HIGH TEMPERATURE STERILIZATION

Chapter 15

Objectives:• As a result of successfully completing this chapter, students will

be able to:

• Discuss factors that impact the effectiveness of sterilization and the methods of heat transfer associated with high temperature sterilization.

• Discuss the advantages of steam sterilization.

• Explain the anatomy of a steam sterilizer and identify the function of each major component.

• Sizes of steam sterilizers• Jacket• Door, Gasket, and Chamber Drain• Thermostatic Trap• Gauges and Controls

Objectives:• Provide basic information about the types of steam sterilizers

• Tabletop• Gravity Air Displacement• Dynamic Air Removal• Steam Flush and Pressure Pulse• Special Purpose Sterilizer (Flash)• Special Purpose Sterilizer (Instrument Washer Sterilizer)

• Provide basic information about the phases in a steam sterilizer

cycle:

• Conditioning• Exposure• Exhaust• Drying

Objectives:• Describe the conditions necessary for an effective steam sterilization

process:

• Contact• Time• Temperature• Moisture

• Explain basic work practices for steam sterilization:

• Preparing devices and packs for steam sterilization • Loading a sterilizer• Unloading a sterilizer• Controlling wet packs• Cleaning and maintaining sterilizers

Objectives:• Explain the basics of dry heat sterilization:

• When dry heat is appropriate.• Advantages and disadvantages of dry heat sterilization. • Types of hot-air convection sterilizers.• Dry heat sterilization procedures.

• Explain the need for quality control and review sterilization process indicators that help assure quality control:

• Need for quality control • Chemical indicators.• Sterilization load control information.• Physical and mechanical monitors.• Biological indicators.• Bowie-Dick tests• Validation and Verification processes

• Review the basics of three special high temperature sterilization concerns:• D-values and sterilization effectiveness• Creutzfeldt-Jakob disease (CJD)• Solutions

Common Methods of Heat Transfer

• Conduction – Heat transfer from one part of an item to another

• Convection – Heat transfer from one point to another as gas or liquid circulates

Factors and Conditions that Impact Sterilization

• Type of microorganisms present

• Number of microorganisms present. (Bioburden)

• Amount and type of soil present

• Amount of protection the medical device provides

BIOBURDENThe number of microorganisms on a contaminated object; also called bioload or microbial load

Steam Sterilization

Advantages of Steam Sterilization

• Low Cost

• Fast Cycles

• Relatively Simple Technology

• Leaves No Chemical Residues or By-products Behind

Steam Sterilizers come in Many Sizes

ANATOMY

of a Steam Sterilizer

Door Gasket

Chamber Drain

THERMOSTATIC TRAPTHERMOSTATIC TRAP

Gauges, Controls, and MonitorsProvide a Visual and Written Record of Sterilizer Cycles

TYPES OF STEAM STERILIZERS

TABLE TOP STERILIZERSFrequently used in Clinics and

Dental Offices

Water Port on a Tabletop Sterilizer

GRAVITY AIR DISPLACEMENT STERILIZERS

Steam sterilizer that uses gravity to remove air from the chamber. As steam enters the gravity

sterilizer chamber, cooler air is forced out through the chamber drain

DYNAMIC AIR REMOVAL STERILIZERS

Steam sterilizers that use a vacuum pump or ejector system to mechanically remove air

from the chamber

GRAVITY AND DYNAMIC AIR REMOVAL STERILIZERS

Differ in their methods of air removal

STEAM FLUSH- PRESSURE

PULSE STERILIZERS

Steam sterilizers that use a repeated sequence of steam flushes and pressure pulses to remove air from the chamber

SPECIAL PURPOSE PRESSURE STERILIZERS

(FLASH STERILIZERS)

Steam sterilizers that are surgical instrument located at point-of-use. They are intended to

be used in emergencies when there is no time for terminal sterilization.

SPECIAL PURPOSE PRESSURE STERILIZERS

(INSTRUMENT WASHER STERILIZERS)

Combination units that wash and sterilize instruments to make them safe for handling

by processing personnel

Terminology

• Terminal Sterilization – The process of sterilizing an item that is packaged

• Flash Sterilization – The process of sterilizing an item that is not packaged

Steam Sterilizer Cycle Phases

• Conditioning

• Exposure

• Exhaust

• Drying

Steam Enters the Chamber

Steam Passes through the Thermostatic Trap

Closed Thermostatic Trap

Steam is Exhausted from the Chamber

DRYING

Begins at the completion of the exhaust phase if packaged items are in the load

Flash (unwrapped) loads have minimal drying times and in some cases, no dry time at all

Conditions Necessary for Effective Steam Sterilization

• Contact• Time• Temperature• Moisture

Frequent Causes of Steam Contact Failures

• Failure to adequately clean the object being sterilized

• Packages wrapped too tightly

• Loads that are too crowded

• Containers that are positioned incorrectly

• Clogged drain strainer

• Mechanical malfunctions

Temperature Requirements

• Steam sterilization must take place at specific temperatures in order to destroy heat resistant bacteria

