Blood Gas (Stewart)
ICU Calculators-RNSH
Info |  

This calculator provides all the parameters derived from Stewart's theory of acid-base balance.
SID means Strong Ion Difference (SIDa and SIDe for SID apparent or effective). SIG is the Strong Ion Gap. BE is the Base excess (SBE for Standar Base Excess).

Stewart's calculations give an estimation of the individual effects of various parameter variation (Sodium concentration, Chloride, Albumine, ...) on the base excess. The total, expected, BE is then the sum of the individual calculated BE effects. This expected BE should be compared with the global BE (calculated from HCO3, pH and pCO2, or obtained from blood gaz machine), to evaluate wether an unmeasured anion might be present (and explain a difference between the expected and the actual BE values).

The results displayed in the right side column are those obatined from formulas that take into account the Hb level (not used in the left column).

HCO3 calculation is also provided (some blood gaz machines do not provide this result).
The "expected pH" is an estimation of the pH that would be observed if pCO2 were the only abnormal value. To be used for the evaluation of the respiratory component of an acidosis / alkalosis.
The "expected pCO2" is an estimation of the pCO2 that should be observed as a compensatory response to an acid-base disorder. To be used for the evaluation of the quality of the compensatory response of the patient.

A more detailed information might be implemented in the future version of the software.

- Step 1 : enter the required values, obtained from blood gaz machine and lab results.
- Step 2 : click "Calculate" button.





pCO2 (mmHg) Lactate (mEq/L)
Na+ (mEq/L) Phosphate (mMol/L)
K+ (mEq/L) Albumin (g/L)
Cl- (mEq/L) Hb (g/dL)*
HCO3- (mEq/L)* Ht (%)**

Expected pH  
Expected pCO2  
BE effect  
eeedSI effect  
Calculated BE
(SBE) (BE)
Calculated HCO3