Henderson-Hasselbalch Equation — FRCA Primary MCQ

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ModeratePhysiology - RespiratoryHenderson-Hasselbalch EquationFRCA Primary

The Henderson-Hasselbalch equation applied to blood pH is:

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Correct answer: E — pH = pKa + log([HCO3-]/[H2CO3])

pH = pKa + log([HCO3-]/[H2CO3]). Since H2CO3 = 0.03 × PaCO2 and pKa = 6.1: pH = 6.1 + log(24/1.2) = 6.1 + 1.3 = 7.4 at normal values.

Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist