Clinical review: The meaning of acid–base abnormalities in the intensive care unit part I – epidemiology

Acid–base abnormalities are common in critically ill patients. Our ability to describe acid–base disorders must be precise. Small differences in corrections for anion gap, different types of analytical processes, and the basic approach used to diagnose acid–base aberrations can lead to markedly different interpretations and treatment strategies for the same disorder. By applying a quantitive acid–base approach, clinicians are able to account for small changes in ion distribution that may have gone unrecognized with traditional techniques of acid–base analysis. Outcome prediction based on the quantitative approach remains controversial. This is in part due to use of various technologies to measure acid–base variables, administration of fluid or medication that can alter acid–base results, and lack of standardized nomenclature. Without controlling for these factors it is difficult to appreciate the full effect that acid–base disorders have on patient outcomes, ultimately making results of outcome studies hard to compare.