Respiratory virus season is here, and some kids may need oxygen supplementation. The handy figure below from this site is a good overview of oxygen delivery devices and max FiO2 achieved. For simple nasal cannula, each 1 L increase raises the FiO2 ~4% above the room air 21% (eg 1 L = FiO2 25%). Remember that when using a non-rebreather it’s very important to make sure the reservoir bag is inflated and there are one-way valves applied on the mask; otherwise you will not be administering close to 100% FiO2.