Biochemical Approach of Acid-Base Disturbances: Diagnosis Algorithm

Abstract

Context: The biochemical approach to acid-base balance classifies disturbances in two categories based on cellular mechanisms. The first one being cellular respiration (ATP), which presents high anion gap and changes in carbon dioxide levels, and the second one, cellular metabolism (ion transport through membrane channels), which evidences normal anion gap and changes in other cations and anions. Objective: To present a new diagnostic algorithm for acid-base disturbances, based on the biochemical approach. Method: Original research with systematic analysis and data organization, following biochemical processes that affect acid-base balance. Results: A simple, three-step algorithm which classifies information in a diagnostic table that connects blood gas analysis results (pH, anion gap or base excess, bicarbonate, carbon dioxide and unmeasured anions) with the biochemical cause and most probable clinical findings. Conclusions: The biochemical approach is considered the new model to understand, explain and diagnose acid-base balance and disturbances. All high anion gap disturbances occur in cellular respiration, while all normal anion gap disturbances occur in membrane channel function. The diagnosis algorithm simplifies and organizes the information to describe medical conditions with data from a blood gas analysis. This approach is the first model to establish a linear correlation between lab results, biochemical cause, and clinical findings of acid-base disturbances.