LOW TEMPERATURE STERILIZATION-ETHYLENE OXIDE (ETO)


Sterilizer
Aerator

THE ETO SYSTEM 

OVERVIEW

Ethylene oxide(ETO) has been the primary sterilant of choice for items that cannot tolerate steam steam sterilization.It has an exceptional ability to penetrate and compatibility with numerous materials that provide broad sterilization applications.ETO uses a process call Alkyation where it destroys microorganisms by preventing it from normaly metabolizing or reprducing.

The ETO STERILIZATION CYCLE CONSISTS OF THREE STAGES.

The first stage is preconditioning stage to make the microorganisms grow.The batch goes through a dwell time under a controlled environment of temperature and humidity.

Second stage:sterilization

A heating jacket is used in this cycle to keep a accurate temperature control. After the doors are locked the cycle starts and goes through a numerous of phases which are
  • Cycle start delay to enable the system to start in stable conditions
  • General cell temperature check
  • Initial vacuum phase
  • Leak rate test
  • First flush
  • Second flush
  • DEC (Dynamic Environmental Conditioning)
  • ETO gas injection
  • sterilization dwell time period under Eto
  • Post dwell vacuum level
  • First wash
  • Second wash
  • Final air admission
  • Final chamber re-evacuation delay
 During these phases a batch report will be generated which includes tolerance ckecks,phase changes,alarm and critical process values. If any abnormal conditions occur the batch will automatically
stop and cause of stoppage will be identified. If there is no stoppage it will automatically carry on to the degassing stage.Batch files includes batch ID,Customer name,product type,start and stop times.

Final stage Degassed stage
In this stage the product goes through a dwell time in a temperature controlled environment to 
rid of any ETO residue(aeration).

LOADING 

  • Items must not overload because it will impede proper air removal,load humidification sterilant, sterilant penetration, and degassing.
  • Items must be properly spaced and do not stack.
  • Metal does not absorb ETO therefore it is ideal to use metal carts or baskets
  • Make sure items do not come into contact with chamber walls

UNLOADABLE

  • Liquids should not be combined with ETO as it will produce harmful chemical by products.
  • Leather items should not be use with ETO because if combined chemicals in the leather may produce chlorohydrins.
  • Excessively wet items should be avoided because ETO is unable to penetrate water layers.
     

MONITORING

Personal monitoring-involves the use of devices affixed directly to the employees clothing.
Area monitoring-that provide real-time,and continuous monitoring of airborne.

Sterilizer Performance Monitors

Physical indicators- Is  what you can see on the system itself on the screen.Eg.pressure gauges,timing
recorders charts and more


Chemical indicators(CI)- Should be placed in every load inside the pack in the center.This will show if all parameters have been met.


Biological indicators(BI)- Here we use a spore called Bacillusatrophaeus. If the cycle is capable of killing this spore then it is a successful cycle.




OTHER INFORMATION:
  • sterilization by alkylation - 3 hrs
  • aeration - 12 hrs at 120 F or 8 hrs at 140 F
  • humidity 50 %
  • BI placed in the center of the load


      =============CAUTION===============                 

  - ETO KNOWN AS CARCINOGEN
     - CAN CAUSE DIZZINESS,VOMITING
        RESPIRATORY IRRITATIONS,NAUSEA