• The two most common temperatures used are:• 2500 F (1210C)• 2700F-2750F (132.20C-1340C)

TIMEIn order for steam sterilization to be effective, all items within the load need to be exposed

to a specific temperature for an adequate amount of time

MOISTUREAdequate moisture is required for steam

sterilization to be effective

SATURATED STEAMSteam that contains the maximum amount of

water vapor. The moisture content of saturated steam should possess a Relative

Humidity of 97% to 100%

Preparing Devices and Packs for Steam Sterilization

Preparing Items for Steam Sterilization

• Use instrument trays that are large enough to evenly distribute that metal mass

• Use only non-linting materials when assembling sets and trays

• Remove stoppers and tubes from drainage bottles and tubing from hemostats and clamps

• Position items to allow for sterilant contact• Disassemble all multi-part instruments• Do not hold instruments together with rubber bands

• Open all jointed instruments

• Items with concave or broad, flat surfaces should be placed on edge

• Heavy instruments should be arranged to they will not damage more delicate items

• Complex instruments should be prepared and sterilized following manufacturers’ instructions

• Central Service Technicians must test and evaluate protective organizing cases sterilization and drying

• Instruments must be inspected to ensure that they are clean

• Instruments should be dry, with the exception of lumens which should be moistened

Preparing Items for Steam Sterilization

Catheters, Tubing, Rubber, and Other Goods

• Due to it’s rough molecular structure, rubber is difficult to clean

• Rubber can break down when exposed to heat, light, acids, solvents, petroleum products, ether and hot metal

• Most rubber items are single-use items• When processing reusable rubber items, follow manufacturer’s guidelines carefully for cleaning and sterilization

WOOD AND CORKCannot be sterilized by any hospital

sterilization method

OILS AND POWDERSCannot be sterilized by steam

NO ITEM SHOULD BE STERILIZED…

Without written instructions from the manufacturer

Paper/Plastic Pouches

• Should be used for small, lightweight items

Small Perforated Boxes

• Should be used to contain small items within instrument sets

• Paper/Plastic pouches should not be used in trays

Textile Packs• Should be made of materials that allow adequate air

removal and steam penetration

• The manufacturer should be consulted for recommendations on package size and density

Basins and Basin Sets• Graduated, nested basins should differ in

diameter by at least 1 inch

• Basin sets should be prepared so all basins are in the same direction to facilitate drainage and air removal

• Non-linting absorbent material should be used to separate the basins

• Basin sets should not exceed 7 pounds in weight

Glass Syringes

Lumens• Moisten with distilled or demineralized water

• Do not moisten more than 2 hours prior to sterilization

Loading the Steam Sterilizer

• Allow for proper steam circulation

Allow Adequate Space to Facilitate Air Removal and Drying

Position solid bottomed items so that water and air are not trapped

inside

When using Paper/Plastic Pouches

• Remember that only the paper side allows air removal, steam penetration, and drainage

Stand Paper/Plastic Laminate on Edge (Use a holder if necessary)

Do Not Lay Paper/Plastic Laminate Pouches Flat

Lay items with perforated bottoms flat

Where Water Cannot Flow, Steam Cannot Go

Position Textile Packs so Layers within them are Perpendicular to the Shelf

Unloading the Steam Sterilizer• Open the sterilizer door according to protocol

• The load should be free from any visible liquid

• Wet items should be considered contaminated

• Do not touch items that have just been removed from the sterilizer

• Do not handle packages until they are cool

Controlling Wet Packs

• Packages are considered wet when moisture in the form of dampness or puddles of water are found on or within a pack

• Wet packs are considered contaminated

Causes of Wet Packs• Wet packs may be the

result of improper placement or positioning of packs or their contents

• Pack density can also increase the incidence of wet packs.

Assembling and Wrapping Instrument Sets

• Use only instrument trays with mesh or perforated bottoms to reduce the risk of wet packs

• Use lint-free tray liners to help absorb moisture and facilitate drying

• Evenly distribute set weight

CLEANING AND MAINTAINING

Steam Sterilizers

Routine Sterilizer Maintenance

Clogged Drain Strainers Can Impede Air Removal

Wipe the Door Gasket. Inspect for Signs of Wear and Defects

Sterilizer Cleaning and Maintenance

• Routinely clean sterilizer carts, carriages, and baskets

• Inspect recording devices, paper charts and printer paper

Sterilizer Cleaning and Maintenance

• Clean the sterilizer chamber according to manufacturer’s recommendations to prevent residue build up

• Check the Chamber Drain Strainer at least daily• Clean and Check the Door Gasket Daily• Clean the inside of the chamber with a non-abrasive

cleaner• Follow Manufacturer’s Specific Instructions

Dry Heat Sterilization

Dry Heat

Advantages • Sterilizes some items that

Steam cannot sterilize• Can sterilize assembled

instruments because of conduction heating

• Will not erode the surface of glass

• Is not corrosive to metals

Disadvantages• Difficult to Control• High Temperature• Slow and Uneven

Penetration• Requires Long Exposure

Times• Limited Packaging

Materials Available• Not suitable to sterilize

fabrics and rubber

Types of Dry Heat Sterilizers

•Gravity Convection

•Mechanical Convection

Gravity Convection Sterilizers

• Prone to air layering which causes temperatures to be uneven

Mechanical Convection Sterilizers

• Utilize a blower system to insure even heating thrughout the cycle.

