Arterial Blood Gas Analysis Calculator

Arterial Blood Gas Analysis Calculator for Pulmonology. The output separates acidemia/alkalemia from CO2 and bicarbonate directions, including apparently normal pH with opposing abnormalities. Winter comparison is conditional on primary metabolic acidosis; no single label resolves all mixed disorders.

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How this calculator works

This limited acid-base companion reports pH, CO2 and bicarbonate directions separately. It calculates a Henderson-Hasselbalch consistency estimate and, when bicarbonate is low, shows the conditional Winter estimate (1.5 x bicarbonate + 8, plus/minus 2 mmHg).

When to use this calculator

Use for an initial adult arterial acid-base assessment with results from the same sample. It highlights directional and compensation clues but does not provide a complete diagnosis, anion gap or oxygenation analysis.

Inputs used

  • Arterial pH
  • Arterial PaCO2 (mmHg)
  • Blood gas bicarbonate (mmol/L)

Clinical interpretation

The output separates acidemia/alkalemia from CO2 and bicarbonate directions, including apparently normal pH with opposing abnormalities. Winter comparison is conditional on primary metabolic acidosis; no single label resolves all mixed disorders.

Worked example

Fictional teaching case. Arterial pH: 7.2; Arterial PaCO2 (mmHg): 60; Blood gas bicarbonate (mmol/L): 18. Result: 7.2 pH. Acidemia. raised PaCO2; low bicarbonate. Henderson-Hasselbalch consistency estimate pH 7.100. Check whether all values come from the same sample and whether bicarbonate is measured or calculated; the discrepancy exceeds this tool's 0.05 consistency flag. If primary metabolic acidosis is established, Winter expected PaCO2 is 33-37 mmHg; measured PaCO2 is above that interval. Mixed disorders remain possible, including when pH is in range. This is an initial acid-base assessment, not a definitive diagnosis.

Limitations and safety notes

A low bicarbonate alone does not prove primary metabolic acidosis. The 0.05 pH consistency flag is a data-quality prompt, not a validated diagnostic cutoff. No anion gap, oxygenation assessment, respiratory compensation timetable or treatment is inferred from these three inputs.

Frequently asked questions

Can normal pH exclude an acid-base disorder?

No. Compensation and opposing primary disorders can produce a near-normal pH despite important abnormalities.

What can change the meaning of this result?

A low bicarbonate alone does not prove primary metabolic acidosis. The 0.05 pH consistency flag is a data-quality prompt, not a validated diagnostic cutoff. No anion gap, oxygenation assessment, respiratory compensation timetable or treatment is inferred from these three inputs.

References

  • Haber primary clinical conference on systematic acid-base assessment. https://pubmed.ncbi.nlm.nih.gov/1843849/
  • Berend et al. physiological approach to acid-base disorders, compensation and mixed processes. https://doi.org/10.1056/NEJMra1003327
  • UCSF clinical handbook verifies conditional Winter compensation equation. https://hospitalhandbook.ucsf.edu/01-algorithm-acid-base-disorders/01-algorithm-acid-base-disorders
  • Publisher correction concerns urine urea/glucose equations, not the implemented acid-base directions or Winter formula. https://www.nejm.org/doi/full/10.1056/NEJMx140053

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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