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Steam sterilization theory and equipmentM.RAGHUVARANM.PHARM 1st SEM (PHARMACEUTICS)UNIVERSITY COLLEGE OF PHARMACEUTICAL SCIENCESKAKATIYA UNIVERSITY

What is sterilization?DefinitionsSterile: Free from any living organismsSterilization: Process of killing or removing microorganisms from a product to insure that it is sterile

Sterilizing AgentsType of agentsChemicalPhysicalMoist heatDry heat

Most clinics use physical agents

Steam Sterilization: Autoclave

Pressurized device that uses heat, steam and pressure to achieve sterilization or decontamination

4Steam AdvantagesSimple 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.Steam DisadvantagesComparatively 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.

6Add Aseptic processes advantages and disadvantages?Principles of Steam SterilizationSterilization: the complete destruction of all forms of microbial life, including bacterial spores

Steam under pressure reaches high temperaturesPrinciples of Steam Sterilization (cont.)The killing power of steam is due to its latent heat of vaporization80 calories: 1 L water to boiling540 calories: 1 L boiling water to steam

Latent Heat of VaporizationFor example:

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

Items that CAN be Autoclaved:Cultures and stocks of infectious materialCulture dishes and related devicesDiscarded live and attenuated vaccinesContaminated solid items such as: petri dishes, eppendorf tips, pipettes, gloves, paper towelItems for sterilizations such as; glassware media, aqueous solutionsDO NOT Autoclave:Any liquid containing:Toxic, volatile, or corrosive chemicalse.x. bleach, formalin, glutaraldehydeCheck MSDS before handCancer drugsDo not break down under high temperaturesHighly toxicRadioisotopes

Lumbers Room 120A

Farquharson 227A

Types of autoclavesTypes14Parts of a Steam SterilizerControl panel with graphDoor handleOuter metal jacket-like chamber built around the inner chamberInner chamberSeries of filtersTemperature measurement of steam sensor

Components of a Steam SterilizerSource of steam- generate own steam or rely on steam from outside sourcePreheat metal jacket build around chamber for outside sources reduces total cycle timeThree main pipesA pipe with inline filters to bring steam to the sterilizer and the chamberA drain pipe for steam, air and water from the chamberA pipe to deliver filtered air to the chamber at eh end of the cycle

Construction of Steam SterilizersSteam 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.17Construction of Steam SterilizersValves: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.Construction of Steam SterilizersGauges: Located on front of sterilizer.Reading chamber pressureReading Jacket pressure.Safety Steam-lock Door:Located in front of chamberWeakest part of sterilizer

How to AutoclaveWhich cycle to usePreparing your items for autoclavingLoading the autoclaveChoosing the cycle settingsUnloading the autoclaveAborting Autoclave

How to Autoclave- Which cycle to useAutoclaves 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 overSolid/Gravity* Best for unwrapped solid items (ie glassware)Solid/Vacuum* Best for wrapped solid items21Gravity vs. Vacuum cycle:

* Gravity: passive exit of air out of autoclave.* Vacuum: autoclave mechanically sucks out air of autoclave before filling with steam (leads to better steam penetration). You CAN use vacuum for any solid items, however, it causes more wear and tear on the autoclave.How to Autoclave - Preparing your itemsSign into log bookKeeps track of autoclave use for maintenance records

Use personal protective equipment!Eye protectionHeat resistant glovesLab coat

How to Autoclave - Preparing your itemsUse a primary containerContainer comes into direct contact with the contaminated or non-sterilized material or fluidDo not fill more than 75% of holding capacity

How to Autoclave - Preparing your itemsUse a primary container (contd)Must NOT be a tightly sealed container (might explode)Primary container must permit heat (steam) penetrationLoosen screw caps or use self venting capsCap open containers with aluminum foil or muslinIf using plastic waste bags, leave a small opening

Loosen screw capsSmall opening24How to Autoclave - Preparing your itemsUse a secondary containerUsed to contain any spillsThe sides of the secondary container must be sufficiently high to contain any spill that may occurTray MUST be autoclave safe

For liquids add waterHow to Autoclave - Preparing your itemsDo not over load primary or secondary containersDo not fill more than 75% to allow expansion without overflow

Do not pack or compress contents

UnautoclavedAutoclaved (regular)Autoclaved (due to being compressed & sealed)26Principle behind autoclave bag over-compression:

Expansion occurs during the high temperature cycle. If the bag is tightly sealed so steam is unable to escape, the risk of explosion may occur.Compression occurs when the temperature begins to drop. If the bag is sealed so steam is unable to escape when the temperature drops, the steam inside cools quickly and creates a vacuum. This causes the bag to compress around the contained contents to potentially puncture and break the bag.

