Hydrogen Peroxide
A hydrogen peroxide gas cloud or low temperature plasma produced by a strong electrical
field is suitable for sterilization of surfaces. Low temperature hydrogen peroxide gas
plasma sterilization has been available in the United States since 1993. Hydrogen peroxide
plasma is formed directly in the sterilization chamber, rather than in a separate reaction
chamber (Figure 114-3). During low temperature hydrogen peroxide gas plasma
sterilization, medical devices and surgical instruments are placed in the sterilization
chamber, and a vacuum is applied to remove the air. A solution of 58% hydrogen peroxide
in water is injected into an outer chamber from a self-contained cassette inserted by
the operator at the beginning of every 10 sterilization cycles. The solution is then vaporized
and allowed to diffuse throughout the sterilization chamber, surrounding the items to
be sterilized. Radio frequency (RF) energy is then applied to create an electromagnetic
field, which in turn initiates the generation of the plasma. At the conclusion of the sterilization
cycle after approximately one hour, the electromagnetic field is turned off, and the
reactive hydrogen peroxide species rapidly revert primarily to water vapor and oxygen.
The sterilization chamber is repressurized, and the air is passed through an activated charcoal
filter to remove any residual hydrogen peroxide.
Advantages of low temperature hydrogen peroxide gas plasma system include an
excellent safety profile for employees. Unlike EtO, liquid chemical sterilants, and other
alternative sterilization technologies, low temperature hydrogen peroxide gas plasma
sterilizer poses little risk to operators and the environment. Exposure to hydrogen peroxide
has been limited to 1 ppm over eight hours by Occupational Safety and Health
Agency (OSHA) regulations. Monitoring by OSHA of the external environment of the
sterilizer during operation has demonstrated that the average concentration of hydrogen
peroxide in the atmosphere over eight hours is 0.018 ppm, while the personal sample
exposure is 0.013 ppm.
Safety for patients has been established through laboratory tests of the low temperature
hydrogen peroxide gas plasma technology prior to market clearance in 1993. These
tests have demonstrated that this technology destroys a broad spectrum of micro organisms,
including Gram-negative and Gram-positive vegetative bacteria, mycobacterium,
yeast, fungi, and viruses, as well as highly resistant aerobic and anaerobic bacterial
spores. In addition, as the hydrogen peroxide breaks down into water and oxygen, there
are no concerns about toxic residues following the completion of a sterilization cycle.
Studies have demonstrated that items processed by this technology are nonirritating and
nontoxic to cells and tissues.