History Definition and Terms Materials to sterilize Preparation Sterilization methods and uses Methods of sterilization Methods of monitoring sterilization Merits / demerits

1. Sterilization
Beza Yasab

2. outline
• Objective
• History
• Definition and Terms
• Materials to sterilize
• Preparation
• Sterilization methods and uses
• Methods of sterilization
• Methods of monitoring sterilization
• Merits / demerits

3. objective
• Take a glance on the history, definition and
some terms used in sterilization
• Know phases before sterilization of surgical
instruments.
• Revise and apply sterilization methods
• Understand why sterilization is of much
importance in Surgery.
• Appreciate advantages and disadvantages of
sterilization

4. History
ANCIENT
• Burning chemicals to allow fumes to deodorize
and disinfect.
• Poet Homer-Odyssey _ Sulfur(SO2): purification.
• Mosses_ purification by fire
• Aristotle_ boil drinking water and burry waste.
• Hippocrates _ boiled water for irrigating wound.

5. MODERN
• 1775, Spallanzani _ boiling of microbes in a
sealed flask for 1hr
• 1880, ‘’Chamberland’s autoclave’’- 1st steam
sterlizer
• 1885, Schimmelbusch_ steam sterilization of
surgical dressings
• 1963, Glutaraldehyde_ 1st liquid chemical
sterilizer as a sterilant for heat-sensitive
instruments.

6. Definition and some terms
DEFINITION
• Sterilization is destruction of all mo.s,
including spores, on inanimate surfaces; the
destruction of all mo.s in or about an object,
as by steam (flowing or presurized), chemical
agents (alcohol, phenol, heavy metals,
ethylene oxide gas), heavy electron
bombardment or UV radiation.

7. TERMS
• Sterile:item(s) that have been rendered free of all
living mo.s, including spores
• Sterile field: specified area, usually the area
immediately around the patient, that is
considered free of mo.s
• Surgically clean:items mechanically cleaned and
chemically disinfected but not sterile
• Terminal sterilization:to render items safe to
handle by sterilization

8. Materials to be Sterilized
Critical Items
confer a high risk for infection if they are
contaminated with any microorganism
Semi-critical Items
Items contact mucous membranes or non-intact skin.
Non critical Items
Items are those that come in contact with intact skin
but not mucous membranes

9. Preparation for sterilization

10. • After decontamination,
1.Inspection _ for blood and soil remnants
2.Reassembly
3. preparation _ ensuring that:
The sterilant comes into contact with all
surface areas.
 The instruments are positioned in a
protective manner until they are used.
The instruments are evenly distributed.
• Packaging (pack, sterilization wrapper, bag, or
accessories)

11. Sterilization methods and uses

12. Methods of Sterilization
• The various methods of sterilization are:
• 1. Physical Method
a. Thermal (Heat) methods
b. Radiation method
c. Filtration method
• 2. Chemical Method
a. Gaseous method

13. The physical methods
Thermal
• most widely used and reliable
• Inexpensive, dependable
• Enzymes and other essential cell constituents.
• Types:
i) Dry Heat (160-1800˚C) Sterilization for
thermo stable products
ii) moist heat (121-1340 ˚C) sterilization is used
for moisture- resistant materials.

14. • Efficiency depends on:
i) the degree of heat,
ii)the exposure time and
ii) the presence of water.
• In the presence of water much lower
temperature and time of exposure are
required to kill microbe than in the absence of
water.

15. i) Dry Heat Sterilization
Ex:1. Incineration
2. Red heat
3. Flaming
4. Hot air oven
ii) Moist Heat Sterilization
1.Dry saturated steam – Autoclaving
2. Boiling water/ steam at atmospheric
pressure
3. Hot water below boiling point

16. Saturated Steam under Pressure:
• Primary method in the OR and by sterile
processing departments.
• Principle:
• moist heat in the form of saturated steam
under pressure within an enclosed
environment.
• items that are not heat, moisture, or
temperature sensitive.

18. Factors affecting the outcome of sterilization include:
• Type and number of organisms
• Concentration of disinfecting agent
• Presence of organic material (e.g., serum, blood , pus)
• Nature (composition) of surface to be disinfected
• Contact time
• Temperature
• . pH
• Biofilms
• Compatibility of disinfectants and sterilants

19. • Cycles depend on type of the medium i.e.
Gravity Air Displacement Sterilizer or
Prevacuum Steam Sterilizer(added 1st &2nd
prevacume phases) for solid objects:
• ||Condition||ExposureExhaustDry cyc.
• A typical liquid sterilization cycle is as follows:
• ConditionExposureExhaust.

