In treatment of mediastinal emphysema, what oxygen concentration is recommended?

• A. 21% oxygen
• B. 50% oxygen
• C. 100% oxygen
• D. 0% oxygen

Answer: (C)

Giving 100% oxygen speeds the resolution of mediastinal air by washing out nitrogen from the trapped gas. When you breathe pure oxygen, the partial pressure of nitrogen in the blood and tissues drops, creating a diffusion gradient that pulls nitrogen from the mediastinal air into the bloodstream. This accelerates absorption of the air and helps the mediastinal emphysema resolve more quickly. Room air (low FiO2) would slow this process, while intermediate oxygen levels provide less benefit than full 100%. A brief use of 100% oxygen is preferred to hasten recovery, with monitoring for potential oxygen toxicity as needed.