Take home message: Do NOT tightly seal autoclave bag allow steam to enter and escape. Do NOT compress contents to allow bag expansion and compression as well as more steam penetration.

This principles apply to microwave usage. DO NOT TRY THIS AT HOME: http://www.youtube.com/watch?v=BgRuS147Duk

How to Autoclave - Preparing your itemsUse temperature sensitive tape Will indicate that high temperature has been achievedWill not prove that decontamination or sterilization was successfulWill assist in keeping track of autoclave and non autoclaved items

BeforeAfter27How to Autoclave - Loading the autoclaveNEVER autoclave liquid loads using a solid load cycleliquids may boil over

Be cautious if autoclave was recently usedRack may be hotUse heat protective gloves

Make sure tray is locked on dollyRack may slide out unexpectedly if not locked

How to Autoclave - Loading the autoclaveFarquharson: Tighten door so that prongs are fully extendedIf noise and/or steam escapes, abort the cycle and tighten the door more

LumbersKeep the door button pushed until the ready prompt is on the screen

How to Autoclave Choosing the CycleFor Liquids:20 mins / litre of liquid, 5 mins per additional litre

For Solids:Glassware (empty): 15 minsInstruments (utensils): 30 minsBiohazardous Garbage: at least 30 mins per full bagUse biological test strips to optimize durationHow to Autoclave Unloading autoclaveWait for autoclave to state END CYCLE before opening door

When opening, stand away from door openingMake sure no one is standing by door opening

How to Autoclave Aborting Only qualified personnel should attempt to troubleshoot an autoclave

FarquharsonLarge autoclave: push abort buttonSmall autoclave: need to manually advance through the autoclave cycle

LumbersPush abort button

Autoclave: Performance IndicatorsHow to know if autoclave is functioning correctly: Physical- Annual testing by certified technician- Pressure, Temperature, Cycle times, recorded on paperChemical- Heat sensitive autoclave tape - Not an indicator of successful sterilization, useful to keep track of autoclaved and unautoclaved itemsBiological- 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 IntegratorsDART- Daily Air Removal Test, verifies complete air removal and checks for leaks.33- monitoring done by person responsible for using autoclaves. - big responsibility- key component of biosafety compliance.- monitoring is crucial when relying on it to treat biohazardous waste or sterilizing liquids.

EXAMPLES of Biological Indicators: 3M Attest Rapid Readout Biological Indicators or Steris Verify Integrator Laminated and EO Integrators.

Biological Indicator Controls/Spore TestsBacillus Stearothermophilus:is used strictly for Steam and dry heat sterilizers.

Tests ability of sterilizer to kill microorganisms.

34Biological IndicatorMust be incubated:Follow manufacturers instructions

Use correct temperature 131-140 degrees F.

Use special incubator

Incubate for 48 hours or follow manufacturers instructionsBiological IndicatorRecord results:Negative- no color change from original.

Positive- color changed is usually amber in color.Take sterilizer out of serviceReport to supervisorRecall all items sterilized in sterilizer for last 24 hour periodTypes of Steam SterilizersGravity Air Displacement Sterilizer- using gravity to remove air from the inner chamberPrevacuum Steam Sterilizer- uses vacuum in two cycles to remove air from the inner chamber

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.

381. Temperature is 250 degrees F to 254 degrees F2. Pressure is 15 to 17 pounds per square inch.

3. exposure time is 30 minutes for unwrapped instruments.Gravity DisplacementSettings: 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.

Gravity Displacement Uses1. Metal ware2. Glassware3. Thermoplastics.4. Linens.5. Rubber.40Pre-vacuum (high temperature) SterilizerDefinition: 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. 41Pre-vacuum Settings:Temperature: 270 degrees F. to 276 degrees F.

Pressure: 27 PSI

3. Exposure Time: 15 to 30 minutes.42Temperature is 272 degrees to 276 degrees

Pressure is 28-30 pounds per square inch

exposure time is 4-5 minutes.Pre-vacuum Sterilizer Uses. Metalware Rubber Thermoplastics43Sterilization: How is it validated?SteamIQ, OQ, PQ of steam sterilizerTemperature 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.sReferencesANSI/AAMI/ISO standards and TIRs available at www.aami.orgUSP 25 order from www.usp.orgPBL Compliance GuidesSterility Assurance ComplianceAssessing BiocompatibilityOnline at www.pacificbiolabs.comThanks

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