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3 What is sterilization? Definitions Sterile: Free from any living organisms Sterilization: Process of killing or removing microorganisms from a product to insure that it is sterile

4 Sterilizing Agents Type of agents Chemical Physical Moist heat Dry heat Most clinics use physical agents

5 Steam Sterilization: Autoclave Pressurized device that uses heat, steam and pressure to achieve sterilization or decontamination

6 Steam – Advantages Simple process: The only two parameters to control are time and temperature. Highly reliable and easily controlled. Widespread capability: All hospitals and many other heath care facilities have steam sterilizers. Excellent process for reusable medical devices that are not adversely affected by temperatures >121C (up to 135 C). Excellent process for liquids that are not heat sensitive.

7 Steam – Disadvantages Comparatively high temperature required: Many products and packaging materials cannot tolerate temperatures of >121C. Generally not appropriate for most single use disposable medical devices produced in high volumes and sold as sterile.

8 Principles of Steam Sterilization u Sterilization: the complete destruction of all forms of microbial life, including bacterial spores u Steam under pressure reaches high temperatures

9 Principles of Steam Sterilization (cont.) u The “killing power” of steam is due to its latent heat of vaporization 80 calories: 1 L water to boiling 540 calories: 1 L boiling water to steam

10 Latent Heat of Vaporization u For example :


12 Action of Steam u Steam contacts a cooler surface, condenses, causing a huge decrease in volume and setting up a negative pressure that draws more steam u Condensation occurs as long as there is a temperature differential u Action of steam ensures: Surface heating, penetration, and protein coagulation

13 Items that CAN be Autoclaved: Cultures and stocks of infectious material Culture dishes and related devices Discarded live and attenuated vaccines Contaminated solid items such as: petri dishes, eppendorf tips, pipettes, gloves, paper towel Items for sterilizations such as; glassware media, aqueous solutions

14 DO NOT Autoclave : Any liquid containing: Toxic, volatile, or corrosive chemicals e.x. bleach, formalin, glutaraldehyde Check MSDS before hand Cancer drugs Do not break down under high temperatures Highly toxic Radioisotopes

15 Lumbers Room 120A Farquharson 227A Types of autoclaves

16 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

17 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 1. A pipe with inline filters to bring steam to the sterilizer and the chamber 2. A drain pipe for steam, air and water from the chamber 3. A pipe to deliver filtered air to the chamber at eh end of the cycle

18 Steam Jacket: Surrounds the inner chamber and stores steam until pressure has been obtained. Inner Chamber: Items to be sterilized are loaded into this compartment without touching.

19 Construction of Steam Sterilizers Valves: Pressure regulating: Maintains the pressure of 15 to 20 psi in the jacket. Safety Valve: Prevents excess pressure build-up. Steam trap: If pressure to high, valve opens and releases pressure.

20 Construction of Steam Sterilizers Gauges: Located on front of sterilizer. Reading chamber pressure Reading Jacket pressure. Safety Steam-lock Door: Located in front of chamber Weakest part of sterilizer

21 How to Autoclave 1. Which cycle to use 2. Preparing your items for autoclaving 3. Loading the autoclave 4. Choosing the cycle settings 5. Unloading the autoclave 6. Aborting Autoclave

22 How to Autoclave- Which cycle to use Autoclaves run 3 types of cycle programs The type of cycle depends on what is being autoclaved: Liquid/Slow exhaust* For autoclaving liquids * Prevents liquids from boiling over Solid/Gravity* Best for unwrapped solid items (ie glassware) Solid/Vacuum* Best for wrapped solid items

23 How to Autoclave - Preparing your items Sign into log book Keeps track of autoclave use for maintenance records Use personal protective equipment! Eye protection Heat resistant gloves Lab coat

24 How to Autoclave - Preparing your items Use a primary container Container comes into direct contact with the contaminated or non- sterilized material or fluid Do not fill more than 75% of holding capacity

25 How to Autoclave - Preparing your items Use a primary container (cont’d) Must NOT be a tightly sealed container (might explode) Primary container must permit heat (steam) penetration Loosen screw caps or use self venting caps Cap open containers with aluminum foil or muslin If using plastic waste bags, leave a small opening Loosen screw caps Small opening

26 How to Autoclave - Preparing your items Use a secondary container Used to contain any spills The sides of the secondary container must be sufficiently high to contain any spill that may occur Tray MUST be autoclave safe For liquids add water