20. • Moisture plays an important part in the steam
sterilization of porous and nonporous items.
The thermal destruction of microbes is the
result of the denaturation and coagulation of
the enzyme-protein system within the cells.
Moisture acts as a catalyst and the
coagulation can occur at lower temperatures
as compared to the much higher
temperatures required in the absence of
moisture.

21. • Air must be completely removed from the
chamber for efficient sterilization of materials
within, otherwise since air and steam don’t
mix, we will have:
1. Temperature variations within the chamber
2. Heat not transferred to and condensation
on the surface of item
• Air is removed either by gravity displacement
or by a prevacuum cycle.

22. • Sterilizing Liquids:
• Steam does not penetrate the liquid; rather it
heats the liquid to 250°F. Several minutes are
needed for the liquid to attain this temperature
and the volume of liquid in the container dictates
the exposure time.
• Flash Sterilization:
• Sterilizing unwrapped items, such as when an
instrument has been dropped or of immediate
need during a surgical procedure.

23. • Prepackaged products for use in the OR and
hospital environment.
• Irradiation thermal and chemical
energydeath of all microbes and spores by
disrupting the DNA
• Gamma rays or beta particles
• times vary depending on the source.
IONIZING RADIATION

24. FILTRATION
• Does not destroy but removes the mo.s. It is
used for both the clarification and sterilization
of liquids and gases
• Prevent the passage of both viable and non
viable particles.
• The major mechanisms of filtration are
sieving, adsorption and trapping within the
matrix of the filter material.
• Ex:HEPA FILTERS

25. • Sterilizing grade filters are used in the
treatment of heat sensitive injections and
ophthalmic solutions, biological products and
air and other gases for supply to aseptic areas.
• Venting systems on fermentors, centrifuges,
autoclaves and freeze driers. Membrane filters
are used for sterility testing

26. GAS STERILIZATION
• Gas sterilization is used to process materials that
cannot be processed using steam sterilization,
such as heat- or moisture-sensitive materials.
• Ethylene oxide _ the predominant chemical used,
but new technologies are emerging, including
plasma and ozone sterilization processes. It takes
16hrs; produces CFCs.
• In instances where steam sterilization has been
impractical, EtO has been an accepted chemical
in sterilizatiation.

27. • Plastics, rubber, and other materials that would
be damaged by the high temperatures of steam
sterilization
• It does not corrode metal and passes through
woven materials just like steam.
• in a closed room specifically designed for EtO
sterilization.
• factors required for proper EtO sterilization
include EtO gas concentration, Temperature,
Humidity, and Time (lower at high temp.)

28. Advantages and disadvantages of gas
sterilization

29. LIQUID CHEMICAL
• Can be used as high-level disinfectants
• peracetic acid, used in the tabletop Steris
process, and gluteraldehyde.
• The peracetic acid systems _ rapid processing
times and maintain a lower instrument
inventory, particularly for endoscopic
instruments.
• Higher inventory of endoscopic equipment
with the use of gluteraldehyde.

30. Methods of monitoring of sterilization
• Mechanical, chemical, and biological
indicators
• MECHANICAL-to control parameters .
Includes: records, clock, and gauges
• CHEMICAL-are internal or external and
monitor exposure . It consists paper
chemically treated with a dye that changes
color in the presence of temperature or the
sterilant.

31. • External- autoclave tape. it is used as a
package closure to keep wraps in place. it is
available for steam and EtO.
• Internal- commercial strips of paper that have
been impregnated with the thermochromic
(color-changing) ink.

32. • Biological_ a device that contains a known
number and specific type of microorganisms that
are killed when exposed to the sterilizing
conditions.
• the only test that assures items are sterile and
the conditions necessary for sterilization have
been met. The BI for steam sterilization contains
the bacterial spore B. stearothermophilusand
Bacillus subtilisis used for EtO.

33. Merit / Demerits of sterilization

35. 1 Filtration
sterilization
Does not
destroy but
removes the
microorganisms
It is used for both
the clarification
and sterilization of
liquids and gases
as it is capable of
preventing the
passage of both
viable and non
viable particles
Does not
differentiate
between viable
and non viable
particles
This method is
Sterilizing grade filters
are used in the
treatment of heat
sensitive injections and
ophthalmic solutions,
biological products and
air and other gases for
supply to aseptic areas

36. References
• Bob L . Caruthers ;Surgical Technology for the
Surgical Technologist: A Positive Care
Approach 1st ed

37. Thank You!!