What alters pH?
The traditional approach to acid-base balance centres around the equations that relate pH, bicarbonate concentration, and PCO 2 . Things then become very simple, because we have really only two major options — there may be perturbations of either: • PCO 2 , resulting in respiratory acidosis or alkalosis; or • [HCO 3 -], reflecting (some even say resulting in ) metabolic acidosis or alkalosis. This traditional approach has the merit of relative simplicity. We say relative simplicity, because proponents of this approach have introduced confusion at many points. The two main schools are: • The Boston school, who use several simple equations to quantify the relative “metabolic” and “respiratory” contributions, depending on whether the derangement in acid-base balance is “acute” or “chronic”; • The Copenhagen school, who have introduced the concepts of “base excess” or “base deficit”, and “standard bicarbonate”. These measures are said to represent standardised values, which purportedly e
