SRG 130 Aseptic Technique

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SRG 130 Aseptic Technique

• Sterilization
• Lecture 130-4

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Anonymous

• A good friend- like a tube of toothpaste- comes
  through in a tight squeeze.

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Text

• Surgical Technology, Principles and Practices,
  Chapter 8

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Objectives

• Distinguish between disinfection and
  sterilization
• Define and understand sterility

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Sterilization

• Is the destruction of ALL microorganisms,
  including spores, on inanimate objects
• Sterility is the absence of any living
  microorganism, including bacteria, viruses, and
  spores
• An object is either sterile or not sterile
• All methods of sterilization require three
  elements concentration, time and temperature

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Elements for Effectiveness

• Concentration refers to the amount or percentage
  of sterilization agent used during the process
• Time is the minimum amount of time a sterilizing
  agent must remain in contact with all surfaces of
  the item being sterilized
• Temperature- each agent has an effective
  temperature range that is specific to the
  particular agent

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Considerations Related to the Product

• Bioburden
• Bioresistance
• Heat/moisture sensitivity/product stability
• Bioshedding of the packaging material
• Biostate
• Nutritional/health state of the microbe
• Density of the packaging for the sterilizing agent

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ConsiderationsRelated to the Process

• Temperature
• Time
• Purity of the agent and the air
• Saturation/penetration
• Capacity of the sterilizer
• Humidity
• Pressure

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Methods/Agents for Sterilization

• Variables
• Nature of the item to be sterilized
• Length of sterilization time
• Cost
• Other

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Agents

• Thermal
• Steam under pressure
• Gravity displacement
• Pre-vacuum
• Flash
• Chemical
• EO/ETO- ethylene oxide
• Activated glutaraldehyde
• Peracetic Acid
• Acetic Acid
• Hydrogen Peroxide plasma
• Ionizing Radiation

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Methods of Microbial Destruction

• Denaturation and coagulation of protein
• Oxidation
• Interference with growth and reproduction

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Thermal Sterilization

• Inexpensive
• Dependable
• Destroys all microbes including spores
• Most common thermal method is saturated steam
  under pressure

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Principles of Steam Sterilization

• Boiling point of water is 212 degrees F
• When water exceeds this temperature, it turns
  into steam
• When steam is pressurized, its temperature rises
• Steam under pressure (Moist heat sterilization)-
  moist heat in the form of saturated steam under
  pressure within an enclosed environment
• For items not heat/moisture/pressure or
  temperature sensitive

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Critical Factors

• Steam must be able to penetrate the wrapping
  material and destroy microbes
• Time
• Temperature
• Moisture
• Pressure
• Contact

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Key Terms

• Autoclave- device to accomplish steam or gas
  sterilization
• Sterilant- agent, physical or chemical capable of
  killing all microorganisms including spores
• Sterile- free of all living microorganisms
  including spores
• Sterilization- process by which all
  microorganisms are destroyed including spores
• Sterilizer- machine used in the destruction of
  all microorganisms including spores
  

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Principles ofSteam Sterilization

• Microbes are killed by the combination of two
  factors- moisture and heat
• Temperature- usually 250/270 degrees F heat is
  transferred to objects being sterilized
  increases the time required to achieve
  sterilization
• Saturation- steam that contains the maximum
  amount of water vapor 2-3 liquid water
• Dry steam is
• Moisture- acts as a catalyst and coagulation can
  occur at lower temperatures
• Condensation- the return of steam back into
  water enables the steam to generate heat needed
  for sterilization

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Principles

• Air- must be completely removed from the chamber
  for efficient sterilization
• Steam displacement of the air allows the steam to
  make complete contact with the surface of items
  to be sterilized
• Air and steam do not easily mix resulting in
  temperature variations within chamber and heat
  not transferred to and condensation on the
  surface of items
• Air is removed either by gravity displacement or
  by a pre-vacuum cycle

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Effectiveness

• Temp, pressure, and moisture level reached in the
  sterilization cycle
• Type of microbe to be destroyed spores
• The number of microbes or bioburden on the items
  to be sterilized
• Amount of soil present on items
• Instruments with box locks, crevices and
  serrations provide hiding places instruments
  must be opened to expose all surfaces to steam

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Contact Reasons for Failure

• Obstructed strainer
• Containers positioned incorrectly on
  sterilization cart
• Items inadequately cleaned
• Wrapped packages placed too close together on
  sterilization cart
• Instrument trays, packs etc wrapped too tightly

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Time

• D-values- amount of time required at any
  temperature to kill 90 of the microbes
• Bacillus stearothermophilus- highly resistant,
  nonpathogenic microorganism used as the
  biological indicator for steam sterilization
• D-value of 2 minutes at 250 degrees F or 20
  seconds at 270 degrees F
• To allow for a wide margin of safety
  B.stearothermophilus has been assigned six
  D-values

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Moisture

• Allows the use of a lower steam temperature
• 12 minutes compared to 6 hours with dry heat
• Saturation is directly related to variations in
  temperature and pressure

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Parts of a Steam Sterilizer

• Control panel with graph
• Door handle
• Outer metal jacket-like chamber built around the
  inner chamber
• Inner chamber
• Series of filters
• Temperature measurement of steam sensor

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Components of a Steam Sterilizer

• Source of steam- generate own steam or rely on
  steam from outside source
• Preheat metal jacket build around chamber for
  outside sources reduces total cycle time
• Three main pipes
• A pipe with inline filters to bring steam to the
  sterilizer and the chamber
• A drain pipe for steam, air and water from the
  chamber
• A pipe to deliver filtered air to the chamber at
  eh end of the cycle

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Types of Steam Sterilizers

• Gravity Air Displacement Sterilizer- using
  gravity to remove air from the inner chamber
• Prevacuum Steam Sterilizer- uses vacuum in two
  cycles to remove air from the inner chamber

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Gravity Displacement Sterilizer

• Uses the principle that air is heavier than steam
• Sterilizer constructed so that steam is injected
  from an outer jacket-type chamber into the inner
  chamber
• Air is pushed downward by gravity through a
  temperature-sensitive valve
• When the sterilization temperature is reached,
  the valve closes

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Gravity Air Displacement Sterilizer

• Cycle
• Condition cycle- reach preset temp timing begins
• Exposure cycle
• Exhaust cycle
• Dry cycle

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Prevacuum Steam Sterilizer

• A vacuum pump removes air
• Reduces total cycle time
• Typical cycle
• Prevacuum cycle
• Conditioning cycle
• Second prevacuum cycle
• Exposure cycle
• Exhaust cycle
• Dry cycle

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Advantages of the Prevacuum

• Increases speed of operation and lowers total
  cycle time
• More efficient at removing air than gravity
  displacement
• Not as dependent on the positioning of load
  contents as gravity sterilizer
• Condensate is produced during preconditioning
  phases, reducing cycle time

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Flash Sterilization

• Process of sterilizing unwrapped items which have
  been dropped during a surgical procedure
• Items must be decontaminated and cleaned
• Items must be disassembled
• Placed in a peforated instrument tray
• Can be performed in a gravity displacement or
  prevacuum sterilizers

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Steam Sterilization Minimum Exposure Cycle
Standards

• Surgical Technology for the Surgical
  Technologist, Chapter 7
• Page 162 Table 7-15 Minimum Steam Sterilization
  Exposure Cycle Standards
• Page 163 Table 7-16 Flash Sterilization Times
  and Temperatures