Certified Surgical Technologist (CST) Practice Exam

What is the minimum number of minutes to sterilize unwrapped metal instruments with lumens in the gravity displacement sterilizer at 270 degrees F?

1. 5

2. 10

3. 15

4. 20

The correct answer is: 10

The minimum time required to sterilize unwrapped metal instruments with lumens in a gravity displacement sterilizer at a temperature of 270 degrees Fahrenheit is 10 minutes. This time frame ensures that the steam has sufficient contact with all surfaces of the instruments, including inside lumens, to effectively kill any microbial life present. Sterilization at this temperature in a gravity displacement sterilizer relies on the principle of steam penetrating the items being sterilized, and a longer exposure time of 10 minutes helps to ensure that all parts, especially the inner surfaces of lumens, are adequately sterilized. This standard is consistent with guidelines provided by organizations such as the Association for the Advancement of Medical Instrumentation (AAMI) and the Centers for Disease Control and Prevention (CDC). Selecting the correct duration is vital for achieving sterilization while minimizing damage to the instruments from excessive heat exposure, which can occur with longer times or higher temperatures.