Chapter 15 High Temp Sterilzation

Special Purpose Pressure Sterilizers FLASH

Often found in operating rooms and surgical suite sub sterile rooms. Only used for emergency sterilization of instruments when there is not time for thermal sterilization.

Process Challange Device

PCD Bowie Dick

Basic work practices for steam sterilization

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

To decrease the temp of steam

Pressure must be decreased

Table top sterilizers

Primarily used in clinics and dental settings

Gauges and Controls ( Monitors)

Provide a visual and written record of sterilization conditions.

RH

Relative humidity

Dry Heat Sterilization

Relatively slow acting sterilizing agents. and generally requires higher temperature than other sterilization processes

Steam Flush Pressure Pulse Sterilizers

SFPP Use a repeated sequence of a steam flush and a pressure pulse to remove air from the sterilizing chamber and processed materials.

Saturated Steam

Should have a relative humidity of 97 percent to 100 percent.

Jacket keeps the chamber temp

Stable to prevent condensation inside

Two types of High temp sterilization used in hospitals

Steam and Dry heat

Autoclave

Steam comes in thru the steam inlet to the Baffle Plate. The baffle plate prevents steam from going right into the chamber, it expands and goes all around between the jacket and chamber walls. The residual air and water go down the drain.

Saturated Steam

Steam that contains the maximum amount of water vapor.

Types of Steam Sterilizers

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

Drain

The coldest and least amount of air pressure because of air pocket inside the chamber.

Steam

The gaseous state of water

Time

The higher the temp the less time that is required to kill and specific organisms.

320 degrees

The most widely used temp for dry heat sterilization, preferably for 2 hours.

Bioburden

The number of microorganisms on a contaminated object, also called bioload or microbioload.

Exposure Phase

The pressure inside the chamber begins to rise as does the steam temp. After the desired temp is reached the control system begins timing the cycles exposure phase.

Convection

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

Flash Sterilization

The process of sterilizing an item that is not wrapped

Terminal Sterilization

The process of sterilizing an item that is packaged

Oxidation

The slow burning up process of coagulating protein in a cell. Causes death of microorganisms

Steam sterilization cycles are based upon

The time temp relationship required to destroy bacterial spores.

Steam Sterilization cycles are based on

Time and temp relationship required to destroy bacterial spores.

Exposure Time

Time for which the sterilizers chamber is maintained within the specified range for temp, sterilant concentration, pressure and humidity

Convection (liquid ad gases)

Transfer of heat from on point (or one molecule) to another as the liquid or gas circulates Sterilization method-Steam

Radiation ( not used in hospitals)

Transfer of heat from one object to another without warming the space between the objects. Example from the sun to the earth

Conduction (solid)

Transmission of heat from one part to another part of the material. Example transfer of heat from one end of a metal bar to the other end of the bar. Sterilzation Method-Dry Heat

Conditioning Phase

Treatment of products within the sterilization cycle but before sterilant admission to attain a predetermined temperature and relative humidity, may be carried out at atmospheric pressure or under pressure

Temperature

Two most commonly encountered temps for steam sterilization is between 250f and 275f.

Table Top Sterilizers

Type of gravity air displacement sterilizer frequently used in clinics and dentists office. Reach the temp of 250F.

Dynamic Air displacement

Uses a vacuum cycle to pump air out and off the chamber

Gravity air displacement

Uses expanding steam to push out residual air out

Dynamic Air displacement

Uses vacuum, pumps air from the chamber before steam is added. Boiling point decreases

Dynamic Air Removal Sterilizers

Usually operate at 250f to 275f, is a pre vacuum sterilizer

Wet Packs

When moisture in the form of dampness, droplets, or puddles of water are found on or within a package after a completed sterilization cycle.

Boiling

When water turns to steam

Jacket

Where the steam enters from an outside source. Surrounds the top, sides and bottom. Steam circulates in this space to preheat the walls.

Expired packs

With linen wrap must be disassembled and the linen must be relaundered too restore moisture.

Steam Flush Pressure SFPP

active air removal

Three types of heat transfer

conduction convection radiation

Gravity Air displacement sterlizers

gravity = passive air removal

Pre-Vacuum Steam Sterilizers

pre-vac = active air removal

To increase the temp of steam

pressure must be increased

Temperatures for steam sterilaztion

range between 270 to 275 f 125 c to 135 c

Freezing to boiling

0c to 100 c (32) to 212 f. Only pure water h20 will freeze or boil.

Simple printout from a steam sterilization cycle usually contains

1. Date and time cycle began 2. Selected cycle parameters and activities such as type of cycle, sterilization temperature and dry times. 3. A written record of annual cycle activities ie. temperatures, exposure times and pressure.

