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STERILIZATION
HEALTHCARE
Steam Sterilizers Operation
and Preventative
Maintenance
Sterilization Fundamentals
Sterilization: A process by which all forms of
microbial life including bacteria, viruses,
spores, and fungi are destroyed
Note: In a sterilization process, the nature of microbial
death is described by an exponential function. Therefore,
the presence of microorganisms on any individual item can
be expressed in terms of probability. While this probability
can be reduced to a very low number, it can never be
reduced to zero. (ANSI/AAMI ST46)
General Terminology Review
Sterility Testing: Product is inoculated directly into
growth medium.
Process Monitoring: Use of mechanical, biological and
chemical indicators to monitor critical sterilization
parameters.
Parametric release: Declaring product sterile based on
records demonstrating that the process parameters
were delivered within specified tolerances. This method
does not include the use of Biological Indicators.
General Terminology Review
• Bio Burden
– # of microorganisms on a contaminated item
• Reduction of Bio Burden:
–
–
–
–
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Hand washing; soap and water
Chemical; high level disinfection
Sanitization
Decontamination
Disinfection
What is a Steam Sterilizer ?
Technology Fundamentals
Steam sterilizers for healthcare have one primary
purpose:
Render instruments
sterile for re-use in a
surgical setting
Sterilization Fundamentals
Steam Sterilizers
– Temperatures ranging from 121-134C at pressures of 15-30
psi are generally recommended to sterilize wrapped or
unwrapped surgical instruments.
– Why Steam?
Easy to
Control
Inexpensive
Non
Toxic
Highly
Effective
Readily
Available
Sterilization Fundamentals
Two Types of Steam Sterilizers:
Vacuum: used for large volumes
of wrapped surgical instruments
Gravity: used for individual
unwrapped surgical instruments
Sterilization Fundamentals
Alternate Sterilization Technologies:
ETO (Ethylene oxide)
Gas Plasma
Low temp.
Ozone
Dry Heat Sterilizers
Ultra High
temp.
Sterilization Fundamentals
• Healthcare Steam Sterilizers
– Typical Dimensions:
•
•
•
•
•
•
16“ wide x 16" high x 16" long (gravity or vacuum)
small
20“ wide x 20" high x 38" long (gravity or vacuum)
24“ wide x 36" high x 36" long (usually vacuum)
24“ wide x 36" high x 48" long (usually vacuum)
medium
24“ wide x 36" high x 60" long (usually vacuum)
Floor loader: 26.5 x 62 x up to 76”
large
Sterilization Fundamentals
• Steam Sterilizers
– Smaller sterilizers: instruments
inserted individually for quick
sterilization
– Larger sterilizers (36" or larger):
can hold entire “carriage” of
instruments for sterilizing
– Floor loader: rises to floor level
where entire cart and carriage
of instruments are inserted for
sterilization
Sterilization Fundamentals
Factors Affecting Sterilization
• Time
– Sterility Assurance Level (SAL) 10-6
– One survivor out of a million (infectious organisms)
• Temperature
– 250F/270F/275F
• Moisture
– Required to coagulate protein
– However, steam quality requires a maximum vapor
content of 3%
Sterilization Fundamentals
Steam Quality Through RO Water
• Reverse-Osmosis (RO): the process of squeezing water
through a semi-permeable membrane.
• RO will separate pure water molecules from dissolved solids
such as Calcium, Sodium and Iron
• Chlorine, Nitrates and Nitrites are removed in the pre-filtration
process.
Sterilization Fundamentals
Benefits of RO in Steam Generation
( Clean Steam)
Balances pH
Reduces downtime
Reduces costly repairs
Extends useful equipment life
Removes hardness
Improves equipment reliability
Sterilization Fundamentals
Other Factors Affecting Sterilization
Proper sterilizer design and use to achieve
time and temperature
Sterilizer area design and quality utilities
feeding unit
Bio Burden reduced prior to sterilization
Adequate contact of the sterilant for all
surfaces
Sterilization Fundamentals
Why is air removal important?
Air and steam do not mix
Air inhibits steam contact
Air is 1.6 times denser than steam
Steam condenses on cool goods
Loading and load size
Packs must be dry
Sterilization Fundamentals
•
•
Decimal Reduction Value (DValue)
• The exposure to sterilant
required to reduce the
population of test organism by
90% (one logarithm) under
stated conditions.
