ISO 11135 Sterilization of Healthcare Products - Ethylene Oxide - Requirements for the Development, Validation and Routine Control of a Sterilization Process for Medical Devices

The standard “ISO 11135 Sterilization of health care products - Ethylene oxide - Requirements for the development, validation and routine control of a sterilization process for medical devices” developed by the International Organization for Standardization (ISO) describes the requirements for the development, validation and routine control of an ethylene oxide sterilization process for medical devices in both industrial and healthcare facility environments.

This standard recognizes the similarities and differences between the two applications. Similarities include the common need for quality systems, personnel training, and appropriate safety precautions. The primary differences relate to the unique physical and organizational conditions in healthcare facilities and the initial status of reusable medical devices submitted for sterilization. Healthcare facilities differ from medical device manufacturers in terms of the physical design of processing areas, the equipment used, and the availability of personnel with adequate training and experience.

The primary function of a healthcare facility is to provide patient care. Medical device reprocessing is just one of the myriad activities performed to support this function.

In terms of the initial situation of medical devices, medical device manufacturing companies usually sterilize a large number of similar medical devices made of virgin material. On the other hand, healthcare facilities must handle and process new medical devices and reusable medical devices with different descriptions and different bioburden levels. Therefore, they face additional challenges such as cleaning, evaluating, preparing and packaging a medical device before sterilization. In this standard, alternative approaches and guidelines specific to healthcare facilities are defined in this way.

Ethylene oxide gas and its mixtures are effective sterilizers used primarily for heat and/or moisture sensitive medical devices that cannot be sterilized with moist heat.

Although the scope of this international standard is limited to medical devices, it specifies requirements and provides guidance that can be applied to other healthcare products.

This standard does not specify the requirements for the development, validation and routine control of a process for the inactivation of several active substances listed in the standard. Specific recommendations have been produced in certain countries for the treatment of materials potentially contaminated with these agents (e.g. ISO 22442-1, ISO 22442-2 and ISO 22442-3 standards).

This standard does not detail a specific requirement to designate a medical device as sterile. Attention is drawn to national or regional requirements to designate medical devices as sterile (e.g. EN 556–1 or ANSI/AAMI ST67 standards).

This standard does not include a quality management system for the control of all production stages of medical devices.

This standard also does not specify the occupational safety requirements associated with the design and operation of ethylene oxide sterilization plants. Ethylene oxide is toxic, flammable and explosive. Incidentally, this standard does not cover the sterilization by injection of ethylene oxide or mixtures containing ethylene oxide directly into packages or a flexible container. ISO 14937 standard applies to such processes.

For the purposes of this standard, the following terms and definitions apply:

• Aeration is the part of the sterilization process in which ethylene oxide or its reaction products are desorbed from the medical device until predetermined levels are reached. This can occur within the sterilizer or in a separate compartment or room.
• Bioburden refers to the population of microorganisms living on or within the product or sterile barrier system.
• A biological indicator is a test system containing living microorganisms that provide a defined resistance to a specified sterilization process.
• Calibration is the set of operations that establishes the relationship between the values ​​of a quantity indicated by a measuring instrument or measuring system, or represented by a material measure or reference material, and the corresponding values ​​performed by standards, under specified conditions.
• A chemical indicator is a test system that reveals changes in one or more predefined process variables based on a chemical or physical change resulting from exposure to a process.
• Conditioning is the processing of the product to reach a predetermined temperature and relative humidity within the sterilization cycle, but prior to the acceptance of ethylene oxide. This portion of the sterilization cycle may be performed at atmospheric pressure or under vacuum.
• The dew point is the temperature at which the saturated water vapor pressure equals the partial pressure of water vapor in the atmosphere. Cooling the atmosphere below the dew point results in water condensation.
• Ethylene oxide injection time is the duration of the stage starting with the initial introduction of ethylene oxide into the chamber and ending with the completion of the injection.
• The exposure time is the period during which the process parameters are maintained within specified tolerances. For the purpose of calculating cycle lethality, it is the sterilization time between the end of ethylene oxide injection and the beginning of ethylene oxide removal.
• An error is when one or more of the process parameters fall outside of specified tolerances.

Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, it also provides certification and testing services defined in the standard “ISO 11135 Sterilization of health products - Ethylene oxide - Requirements for the development, validation and routine control of a sterilization process for medical devices” with its trained and expert staff and advanced technological equipment.