Steam sterilization theory and equipment

1. Steam sterilization theory and equipment M.RAGHUVARAN M.PHARM 1st SEM (PHARMACEUTICS) UNIVERSITY COLLEGE OF PHARMACEUTICAL SCIENCES KAKATIYA UNIVERSITY

2. 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

3. Sterilizing Agents • Type of agents • Chemical • Physical • Moist heat • Dry heat • Most clinics use physical agents

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

5. 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.

6. 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.

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

8. Principles of Steam Sterilization (cont.) • 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

9. Latent Heat of Vaporization • For example:

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

12. 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

13. 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

14. Types of autoclaves • Lumbers Room 120A • Farquharson 227A

15. 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

16. 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

17. Construction of Steam Sterilizers 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.

18. 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.

19. 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

20. How to Autoclave • Which cycle to use • Preparing your items for autoclaving • Loading the autoclave • Choosing the cycle settings • Unloading the autoclave • Aborting Autoclave

21. How to Autoclave- Which cycle to use • Autoclaves run 3 types of cycle programs • The type of cycle depends on what is being autoclaved:

22. 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

23. 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

24. 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 Small opening Loosen screw caps

25. 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

26. Unautoclaved Autoclaved (regular) Autoclaved (due to being compressed & sealed) 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

27. 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 Before After

28. 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

29. 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

30. 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

31. 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

32. 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

33. Autoclave: Performance Indicators • How to know if autoclave is functioning correctly:

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

35. 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

36. 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

37. 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

38. Types of Steam Sterilizers • 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.

39. 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.

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

41. 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.

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

43. Pre-vacuum Sterilizer Uses. Metalware Rubber Thermoplastics

44. 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

45. References • ANSI/AAMI/ISO standards and TIRs available at www.aami.org • USP 25 – order from www.usp.org • PBL Compliance Guides • Sterility Assurance Compliance • Assessing Biocompatibility • Online at www.pacificbiolabs.com

46. Thanks • Comments? • Questions?