Approaching a phenomenal contradiction in acid-base physiology

The study focuses exclusively on the results of an arterial blood gas report, which reveal a phenomenal contradiction if one follows the physiological and physicochemical approaches as well as the standard base excess determination to interpret an acid-base disturbance. The aim of this article is not to fully describe a clinical case and make a differential diagnosis but to analyze the blood gas report data in detail and present the conclusions that result from the application of the different approaches that exist for the interpretation of acid-base disorders.

The results of an arterial blood gas report of a patient with severe lactic acidosis were cross-examined using the standard base excess method and the physiologic and physiochemical approaches. The causes of the contradiction are discussed with a commentary on the underlying pathophysiology.

The study revealed the presence of a normal anion gap (even after correction for albumin levels), a slightly increased strong ion gap and a moderately decreased standard base excess in a patient with severe lactic acidosis.

This real-life case provides an opportunity to give a brief overview of the current methods for investigating acid-base disturbances in a practical way, emphasizing both the common background and the conceptual differences and similarities.