Sterilization

Sterilization

1. Methods

   • Steam (autoclave)
     • May corrode metals
     • Simple, fast, low cost
     • 20min 121C at 100 kPa
   • Irradiation
     • Gamma
       • Excellent penetration ability
       • Incompatibility with electronics and some polymers (PTFE)
       • High capital cost and specialized facilities required
       • Cobalt-60 source, 25 kGy dose, few hour rad time, low temp
     • E-beam (high energy electrons)
       • Does not penetrate as well as gamma
       • Few seconds to minutes rad time, still costly
   • Gas (ethylene oxide)
     • May leave residues
     • Toxic, highly reactive gas
     • Exposure and post condition cycle 12-20h
     • Heat 55C , humidity 70%
     • Widely used, compatible with wide range of materials
   • Dry heat
     • Simple and cheap method
     • Can be used on very limited range of materials

2. Criteria for the need for sterilization

   • Critical devices
     • Surgical instruments, catheters, implants, probes
     • Contact with tissues, blood, vessels
   • Semi critical devices
     • Contact with mucous membranes or non-intact skin
     • Airway-management equipment, endoscopes
   • Non-critical devices
     • Skin contact only
     • Bedpans, blood pressure cuffs etc

3. Verification of effectiveness

   • Physical indicators
   • Chemical indicators
   • Biological indicators

4. Packaging

   • General requirements
     • Permeable to air and sterilization gases
     • Integrity on loading, shipping, storage
     • Protect the device and its properties
     • Enable aseptic handling
     • Not evolve toxic substances
   • Types
     • Bubble (push through)
     • Bag (double)
     • Boxes & containers
   • Testing
     • Permeability and integrity
     • Physical resistance to puncture, tear
     • Properties of seals and indicators