FAQ: Applications and Limitations of Parametric Release

Parametric release is a concept for release of sterilized product loads that relies solely on physical process indicators, i.e., time, temperature, pressure readouts, rather than chemical and/or biological indicators.

Yes. Parametric release can theoretically be applied to all terminal sterilization processes. However, parametric release is most often used for steam and radiation sterilization processes due to the reliability of these sterilization methods.

No. Parametric release has been used by Medical Device and Pharmaceutical manufacturers for many years.

The requirements to achieve parametric release are defined in various international sterilization standards. Relative to steam sterilization, the most pertinent standard is ISO 17665-1: 2006 Sterilization of health care products – Moist heat – Part 1: Requirements for the development, validation and routine control of a sterilization process for medical devices.

The 17665-1: 2006 standard has been adopted by the AAMI organization as ANSI/AAMI/ISO 17665-1: 2006, however, it is considered applicable only for Medical Device and Pharmaceutical manufacturers. AAMI’s philosophy, as determined by its membership including hospital practitioners, medical device manufacturers and regulatory personnel, is that this standard is not appropriate for use in health care facilities based on the document’s requirements for technical expertise and physical resources. The standard recommended by AAMI for steam sterilization assurance in health care facilities is ANSI/AAMI ST79: 2006 Comprehensive guide to steam sterilization and sterility assurance in health care facilities. The ST79 document does not require validation of the sterilization process but does require implementation of a quality system and routine monitoring with physical, chemical and biological indicators.

Standards such as ANSI/AAMI/ISO 17665-1 for steam sterilization require that the sterilization process be validated. Validation requires a high level of repetitive testing to define and document the capability of the sterilization process for the product being sterilized. Validation of the sterilization process includes:

• Verification of sterilizer operation and separate systems for sterilizer control and monitoring
• Verification of steam quality
• Control and monitoring of instrument bioburden levels, i.e., validation of cleaning processes
• Standardized packaging
• Standardization and testing of ALL loading configurations
• Standardized cycles for each loading configuration
• Defined and validated procedures for sterilizer unloading, item transfer and storage

Additionally, to ensure that all operations in the sterilization process are conducted the same each and every time, a quality system such as outlined in the ISO 9000 series standards must be implemented and functional in the sterilization area.

Yes, some do, although the actual number or percentage of hospitals using parametric release as specified in ISO 17665-1: 2006 is unknown; the number is believed to be small. European countries that are members of the European Union are obligated by law to follow European standards for sterilization. As the ISO sterilization standards are now adopted by Europe, hospitals in most European countries are obligated to follow appropriate sterilization standards such as ISO 17665-1. It is questionable, however, as to whether or not health care facilities truly have the capabilities and resources to comply with the requirements of the 17665-1 standard.

Due to the high cost, other resources (which are significant) and load consistency requirements needed to achieve validation and implement parametric release, it is unlikely that this method of sterilized items release will become a reality in U.S. health care facilities in the foreseeable future.