Time and optimal conditions required for sterilizing surgical instruments

NEW ORLEANS — Various methods are available for sterilizing surgical instruments to protect patients from toxic anterior segment syndrome and other infections, an expert said here.

Barbara Ann Harmer, RN, described essential sterilization techniques at the American Academy of Ophthalmology meeting.

"The sterilizing agent, whatever type of sterilizer that you have, must in fact be in contact with all of the surfaces of the items you are sterilizing," Ms. Harmer said. "You must have sufficient time and appropriate conditions: temperature, pressure, humidity and concentration."

Steam, the "oldest, cheapest and most used" sterilization method, destroys all resistant bacterial spores and leaves no toxic residue, she said.

Air dilution, a type of steam, is commonly used in medical offices and surgical centers. Air dilution machines generate their own steam. Water used for air dilution should be distilled or deionized, and vats must be emptied and refilled after each use, Ms. Harmer said.

Gravity displacement, another type of steam, involves an injection of pressurized heat and steam in an autoclave, she said.

Medical professionals started using ethylene oxide, a toxic organic chemical combined with fluorochlorocarbons, in the late 1960s but had to consider other sterilization methods when the federal Clean Air Act required that fluorochlorocarbons 1be removed from sterilizing gases by 1996, Ms. Harmer said.

Dry heat, which destroys organisms by oxidation, is not user-friendly because it requires high temperatures and long exposure time, she said. However, she noted that dry heat dulls and corrodes instruments less than other methods.

Gas plasma sterilization involves hydrogen peroxide vapor. There is only one gas plasma method approved by the U.S. Food and Drug Administration, Ms. Harmer said.

Other sterilization methods include cold sterilization and liquid chemical sterilization, she said.