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Process challenge device (or PCD) is an item designed to simulate product to be sterilized and to
constitute a defined challenge to the sterilization process and used
to assess the effective performance of the process. A PCD is a
challenge test pack or test tray that contains a biologic indicator,
a Class 5 integrating indicator, or an enzyme-only indicator.
The size and composition of the biological
indicator test pack should be standardized to create a significant
challenge to air removal and sterilant penetration and to obtain
interpretable results. There is a standard 16-towel pack
recommended by AAMI for steam sterilization consisting of 16 clean,
preconditioned, reusable huck or absorbent surgical towels each of
which is approximately 16 inches by 26 inches. Each towel is folded
lengthwise into thirds and then folded widthwise in the middle. One
or more
biological indicators
are placed between the eighth and ninth towels in the approximate
geometric center of the pack. When the towels are folded and placed
one on top of another, to form a stack (approximately 6 inch height)
it should weigh approximately 3 pounds and should have a density of
approximately 11.3 pounds per cubic foot. This test pack has not
gained universal use as a standard pack that simulates the actual
in-use conditions of steam sterilizers.
Commercially available disposable BI test
packs that have been shown to be equivalent to the AAMI 16 towel
test pack also may be used. The test pack should be placed flat in
an otherwise fully loaded sterilizer chamber, in the area least
favorable to sterilization (i.e., the area representing the greatest
challenge to the biological indicator). This area is normally in
the front, bottom section of the sterilizer, near the drain. A
control biological indicator
from the lot used for testing should be left unexposed to the
sterilant, and then incubated to verify the pre-sterilization
viability of the test spores and proper incubation. The most
conservative approach would be to use a control for each run;
however, less frequent use may be adequate (e.g., weekly).
ATS, Inc. also stocks BI test packs or Bowie-Dick test packs – see
Supplies.
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