Corrigendum to ‘Acid–base balance: a review of normal physiology’ [BJA Education 22 (2022) 396–401]

The authors regret that an error was present in the formulation of Henderson Hasselbach equation on page 398. The correct equation appears below:

Taking negative logarithms

pH = pKa + log₁₀ [A-]/[HA] (Henderson-Hasselbach equation)

There was also an error in the equation describing the application of the Henderson-Hasselbach equation to the bicarbonate buffer system. The correct equation appears below:

pH = pKa + log [HCO₃^-]/[CO₂] or pH = pKa + log [HCO₃^-]/[αPCO₂]

where α is the solubility of CO₂ in blood; using Henry's Law [H₂CO₃] = αPCO₂

The authors would like to apologise for any inconvenience caused.