Oxygenation Indices Calculator

oxygenation indicies in ventilated patients

1)P/F= Pao2/fio2

- PaO2 (Partial Pressure Of Arterial O2,mmHg) from ABG

- FiO2 (Inspired Oxygen Concentration) from ventilator like 40%, 50%, up to 100%..enter it like 0.4(for 40% FiO2).

e.g. PaO2= 125 & FiO2 provided by ventilator is 70%

P/F= 125/0.70

= 178

2)a/A: PaO2/PAO2

-Pao2 (Partial Pressure Of Arterial O2, mmHg) from ABG report

-PAO2 = (760-PBO2)*FiO2-(PaCo2*1.25)

Where

760 - barometric pressure at sea level,

PBO2 - water vapour pressure=47,

FiO2 (Inspired Oxygen Concentration) from ventilator in decimal

PaCO2 (Partial Pressure Of Arterial CO2, mmHg) from ABG report

1.25 is constant & it is to be ignored when fio2 provided is more than 60%

e.g.. PaO2 =125, FiO2=40%(0.4), PaCO2= 35

PAO2=(760-47)*0.4-35*1.25

= 285.2-43.75

=241.45

a/A= 125/241.45

=0.517

3)oxygenation index(O.I.)= FiO2/PaO2*MAP

-Pao2 (Partial Pressure Of Arterial O2, mmHg) from ABG report

- FiO2 (Inspired Oxygen Concentration) from ventilator in decimal

-MAP (mean airway pressure, mmHg) from ventilator

e.g. FiO2=100%(1), PaO2 =225, MAP=14

O.I.= 100/225*14

= 6.2

4)Alveolar-arterial Gradient(A-a)=PAO2-PaO2

-Pao2 (Partial Pressure Of Arterial O2, mmHg) from ABG report

-PAO2 = (760-PBO2)*FiO2-(PaCo2*1.25)

Where

760 - barometric pressure at sea level,

PBO2 - water vapour pressure=47,

FiO2 (Inspired Oxygen Concentration) from ventilator in decimal

PaCO2 (Partial Pressure Of Arterial CO2, mmHg) from ABG report

1.25 is constant & it is to be ignored when fio2 provided is more than 60%

e.g.. PaO2 =125, FiO2=40%(0.4), PaCO2= 35

PAO2=(760-47)*0.4-35*1.25

= 285.2-43.75

=241.45

A-a=241.45-125

=116.45

5)Sodium Correction for Hyperglycemia(US Units,mg/dL)=

Serum Sodium+0.016(Serum Glucose-100)

-Serum Sodium(mEq/L)

-Serum Glucose(mg/dL)