Sterilization refers to any process that effectively kills or eliminates transmissible agents (such as fungi, bacteria, viruses, spore forms, etc.) from a surface, equipment, article of food, medication or biological culture medium. Sterilization can be achieved through application of heat, chemicals, irradiation, high pressure or filtration.
Medical devices are sterilized initially at the time of manufacturing and if reusable must be be routinely sterilized and validated to conform to regulatory standards. The sterilization method chosen is based on the product’s ability to withstand heat and extent of sterilization required.
The sterilization process for a newly manufactured device is inclusive of but not limited to the following steps: Cleaning, Packaging, Sterilization and Sterilization monitoring. In addition to these, resuable devices also require Decontamination and periodic revalidations/dose audits.
This involves the removal of debris and other matter on the device surface that would hinder full penetrtation of the sterilization process. Cleaning is performed through the use of basic cleaning supplies such as water, detergent and alcohol.
Devices are pre-packaged before they are put through the sterilization process. This is done so that after sterilization, products aren’t exposed to the elements, and therefore remain sterile at the time of use. Specialized pakaging/pouches are used which allow the sterilizing agent such as rays/heat/chemicals to penetrate and purify the device, but also protect the device from external contaminants.
The method of sterilization is chosen based on the product’s compatibility with heat and chemicals. To attain the recommended sterility levels, the device must be exposed to the sterilizing agent (steam, chemical, hot air, etc) for an appropriate length of time. Popular methods of sterilization are listed in the table below:
|Heat/High Pressure||Wet/Steam Sterilization
Dry Heat Sterilization
|Chemical||Ethylene Oxide (EtO)|
The sterilization process and its effectiveness can be monitored through the use of Indicator Tape and by performing Spore Tests/Biological Indicator tests respectively. Indicator tape is typically attached to the package/pouch undergoing sterilization and changes color, indicating that desired sterility levels/conditions have been met. The tape does not inform us however of the extent of microbial kill on the device. This is done through spore tests.