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Expected PaCO₂ (Winter's formula)

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Expected PaCO₂ = 1.5 × HCO₃⁻ + 8 (± 2) in metabolic acidosis.

mmol/L

Expected PaCO₂

26 mmHg (± 2)

Formula

1.5 * hco3 + 8

Notes

Measured PaCO₂ above the range = additional respiratory acidosis; below = additional respiratory alkalosis.

References

  1. Albert MS, Dell RB, Winters RW. Quantitative displacement of acid-base equilibrium in metabolic acidosis. Ann Intern Med 1967;66:312-22.

Used in

Five-step blood gas interpretation

Calculators support, not replace, clinical judgement. Check inputs and units, and confirm doses with your unit protocol.