Sterility Assurance Level (SAL)
• Probability of a non-sterile unit.
As a minimum sterilization
cycles are designed to provide
a 1 in a million chance of a
non-sterile unit. SAL = 10-6
1000000
100000
10000
1000
100
10
1
0.1
0.01
0.001
0.0001
0.00001
0.000001
No
D-value
S
K
10-6
exposure
SAL
SAL
Sterilization Fundamentals
More about D-Value and SAL...
The SAL is extrapolated from the survivor curve
based on the D-value of the Biological Indicator and
exposure time.
Traditional cycle development is driven by
determining the time for complete kill of a 106 BI and
double the cycle time to achieve SAL of 10-6
Sterilization Fundamentals
3 Primary Factors of Sterility Assurance
1. Process Control - Reproducible and controlled conditions
2. Process Monitoring - Biological indicators, chemical
indicators, mechanical gauges, cycle charts or printouts,
etc.
3. Good Manufacturing Practices (GMP) - Includes record
keeping, inspection of materials, process validation and
equipment maintenance and calibration
Complete sterility assurance can only be achieved by testing
each item processed - a destructive and impractical
procedure.
Sterilization Fundamentals
Sterilization Cycle Talk:
Getinge Vacuum Cycle
The actual sterilizer cycle as logged in our digital software solution, T-Doc
Sterilizer Maintenance
• Why should we have preventative maintenance on a
sterilizer?
• What happens in the sterilizer during a cycle?
• What should I look for the start of my shift?
• What can effect the sterilization process that I can control?
• What can effect the sterilization process that I can not control
directly?
Sterilizer Maintenance
Why should we have preventative maintenance on a sterilizer?
1. Keeps the machine running to manufactures recommended
specifications
2. Minimizes the amount of downtime
3. Provides assurance that the unit is running optimally
4. Extends the life of the sterilizer
5. Ensures the unit is safe for operating- no chamber cracks, faulty
valves etc
6. Ensures the appropriate sterility is met by the system as it was
intended to provide at time of manufacturing
Sterilizer Maintenance
Sterilizer Video - What Happens during a sterilization cycle
Sterilizer Maintenance
What should I look for when start of my shift?
1.
2.
3.
4.
5.
6.
Ask the person who you are replacing if there have been any
autoclave problems during their shift. Keep a log book of events for
of date, time, unit number, copy of print out and what occurred.
Check gasket for wear and tear on the machines you are using
Check chamber and drains to ensure no paper or items are
obstructing the drain
Check the printer paper to ensure you have enough
Verify you have appropriate materials for logging, biological tests and
bowie dick tests if required for your shift
Check to see if you’ll be required to process stat loads etc during
your work period to allow you to manage the flow
Sterilizer Maintenance
What can effect the sterilization process that I can control?
1. The proper loading and spacing of the sterilizer cart/trolley
2. Using the proper packaging material
3. Checking to ensure drain is not plugged and is cleaned at regular
intervals
4. Cleaning of the chamber and carts at regular intervals
5. Proper cool down area away from air conditioning
6. Items being sterilized are dry, containers, blue silicone liners dry as
well as plastic bowls etc
7. Being able to properly read the tests – BD, Biological, Indicators,
Integrators etc
8. Prequalification of the units after a major repair of the sterilizer
Sterilizer Maintenance
What can effect the sterilization process that I can not control
directly?
1.
2.
3.
4.
5.
6.
7.
The sterilizer malfunctioning
Steam supply staturation drops below 97%
Water pressure drops
Electrical power failure
Failure of BD Test – redo test and check results – 2nd failure
contact service for repair
Consistently wet steam or dirty steam – (tea effect) – You can
perform a warm-up prior to the bowie dick test and this will help
remove as much moister from the lines as possible.
Dirty steam – you can have filters placed at the feed of the units to
filter out debris and some of the chemicals used by maintenance
to clean the steam lines
Sterilization Fundamentals
Who establishes the proper
sterilization parameters for
reusable medical devices?
Answer: The responsibility for safe and effective
sterilization of reusable medical devices is the shared
responsibility of both manufacturers, and users of the
devices. Reichert & Young, p. 132
Summary - Key Learnings
• Reviewed General Terminology
• Reviewed the Sterilization Fundamentals
•
Reviewed Sterilizer Maintenance and areas that
can be controlled by MDRD employee
Sterilizer Maintenance
Questions?
Thank you for your Time
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