The Van Slyke Equation

Abstract

The Henderson-Hasselbalch equation has always occupied a central place in the description of the acid-base status of the blood. An equation of similar importance is the equation for the CO₂ equilibration curve of blood in vitro. It is proposed to name this the Van Slyke equation:

a - 24.4 = - (2.3 ± b + 7.7) ± (c - 7.40) + d/(1 - 0.023 ± b), where

a = bicarbonate concentration in plasma /(mmol/l)

b = hemoglobin concentration in blood /(mmol/l)

c = pH of plasma at 37°C

d = base excess concentration in blood /(mmol/l).

These two equations provide an arithmetic algorithm for calculation of the various acid-base variables of the blood after measuring the pH, the pCO₂, and the hemoglobin concentration