Chemistry

Winters' Formula

Expected pCO₂ in metabolic acidosis.

Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.

When to use

Use in a metabolic acidosis to check whether respiratory compensation is appropriate.

Why use

It identifies a coexisting respiratory disorder when the measured pCO₂ differs from expected.

Critical actions

Expected pCO₂ = 1.5 × HCO₃ + 8 (±2) mmHg. A measured pCO₂ above the range suggests a concurrent respiratory acidosis; below suggests a respiratory alkalosis.

Evidence & references

Albert MS et al. Quantitative displacement of acid-base equilibrium in metabolic acidosis. Ann Intern Med. 1967.

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