Sterilization is the process of complete removal and/or destruction of all forms living micro-organisms including bacteria and their spores within of about an object. There are several ways by which sterilization can be accomplished: a) Physical Means: heat, radiation and filtration and; b) Chemical Means: such as phenols and other chemical agents.
There are important things to remember with sterilization and disinfection:
1. We must have basic knowledge of the proper method of loading and operating sterilizers and autoclaves.
2. Know the correct method of cleaning, preparing, packing and wrapping of all articles to be sterilized.
3. Know the various methods and timing of sterilization.
4. Learn the proper use of “Sterilization Indicators”.
5. Know the care and storing of articles after sterilization.
6. Remember the importance of systematically taking culture tests to determine the efficiency of sterilization.
Methods and Timing of Sterilization
I. Sterilization by Heat
a) Boiling Water (Timer to be set after water reaches boiling point. Temperature 2120F at sea level.). Recommended time for sterilization of various articles:
· 1 hour – water sterilizers (re-sterilize every 12 hours)
· 30 minutes – instruments used for bone case.
· 20 minutes – basic and special instruments.
· 10 minutes – separate instruments.
· 10 minutes – rubber material, i.e., suction tubing, drains and catheters.
b) Pressure steam (high speed). Recommended time and temperature:
· 3 minutes, temperature 2540F at 27 lbs. pressure-basic instruments.
· 5 minutes, @ above setting- instruments used for bone cases.
· 3 minutes, temperature 2540F at 27 lbs. pressure – rubber goods of all kinds.
c) Pressure steam (autoclave). Recommended time and temperature:
· 1 hour @ 2500F at 20 lbs. pressure – large packs and drums.
· 45 minutes @2500F at 270 lbs. pressure – medium and small packs.
· 15 minutes @ 2500F at 20 lbs. pressure – gloves, glassware, rubber materials, spinal and local anesthesia sets.
· 10 minutes @ 2500F at 20 lbs. pressure – ampoules of spinal anesthesia solution.
d) Dry Heat (hot air). Recommended only where direct contact of the material and substance with pressure steam is impractical or unattainable:
· 60 minutes, temperature 3200F for all glassware and sponges wrapped.
· 75 minutes, temperature 3200F for syringes in test tubes.
· 2 hours, temperature 3200F for glycerin, mineral oil in bone wax.
· 3 hours, temperature 3200F for powders.
1. Solutions and gloves to be autoclaved separately.
2. Re-sterilize all articles not used within 7 to 14 days from date of sterilization.
II. Sterilization by Chemicals
Chemical are used when heat would destroy the article to be sterilized:
- 24 hours – Plastic Prosthesis and polyethylene tubing clear zephiran chloride solution 1-1000.
- 30 minutes – all sharps (knives, scissors and suture needles). Zephiran Chloride solution 1-1000 with Sodium Nitrite added (1oz to a gallon).
- 15 minutes – all light cords and GU. Scopes – Mercury Cyanide solution 1-1000.
- 15 minutes – Bronchoscopic light carriers, cords and plastic tape instruments – alcohol 70% solution.
a. Rinse with sterile water when using Cyanide solution.
b. Wipe with sterile towel when using Zipheran or Alcohol solution.
Suggested colors for the following solutions:
· Carbolic Acid = Red by Pharmacy
· Cyanide of Mercury = Pink of Pharmacy
· Alcohol % = Light-blue, using Methylene Blue, 1 drop to 1000 cc.
· Zephiran Chloride with Sodium Nitrite added Cocaine Solution = Purple, using Gentian Violet, 3 drops to 1 gallon. Pale blue using Methylene blue, dip wood end of applicator lightly in Methylene blue and stir in solution.
· Orange red, colored by using 14 gms. Of Zephiran Tint to 1 gallon of solution. This is used for the routine skin prep.
The above solutions and colors have proved satisfaction by practice may vary in different hospitals.
Disinfection (germicide/bactericide) is the chemical agent which destroys pathogenic organism.
Kinds of disinfectants:
a) oxidizing agents: H2O2, KMnO4
b) Halogens: iodine, chorine, etc.
c) Acids: HNO3, etc.
d) Alkalies: KOH, etc.
e) Salts of heavy metals: KMnO4
f) Cases: Formaldehyde
g) Soaps: Commercially available bactericidal soaps.
h) Certain organic compounds: phenols, alcohols and merthiolate.