🧪 Anion Gap (AG)

AG = Na⁺ − (Cl⁻ + HCO₃⁻)

Normal reference: 8–12 mmol/L (albumin ≈ 4 g/dL)

• High AG → unmeasured acids → HAGMA
• Normal AG → bicarbonate loss / renal acid retention → NAGMA

🧪 Corrected Anion Gap (Albumin-Adjusted)

Corrected AG = AG + 2.5 × (4 − Albumin)

• Accounts for hypoalbuminemia
• Advisory only — does not drive diagnosis

🫁 Winter's Formula (Metabolic Acidosis)

Expected PaCO₂ = (1.5 × HCO₃⁻) + 8 ± 2

Use only when HCO₃⁻ is low

🫁 Respiratory Compensation in Metabolic Alkalosis

Expected PaCO₂ = 40 + 0.7 × (HCO₃⁻ − 24) ± 5

🧮 Adjusted Bicarbonate (Delta-Gap Implementation)

Adjusted HCO₃⁻ = HCO₃⁻ + (AG − 12)

Interpretation:

• 18–30 → Pure HAGMA
• <18 → HAGMA + NAGMA
• >30 → HAGMA + metabolic alkalosis

Represents delta-delta analysis in a clinically direct form.

📊 Delta Ratio

Delta Ratio = (AG − 12) ÷ (24 − HCO₃⁻)

• <1 → HAGMA + NAGMA
• 1–2 → Pure HAGMA
• >2 → Metabolic alkalosis / chronic hypercapnia

🫁 Respiratory Acidosis Compensation

• Acute: PaCO₂ ↑10 → HCO₃⁻ ↑1
• Chronic: PaCO₂ ↑10 → HCO₃⁻ ↑3–4

🫁 Respiratory Alkalosis Compensation

• Acute: PaCO₂ ↓10 → HCO₃⁻ ↓2
• Chronic: PaCO₂ ↓10 → HCO₃⁻ ↓4–5

🧬 VBG ↔ ABG Logic

• VBG pH ≈ ABG − 0.03
• PvCO₂ ≈ PaCO₂ + 4–6 mmHg
• Oxygenation indices are ABG-only

🧠 Interpretation Hierarchy

1. Anion Gap
2. Adjusted HCO₃⁻
3. Delta Ratio
4. Compensation formulas
5. Corrected AG (context only)

⚠️ Notes

• Delta-delta is implemented via Adjusted HCO₃⁻
• Corrected AG is contextual, not diagnostic
• This tool is for clinical decision support