ABSTRACT

The invention of the pH probe ushered in a new era of critical care medicine where a definable physiologic endpoint became possible. A series of somewhat contradictory theories regarding acid-base interpretation were developed culminating in the great “Trans-Atlantic Debate” which occurred in the wake of the pH probe’s creation (1). Most of the controversy revolves around the explanation of the metabolic component (i.e., what causes hydrogen ions [Hþ] to increase, decrease, or be buffered). The period during the late 1960s and early 1970s witnessed the evolution of the “classic model” based on the Henderson-Hasselbach relationship and the “standard base excess” (SBE) concept whose roots trace back to standard bicarbonate and buffer base (BB). Both of these models evolved into the establishment of nomograms and formulas for guiding acid-base management.