Sterilization

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’’- 1 st steam sterlizer 1885, Schimmelbusch _ steam sterilization of surgical dressings 1963, Glutaraldehyde _ 1 st 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 sterilizatio n: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 E nzymes 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.

17. 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

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

19. 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.

20. 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.

21. 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: S terilizing unwrapped items , such as when an instrument has been dropped or of immediate need during a surgical procedure.

22. 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

23. FILTRATION D oes 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

24. 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

25. 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 .

26. P lastics , 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 r equired for proper EtO sterilization include EtO gas concentration, Temperature, Humidity, and Time (lower at high temp.)

27. Advantages and disadvantages of gas sterilization

28. 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. H igher inventory of endoscopic equipment with the use of gluteraldehyde .

29. 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 .

30. 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.

31. 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 .

32. Merit / Demerits of sterilization

33. 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

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

35. Thank You!!