Winters' Formula for Metabolic Acidosis Compensation
Winters' Formula for Metabolic Acidosis Compensation
mEq/L
Expected pCO₂:
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Calculates the expected pCO₂ compensation in a purely metabolic acidosis.
Why Use
In a compensated state, a patient with a metabolic acidosis should be able to compensate by developing a respiratory alkalosis. Winters' Formula predicts this level of “appropriate” compensation.
When to Use
A patient with a suspect pure metabolic acidosis. A patient with a mixed acidosis to determine level of compensation.
Formula
Expected pCO₂ = 1.5 × HCO₃- + 8 ± 2 Note: although the original Winters formula used a standard error of ±2, newer data suggest that pCO₂ may vary up to ±5 ( Adrogué and Madias 2010 ).
Advice
Users may be interested in the MDCalc ABG Analyzer which can attempt to assess for different forms of acid-base disorders. The Anion Gap calculator can also help determine the type of acidosis (gap vs. non-gap).