Designer of steam sterilizers

Charles Chamberlain
1880

Important factors for sterilization

Type of microorganisms present
Number of microorganisms (bioburden)
Amount of protection a medical devices provides

What is bioburden?

The number of microorganisms on a contaminated object, also called bio load, or microbial load

Transmission of heat from one part to another part of a material. Methods of high temperature sterilization (steam)

Conduction (solids)
Dry heat

Transfer of heat from one point (or molecule) to another as liquid or gas circulates. Methods of high temperature sterilization (steam)

Convection (liquids or gases)
Steam

Transfer of heat from one object to another without warming the space between the objects. Methods of high temperature sterilization (steam)

Radiation
Not used in hospitals

Steam sterilization benefits

Low cost
Fast cycles
Simple technology
Leaves no chemical residue

Size of steam sterilizers

Small table top (clinics and dentists)
Mid size units
Large size units

Component of steam sterilizer - Surrounds top, middle and bottom of the vessel

Jacket

Component of steam sterilizer - weakest part of a steam sterilizer, can be tightened but not loosened while the chamber is under pressure

Door & Gasket

Component of steam sterilizer - Located at the front or center of the floor in most sterilizers

Chamber drain

Component of steam sterilizer - Located in the drain line and is the coolest place in the sterilizer. Controls the flow of air and condensate

Thermostatic trap

Component of steam sterilizer - Provides a written record of sterilization

Gauges and control monitoring

Type of gravity air displacement, typically used in clinics and dentists

Table top sterilizers

What sterilizer operates at 250 degrees F

Table top sterilizers

Small to medium sized sterilizer - hot air is introduced while rising to the top forcing cooler air to the bottom of the chamber

Gravity Air Displacement Sterilizer

What additional items can a Gravity Air Displacement Sterilizer be used for

Sterilize liquids

Similar in construction to gravity sterilizer except that a vacuum pump or water ejector removes the air during preconditioning phase

Dynamic Air Removal Sterilizer

Temperature that Dynamic Air Removal Sterilizer operates at

270 DF

What indicator is used to ensure a Dynamic Air Removal Sterilizer have all air removed

Bowie Dick

Special purpose pressure sterilizer intended for emergency use

Flash sterilization

A sterilizer that uses higher temperatures for shorter exposure times to handle emergency sterilization of dropped instruments

Flash sterilizer

Combination units that wash and sterilize instruments to insure the safety of processing personnel

Instrument washer (IWS) Sterilizer

Steam Sterilizer Cycle phase 1

Conditioning

Steam Sterilizer Cycle phase 2

Exposure

Steam Sterilizer Cycle phase 3

Exhaust

Steam Sterilizer Cycle phase 4

Drying

Process of sterilizing an item that IS NOT packaged

Flash (sterilization)

The process of sterilizing an item that IS packaged

Terminal sterilization

Passive or active air removal - Gravity

Passive air removal

Passive or active air removal - Pre vacuum steam sterilizer

Active air removal

Passive or active air removal - Pulse (Steam flush SFPP)

Active air removal - SFPP

(STEAM)Once door is closed steam enters at the back portion and strikes a baffle plate to prevent steam from hitting the load

Conditioning

(STEAM) Pressure begins to rise, with temperature, system begins timing the ..... stage

Exposure

(STEAM) At the end of the exposure phase, chamber drains, steam is removed through ..... line

Exhaust

(STEAM) Conclusion of exhaust phase, uses the heat of the chamber walls to activate ..... cycle

Drying

Conditions necessary for effective steam sterilization

Contact
Time
Temperature
Moisture

In order to be effective steam sterilizers much reach ........

250-270 DF depending on load

Inadequate exposure ........ can lead to failure of the process

Time

When boiling water begins the volume increases gently. As it continues water changes to steam and temperature rises

Time and temperature relationship

Steam that contains the maximum amount of water vapor

Saturated steam

Absolute pressure (-)atmospheric pressure (14.7 psi at sea level) also called over pressure

Gauge pressure (steam)

Gauge pressure (psi) + atmospheric pressure (14.7 psi at sea level)

Absolute pressure (steam)

Dry steam: the condition of steam when its temperature is too high relative to pressure in steam table

Superheated steam

Higher elevation =

Higher psi eg Denver is 3 psi higher than sea level

Several environmental factors can reduce its life eg heat, light, acids

Catheters, tubing, rubber

The weight of wrapped basin sets should not exceed ....

