Which ABG finding is most consistent with diabetic ketoacidosis?

Which ABG finding is most consistent with diabetic ketoacidosis?

• A. Metabolic alkalosis
• B. Metabolic acidosis
• C. Respiratory alkalosis
• D. Normal ABG

Answer: (B)

In diabetic ketoacidosis, lack of insulin triggers production of ketoacids, which lowers bicarbonate and the blood pH, producing an anion-gap metabolic acidosis. The body tries to compensate by breathing faster to blow off CO2, so the PaCO2 falls as a respiratory compensation. So the ABG most consistent with DKA shows metabolic acidosis with appropriate respiratory compensation—low pH, low bicarbonate, and low PaCO2. The other patterns don’t fit: metabolic alkalosis would raise pH and bicarbonate; respiratory alkalosis would raise pH with low CO2 but not the low bicarbonate seen in DKA; a normal ABG would not show acidosis.

In diabetic ketoacidosis, lack of insulin triggers production of ketoacids, which lowers bicarbonate and the blood pH, producing an anion-gap metabolic acidosis. The body tries to compensate by breathing faster to blow off CO2, so the PaCO2 falls as a respiratory compensation. So the ABG most consistent with DKA shows metabolic acidosis with appropriate respiratory compensation—low pH, low bicarbonate, and low PaCO2. The other patterns don’t fit: metabolic alkalosis would raise pH and bicarbonate; respiratory alkalosis would raise pH with low CO2 but not the low bicarbonate seen in DKA; a normal ABG would not show acidosis.