What is the function of the O2 flush button on an anesthesia machine?

• A. Delivers high-flow O2 directly to the breathing circuit bypassing the vaporizer
• B. Delivers a controlled mix of O2 and nitrous oxide
• C. Activates the scavenging system
• D. Initiates warm-up of the machine

Answer: (A)

The O2 flush button provides a very high-flow of oxygen directly into the breathing circuit, bypassing the vaporizers and the standard flowmeter pathway. This allows a rapid purge of the circuit and a quick increase in the inspired oxygen concentration when needed. It’s not meant for delivering a controlled anesthetic gas mix or for warming the machine; it bypasses the vaporizer so the gas entering the patient is essentially pure O2. Use with caution, because delivering such a high flow can raise circuit pressure if the exhaust isn’t able to vent properly.