Which option represents the fraction of inspired oxygen delivered to a patient?

• A. Fractional Inhaled Oxygen
• B. Fraction of Inhaled Oxygen
• C. Forced Inspired Oxygen
• D. Fractional Inspired Oxygen

Answer: (D)

Fractional Inspired Oxygen is the standard term for the fraction of the gas inhaled by a patient that is oxygen. It represents how much oxygen the patient actually receives from the inspired air, with room air providing about 21% oxygen (FiO2 ~ 0.21) and higher values achieved with supplemental oxygen up to 100%. The other phrasings aren’t the conventional terminology used in clinical practice, so the correct choice is Fractional Inspired Oxygen.