The oxygen flush button on an anaesthesia workstation is pressed repeatedly while the circuit is connected to a paralysed patient with the ventilator running. The most serious hazard associated with this action is:

• A Dilution of volatile agent leading to intraoperative awareness
• B Delivery of a hypoxic mixture because the flush bypasses the needle valves
• C Overheating of the common gas outlet
• D Barotrauma from high flow gas delivered directly to the breathing circuit without a pressure limiting valve ✓

Explanation

The oxygen flush delivers 35 to 75 L/min of pure oxygen directly to the common gas outlet, bypassing both the vaporizers and the flowmeter needle valves. Because it does not pass through the ventilator pressure limiting mechanisms, holding it against a closed expiratory path can generate very high circuit pressures rapidly and cause barotrauma. Agent dilution is a real but less acute concern, and the flush delivers 100 percent oxygen, not a hypoxic mixture.

Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.