Intermediate
Technical
In the Industry Vocabulary Test
FiO2
Pronunciation: FIE-oh-two
Also written as: FiO2 — Fraction of Inspired Oxygen
Fraction of inspired oxygen; the percentage of oxygen in the gas mixture delivered to a patient.
Full Definition
FiO2 represents the fraction or percentage of oxygen in the inspired gas mixture, expressed as a decimal (0.21-1.0) or percentage (21-100%). Room air has an FiO2 of 0.21 or 21%. In neonatal care, FiO2 is carefully titrated based on oxygen saturation targets to provide adequate oxygenation while minimizing the risk of oxygen toxicity and retinopathy of prematurity. Modern practice emphasizes using the lowest FiO2 necessary to maintain target saturations.
Usage
Usage note: Express as decimal (0.21) in medical records; percentage (21%) in family communication.
In Context
- "The FiO2 was reduced from 0.4 to 0.3 as oxygen saturations remained stable above 90%." — Respiratory therapy note
- "Target oxygen saturations of 88-92% were maintained with an FiO2 of 0.25 on CPAP." — Progress note
Also known as
fraction of inspired oxygen
oxygen concentration
Don't confuse with
oxygen saturation
PaO2
oxygen flow rate