🧪 Base Excess (Approximate SBE)
UseWhen to use: ABG teaching when comparing metabolic acid-base status beyond HCO₃ alone.
StrataNegative BE is a base deficit cue; analyser Siggaard-Andersen BE may differ slightly with Hb.
LimitsWhen not to use: venous-only gases without caveats. · Pitfall: mixing standard BE with buffer-base reports. · Not a perfusion diagnosis alone.
SourceApproximate extracellular base excess teaching formula
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
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Methodology · worked example, guidelines & full notes
HCO₃−24.8+16.2×(pH−7.4).
When to use
When to use: ABG teaching when comparing metabolic acid-base status beyond HCO₃ alone.
How it works
BE ≈ HCO₃ − 24.8 + 16.2×(pH − 7.4).
Key points
- HCO₃−24.8+16.2×(pH−7.4).
- ABG metabolic adjunct.
- Next: AG / Winter / lactate.
References
- Approximate extracellular base excess teaching formula
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| pH | 7.28 |
|---|---|
| HCO₃⁻ | 16 mmol/L |
| PaCO₂ (optional) | 32 mmHg |
→Approx. base excess-10.7mmol/L
- Formula：HCO₃−24.8+16.2×(pH−7.4)
- PaCO₂：32 mmHg (context)
- Cue：< −6 — larger base deficit teaching band
Verification & sources · governance
FAQ
Frequently asked questions
- Does Base Excess (Approximate SBE) upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is Base Excess (Approximate SBE) calculated in practice? Can you show a worked example?
- Inputs: pH 7.28, HCO₃⁻ 16 mmol/L, PaCO₂ (optional) 32 mmHg → Result: Approx. base excess -10.7 mmol/L（Formula: HCO₃−24.8+16.2×(pH−7.4), PaCO₂: 32 mmHg (context), Cue: < −6 — larger base deficit teaching band）