Henderson-Hasselbalch (pH from HCO₃ and PaCO₂)
Calculates pH, or checks a blood gas for internal consistency.
Inputs
0 of 2mEq/L
mmHg
Optional, to check consistency.
When to use
- Checking that a blood gas is internally consistent.
Pearls and pitfalls
- If the calculated pH differs from the measured pH by more than about 0.03, suspect a lab or transcription error.
Why use
Catches inconsistent gases before interpretation.
pH = 6.1 + log₁₀(HCO₃ ÷ (0.03 × PaCO₂))