There is growing interest in quantitative physical chemical analysis o
f acid-base physiology among intensivists. Acid-base dilemmas seen in
the intensive care unit are not always well addressed by the tradition
al approaches. Quantitative physical chemical analysis also allows for
the exploration of unexplained anion-induced acidosis where the famil
iar anion gap is insufficient or inaccurate. This approach emphasizes
the application of accepted physical chemical principles and identific
ation of independent and dependent acid-base variables. In aqueous sol
utions, water dissociation is the major source of free hydrogen ions.