What is steam sterilization?

By definition, sterilization means destruction of all forms of microbial life. The process of sterilization may vary with the different types of requirements for handling and disinfecting the medical equipments. Quite often, the sterilization in the hospitals is carried out with steam under pressure or liquid or gaseous chemicals. Known as steam sterilization, it involves heating in an autoclave containing saturated steam under a pressure of 15 psi which further helps to accomplish a chamber temperature of at least 121°C. Using pressurized steam at such a high temperature ensures eradication of all microbial cells including spores, which are usually believed to be heat resistant.

Steam sterilization process is not as simple as it sounds to be. The success of this method depends on a number of critical factors that includes: a) Maintaining high temperature; (b) Proper saturation of the heat; and (c) complete elimination of heat at the beginning. A wide variety of autoclaves is available that are designed to hold all types of medical instruments. Some autoclaves make use of a steam activated exhaust valve which remains open to control the exit and access of air and steam until the steam sets off the valve to close. Contrary to this, other steam sterilizers’ known as prevacuum sterilizer utilizes a pre-cycle vacuum to bring the process of removal of air into the effect before introducing the steam. Such a type of steam sterilizer was especially designed to overcome the problem of air trapping in the chamber during steam sterilization.

The sterilization equipments are physically placed in a sterilization tray which is also commonly known as an instrument tray. Not all trays for sterilization provide same air removal and steam ingress characteristics. All the instruments that are introduced directly to operate any part of the body must be steam sterilized before being washed and placing in the sterilization tray. Depending on the design, these instrument trays can contain single sterilization equipment or a set of sterilization equipments.