PedsCases: Pediatric Education Online · PedsCases Team

Approach to Metabolic Acidosis in Pediatric Patients

July 1, 2024·22 min·2 clips

Jonah's blood gas shows a pH of 7.14 and bicarbonate of 10, indicating severe metabolic acidosis.

This educational episode from PedsCases presents a clinical approach to metabolic acidosis in children, hosted by a medical student and developed with pediatric residents and physicians. The hosts use a detailed case of a 10-year-old boy named Jonah, who presents with confusion, vomiting, and fatigue, to illustrate key diagnostic steps. They define metabolic acidosis as a process increasing hydrogen ions and decreasing bicarbonate, contrasting it with respiratory acidosis. The episode analyzes Jonah's vital signs, physical exam findings, and initial lab results, including a venous blood gas showing a pH of 7.14 and bicarbonate of 10. It explains how to calculate the anion gap, which for Jonah is 28, indicating an Anion Gap Metabolic Acidosis (AGMA). The differential for AGMA is reviewed using the "CAT MUD PILES" mnemonic, covering causes like toxins, uremia, and diabetic ketoacidosis. The hosts calculate the delta-delta ratio, which for Jonah is 0.857, confirming a pure AGMA. Jonah's history of polyuria, polydipsia, and weight loss, alongside hyperglycemia and ketonuria, leads to a diagnosis of diabetic ketoacidosis (DKA). The discussion notes that management focuses on treating the underlying cause, following a DKA protocol with fluids, insulin, and electrolyte monitoring. Follow-up labs six hours later show a normalized anion gap but a persistent non-anion gap metabolic acidosis, attributed to saline resuscitation. A key insight is that venous blood gases are clinically acceptable proxies for arterial samples in children, despite the latter being the gold standard. The episode clarifies that a negative base excess indicates metabolic acidosis or compensated respiratory alkalosis. It details how respiratory compensation for metabolic acidosis manifests as Kussmaul respirations, as seen in the case. The hosts emphasize that multiple acid-base disorders can coexist, requiring tools like the delta-delta ratio for interpretation. A memorable point is that a common side effect of treating DKA with normal saline is a hyperchloremic, non-anion gap metabolic acidosis. The tone is instructional and methodical, designed for clinical learners working through a structured diagnostic puzzle. The style is case-based and conversational, clearly explaining physiological concepts and calculations. This episode is ideal for medical students, pediatric residents, or any clinician seeking a clear framework for evaluating metabolic acidosis in pediatric patients. Listeners looking for broad, non-clinical health topics or advanced, specialist-level debate might find it too narrowly focused.

As heard by us

A clear pediatric acid-base review built around a DKA case.

This episode gives a clear walk through metabolic acidosis using diabetic ketoacidosis as the main case. It moves from the definition to the split between respiratory and metabolic causes, then into the differential, lab work, and management without losing the thread.

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Use this when a pediatric metabolic acidosis case needs sorting.

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