Steam sterilization is preferred because

1. It is low cost 2. Sterilization cycles are fast. 3. It is relatively simple technology 4. It leaves no chemical residues or by products behind.

Anatomy of Steam Sterilizers

1. Jacket 2. Door, gasket and chamber drain 3. Thermostatic trap 4. Gauges and controls

3 states of water

1. Solid - ice 2. Liquid 3. Gaseous-steam

What effects sterilization methods

1. Type of microorganisms present. Some are more resistant that others. 2. The number of microrganisms (bioburden) present. The more the harder to sterilize 3. The amount and type of soil present. Soil acts as a shield to protect microorganism. 4. The amount of protection the medical device has. Microorganisms can be protected by cracks and crevices of the device and its designs.

Absolute Pressure

14.7 pounds per square inch at sea level

Conduction

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

Sterilant

A medium that facilitates sterilization

Flash Sterilizer

A sterilizer that uses higher temps for shorter exposure time to handle emergency sterilization of dropped instruments.

Bowie Dick Test

AKA Residual air removal test. Tests if residual air was removed from chamber also tests door gasket

Heat transfer

AN energy exchanged between the sterilizing agent and the object being sterilizied

Gauge Pressure-Steam Sterilizer

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

Dynamic Air displacement

Action of air removal

Steam Sterilization

Aka Gravity Air Displacement

Gauge Pressure

Always 15 psi lower than the absolute pressure. If the pressure exceeds the temperature the steam contains air, If the pressure is lower than indicated superheat is indicated.

Door gaskets

Are checked daily at the beginning of each shift and clean with lint dry cloth

Bowie Dick tests are performed to

Assure the actual removal of air and the integrity of the sterilizer

Drying Phase

Begins after the exposure phase. Uses the heat of the chamber walls as well as heated filtered fresh air to re-vaporize any liquid water and to remove it from the load and the chamber.

Gas or Steam

Bigger than water, same amount of water but steam will consume more space

Chemical Indictator

CI tapes ad inserts. If exposed to steam or heat it will turn color, same as wrapping tape.

3 stages of decontamination

Cleaning, disinfection and sterilzation

Thermostatic trap

Closes passage way from air and steam

IWS

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

Steam Sterilizer Cycle Phases

Conditioning Exposure Exhaust Drying

Conditions necessary fro effective steam sterilization

Contact Time Temp Moisture

Gravity Air Displacement Sterilizers

Create steam in the presence of air, also can sterilize liquids

Sterilization

Distruction of all microorganisms

Door, Gasket and chamber drain.

Door is the weakest part of the sterilizer.

Superheated Steam

Dry Steam. the condition of steam when its temp to high relative to its pressure in a steam table. When steam is dry it will be inefficient at thermal transfer.

Exhaust Phase

End of the exposure phase, chambers drain is opened and the steam is removed through the discharge line. The creates a slight chamber vacuum and sterile filtered air is gradually re introduced into the chamber through a special filter.

Wet Pack

Equals unsterilization

Condensation

Equals wet pack

Two basic sterilization cycles

Flash Terminal

Absolute pressure - steam sterilizer

Gauge pressure, psi.- machine produced plus atmosphere pressure 14.7 psi at sea level

Two types of sterilizers

Gravity air displacement Dynamic Air displacement

Convection

Heat transfer by circulating gas-air or steam

Conduction

Heat transfer by direct contact

Steam Destroys by

Heat, Pressure and time

Geobacillus Stearothermophiles

Highly resistant but relative harmless nonpathogenic microorganism used to challange steam and dry heat sterilizers. A spore or bacteria with a hard shell around it that makes it harder to kill.

Julian Date

How long its been from the first day of the January

Instrument washer sterilers

IWS wash and sterilize instruments. Most frequently used to decontaminate instruments placed into the sterilizer prior to cleaning.

Process Indicators

Intended for use with individual packs or containers to demonstrate that the unit has been exposed to the sterilization process, and to distinguish between processed and unprocessed units. Source ANSI/AAMI ST 60.

Residual Air

Is leftover air that is displaced by expanding steam aka gravity air displacement (on the test)

Dry Saturated steam

Is mandatory for effective steam sterilization.

If drain is clogged

It can not remove condensation from steamed air. This will produce wet packs

Steam sterilization has long been preferred because

It is low cost, sterilization cycles are fast, It is relatively simple technology, it leaves no chemical residues or by products behind

The Jacket of the autoclave

Keeps the chamber warm to prevent condensation

The most frequent reason sterilization failure

Lack of contact between steam and the microorganisms on the entire surface of the device being sterilized.

Gross

Large chunks of soil or bio burden

Thermostatic trap

Located in the drain line. A sensor in the trap measures steam temperature, and automatically controls the flow of air and condensate from the sterilizing chamber.

Mechanical Indicator

MI Machine gauges temp, pressure and time