action if applicable. These documents are an integral part of the sterilization register and must be retained for at least 5 years.
Digital traceability allows automatic archiving of control results and linking them to the relevant sterilization cycles, eliminating the risk of loss or oversight.
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