While considering methods for sterilization procedures, it is important to differentiate between sterilization and disinfection.
* Sterilization kills all viable microorganisms.
* Disinfection only reduces the number of viable microorganisms.
High-level disinfection will kill most vegetative microorganisms but will not kill the more resistant bacterial spores. Commonly used disinfectants such as alcohol, iodophors, quaternary ammonium and phenolic compounds are not effective sterilants and, therefore, are not acceptable for use on items intended to be used in survival surgical procedures.
The preferred methods of sterilization are high-pressure steam/temperature (in autoclaves) for items that can withstand high temperature and ethylene oxide gas for items that cannot withstand high temperature. However, cold chemical sterilants may be used effectively for many items.
Approved sterilization procedures:
* High pressure/temperature steam sterilization using an autoclave and appropriate monitoring systems (i.e. spore strips, etc.) to assure sterility.
* Gas sterilization with ethylene oxide using an approved gas sterilizer and appropriate monitoring systems to assure sterility and personal safety.
* Cold (chemical) sterilization used properly. Effective and proper use of cold sterilization is dependent on many factors including:
o The use of chemicals classified as “sterilants”. Those classified only as “disinfectants” are not adequate.
o The physical properties of the item being sterilized. It must be relatively smooth, impervious to moisture, and be of a shape that permits all surfaces to be exposed to the sterilant.
o Adequate exposure to all surfaces, both interior and exterior. Tubing must be completely filled and the materials to be sterilized must be clean and arranged in the sterilant to assure total immersion. The items being sterilized must be exposed to the sterilant for the prescribed period of time.
o Use of efficacious solutions: The sterilant solution must be clean and fresh. Most sterilants come in solutions consisting of two parts that when added together form what is referred to as an “activated” solution. The shelf life of activated solutions is indicated in the instructions for commercial products. Generally, this is from one to four weeks.
o Rinse instruments, implants, and tubing (both inside and out) should be rinsed with sterile saline or sterile water prior to use to avoid tissue damage.
Approved Sterilization Products: There are many acceptable commercial sterilants available and their use is encouraged over preparing solutions from basic ingredients. Only products classified as sterilants are to be used for sterilizing instruments and implants for surgery and they must be used according to the manufacturer’s recommendations for sterilization. Following are examples of commercial products listed by brand names:
* Heat (glass bead sterilizers) is effective at sterilizing materials that do not heat sensitive (metal instruments). These devices are very effective and convenient to use. Caution must be exercised to rinse the heated instruments in cool sterile saline BEFORE introducing the instruments into a body part.
* Cidex: Active ingredient: 2% Glutaraldehyde. The manufacturer’s instructions indicate that a minimum of 10 hours is required for sterilization. Cidex comes in two formulations, Cidex and Cidex-7 (long-life). The shelf life of activated Cidex is 15 days and of activated Cidex-7 is 28 days.
* Clidox: Active ingredient: Chlorine dioxide. 1:5 mixture must be mixed daily. 1:18 mixture is good for 14 days. 1:5 is a good sterilant; 1:18 is a disinfectant.
* Alcide: Active ingredient: Sodium hypohlorite 1.37%. The manufacturer’s instructions indicate that a minimum of 6 hours is required for sterilization. The shelf life of the activated solution is 14 days.
* Other acceptable sterilants are the following chemicals classified as sterilants by the Centers for Disease Control (CDC). These are the chemical ingredients of some of the commercial sterilants:
o Glutaraldehyde (2%) for a minimum of 10 hours.
o Formaldehyde (8%) / Alcohol (70%); minimum of 18 hours.
o Stabilized hydrogen peroxide (6%) for a minimum of 6 hours.