✿The Henderson-Hasselbalch equation is used to calculate the pH of a solution based on the concentrations of bicarbonate ion (HCO3−) and carbon dioxide (CO2), as well as the dissociation constant (K1).

✿The equation is: pH=pK+log⁡([HCO3−][CO2])pH=pK+log([CO2][HCO3−])

✿In clinical practice, the bicarbonate to carbon dioxide ratio ([HCO3−][CO2][CO2][HCO3−]) is typically measured to assess acid-base balance in the blood.

✿The ratio is determined using the concentrations of bicarbonate (HCO3−HCO3−) and the partial pressure of carbon dioxide (pCO2pCO2) in arterial blood gases.

✿The conversion factor to relate pCO2 (in mmHg) to CO2 concentration (in mmol/L) is approximately 0.03.

✿The Henderson-Hasselbalch equation provides a way to estimate pH based on these measured values.

Review: Acid-base balance (Physiology)