FiO₂: Understanding How Much Oxygen Your Baby Is Receiving
What Is FiO₂?
FiO₂ stands for fraction of inspired oxygen. Simply put, it tells you the percentage of oxygen in the air-and-oxygen mixture your baby is breathing.
Room air—the air we normally breathe—contains about 21% oxygen, so room air has an FiO₂ of 0.21, or 21%.
If your baby needs additional oxygen, the NICU team can increase the FiO₂.
What Do the Numbers Mean?
You may hear your baby's nurse, respiratory therapist or provider say something like:
“Your baby is on 30% oxygen.”
That means the FiO₂ is 30% (0.30).
FiO₂ is different from the oxygen saturation (SpO₂) number you see on your baby's monitor.
FiO₂ = how much oxygen your baby is receiving.
Oxygen saturation (SpO₂) = an estimate of how much oxygen is being carried in your baby's blood.
These numbers are related, but they are not the same thing.
Why Does FiO₂ Change?
Your baby's oxygen needs can change throughout the day. The NICU team may adjust FiO₂ based on factors such as your baby's oxygen saturation, breathing effort and overall clinical condition.
Premature babies can be particularly sensitive to both too little and too much oxygen, which is why oxygen is carefully adjusted to the target range prescribed for your baby.
Seeing the FiO₂ go up temporarily does not always mean something is wrong. Your baby's team looks at the whole clinical picture rather than one number alone.
