Traditional sterilization processes used for medical products include steam, ethylene oxide (EtO), ionizing radiation (gamma or E-beam), low-temperature steam and formaldehyde, and dry heat (hot air).
These methods can be divided into three categories, based on the nature of the sterilant and its reaction with microorganisms: physical processes (ionizing radiation, dry heat); physicochemical processes (steam, steam/formaldehyde); and chemical processes (EtO, glutaraldehyde).
Chemical and physicochemical processes depend on direct physical contact between molecules of the sterilant and the microorganism to be killed. In consequence, access must be available to the surfaces of the product to be sterilized and the packaging material must be porous or permeable to these molecules.
Purely physical processes such as ionizing radiation may be used for product designs and packaging materials that are impermeable to gases as long as they are "transparent" to energy of the wavelengths employed in the sterilization process.
Over the past few years, the development of the art of sterilization has accelerated, with the introduction of several new processes. At least one reason for this is the potential decline in the use of EtO in hospitals. This is a result both of increased concern over the toxicity of residuals and of the need to eliminate the use of chlorofluorocarbons (CFCs), which had previously been employed to minimize the flammability and explosion risks of the ETO.
Another prominent trend is the proliferation of various minimally invasive therapies, and the need for appropriate sterilization protocols for the equipment used in these procedures. |
