Module 10 : Types of Dry Heat Sterilization, Sterilization
Validation and Chemical Indicators for Sterilization
Dr. Badria Mahrous Abd El-Hammed Mohammed
Assistant professor of Medical Surgical Nursing
Faculty of Applied Medical Sciences, Nursing Department
Al-Baha University – KSA
bmahrous@bu.edu.sa
Low Temperature Sterilization Considerations
• Temperature involved: is the method compatible with
the devices being processed?
• Cycle time: will this fit with the workload/turnaround
time of the CSSD?
• Availability of equipment
• Validation requirements
• Compatibility with devices being processed
Low temperature sterilization methods: Important Tips
It have been increasingly used in CSSD due to the increase
use of delicate sensitive to heat surgical instruments and
devices.
Ethylene Oxide (EO), Hydrogen Peroxide (H2O2) and Ozon
are the most commonly low temperature Sterilizers used in
CSSD worldwide.
Low temperature sterilization methods: Important Tips
Low temperature sterilization
involves using chemicals with
potential toxic properties.
CSSD Specialists must be fully
trained on how to use these
types of sterilizers in optimum
safe and effective manner.
Types of low temperature sterilization:
1/ Ethylene Oxide (EO)
These sterilizers operate at 37 ºC or 55 ºC and duration time of 8-12
hours so are suitable for heat sensitive items.
They are used commercially and in some hospitals, but are banned in
hospital settings in many countries due to the costly health and safety
requirements for operating and housing these machines.
The EO process works well for heat sensitive equipment such as
invasive flexible endoscopes, and cardiac and ophthalmic devices,
but requires very long cycle durations to allow of adequate
aeration.
A typical cycle consists of:
• Load pre-conditioning—vacuum and humidification
• Sterilizing gas exposure
• Gas exhaust and air purge
2/ Gas plasma
This method is also suitable for heat
sensitive items such as flexible
endoscopes or complex laparoscopic
instruments as the operating
temperature is 45 less than 55 ºC.
The cycle time can vary from 45–75-
24-75 minutes but no aeration is
required as the byproducts are non
toxic(water vapor and oxygen).
A typical cycle consists of:
A vacuum to remove air,
Injection and diffusion of the Hydrogen Peroxide
Gas plasma generation via radio (RF) ENERGY for a
defined sterilization time
Venting of filtered air into the chamber through High
Efficiency Particulate Air (HEPA) filter
3/ Vaporized hydrogen Peroxide
It is a sterilization method utilizes
hydrogen peroxide to kill wide
spectrum of microorganism through
oxidization. The cycle takes 28-55
minutes at less than 50 ºc.
lumened and non- lumened
instruments can be sterilized in
these machines based on the
program you select.
Typical cycle consist of:
Conditioning to remove air and moisture
Leak test
Injection of Hydrogen Peroxide to the chamber for
sterilization
Aeration
N.B:
Cellulose – containing packaging material can not be used in
Hydrogen peroxide sterilizers as the absorb the peroxide and
interrupt effective sterilization.
4/ Ozon Sterilization
4/ Ozon Sterilization
This low temperature sterilization system eliminates the
need for purchasing a sterilant by generating O3.
The processing cycle takes 4 hours and 30 minutes at 30.8-
36 cº.
The method must be approved by the medical device
manufacturer for sterilization.
Typical cycle consist of:
Vacuum and humidification
Injection of the O3
Sterilization
Ventilation
Sterilization Validation
Sterilization Validation
Validation establishes documented evidence providing a high
degree of assurance that a specific process will consistently produce
an end result meeting specifications and quality attributes by:
Measuring the critical parameters of the process such as
temperatures, time and pressure, load configuration (contents) and
documentation of the results.
Assuring all components of the process such as proper cleaning,
functionality, packing, wrapping are met.
Proper protocol management
Steam Sterilizer Testing
Routine testing of sterilizers should be performed
daily, weekly, quarterly and yearly as per ISO 17665.
Steam Sterilizer Testing
Daily
Bowie-Dick test for steam penetration (also known as air removal
test).
Bowie-Dick test for steam penetration
Steam Sterilizer Testing
Weekly
• Safety checks
• Vacuum leak test
• Air detector function test (if equipped)
• Automatic control test
• Bowie-Dick test
Quarterly
• All the above plus
• Thermometric test,
• Surgical instrument calibration verification
Steam Sterilizer Testing
• All the above plus
• Steam quality tests
- Non-condensable gas
- Steam superheat
- Steam dryness
- Endotoxins
• Testing of dry heat sterilizers
Yearly • Thermocouple test
• Biological indicators
• Chemical indicators
Ethylene Oxide Sterilizer Testing
- Physical parameters i.e. temperature, pressure and humidity
- Biological indicators
- Chemical indicators
Chemical indicators: change color Biological indicators
Gas Plasma Sterilizer Testing
• Physical parameters i.e. temperature, pressure and humidity
• Biological indicators
• Chemical indicators
Chemical Indicators for Sterilization
ISO 11140 classifies chemical indicators into six types, according to
their intended use. They are further subdivided by their indicated
sterilization process. The classifications describe the characteristics and
intended use of each type of indicator and has no hierarchical
significance.
Chemical Indicator
Can detect incorrect packing
Incorrect loading, sterilization malfunction
Chemical Indicator Types
Types Purposes
Type 1: Process These Indicators are intended for use with packs or containers to
indicators indicate that they have been directly exposed to the sterilization
process and to distinguish between processed and unprocessed
units.
reusable medical devices are sterile.
Type 2: Indicators for These Indicators are intended for use in specific test procedures,
use in specific test such as the Bowie-Dick test for air removal.
These Indicators are designated to react to one of the critical
Type 3: Single sterilization variables, e.g., time and temperature, and are intended
variable Indicators to indicate exposure to a predetermined sterilization process
variable, e.g.134°C
Chemical Indicator Types
Types Purposes
These Indicators are designated to react to two or more of the
Type 4: Multivariable critical sterilization variables, e.g., time and temperature, and are
indicators intended to indicate exposure to predetermined sterilization
process
These Indicators designated to react to all critical variables of the
sterilization process, e.g., time, temperature and presence of
Type 5: Integrated
moisture, and are intended to be equivalent to or exceed the
Indicators
performance requirements given in the ISO 11138 series for
biological indicators
These Indicators are designated to react to all critical variables of
the sterilization process, e.g., time, temperature and presence of
Type 6 Single variable moisture, and are intended to match the critical variables of
Indicators specified sterilization cycles
Any Question????
