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sterilization - PowerPoint

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									Surgical Preparation

            Lobna El Fiky
          Assistant Professor of
           ORL, H&N surgery
          Ain Shams University
Historical perspectives

   Antiseptic = Greek for “against putrefaction”
   Accidental observation of certain substances
    stopped putrefaction of meat…
   Mercuric Chloride: Arabian physicians in
    Middle Ages
   Tincture of iodine: 1839
   Pasteur‟s publication: 1863: microbial origin
    of putrefaction
Historical perspectives

   As often in history of medicine: Change of
    practice depended on the persistence of
    John Lister 1870,
   He introduced vigorous application of phenol
    in surgery, for dressing wounds, for
    sterilization of instruments

   It is the process that destroys all microorganisms
    (including bacterial microspores).
   The skin could never be sterilized without its own

   A process which destroys only the vegetative
    forms of organisms =basically clean.
   A disinfectant (germicide, antiseptic): any
    chemical substance with either a bactericidal or
    a bacteriostatic action.
   Antiseptic -- Agent applied to living tissue
   Disinfectant -- Agent applied to inanimate
Surgical Disinfection

   This is an essential part of a programme for
    the control of infection.
   High Risk Items: as they come in close
    contact with broken skin or those that breach
    mucous membranes or are introduced into a
    sterile cavity.
Requirements for decontamination

The basic requirements for good decontamination
  practice are:
 A Management control system;
 Appropriate facilities;
 Appropriate equipment;
 Properly trained and supervised staff;
 Ensuring that single use medical devices are not
 Records of decontamination are kept.
Methods of Disinfection

   Physical: The most important as they can be relied on to
    ensure the sterilization of articles used in the treatment
    of patients:
    –   Thermal: Heat or Steam
    –   Radiation: infra-red radiation, - rays,  particles
    –   Filtration:utilizing filters capable of screening out microorganisms
   Chemical: Less effective, used for personnel
    –   Organic
    –   Inorganic
   Gaseous disinfectants: very efficient, not routine
    –   Formaldehyde gas
    –   Ethylene oxide

   Cleaning is vital prior to any decontamination
   „Detergent‟ removes the nutritive material on
    which bacterial survival and multiplication
    may take place.
   This reduces the number to a level which is
    not harmful for health.

   Effective cleaning to remove protein from
    medical devices is paramount (agents such as
    CJD are not inactivated by heat).
   Dismantle or Open the instrument to be cleaned
   Friction for 2-3 minutes
   Brush, Wipe, Agitate, Irrigate, jet wash or
    hand spray the item to dislodge and remove all
    visible soil
   Rinse the item thoroughly with clean water
   Drying
        Physical Methods of Disinfection

                       DRY HEAT
   Kills by Destructive oxidation of cell constituents
   Surest incineration
   Hot-air oven:
    –   inefficient, poor conductor of heat, penetrates feebly.
    –   160°C for 1 hour: damages fabrics, melts rubber
    –   Used for: Glassware, oily fluids, powders
     Physical Methods of Disinfection

                      MOIST HEAT
    Effective at low temperature, in a shorter period
    of time
   Boiling: 100°C for 30 minutes
   Pasteurisation: 63°C for 30 minutes
   Tyndallisation: steaming for 20 minutes for 3
    successive days
   Steaming under pressure= Autoclaving
Advantages of steam

   Kills by denaturing & coagulating enzymes &
   More rapid (maximum needed time 45mn) & at
    lower temperature
   Condensation of steam leads to liberation of
    latent heat which raises the temperature, and
    gives more penetration
   Half dense as air, so has better penetration
Steam Sterilization: Autoclave

   Principle: An autoclave is a self locking
    machine that sterilizes with the high
    temperature that steam under pressure
    can reach.
   High-vacuum pumps remove as much as
    possible air before the steam is admitted,
    so the required temperature is reached
    very rapidly.
Steam criteria

   Dry: no suspended droplets of water
   Close to its point of condensation: not
   Free from air: as it decreases the temperature
    and the penetration
   Temperature
    –   121°C: 15mn-30mn
    –   134°C: 4-7mn Flashing
Steps of autoclaving

   Water in the surrounding container full and heated
   Articles in cabinet, doors bolted
   Vacuum to evacuate as much air as possible
   Steam is admitted at a high pressure of and when the
    thermometre reaches the required temperature,
    sterilisation begins
   Sterilisation is continued for the required time and then
    the steam is turned off.
   Drying is carried-out by reapplying a vacuum to evacuate
    the steam, introducing dry filtered air into the cabinet (for
    15 minutes).
Efficient Autoclaving
   All instruments must be double
    wrapped in linen or special paper or
    placed in a special metal box
    equipped with a filter before
   The white stripes on the tape change
    to black when the appropriate
    conditions (temperature) have been
   Expiration dates should be printed on
    all equipment packs.
   There should be a uniform
    development of bars throughout the
    length of the strips.
   Ready made plastic bags with strips
    printed with a sensitive ink.
Control of autoclave efficiency

