NC and FiO2 oxygen conversion

Q: 6 L per minute of oxygen via low flow nasal cannula (NC) is approximately equal to?

A) 28% FiO2 of oxygen
B) 35% FiO2 of oxygen
C) 45% FiO2 of oxygen
D) 60% FiO2 of oxygen
E) It is hard to compare equivalency between NC and FiO2 level of oxygen


Answer:  C

Actually, there is a calculator developed to find equivalency of NC and FiO2 level of oxygen. This may be of help in converting or weaning patients from mask ventilation to nasal cannula.

Calculators can be found online but a simple rule of thumb is that the fraction of oxygen that is inspired (above 2I%) increases by 4% for every additional liter of oxygen flow administered.



Reference: 

AARC Clinical Practice Guideline, In Vitro pH and Blood Gas Analysis and Hemoximetry, Respiratory Care, 38:505-510, 1993