Page 178 - Assurance of Sterility for Sensitive Combination Products and Materials

160 Assurance of sterility for sensitive combination products and materials

used. Once all of the air is removed from the chamber the sterilizer enters
the exposure phase of the cycle.
There are two basic types of steam sterilization that are used: terminal
sterilization and immediate use steam sterilization (IUSS).
Terminal sterilization It is critical that medical devices are adequately
cleaned prior to sterilization. Just like in disinfection, it may not be possible
to sterilize a device that is not clean. Devices are terminally sterilized within
containers, wrappers, or other primary packaging that is designed to main-
tain the instruments’ sterility and enabling the devices to be stored for later
use. At the end of a terminal sterilization cycle, the device must be dry. If a
device/instrument set is wet, it is considered contaminated. Terminal steril-
ization processes are validated to show that they provide a sterility assurance
−6
level (SAL) of 10 . This has been considered the gold standard.
Immediate use steam sterilization IUSS is a method of steam ster-
ilization used on a medical device to be sterilized and used quickly. As the
name implies, “immediate use” indicates that the device should be removed
quickly from the sterilizer and aseptically transferred to the sterile field.
The sterilization cycle used is abbreviated and it is not intended that the
device(s) be stored for future use. The same critical processing steps used for
terminal sterilization must be followed prior to using IUSS, i.e., cleaning,
decontaminating, inspection, and transporting. It is recommended that ster-
ilization containers approved for use in an IUSS process should be used for
sterilization and transportation of the devices.

EO sterilization EO is a flammable and explosive colorless gas that is
used for sterilization of heat- and moisture-sensitive medical devices. EO
is a very effective gas sterilant that has exceptional penetration capabili-
ties. Because of its penetration capabilities, it is necessary to aerate devices
sterilized with EO. Aeration is a method of removing residual EO and its
by-products from the devices after sterilization. There are several disadvan-
tages associated with EO sterilization.
(1) The sterilization cycle time is lengthy
The cycle includes a sterilization cycle followed by aeration. Depending
on the temperature used for sterilization the typical complete cycle
time can vary between 10 and 16 h.
(2) EO is also a known carcinogen and mutagen. For this reason, there are
strict controls on emission of the EO after completion of the steril-
ization and aeration processes. In many states abatement and operator
permitting is required.