Enter ABG values
pH is calculated using: pH = 6.1 + log10( HCO₃⁻ / (0.03 × PaCO₂) )
A = Acid (pH < 7.35, CO₂ > 45, HCO₃⁻ < 22)
B = Base (pH > 7.45, CO₂ < 35, HCO₃⁻ > 26)
N = Normal (within range)
Interpretation:
A + N = A → Respiratory acidosis
N + A = A → Metabolic acidosis
B + N = B → Respiratory alkalosis
N + B = B → Metabolic alkalosis
A + A = A → Mixed acidosis
B + B = B → Mixed alkalosis
A + B = A or B + A = A → partially compensated acidosis; the acidic side is primary and the opposite abnormality is compensatory
A + B = B or B + A = B → partially compensated alkalosis; the alkalotic side is primary and the opposite abnormality is compensatory
A + B = C or B + A = C → compensated pattern; the pH block displays C because opposing abnormalities balance each other
N + N = N when both components are normal and the calculated pH also remains normal; if the calculated pH is abnormal despite normal components, the page shows a yellow warning pattern such as N + N = A or N + N = B
If a pattern does not match one of these standard combinations cleanly, interpret it with the clinical picture and trend of repeat ABGs
Example: pH 7.20, CO₂ 55, HCO₃⁻ 24 → pH=A, CO₂=A, HCO₃⁻=N → A + A + N = Acidosis. Cause: CO₂ is A → Respiratory acidosis.