Paediatric acid-base disorders: A case-based review of procedures and pitfalls

Acid-base disorders occur frequently in paediatric patients. Despite the perception that their analysis is complex and difficult, a straightforward set of rules is sufficient to interpret even the most complex disorders - provided certain pitfalls are avoided. Using a case-based approach, the present article reviews the fundamental concepts of acid-base analysis and highlights common mistakes and oversights. Specific topics include the proper identification of the primary disorder; distinguishing compensatory changes from additional primary disorders; use of the albumin-corrected anion gap to generate a differential diagnosis for patients with metabolic acidosis; screening for mixed disorders with the delta-delta formula; recognizing the limits of compensation; use of the anion gap to identify 'hidden' acidosis; and the importance of using information from the history and physical examination to identify the specific cause of a patient's acid-base disturbance.