Abstract
A new approach to acid-base physiology, presented by Peter A. Stewart, is now accepted not only in experimental but also in some clinical situations. In his approach, changes in hydrogen ion concentration occur in consequence of water dissociation. Furthermore, hydrogen ion concentration is determined by three independent variables: PaCO2, strong ion difference (SID), and total weak acid. Neither bicarbonate nor hydrogen ion are independent, rather they are controlled by the independent variables. Albumin can work as an acidifying factor, and chloride ion, by changing SID, can play an important role in acid-base balance. Stewart approach can precisely explain “dilution acidosis” and “metabolic acidosis induced by cardiopulmonary bypass” which are hardly explicated with the old method. We believe that Stewart approach helps us to understand complex acid-base physiology.
