Final answer:
Instruments in an autoclave should be sterilized using steam. The autoclave operates under high pressure to achieve temperatures necessary to kill all microorganisms, including endospores, and quality control measures are used to ensure the process's effectiveness.
Step-by-step explanation:
When sterilizing instruments using an autoclave, the machine should be filled with steam. Autoclaves rely on moist-heat sterilization, which utilizes high-pressure steam to elevate temperatures above the boiling point of water, effectively killing microorganisms such as bacteria, viruses, and especially endospores. The air in the chamber is displaced by the steam to allow for even and thorough sterilization of the instruments. It is important to ensure that the steam directly contacts the items being sterilized, which is why containers with liquids are left loosely closed and instruments are loosely wrapped. This is because the steam must be able to penetrate these materials to achieve complete sterilization. Consistently meeting the standard operating temperatures of 121 °C or 132 °C, typically at a pressure of 15 to 20 pounds per square inch (psi) for a duration of at least 20 minutes, is vital for the process to be successful. Quality control measures, such as the use of heat-sensitive autoclave tape and biological indicators, are routinely employed to confirm the effectiveness of the sterilization process.