FiO2

FiO₂ is the fraction of inspired oxygen in a gas mixture. [1]

Estimates only

NOTE: Most FiO₂s listed in this table are estimates only for the completion of the APACHE II score. The actual FiO₂ that a patient gets varies due to a number of factors.

Nasal Prongs			Partial Rebreath Mask			Simple Flow Mask
Room Air	21%		8 LRB	65%		6 Lpm	35%
1 LNP	24%		10 LRB	65%		7 Lpm	40%
2LNP	28%		12 LRB	65%		8 Lpm	45%
3 LNP	32%		13 LRB	70%		9 Lpm	50%
4 LNP	36%		15 LRB	70%		10 Lpm	55%
5 LNP	40%		15 LRB + 5 L NP	70%
6 LNP	44%		10 LRB + 5 L NP	70%		Cold Pot
7 LNP	48%		10 LRB + 3 L NP	70%			35%
8 LNP	50%		15 LRB + 7 L NP	70%			40%
							50%
Non Rebreath Mask			Venturi Face Mask				70%
10 LNRB	70%		3 Lpm	24%			100%
15 LNRB	70%		4 Lpm	26%
20 LNRB	80%		5 Lpm	28%		BiPAP
25 LNRB	80%		6 Lpm	30%		5 L	40%
30 LNRB	80%		9 Lpm	35%		10 L	60%
100 LNRB	80%		12 Lpm	40%		15 L	70%
			15 Lpm	50%		Flush	70%

Relevance

The FiO₂ is used to calculate the AaDO2 which is a component of the APACHE score as follows:

for FiO2 >= 50 %, 
AaDO2 = ((FiO2 * 713) - PO2) - Serum CO2