OF STERILIZATION METHODS |EtO
CAN YOU STERILIZE WITH ETO MICRO-DOSE ?
EtO-MD Sterilization and Autoclave Sterilization Complement each
Steam autoclave is
the oldest and safest sterilization method
in the medical equipment industry, its only drawback being
the harsh conditions it imposes on the items being sterilized,
by exposing them to extreme heat, pressure and humidity for 10-60
minutes. The steam reaches 121-148°C
(250-300°F) in the pressure chamber at 15 P.S.I. The sterilization
period is dependent on the temperature and size of load.
autoclave cycles allow the user to customize the sterilization
cycle for items such as hard items, wrapped items, liquids in
vented containers, waste, and glassware. The fastest steam sterilization
used is flash sterilization and it can be accomplished using
either gravity-displacement, or pre-vacuum cycles. It is generally
a high-speed steam sterilization of an unwrapped instrument or
device for 3 to 10 minutes in 132°C
saturated steam. This
type of sterilization is only intended for use in hospital operating
rooms for urgently needed equipment.
In the steam autoclave process, microorganisms
are killed by heat, and this is accelerated by the addition of
moisture. Steam by itself is not sufficient for sterilization,
and pressure that is greater than atmospheric is needed to increase
the temperature of steam for thermal destruction of microbial life.
Steam, for a specified time at required temperature, must penetrate
every fiber and reach every surface of items to be sterilized.
When steam enters the sterilization chamber under pressure;
condenses upon contact with cold items.
condensation frees heat, simultaneously heating and wetting all
items in the load, thus providing heat and moisture.
thing will be killed when exposed to saturated steam at 120°C
longer than 15 minutes. As the autoclave's temperature is increased,
time may be decreased. A minimum temperature-time relationship
must be maintained throughout all portions of load to obtain
effective sterilization. At the end of the cycle, re-evaporation
of water condensate must effectively dry contents of the load
to maintain sterility.
Steam autoclave is used mostly for surgical
instruments. This method is not well suited for heat sensitive
materials and instruments. Many surgical instruments are not designed
to withstand prolonged heat and moisture of the steam sterilization
process. This leads to the search of an alternative sterilization
method: EtO sterilization.
Ethylene Oxide ( EtO) Gas
Chamber EtO Sterilization
Oxide (EtO or EO) gas was introduced in the 1950’s, and
it is an effective, low temperature
chemical sterilization method. It also takes longer than
typically, 16-18 hours for a complete cycle. Temperatures reached during
sterilization are usually in the 50-60°C range. Ethylene
oxide ( EtO) is a chemical agent that
kills microorganisms, including spores. EtO gas
must have direct contact with microorganisms on the items to be
aeration time may be long and is needed to make sterilized items
safe for handling
and patient use.
In general, EtO gas
is a reliable and safe agent for sterilization when handled properly.
OSHA also has
special handling guidelines for Ethylene Oxide.
used to sterilize items that are heat or moisture sensitive,
especially when large loads are possible, in order to benefit
from economies of scale. Particlularly
suited for semi-industrial applications.
System: EtO micro-dose sterilization
order to fill the void between the chamber sterilization and
the autoclave sterilization system, Andersen developed in the
late 50's the gas-diffusion sterilization method whereby a
specially designed bag is used in order to eliminate
the need to flood a chamber with EtO. This has the effect
of minimizing the use of gas and tremendously reducing the economic
and environmental costs associated with the traditional process. This
system has been used extensively worldwide among various user
groups such as hospitals, veterinarian practices, dental practices
and medical device manufacturers.
Due to its
handling ease, affordability and tremendous versatility,
gas-diffusion technology has emerged as an all-purpose, widely
accepted sterilization method especilly suited for expensive
medical equipment (endoscopes, electronics, fiber-optics, prosthesis,
etc.), disposable items, delicat items (paper, plastics, rubber)
that heat would damage, and all sorts of medical devices. For
a more complete list of the items that can be sterilized using
gas-diffusion sterilization, see the alphabetical product
list. Also see Andersen's
EtO vs. Autoclave Comparison Table
EtO micro-dose sterilization
|3.5 h. up
||16 h. up
materials excluding liquids, food or drugs. You can sterilize
plastic, paper, electronics, etc.
excluding liquids, food or drugs. You can sterilize plastic,
paper, electronics, etc.
||Stainless steel, pyrex, selected rigid materials
Typical practice type
|Clinical, hospital, dental, veterinarian, medical device
medical device manufacturing
||Clinical, hospital, dental
Operator skill level
|None if abated
||High energy use
System Price range
-Sterilizer virtually anything
- Can sterilize and package in one step
-Minimal gas use
-Sterilizer virtually anything
- Relatively small loads
- Requires special safety handling
- Not suited for liquids, drugs nor foods.
special safety handling
- Relativel;y small loads
Wets and heats
-Not suited for heat sensitive materials
Excellent as general-purpose sterilizer.
Great for scopes
and high-end medical equipment.
|Cost-effective sterilization for large loads.
||Excellent for quick sterilization of metal instruments