Acid-base – a historical perspective

One of the principal clinical uses of blood gas analysis is assessment of patient acid-base status, but over the years controversy has dogged understanding of the principles of acid-base physiology and interpretation of blood gas results. 

In a brief review of the history of clinical acid-base balance, the author explains these controversies, and in so doing successfully illuminates current understanding of acid-base balance, an aspect of critical care that non-experts sometimes find less than luminous. 

A central premise of the article is that understanding of the controversies surrounding acid-base balance is aided by examination of the various definitions of an acid that have been invoked by acid-base physiologists over the years, and the article begins with a historical perspective to the fundamental question: what is an acid? 

Reference is made to the work of early luminaries of acid-base physiology, including Brøndsted and Lowry, Van Slyke, Henderson and Hasselbach. The controversies addressed include the so-called "great trans-Atlantic debate" that began in the 1960s. The major protagonists were Siggaard-Andersen in Copenhagen and Relman in Boston, the debate centering on the clinical utility of base excess, a parameter devised by Siggaard-Andersen in the late 1950s.

In more recent times, controversy has surrounded the work of Peter Stewart whose book published in 1981 introduced a radical approach to the pathophysiology of acid-base balance. The article provides an overview of this radical approach, including an analysis of how it is applied in an actual patient case study. The Stewart legacy ensures that acid-base physiology will continue to be a subject of debate in the years ahead.