Document No. 715-7000
Revision E
Page 49 of 63
What is the diluted FiO
2
?
Estimating your FiO
2
after dilution with NO gas, given your NO flow setting, and total ventilator
gas flow
Estimated FiO
2
=
Initial FiO
2
- (NO Flow / Total Flow O
2
+ Total NO Flow)
100
Example:
Initial
FiO
2
= 1.0 (100%)
NO flow = 0.31 LPM (800 ppm gas, bal Nitrogen)
Ventilator flow = 10 LPM
Total flow = 10.31 LPM
Estimated FiO
2
= 1 - (0.31 / 10.31 LPM) = 0.97
Estimated % O
2
= 1 - (0.31 / 10.31 LPM)
100 = 97%
When delivering ~ 25 ppm NO (~ 0.31 LPM) in ~ 10 LPM of 100% oxygen, you can
expect the % O
2
to be diluted by ~ 3%.
In this case, the maximum FiO
2
you can expect is ~ 0.97.
How are we doing?
Oxygen Index Calculation:
Oxygen Index (OI) = Paw
FiO
2
100 / PaO
2
, (mmHg)
Interpretation:
Most centers interpret less than 15 as good.
Mean airway pressure in cmH
2
O = Paw
Fraction of inspired oxygen = FiO
2
Arterial oxygen tension in mmHg = PaO
2
Example: Pre Nitric Oxide Data
FiO
2
= 1.0 (100%)
PaO
2
= 65 mmHg
Paw (Mean Airway Pressure) = 15 cmH
2
O
Oxygen Index (OI) = 15
1
100 / 65 = 23