   Bowie-Dick test: Used for high-vacuum autoclaves, Done
    every day:
    –   In the middle of a test pack of towel, a paper on to which a strip of
        a specific tape is put, for testing.
    –   Uniform development of dark color indicates that the steam has
        passed freely and rapidly to the center of the load.
   Biological sterilization indicators: Spores of a non-
    pathogenic organism: Done weekly
    –   They are killed at 121°C after 15 minutes.
    –   Attempts to culture them is subsequently made

   High energy ionizing radiation destroys
    microorganisms and is used to sterilize
    prepacked, Single-use, surgical equipment
    by manufacturers
   Common sources of radiation include
    electron beam and Cobalt-60

 Be active against a wide range of organisms and
  spores. Only few are truly sterilizer
 Have a rapid action
 Should not be toxic or irritant to the skin
 Should be Persistent

  There is no one disinfectant which can be
     used to kill all micro-organisms in all
Types of Chemical disinfectants

   Inorganic:
    –   Iodine
    –   Chlorine
   Organic:
    –   Alcohols
    –   Aldehydes
    –   Phenols
    –   Cationic surface-active agents
Inorganic disinfectants

       The halogens: Chlorine and Iodine
   Have a rapid action against vegetative
    organisms and spores= true sterilizers
   Their action is annulled by foreign organic
Iodine disinfectants

        The broadest spectrum of all topical anti-infectives, with action
        against bacteria, fungi, viruses, spores, protozoa, and yeasts.
   Tincture iodine:
     – 2.5% iodine & 2.5% potassium iodide in 90% ethanol.
     – Best skin disinfectant
     – Irritating to raw surfaces: due to its alcoholic component
     – Allergic dermatitis
   Iodophors: Solutions of iodine in non-ionic detergents= Povidone
    iodine= Betadine
     – Less irritating and less staining
     – Less disinfectant than tincture
Chlorine disinfectants

   Powerful, Disinfect water
   Particularly active against viruses
   Concentrated solutions too corrosive
   Usually diluted with a compatible detergent
Organic Disinfectants

   Alcohols: bactericidal: 50-70% ethanol
   Aldehydes:
    –   Formalin: irritant, powerful=sterilizer
    –   Glutaraldehyde: less irritant, not volatile, more rapid action.
   Phenols: continued activity in organic matter as human
    –   Phenol: Toxic, expensive
    –   Cresols: Lysol
    –   Chloroxylenol: Dettol
    –   Chlorhexidine: Hibitane- Alkanol
    –   Hexachlorophane
   Cationic surface-active agents:
    –   Cetrimide: Cetavlon

  Isopropyl Alcohol 70% (or Ethyl Alcohol 90%)
  Causes protein denaturation, cell lysis, and metabolic
  Degreases the skin.
   Ineffective against bacterial spores and poorly effective
   against viruses and fungi.
Glutaraldehyde (Cidex)

Cold Sterilization:
 Instruments must be dry before immersion.
 Glutaraldehyde is bactericidal, fungicidal,
  viricidal, and sporicidal
 Sterilization: a 10 hour immersion. This
  prolonged chemical action can be more
  detrimental to surgical instruments.
 3 hours exposure time is needed to destroy
 If the instruments need to be "disinfected"
  only, cold sterilization is okay as
  disinfection will take place in only 10

   Formaldehyde & glutaral
   Lysoformin: liquid concentrate with which any dilution
    required can be made by simply adding water (20ml + 4-
   The timing depends on the concentration used:
    –   flexible endoscopes         1.5 % - 30 min
    –   deactivation of HBV & HIV   2.0 % - 15 min
   Used for heat labile instruments and cleaning
   Does not harm metal instruments
            Chlorhexidine Gluconate
              Hibitane vs Alkanol

Broadest spectrum
Better residual activity than iodophors
Occasional skin sensitivity
Rapid action
Residual activity is enhanced by repeated use
Less susceptible to organic inactivation than povidone iodine
 Occasional skin sensitivity.
 Inactive against bacterial spores
 Activity against viruses and fungi is variable and inconsistent
 May harm metal instruments
Gaseous Disinfection
Ethylene Oxide Sterilization: EO Gas

   Colorless gas, available as cartridges
   Toxic and flammable, Odor similar to
   Has an extremely well penetration, even
    through plastics
   Microorganism destruction is caused by a
    chemical reaction
   Effective sterilization is dependent on
    concentration of gas, exposure time,
    temperature, and relative humidity
   Powerful sterilizer: Kills all known
    viruses, bacteria (including spores), and
EO Gas Sterilizer