27 How to Autoclave - Preparing your items Do not over load primary or secondary containers Do not fill more than 75% to allow expansion without overflow Do not pack or compress contents Unautoclaved Autoclaved (regular) Autoclaved (due to being compressed & sealed)

28 How to Autoclave - Preparing your items Use temperature sensitive tape Will indicate that high temperature has been achieved Will not prove that decontamination or sterilization was successful Will assist in keeping track of autoclave and non autoclaved items BeforeAfter

29 How to Autoclave - Loading the autoclave NEVER autoclave liquid loads using a solid load cycle liquids may boil over Be cautious if autoclave was recently used Rack may be hot Use heat protective gloves Make sure tray is locked on dolly Rack may slide out unexpectedly if not locked

30 How to Autoclave - Loading the autoclave Farquharson: Tighten door so that prongs are fully extended If noise and/or steam escapes, abort the cycle and tighten the door more Lumbers Keep the door button pushed until the ready prompt is on the screen

31 How to Autoclave – Choosing the Cycle For Liquids: 20 mins / litre of liquid, 5 mins per additional litre For Solids: Glassware (empty): 15 mins Instruments (utensils): 30 mins Biohazardous Garbage: at least 30 mins per full bag Use biological test strips to optimize duration

32 How to Autoclave – Unloading autoclave Wait for autoclave to state END CYCLE before opening door When opening, stand away from door opening Make sure no one is standing by door opening

33 How to Autoclave – Aborting Only qualified personnel should attempt to troubleshoot an autoclave Farquharson Large autoclave: push abort button Small autoclave: need to manually advance through the autoclave cycle Lumbers Push abort button

34 Autoclave: Performance Indicators How to know if autoclave is functioning correctly: Physical - Annual testing by certified technician - Pressure, Temperature, Cycle times, recorded on paper Chemical - Heat sensitive autoclave tape - Not an indicator of successful sterilization, useful to keep track of autoclaved and unautoclaved items Biological - Tests ability of autoclave to sterilize effectively - Bacillus stearothermophilus spore strips often used because they are resistant to steam sterilization. - EZ Test (SGM Biotech) (Fisher Sci #29801 074) - 3M Attest Rapid Readout Biological Indicators - Steris Verify Integrator Laminated and EO Integrators DART - Daily Air Removal Test, verifies complete air removal and checks for leaks.

35 Biological Indicator Controls/Spore Tests Bacillus Stearothermophilus:is used strictly for Steam and dry heat sterilizers. Tests ability of sterilizer to kill microorganisms.

36 Biological Indicator Must be incubated: Follow manufacturers instructions Use correct temperature 131-140 degrees F. Use special incubator Incubate for 48 hours or follow manufacturers instructions

37 Biological Indicator Record results: Negative- no color change from original. Positive- color changed is usually amber in color. Take sterilizer out of service Report to supervisor Recall all items sterilized in sterilizer for last 24 hour period

38 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

39 Types of Steam Sterilizers 1. Gravity displacement. a. Definition: Gravity pushes air through the packages and down through the drain. Sterilization begins when steam passes the thermometer and reaches the desired temperature.

40 Gravity Displacement Settings: Temperature- 250 degrees F. to 254 Degrees F. Pressure- 15 to 17 pounds per square inch(PSI) Exposure time- 30 minutes for wrapped instruments. Minimum 15 minutes.

41 Gravity Displacement Uses 1. Metal ware 2. Glassware 3. Thermoplastics. 4. Linens. 5. Rubber.

42 Pre-vacuum (high temperature) Sterilizer Definition: Air is completely evacuated from the chamber by a vacuum. The steam-injector helps eliminate the air out of packages. Steam then penetrates the packages on all surfaces.

43 Pre-vacuum Settings: 1. Temperature: 270 degrees F. to 276 degrees F. 2. Pressure: 27 PSI 3. Exposure Time: 15 to 30 minutes.

44 Pre-vacuum Sterilizer Uses. Metalware Rubber Thermoplastics

45 Sterilization: How is it validated? Steam IQ, OQ, PQ of steam sterilizer Temperature profiles of product during sterilization cycles ( using thermocouples) Fractional and/or half cycles with product & B.I.s (G. stearothermophilus) Then sterility testing of product & B.I.s

46 References ANSI/AAMI/ISO standards and TIRs available at USP 25 – order from PBL Compliance Guides Sterility Assurance Compliance Assessing Biocompatibility Online at

47 Thanks Comments? Questions?


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