Essentials of Steam Sterilization

Sep 10, 2024

Lecture Notes: Steam Sterilization

Introduction

  • The lecturer begins by discussing the struggle with adjusting the video camera.
  • Steam Sterilization is the main topic of the lecture.

Basics of Steam and Sterilization

Steam

  • Steam is the gaseous state of water.
  • Water exists in three states: solid (ice), liquid (water), and gas (steam).
  • Boiling point of pure water is at 100° Celsius or 212° Fahrenheit.
  • Contaminated water boils at different temperatures.
  • Steam has a larger volume compared to water.

Sterilization

  • Sterilization is the destruction of all microorganisms.
  • Stages of Sterilization:
    • Cleaning: Removal of gross visible and invisible soil (big chunks of dirt).
    • Disinfection/Decontamination: Destruction of most microorganisms.
    • Sterilization: Destruction of all microorganisms.

Properties of Steam in Sterilization

  • Steam is bigger than water, expanding to fill larger volumes.
  • Increased pressure is essential in steam sterilization.
  • Steam sterilization involves pressure and heat to kill microorganisms.
  • Time is a critical factor; sterilization must be complete.

Important Terms

Sterilant

  • A medium that facilitates sterilization.
  • In steam sterilization, steam acts as the sterilant.

Gravity Air Displacement

  • Residual air is displaced by expanding steam.
  • Gravity air displacement occurs at approximately 250°F or 121°C.

Dynamic Air Removal

  • Uses vacuum pumps to remove residual air before steam is injected.
  • Involves higher temperatures (270-275°F or 131°C).

Sterilization Equipment

Pressure Cooker Model

  • Simplifies understanding of steam sterilizers.
  • Consists of a pot, lid, valve, and heat source.
  • Steam expands, displacing air, and increases pressure.

Advanced Sterilizers

  • Use a jacket to maintain stable temperature and prevent condensation.
  • Dynamic air removal sterilizers use vacuum pumps for efficiency.
  • Ensure no air pockets are present to prevent incomplete sterilization.

Tests and Indicators

Process Challenge Devices (PCDs)

  • Challenge sterilization to ensure efficacy.

Biological Indicator

  • Uses Geobacillus stearothermophilus spores.
  • Tested minimally once a week, or every load for mixed loads.

Chemical Indicator

  • Changes color when exposed to steam and heat.
  • Includes tape and internal strips within packs.

Mechanical Indicators

  • Monitored with every load: temperature, pressure, and time gauges.

Bowie-Dick Test

  • Used in dynamic air removal systems for air removal verification.

Heat Transfer in Sterilization

  • Conduction: Direct contact.
  • Convection: Circulating gas (e.g., steam is an example).
  • Radiation is not used in hospital sterilization.

Loading and Procedure

  • Avoid overloading sterilizers; ensure space for steam circulation.
  • Packages should not touch chamber walls or each other.
  • Wrap items properly; not too tightly to ensure sterilant penetration.

Conclusion and Practical Advice

  • Understand and apply steam sterilization concepts for job interviews.
  • Reliability and proper knowledge are key in sterilization roles.
  • Be aware of humor and anecdotal stories that illustrate concepts.

Note: All information discussed is critical for understanding and will appear on the test. Review notes and chapters thoroughly.