The Detail EtO Sterilization Cycle
A typical EtO sterilization cycle comprises three main stages:
Preconditioning
This stage prepares the chamber to create optimal conditions for temperature, pressure, and humidity. First, air is evacuated to enhance gas penetration, followed by a leakage test to ensure safety for personnel and the environment. Steam is then injected to humidify the load, as EtO functions effectively only in moist conditions. The chamber is heated using hot air or hot water circulating in the jacket, which is maintained at a consistent temperature to prevent fluctuations.
EtO sterilization cycle
During this phase, EtO is introduced into the chamber through evaporation, along with steam to maintain humidity. Once the desired concentration of EtO is reached, the sterilization process begins. Lower gas concentrations require longer sterilization times. Since EtO is absorbed by various plastics, it’s crucial to monitor and maintain appropriate concentration levels throughout the process.
Aeration (Degassing)
Aeration is the longest and most critical part of the cycle. Materials like plastics and rubbers can absorb EtO, posing risks if used on patients. Thus, extensive aeration is essential to remove any residual gas. This is achieved by circulating HEPA-filtered air over the load at temperatures between 30°C and 50°C, typically for 48 hours, which can slow instrument turnaround. A dedicated infrastructure with gas-tight ventilation is required, as using the hospital’s ventilation system poses safety hazards. Regular gas leak tests on the ventilation piping are vital to minimize risks.
Advantages of EtO Sterilization:
Low temperature
High efficiency in destroying microorganisms, including resistant spores(1-120m³?
Large chamber capacity, accommodating significant volumes
Non-corrosive to plastics, metals, and rubber