Medical Education Tool
ABG Tutor / Tic-Tac-Toe
Arterial blood gas interpretation & compensation recognition
Interactive Practice
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Case ABG Values
pH
—
PaCO₂
—
mmHg
HCO₃⁻
—
mEq/L
PaO₂
—
mmHg
to begin a new ABG scenario.
Normal Reference Ranges
| pH | 7.35 – 7.45 |
| PaCO₂ | 35 – 45 mmHg |
| HCO₃⁻ | 22 – 26 mEq/L |
| PaO₂ | 80 – 100 mmHg |
| Compensation Formulas | |
| Metabolic Acidosis | Winter's: PaCO₂ = 1.5×HCO₃⁻ + 8 ±2 |
| Metabolic Alkalosis | PaCO₂ = 0.7×(HCO₃⁻−24) + 40 ±5 |
| Resp Acidosis | HCO₃⁻ ↑ 3.5 per 10 mmHg CO₂ (chronic) |
| Resp Alkalosis | HCO₃⁻ ↓ 5 per 10 mmHg CO₂ (chronic) |
Classification Grid
Click each cell to classify the value as Acidic, Normal, or Alkaline.
| Acidic | Normal | Alkaline | |
|---|---|---|---|
| pH | < 7.35 |
7.35–7.45 |
> 7.45 |
| PaCO₂ | > 45 |
35–45 |
< 35 |
| HCO₃⁻ | < 22 |
22–26 |
> 26 |
Note: For PaCO₂, elevated = acidic and decreased = alkaline (inverse of pH direction).
Your Interpretation
