SterilizationQuestion 29 of 100
What is the fundamental difference between a gravity displacement cycle and a dynamic-air-removal (prevacuum) cycle?
a.Gravity relies on incoming steam to push air down and out the drain, while dynamic-air-removal uses vacuum pulses to actively pull air out before steam is admitted
b.Gravity operates at a lower temperature than any dynamic-air-removal cycle
c.Gravity uses saturated steam and dynamic-air-removal uses dry heat
d.Gravity requires a biological indicator while dynamic-air-removal does not
Explanation
In a gravity cycle, steam entering the chamber displaces cooler, heavier air downward through the drain, which is slower and less reliable for porous items and lumens. Dynamic-air-removal cycles mechanically evacuate air with vacuum pulses or steam flushes so steam contacts every surface almost immediately. Both cycles use saturated steam, both are monitored with biological indicators, and both can run at 270 degrees F.
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Related questions on this topic
- A wrapped instrument set is being sterilized in a dynamic-air-removal steam sterilizer at 270 degrees F (132 degrees C). What is the typical minimum exposure time?
- What is a standard gravity displacement steam cycle for a wrapped instrument set at 250 degrees F (121 degrees C)?
- A technician opens the department at the start of the day shift and must schedule the Bowie-Dick test for a dynamic-air-removal sterilizer. How often is the test required?
- A Bowie-Dick test sheet comes out of the sterilizer with a pale, uneven center and darker edges. What does this indicate and what should be done?
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- Why is saturated steam, rather than superheated or wet steam, required for steam sterilization?
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