Expected PaCO2 (metabolic alkalosis)
Expected PaCO2 in metabolic alkalosis (Narins-Emmett 1980): the respiratory-compensation band vs the measured PaCO2.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Measured HCO3
- 40 mEq/L
- Measured PaCO2
- 51 mmHg
Result: Expected PaCO2 51.2 mmHg (0.7 x [HCO3 - 24] + 40): the measured 51 mmHg matches the expected 51.2 mmHg (+/-5), consistent with appropriate compensation.
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What the result means
- Reading
- a measured PaCO2 above the expected band suggests an added respiratory acidosis; below it, an added respiratory alkalosis.
What you enter
- Measured HCO3
- Measured PaCO2
How this is calculated
- Formula
- expected PaCO2 = 0.7 x (HCO3 - 24) + 40 (+/-5); the metabolic-alkalosis complement of Winter’s formula.
Narins RG, Emmett M. Simple and mixed acid-base disorders: a practical approach. Medicine (Baltimore). 1980;59(3):161-187. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.