   Is used in large hospitals, as it is expensive,
    dangerous, needs more expertise.
   Used for heat sensitive instruments: fabrics,
    plastics, suture material, lenses, endoscopes,
    electrical equipment and finely sharpened
   At 20°C-25°C: sterilization takes 18hours
   At 50°C-60°C: sterilization takes 4 hours
   In Demerdash: The average of the cycle is 8-14
Sterility Check List

    Before assuming a pack is sterile, always
    evaluate the following before opening the
   Expiration date
   Indicator color change
   General condition of wrapper and how it
    had been stored
   Always check for holes or moisture damage
               Standards for
     Surgical Scrubbing, Gowning and

   The pre-surgical practice of scrubbing,
    gowning and gloving is integral to the
    minimization of risk of infection from micro-
    organisms present in the wound at the time
    of surgery.
Accessing to the operating theatre

   Wear prescribed
    operating suite attire
   Remove jewellery
   Keep fingernails short,
    clean, healthy
   Wear appropriate
    protective attire: masks,
    head, overshoes..

 What went inside the machines is
      the STERILISED material
 Personnel are only DISINFECTED
Surgical Hand scrub

   No touch: infrared robinets, with your elbow, leg…
   Use brush??
   The ideal duration of the scrub is not agreed.
   Accepted time is 5 minutes: appears safe
   Some surgeons do not rinse off the chlorhexidine or
    Betadine in order to enhance residual activity.
   Alternative: Two-stage surgical scrub:
     – an initial 1- or 2-minutes scrub with 4% chlorhexidine
       gluconate or povidone-iodine followed by application
       of an alcohol-based product
Surgical Hand scrub

   Trim fingernails and Wash for 30-60 seconds
    with surgical scrub.
   Scrub fingers with a sterile scrub brush
   Make sure to scrub all sides of each finger,
    including the area between fingers.
Surgical Hand scrub

   Scrub hands and arms with a sterile scrub brush. Make
    sure to scrub each surface of each hand and arm
   An accepted contact time is 10 brush strokes per surface
   During scrubbing, rinsing and drying, hands are held
    above elbows. This is done so that water will not be
    dripping from upper arms onto lower arms and hands
Drying Hands

   A sterile towel is included within the sterile gown pack.
   One hand and forearm are dried by one side of the towel.
   Always dry in the direction of hand to elbow so that
    contamination of the upper arm is not spread by the towel
    to the surgeon's hand.

   All gowns are folded and packaged for sterilization, with
    the inside exposed so that the surgeon may handle the
    gown without contaminating the outside of the gown.
   Grasp the exposed inside of the gown and lift the gown
    away from the table.
   Your hands are disinfected and the gown is sterilized

   Unfold the gown by placing hands into the white arm
    holes. Continue placing hands and arms through the

   An assistant fastens the neck tie and the
    inside waist tie.
Types of Gowns

   Disposable Paper Gown: resistant to wetting so they
    are less permeable to bacteria, expensive. It is usually a
    wrap around gown. The ties "wrap around" the surgeon.
   Linen (cloth): comfortable and reusable. When it
    becomes wet, bacteria can permeate. The cloth gown is
    also known as a front sterile gown. The gown is just tied
    in the back.

 Sterile surgical gloves can be worn by:
 Open method:
    –   The gloves are presented to enable the introduction of the
        hands on the inside surface directly
    –   The nurse with her sterile glove opens the glove for the
        surgeon who introduces directly his hands on the inside surface
        of the glove


Closed gloving:
   This is the introduction of hands covered with the
    cuff of a sterile gown.
   So, If you are planning on closed gloving, do not
    thrust hands through the cuffs.
   This is usually performed by the first person to
    be sterilized= the nurse
Gloving: Closed method

   An assistant opens the sterile pack of gloves and drops
    them into the sterile field.
   The inside of the cuff of the glove is grasped by the
    opposite hand (still within the gown) until introduction
Patient Preparation

   Sterilization is best done with a detergent
    followed by a disinfectant on a larger area of the
    surgical field. H&N??
   Use Ample Detergent
   Scrub roughly the skin in any direction for 2-3mn
         ??Remove the excess of the detergent
   Apply the disinfectant first on the most clean area
   Scrub in one direction only

   Standard head drape: two towels, one under
    the shoulders and the other wrapped around
    the head
   Better to suture the drapes to the skin to
    prevent shifting
   Towels are used for lateral draping
   Drapes should lie flat
Practical Sterilization
Instruments sterilization

   Metal Instruments: Avoid chemical sterilization
    –   Autoclave
    –   EO chamber
    –   Formaldehyde beads or powder
   Sharp-edged: avoid heating & wetting:
    –   EO chamber
    –   Formaldehyde beads or powder
Practical Sterilization
Instruments sterilization

   Catheters, gloves,…: depend on pre-sterilized,
    disposable equipment
    –   Radiation
    –   EO chamber
   Endoscopes: avoid heat
    –   Cidex
    –   Lysoformin
    –   Autoclaving
   Handles of drills:
    –   Autoclave after washing and oiling
    –   EO chamber

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