CONVECTIONThe process of heat transfer by the

circulation of currents from one area to another

Dry Heat Cycle Phases

•Heat Up

•Exposure

•Cool Down

Items must be:

•Clean

•Dry

•Packaged

Preparation of Specialty Items

Oils and Powders

• Both Oils and Powders should be packaged less than 1 ounce and less that .25” deep

• The required sterilization temperature should be based on manufacturer’s recommendations

Impregnated Gauze Strips

• Strips should be placed in a stainless steel container and covered with petroleum jelly or other oil-based liquid

• Depth should not exceed .5”

Syringes and Needles

•Must be thoroughly Dry

•May be assembled

Instruments

• Must be thoroughly Dry

• May be assembled

• Ratchets and Boxlocks may be closed

• Screws may be tightened as necessary

Dry Heat Packaging Materials• Heat Resistant Glass

• Stainless Steel Trays

• Cotton Muslin (if the chamber temperature does not exceed 400 degrees F.)

• Aluminum Foil

• Nylon Films

• Certain Sterilization Containers (Check Manufacturers’ Recommendations)

STERILIZATIONQuality Control

PROCESS INDICATORDevices intended for use with individual units

(for example, packs or containers) to demonstrate that the unit has been exposed to the sterilization process, and to distinguish between processed and unprocessed units

External Chemical Indicator Tape

Before Processing After Processing

Examples of Internal Chemical Indicators

Examples of Internal Chemical Integrators

LOAD CONTROL NUMBER

Label information on sterilization packages, trays, and containers that identifies the

sterilizer, cycle run, and date of sterilization

Load Control Information*

Sterilizer Number

Load Number

Date Sterilized

*Must be placed on each item Sterilized in the Central Service Department

S-1 L-5

05-03-07

Example of a Label Applicator Gun for Load Control Information

JULIAN DATEThe Julian day or Julian day number (JDN) is the number of days that have elapsed since

January 1st

Sterilization Logging Information• Date and time of the sterilizer load control number

(sometimes called the lot number) which includes sterilizer information.

• Specific items sterilized including:• Quantity of items• User (destination) department• Complete item description

• Exposure time and temperature• Sterilizer operator identification• Results of biological testing (if applicable)• Response of the CI placed in the BI test pack (if applicable)• Results of the Bowie-Dick testing, if performed

Physical (Mechanical) Monitoring

• Includes information from time, temperature, and pressure recorders

• Must be checked after each load before the load is released

BIOLOGICAL INDICATORS (BIS)

Provide a measure of sterilization process lethality

Examples of Biological Indicators

BI Process Challenge Device (PCD) Placement

BI Test pack

Process Challenge Devices

• Guidelines for Process Challenge Devices are discussed in detail on pages 318 – 320 of the text

BOWIE-DICK TESTSTests used to evaluate the efficacy of air

removal in dynamic air removal sterilizers

Examples of Bowie-Dick (Air Removal) Tests

VALIDATIONProcedures used by equipment

manufacturers to obtain, record, and interpret test results required to establish that

a process consistently produces a sterile product

VERIFICATIONProcedures used by healthcare facilities to confirm

that the validation undertaken by the equipment manufacturer is applicable to the specific setting

Specific information about verification recommendations is discussed in detail on pages 321

– 322 of the text

SPECIAL HIGH TEMPERATURE STERILIZATION

Concerns

D-VALUEThe amount of time required to kill

90% of the microorganisms present

Creutzfeldt-Jakob Disease

• Specific information regarding procedures for CJD are discussed on pages 324 – 325 of the text.

SOLUTION PREPARATION

ANSI/AAMI ST79:2006, section 8.5.7 states: “Primarily for personnel safety reasons,

inhospital preparation of and sterilization of parenteral and irrigation solutions is

discouraged. When solutions are processed in the hospital (i.e. emergency situations), processing should be performed by trained

personnel”

Types of Solutions

Parental Solutions

•Solutions that are administered to patients intravenously

External Solutions

•Solutions that are normally used for irrigating, topical application, and surgical use that are given orally or by inhalation

Flasking Technique• Use only Borosilicate Glass Bottles

• Fill with freshly distilled water

• Use only vented closures that will allow air and steam to escape

• Overfill by 3% - 5% to allow for evaporation during sterilization