Chemical indicators are one of the three critical devices for
process. They are designed to respond with a characteristic
chemical or physical change to one or more of the physical
conditions within the sterilizing chamber. Chemical indicators
are intended to detect potential sterilization failures
immediately that could result from incorrect packaging, incorrect
loading of the sterilizer, or malfunctions of the sterilizer. The
Association for the Advancement of Medical Instrumentation has
defined five classes of chemical indicators: Class 1 (process
indicator); Class 2 (Bowie-Dick
test indicator); Class 3 (single-parameter indicator); Class 4
(multi-parameter indicator); and Class 5 (integrating indicator).
defines a physical*/chemical sterilization process indicator (21
CFR 880.2800(b)) as: A device intended for use by a health care
provider to accompany products being sterilized through a
sterilization procedure and to monitor one or more parameters of
the sterilization process. The adequacy of the sterilization
conditions as measured by these parameters is indicated by a
visible change in the device.
one study, chemical indicators were more likely than biological
indicators to inaccurately indicate sterilization at marginal
sterilization times (e.g., 2 minutes). Chemical indicators should
be used in conjunction with biological indicators, but based on
current studies should not replace them because they indicate
sterilization at marginal sterilization time and because only a
biological indicator consisting of resistant spores can measure
the microbicidal killing power of the sterilization process.
Placement of chemical indicators:
Chemical indicators are affixed on the outside of each pack to
show that the package has been processed through a sterilization
cycle, but these indicators do not prove sterilization has been
achieved. Preferably, a chemical indicator also should be placed
on the inside of each pack to verify sterilant penetration.
Chemical indicators usually are either heat-or chemical-sensitive
inks that change color when one or more sterilization parameters
(e.g., steam-time, temperature, and/or saturated steam; ETO-time,
temperature, relative humidity and/or ETO concentration) are
present. If the internal and/or external indicator suggests
inadequate processing, the item should not be used. An
air-removal test (Bowie-Dick Test – a Class 2 indicator) must be
performed daily in an empty dynamic-air-removal sterilizer (e.g.,
pre vacuum steam sterilizer) to ensure air removal.
The “pass” response of a chemical indicator does not prove the
item accompanied by the indicator is necessarily sterile.
Indicators come in many different forms including on
Bowie-Dick Tests and more
Supplies for our