how to get A-a gradietnt? - ahyu

[ArchivalUser]

let's say ph 7.2, co2-32,po2-79.oxy saturation 95%

[ArchivalUser]

Atmospheric Pressure (760 mm Hg or 101.33 kPa @ sea level) mm Hg
PaO2 (arterial O2) mm Hg
PaCO2 (arterial CO2) mm Hg
FIO2 (fraction inspired O2 - room air is 21%) %
Age (for calculating normal A-a Gradient) years
A-a O2 Gradient (Alveolar - Arterial) mm Hg
Expected A-a Gradient Based on Age mm Hg
A-a O2 Gradient = [ (FiO2) * (Atmospheric Pressure - H2O Pressure) - (PaO2/0.8) ] - PaO2 from ABG

Normal Gradient Estimate = (Age/4) + 4

[ArchivalUser]

A-a gradient =150-(1.25xpco2)-po2

[ArchivalUser]

On room air, A-a is 150-Pco2(1.25) -Po2 ( here, fio2 is 21% 0r 0.21)
on any other oxygen, A-a is 713(Fio2) - Pco2(1.25) - Po2

[ArchivalUser]

Northeast ... I think in the formula you have given it should be paCO2/0.8 instead of paO2/0.8

[ArchivalUser]

yes harish. u r right.

[ArchivalUser]

et's say ph 7.2, co2-32,po2-79.oxy saturation 95%

(150-32*1.25)-79?

o2 saturation 95% -- how about in formula?

i am craxy

[ArchivalUser]

O2 saturation not required to calculate A-a O2 gradient

[ArchivalUser]

Fio2 is required to calculate the formula not 02 saturation

[ArchivalUser]

put po2 in the formula -po2 79 is like sat 95