The Steam Sterilization Process
- The steam sterilization principle is centered around exposing items to steam contact for a specified amount of time and under specified temperature conditions. Steam sterilization is typically used in hospitals for sterilizing the surfaces of wrapped goods or hollow items, and contains three important parameters: Temperature, steam under pressure and time.
- The process is conducted by supplying dry, saturated steam under pressure into an autoclave. The heat from the condensation of steam envelops the items in the sterilizer and kills the microorganisms in an easy and fast manner. It does so by irreversibly damaging the cells by coagulation.
- Steam sterilization takes a minimum of 15 minutes at 121 °C and a pressure of 2 ABS – or a minimum of 3 minutes at 134 °C and a pressure of 3 ABS for the items to be sterilized. However, cycle times may be longer depending on the particular items being sterilized. Objects that are sterilized with steam are often non heat-sensitive items, e.g. simple surgical instruments, dental instruments, reusable medical equipment, textiles or surgical equipment with cavities.
Validating Your Steam Sterilization Process
- According to international regulations, your steam sterilization process must be validated at least once a year to ensure a sterile result. This requires accurate measuring equipment to gather data on temperature, pressure and time throughout the process.
- The data you gather is then evaluated and compared to the relevant regulations in order to determine the quality of your sterilization – and thereby ensure compliance.
IQ, OQ and PQ Qualifications
Unlike qualifications of your autoclave, where you only have to perform installation qualifications (IQ) and operational qualifications (OQ), the validation of your process also requires a performance qualification (PQ).
- Installation Qualification:Verifies that the system is installed properly
- Operational Qualification:Verifies that your system works as intended
- Performance Qualification:Verifies the effectiveness of your sterilization process for a specific cycle or load. To perform a PQ, you need high-end measuring equipment to accurately determine your result
The results from your validation analysis are then used to control whether or not your autoclave complies with international standards, such as ISO 17665.
Ensuring Saturated Steam in your Autoclave
- Furthermore, it is critical that you are able to determine whether the steam used in your autoclave is saturated. Non-saturated steam places the entire sterilization process at risk, as the steam may not sufficiently reach every area of the equipment that’s meant to be sterilized.
- To obtain saturated steam, use temperature mapping equipment, validated software, and potentially, an electronic Bowie Dick Test system. These systems will ensure that you comply with the required norms and prove that your steam is saturated – and thereby ready to sterilize.
Equipment for Validation and Qualification
Both wireless data loggers and thermocouple systems are a suitable choices when looking for qualification and/or validation equipment for steam sterilization and autoclaves.
- Wireless loggers are, due to the RTD sensor design, very accurate and stable, which makes them the ideal option for both qualifying the autoclave and validating the steam sterilization process.
- A wired thermocouple system can also be used and may initially be the more economical option but will ultimately require far more resources to operate.
When using a wired thermocouple system for autoclave validation, there is the added challenge of maintaining the pressure and vacuum integrity. This is due to the necessity of using a feed-through system to allow the thermocouples into the chamber. Ellab’s feed-through system has been tested rigorously to ensure minimal leakage and optimal qualification efficiency.
Controlling Steam Quality with a Bowie Dick Test
- To ensure properly sterilized products, testing an autoclave’s steam penetration ability is crucial. This requires running a Bowie Dick test program.
- The Bowie Dick test is an important daily routine control conducted on autoclaves. The purpose of which is to ensue proper penetration of steam, to allow it to successfully reach every corner of the chamber, as well as the product. Fully sterilizing it upon contact.
- A Bowie Dick test is, however, only as reliable as the piece of third party equipment gathering the data. Which is why Ellab has developed the Bowie Dick Sensor, a highly innovative solution for electronic Bowie Dick testing