Which precaution is recommended after stopping nitrous oxide anesthesia to prevent diffusion hypoxia?

• A. Administer oxygen for several minutes after stopping
• B. Increase the duration of anesthesia
• C. Use pure oxygen during anesthesia only; not after
• D. No special precautions are needed

Answer: (A)

Diffusion hypoxia happens because nitrous oxide is still diffusing into the alveoli after you stop delivering it, diluting the alveolar oxygen and lowering the oxygen tension in the blood. The best way to prevent this is to flush the lungs with 100% oxygen for several minutes after stopping nitrous oxide. This high oxygen washout quickly replaces the alveolar gas, prevents hypoxemia, and helps ensure normal oxygen delivery as the nitrous oxide clears from the body.

Giving oxygen only during anesthesia, or extending anesthesia duration, doesn’t address the gas already present in the alveoli after discontinuation. No special precautions would miss the immediate post-stop period where diffusion hypoxia can occur.