The Operating Theatre journal April 2021

Assuring Sterility in Surgical Instruments Reprocessing
By Adebusola Owokole, Founder/President, The Operating Room Global (TORG).
https://www.operatingroomissues.org/
March, 2021
OVERVIEW: The delivery of sterile surgical instruments for use in
patient care depends not only on the effectiveness of the sterilization
process but also on the unit design, decontamination, disassembling
and packaging of the device, loading the sterilizer, monitoring, sterilant
quality and quantity, and the appropriateness of the cycle for the load
contents, and other aspects of device reprocessing. Sterility assurance
level (SAL) is the probability that a single microbe would remain on
an instrument after sterilization and is a cornerstone of a successful
infection prevention program. An effective sterilization protocol will
help ensure the delivery of safe care.
CLEANING: The first critical step to sterility assurance in reprocessing
is cleaning. Before instruments can be sterilized, they must be free of
bioburden and foreign material i.e., organic residue and inorganic salts
that interfere with the sterilization process by acting as a barrier to the
sterilization agent. Bioburden and debris can impede the sterilant from
reaching the surface. If cement is discovered on a surgical instrument
that has been reprocessed, removing the cement can expose a surface
that steam did not reach, and viable microorganisms could exist.
Several types of automated mechanical cleaning machines e.g., utensil
washer-sanitizer, ultrasonic cleaner, washer-sterilizer, dishwasher,
washer-disinfector may facilitate cleaning and decontamination of most
items. This increases productivity, improves cleaning effectiveness,
and decreases worker exposure to blood and body fluids. Delicate and
intricate objects and heat- or moisture-sensitive articles may require
careful cleaning by hand.
STERILIZATION CYCLE VERIFICATION: Sterilization process is verified
by running three consecutive empty steam cycles with a biological and
chemical indicator in an appropriate test package or tray, or with a
Bowie-Dick test in a pre-vacuum steam sterilizer. Each type of steam
cycle used for sterilization (e.g., vacuum-assisted, gravity) is tested
separately. The sterilizer is not put back into use until all biological
indicators are negative and chemical indicators show a correct endpoint
response. Once the cycle is complete, physical monitors of
time, temperature and pressure provide a real-time evaluation of the
sterilization process.
PHYSICAL FACILITIES: The central processing area(s) ideally should
be divided into at least three areas: decontamination, packaging,
and sterilization and storage. Physical barriers should separate the
decontamination area from the other sections to contain contamination
on used items. The recommended airflow pattern should contain
contaminates within the decontamination area and minimize the flow
of contaminates to the clean areas. The sterile storage area should be
a limited access area with a controlled temperature (may be as high as
75°F) and relative humidity (30-60% in all works areas except sterile
storage, where the relative humidity should not exceed 70%).
PACKAGE INTEGRITY: Package integrity should be verified after
the sterilization process, before instruments are stored, and again
immediately before opening the package for use. Once the sterilization
cycle is complete and the physical monitors have been verified, surgical
instruments should be allowed to cool and dry. If packages contain
moisture externally or internally after sterilization and appropriate
cooling, they should be considered contaminated. In addition to
moisture, packages should also be inspected for damage (e.g., tears,
stains, or improper seals). If such packs are found, they should be
reprocessed.
PACKAGING MATERIALS: There are several choices in methods to
maintain sterility of surgical instruments, including rigid containers,
peel-open pouches (e.g., self-sealed or heat-sealed plastic and paper
pouches), roll stock or reels (i.e., paper-plastic combinations of tubing
designed to allow the user to cut and seal the ends to form a pouch)
and sterilization wraps (woven and nonwoven). The packaging material
must allow penetration of the sterilant, provide protection against
contact contamination during handling, provide an effective barrier
to microbial penetration, and maintain the sterility of the processed
item after sterilization. In central processing, double wrapping can be
done sequentially or non-sequentially (i.e., simultaneous wrapping).
Wrapping should be done in such a manner to avoid tenting and gapping.
LOADING: Loading procedures must allow for free circulation of steam
(or another sterilant) around each item. There are several important
basic principles for loading a sterilizer: allow for proper sterilant
circulation; perforated trays should be placed so the tray is parallel
to the shelf; nonperforated containers should be placed on their edge
(e.g., basins); small items should be loosely placed in wire baskets; and
peel packs should be placed on edge in perforated or mesh bottom
racks or baskets.
STORAGE AND HANDLING: Safe storage times for sterile packs vary
with the porosity of the wrapper and storage conditions (e.g., open
versus closed cabinets). Heat-sealed, plastic peel-down pouches and
wrapped packs sealed in 3-mil (3/1000 inch) polyethylene overwrap
have been reported to be sterile for as long as 9 months after
sterilization. Supplies wrapped in double-thickness muslin comprising
four layers, or equivalent, remain sterile for at least 30 days. Any item
that has been sterilized should not be used after the expiration date has
been exceeded or if the sterilized package is wet, torn, or punctured.
Aseptic technique is used to prevent contamination following the
sterilization process. Sterile supplies should be stored far enough from
the floor (8 to 10 inches), the ceiling (5 inches unless near a sprinkler
head [18 inches]), and the outside walls (2 inches) to allow for adequate
air circulation, ease of cleaning, and compliance with local fire codes.
Sterile supplies should not be stored under sinks or in other locations
where they can become wet. Closed or covered cabinets are ideal but
open shelving may be used for storage. Any package that has fallen
or been dropped on the floor must be inspected for damage to the
packaging and contents (if the items are breakable). If the package is
heat-sealed in impervious plastic and the seal is still intact, the package
should be considered not contaminated. If undamaged, items packaged
in plastic need not be reprocessed.
BIOLOGICAL INDICATOR TESTING: The biological indicator (BI) test, the
most widely accepted method for monitoring steam sterilization, also
known as the spore test, provides a direct assessment of the sterilizer’s
lethality by killing highly resistant bacterial spores. Note that BIs only
test one aspect of instrument reprocessing. Biological indicators are
recognized by most authorities as being closest to the ideal monitors of
the sterilization process they measure the sterilization process directly
by using the most resistant microorganisms i.e., Bacillus spores, and
not by merely testing the physical and chemical conditions necessary
for sterilization.
CHEMICAL INDICATOR TESTING: Chemical indicators are convenient,
are inexpensive, and indicate that the item has been exposed to the
sterilization process. 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
colour 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. An air-removal test
(Bowie-Dick Test) must be performed daily in an empty dynamic-airremoval
sterilizer (e.g., pre-vacuum steam sterilizer) to ensure air
removal.
CONCLUSION
Sterility assurance practices require a comprehensive program that
ensures operator competence and proper methods of cleaning and
wrapping instruments, loading the sterilizer, operating the sterilizer,
and monitoring of the entire process. Together, these methods will
provide sterility assurance and peace of mind regarding reprocessed
instruments.
REFERENCES
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4. Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic
Infectious Diseases (NCEZID), Division of Healthcare Quality Promotion (DHQP) Sterilizing
Practices: Guideline for Disinfection and Sterilization in Healthcare Facilities (2008).
Accessed 12th October, 2020.
5. Kelli C. Mack, and Daniel A. Savett (2016). Assurance in Dental Instrument Reprocessing.
Accessed 15th October, 2020.
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