Which of the following physical properties are required for an autoclave to sterilize biohazardous material?

1. Dry heat
2. A vacuum
3. 100% humidity
4. Increased air pressure
a. 2 and 3 c. 1, 2, and 4
b. 1 and 3 d. 2, 3, and 4

ANS: D
Air is evacuated, moisture is added (100% humidity), and the pressure inside the autoclave is raised to 15 to 20 lb-force per square inch gauge (psig). Air is evacuated from the chamber be-cause residual air prolongs the penetration time of steam, thus increasing the total autoclave cycle time. Pressure is used to raise the temperature of the steam, which is critical because the amount of time required to achieve sterilization depends on the temperature inside of the autoclave. Dry heat is not used during autoclaving.