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Winters Formula Calculator

Estimate the anticipated arterial PaCO2 that should accompany a given serum bicarbonate in pure metabolic acidosis.

Clinical Chemistry #acid-base #metabolic-acidosis #winters-formula #paco2 #blood-gas
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Formula & Clinical Notes

Formula

Anticipated PaCO₂ = 1.5 × [HCO₃⁻] + 8 ± 2

Clinical Notes

Winters formula predicts the expected respiratory (PaCO2) response to a primary metabolic acidosis. In pure metabolic acidosis the measured PaCO2 should fall within the anticipated value plus or minus 2 mmHg. A measured PaCO2 above the expected range indicates a superimposed respiratory acidosis (inadequate compensation); a measured PaCO2 below it indicates a respiratory alkalosis. In the presence of another acid-base disturbance the derivation does not apply.

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