Bench-to-bedside review: A brief history of clinical acid–base

The history of assessing the acid-base equilibrium and associated disorders is intertwined with the evolution of the definition of an acid. In the 1950s clinical chemists combined the Henderson-Hasselbalch equation and the Bronsted-Lowry definition of an acid to produce the current bicarbonate ion-centred approach to metabolic acid-base disorders. Stewart repackaged pre-1950 ideas of acid-base in the late 1970s, including the Van Slyke definition of an acid. Stewart also used laws of physical chemistry to produce a new acid-base approach. This approach, using the strong ion difference (particularly the sodium chloride difference) and the concentration of weak acids (particularly albumin), pushes bicarbonate into a minor role as an acid-base indicator rather than as an important mechanism. The Stewart approach may offer new insights into acid-base disorders and therapies.