These two graphs explain the percentage of nasal cannula oxygen in the inspired volume, and the minimal effect that O2 purity has on FIO2. Also this is provided with the scientific source that has produced the statistics.
RR 20-30/min, 2-3 LPM, I:E 1:2
|OXYGEN SOURCE||ROOM AIR||LIQUID OXYGEN (2LPM)|
|nasal cannula FIO2 equation||21% x 500ml = 105ml||99,6% x 33ml = 33ml
21% x (500-33)ml = 98ml
|Calculated FIO||105/500 = 21%||131/500 = 26.2%|
Nasal cannula FIO2 equation. Clinical Application of Blood Gases. Shapiro BA. 5th ed RR/20min, I:E, inspiration 2s, 2 LPM = 33ml/s105/500 = 21%