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Medical Device Ethylene
Oxide (ETO/EO) Sterilization: Validation and other
challenges
The total length of the process can vary
depending on the goods that are being sterilized, but
typical cycles are between 36 and 48 hours. There are two
main ways to divide the cycle; a three-phase cycle and a
five phase cycle. The difference being that a threephase
cycle does factor in the pre and post exposure phases.
Three phases of EtO Sterilization
A typical three phase EtO sterilization
cycle can be summarized as follows:
Preconditioning:
Provides temperature and humidity
conditions to entice infectious agents to come out of
hibernation
Sterilization / Conditioning:
Exposure to the sterilizing agent at the
specified temperature, RH% and pressure levels
Aeration:
Et0 gas is removed using changes of air in
the sterilization chamber removing any EtO particles. This
process is usually taking place in a separate chamber or
room. Time and temperature are monitored.
Validation Stages – definition /
explanation Validation – Is a process where documented
evidence is generated to
demonstrate that the equipment, product and/or process do
what it purports to do.
INSTALLATION QUALIFICATION (IQ)
• Generally, Equipment specific Activities
conducted to demonstrate that equipment has been installed
or modified as designed.
In health care facilities, process and
equipment characterization are generally the
responsibility of the sterilizer manufacturer. The
management of the health care facility should have
controls in place to ensure that the equipment it
purchases conforms to national, regional, and local
regulations and is suitable for use to sterilize products
that require EO sterilization. Sensors, data loggers and
other monitoring equipment forms critical part of IQ
The management of the health care facility
should ensure that the facility has the infrastructure
necessary to correctly operate the sterilizing equipment
and to achieve effective sterilization of
medical devices.
Software and it’s validation. Software
used to control and/or monitor the process shall be
prepared and validated in accordance with the elements of
a quality system that provides documented evidence that
the software meets its design specification.
OPERATIONAL QUALIFICATION (OQ)
• Product, Process or Equipment
• Activities conducted to demonstrate that changes in an
existing product/process, piece of equipment, new
product/process scale-up or new installations operate as
designed.
VALIDATION OR PROCESS QUALIFICATION
(PQ)
• Product or Process
• Activities conducted using the specified product /
process / equipment, i.e., one that has been “qualified”,
to demonstrate that the system (product/process/equipment)
does what it purports to do consistently and reproducibly.
• PQ consists of both microbiological and physical
performance qualification and is performed in the
equipment used to sterilize the product.
Most often, the validation of an EO cycle
follows the half-cycle or “over-kill” method using
Biological Indicators (BI's) and product. This method
demonstrates that the resistance of the microbiological
challenge test system is equal to or greater than the
product bioburden.
An Ethylene Oxide (EO) Sterilization
Validation is designed to assist the manufacturer in the
development of a sterilization process that delivers the
appropriate sterility assurance level and
ensures repeatability for each product
type developed.
Standard ISO 11135:2014 covers following,
with referred clause numbers:
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