What is the term for replacing nitrogen in the lungs with oxygen and filling the functional residual capacity with 100% oxygen, typically lasting several minutes?

• A. Pre-oxygenation
• B. Induction
• C. Recovery
• D. Emergence

Answer: (A)

This tests the concept of preoxygenation. Preoxygenation is the process of replacing air in the lungs with 100% oxygen before induction, so nitrogen is washed out and the functional residual capacity is filled with oxygen. This creates an expanded oxygen reservoir in the lungs, delaying hypoxemia during the period of apnea that occurs when the airway is secured. It’s especially important in patients with reduced lung reserves or high oxygen consumption, and it typically lasts several minutes of breathing 100% oxygen.

Induction refers to turning anesthetic agents on to achieve unconsciousness, not specifically about building an oxygen reserve. Recovery and emergence describe postoperative processes of waking up and returning to baseline, which are unrelated to the preoxygenation step.