Appendix B: Instrument Sterilization (Standard and Nonstandard)

Definitions

- Cleaning: Removes dirt, debris, and biological material from surgical instruments
- Disinfect: Cleaning with a disinfectant to destroy bacteria
- Sterilize: Making free from bacteria or other living organisms

Notes

- Cleaning, disinfecting, and sterilizing are the three levels of instrument care.
- Critical tools are those that make contact with open wounds, open vasculature, and/or organs. Semicritical tools are those that contact the mucosa, and noncritical tools are those that contact intact skin.
- Sterilization is the goal for any tools that will be used for surgical intervention; however, if life depends on it and sterilization is not an option; disinfection can be achieved using one of the options listed below as the “Better” option.
- The goal of sterilization is to eliminate the presence of bacteria, viruses, parasites, and particulates; bacterial spores are the most difficult to destroy.
- For all nonstandard sterilization techniques, gross contamination should be removed from all instruments/equipment by scrubbing with soap and water first.
- Chemical sterilization elements should never be combined.
- Steam with distilled water is the preferred sterilization technique.

BEST: Remove gross contamination, using soap and water, then sterilize by steam or dry heat using one of these techniques:

- Steam sterilization using one of the following techniques and the following temperatures: 121°C (250°F) for 30 minutes or 132°C (270°F) for 4 minutes
- Autoclave (portable or standard size) and distilled water
- Steam sterilization using the SF medical Tac-Set portable sterilizer pot (NSN: 6530-00-926-2022), according to the manufacturer’s operating instructions:

1. Remove the cover by loosening the wing nuts in a counterclockwise motion. Always undo two opposite wing nuts at a time.
2. Lubricate the metal-to-metal seal where side wall and bevel meet on the inside of the sterilizer. Use petroleum jelly or mineral oil.
3. Remove the aluminum inner container. Pour clean (preferably distilled) water into sterilizer to a depth of not less than three-fourths of an inch, but no more than 1 inch.
4. Place inner container rack into inner container with the lip or edge side downward. Place articles to be sterilized on container rack. Only steam should make contact with articles. Replace packed inner container into sterilizer, ensuring the air exhaust tube channel is in position on the right side of the container when it is placed into the unit.
5. Place sterilizer cover on unit, making sure that the index alignment arrow on the cover aligns with index line/arrow on the side of the bottom. Ensure that the flexible tube is inserted into the guide channel on the inside wall of the aluminum container. Tighten the wing nuts evenly, always tightening down two opposite nuts simultaneously to assure a proper seal.
6. Place unit onto a heat source. Open the control valve by placing valve lever in an upright position. It is important that steam be permitted to escape vigorously for at least 7 minutes or until the flow of steam is continuous. Afterwards, close the control valve. When pressure gauge reaches 17–19 psi, reduce heat as necessary to maintain a constant pressure of 17–19 psi within the unit.
7. The sterilization period begins when the pressure steam gauge needle registers in the green sterilization band shown on the face of the gauge (i.e., 17–21 psi). This should be no less than 35 minutes. Note: At altitudes higher than sea level, settings need to be adequately adjusted to compensate for the effect of altitude on water’s boiling point. The manufacturer suggests increasing pressure by 0.5 psi for every 1,000 feet of elevation above sea level.
8. At the end of the sterilization period, remove unit from heat source and move the lever on the control valve to an upright position to allow the steam to escape. With caution, loosen wing nuts and remove the cover to retrieve sterilized items.

Dry Heat

- Dry heat may also be used to sterilize surgical instruments.
- Instruments can be wrapped in aluminum foil or placed in sterilization trays before putting them in the oven.
- Allow the instruments to cool to room temperature inside the oven before use or storage.
- Instruments can be heated to any of the following to be considered sterilized:
  - 180°C (356°F) for 30 minutes
  - 170°C (338°F) for 1 hour
  - 160°C (320°F) for 2 hours
  - 149°C (300°F) for 2.5 hours
  - 141°C (286°F) for 3 hours

BETTER: Remove gross contamination using soap and water, then sterilize with improvised autoclave or chemical disinfection.

- Improvised autoclave using a pressure cooker that can reach the steam sterilization temperatures listed above.
  - Place wire rack in the bottom to prevent the instruments from becoming submerged. Only steam should make contact with the instruments. Begin timing for sterilization once steam starts to vent from the pressure cooker.
  - Pressure cookers operate at various pressures and temperatures. Sterilization time of 60 minutes is recommended.
- Glutaraldehyde (Cidex©; Johnson & Johnson): Widely available and accepted as a high-quality disinfectant in healthcare facilities.
  - Can be used to sterilize aluminum, brass, copper, stainless steel, plastics, and elastomers.
  - Once the container is open, the chemical has a limited shelf life—a minimum of 14 days, usually 28–30 days; refer to the specific product’s manual for the exact shelf life.
  - Test strips can indicate the efficacy of an opened container of glutaraldehyde.
  - Alkaline glutaraldehyde mixes are more effective than acidic glutaraldehyde mixes.
  - Items should be soaked for 60 minutes for maximum efficacy.
  - Long-term exposure can cause irritation to tissues; rinse tools before use.
- Formaldehyde: Prepare 5% formaldehyde solution.
  - Both metallic and plastic medical equipment can be sterilized using formaldehyde.
  - Wrap a 5mg tablet of formaldehyde in gauze and crush the tablet.
  - Place the gauze-wrapped tablet in 100mL of potable water (can be cold water).
  - This solution can be stored for up to 30 days without losing its potency.
  - Lower concentrations of formaldehyde can be used, but the amount of time the instruments are submerged in the solution needs to be increased to compensate for this change.
  - Clean the instruments with soap and water, and remove any blood and tissue.
  - Soak the instruments in the 5% formaldehyde solution for at least 1 hour but preferably for 12–24 hours.19,20
  - Duration should be closer to 24 hours if 1% formaldehyde solutions are used (i.e., 5mg tablet in 500mL of water).
  - The instruments and formaldehyde solution can be kept at room temperature.
  - Remove the instruments and rinse with water or saline before use.
- Alcohol: 60% to 90% minimum; tools need 3 hours of contact time. Consumable alcohol must be a minimum of 120 proof. This method is not sporicidal and, therefore, not recommended as a primary modality for surgical items.
- Sodium hypochlorite (household bleach)
  - This disinfectant is caustic to eyes, oropharynx, esophagus, and gastric tissue.
  - Undiluted (5.25%) sodium hypochlorite should be used to disinfect instruments categorized as critical.
  - Instruments should have a minimum contact time of 5 minutes.

MINIMUM: Remove gross contamination, using soap and water, then boil instruments in at least 100°C (212°F) water for at least 1 minute.

NOTE: This method does not sterilize instruments and should be used as a last resort for surgical instruments.