Metabolic acidosis in the critically ill: lessons from physical chemistry

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