7 pounds

What should be moistened with distilled water or demineralized water so air can be more easily displaced

Lumens

Least used and least understood sterilizing agent

Dry heat

Dry heat is a relatively ....... sterilizing agent, and requires ..... temperature

slow acting / higher

Dry heat has the ability to penetrate a variety of materials, including

oils, petroleum jelly, and closed containers not permeable to steam

Dry heat sterilization is achieved by ....... heat

Conduction

Dry heat advantages:

Can sterilize powers/oils
Will not erode the surface of glass
Does not have a corrosive effect on metals
Will reach all surfaces

Dry heat disadvantages:

Difficult to control
Penetrates materials slowly and unevenly
Requires long exposure times
Requires high temperatures
Not suitable to sterilize fabric or fubber goods

A heat transfer method in which heat is absorbed by an items exterior surface, and passed inwards to the next layer

Conduction

The process of heat transfer by the circulation of current from one area to another

Convection

As air within the chamber is heated, it rises and displaces cooler air that descends into the lower part of the chamber.

Gravity Convection
Prone to air layering which casues inconsistent temps

Utilizes a blower system to insure even heating throughout the cycle

Mechanical Convection

Devices intended for use with individual units - packs or containers

Process indicators

Systems that reveal a change in one or more predefined process parameters or physical change

Chemical indicators

Tape, load cards, Labels etc

External indicators

Processing indicators used within individual packs to demonstrate that they have been exposed in the sterilization process

Class 1 indicators

Indicators, such as the Bowie Dick

Class 2 indicators

Single parameter indicators to react to one of the critical parameters of sterilization

Class 3 indicators

Multi parameter indicators that react to two or more critical parameter's

Class 4 indicators

Integrating indicators designed to react to all critical parameters over a specified range of sterilization cycles

Class 5 indicators

Label information on sterilization packages etc

Load control number

Number of days that have elapsed since January 1st

Julian date

Include time, temp, pressure records, digital printouts and gauges

Physical Mechanical Monitoring

Geobacillus stearothermaophilus

Steam sterilizer bacteria

Bacillus atrophacus

Dry heat bacteria

Procedures used by equipment manufacturers to obtain, record, and interpret test results in a sterile product

Validation

Procedures used by healthcare facilities to confirm that the validation undertaken by the equipment manufacturer is applicable to the specific setting

Verification

The amount of time to kill 90% of the microorganisms present

D-Value

Death occurs in a definite relationship to time, and this rate is governed by factors including temp, age of test culture

D-Value Sterilization Effectiveness

Caused by abnormal proteins called prions

Creutzfeldt-Jacob Disease (CJD aka mad cows disease)

Virus like infectious agents that cause neurodegenerative disease

Prions

Solutions that are administered to patients intravenously

Parental solutions

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

External solutions

The continual movement of water from the atmosphere to the earth and back to the atmosphere

Hydrologic cycle

A water treatment process which dissolves impurities are separated from the water

Reverse osmosis

Can be used to produced distilled water and isotonic solutions

Flashing technique
250-254 DF

The probability of a viable microorganism being present on a product unit after sterilization

Sterility assurance level (SAL)

Limits developed by OASHA to indicate the maximum airborne exposure an employee may be exposed to

Permissible exposure limits (PELs)

The employees average airborne exposure in any 8 hour workday

Time weighted average (TWA)

The process by which Ethylene Oxide destroys microorganisms, inability of the cell to metabolize

Alkylation

The act or process of oxidizing - chemical breakdown of nutrients for energy

Oxidation

Process monitoring consist of:

"4Rs" Run, read, recor, and retain

Terminal low sterilization methods

ETO
Hydrogen peroxide
Ozone

Low temperature - To be effective it must meet a sterility assurance level of:

10-6

Toxicity standards low level
ETO

1.0ppm
800 ppm

Toxicity standards low level
Hydrogen peroxide

1.0ppm
75ppm

Toxicity standards low level
Ozone

0.1ppm
10ppm

ETO Benefits

Small molecule that can penetrate through plastics
Kills microorganisms by reacting with molecules
targets specific molecules

A process in which a device is subjected to moving air

Aeration

The amount of ETO that remains after they are sterilized

Residual chemicals

Effective alkylating agent that kills wide range of microorganisms, destroys ability to reproduce

ETO method

Popular low sterilization method because of short cycle times that allow faster turn around

Hydrogen Peroxide (Gas plasma) sterilization method

Not compatible with powders and stronger absorbers such as paper, or linen. It cannot be used to process liquids

Hydrogen Peroxide (Gas plasma)

Destroys microorganisms by oxidation, and H2O2

Hydrogen Peroxide aka Gas plasma

Relatively new low temp sterilization method, requires no sterilant.

Ozone (O3)

Overview ETO

Alylation
1-4 hours exposure plus 8-12 aeration
Time, temp, ETO, Relative humidity
Flush load with warm filtered air
Long total cycle
1.0 ppm
All standard packaging

Hydrogen perioxide/Plasma Overview

Oxidation
28-50 min depends on load
Time, temp, concentration, vacuum level, plasma
1.0ppm
Non woven or tyveck

Ozone overview

Oxidation
4 hour exposure
Time, temp, concentration, relative humidity
0.1ppm
Compatible most products