Which arterial blood gas result indicates metabolic acidosis typical of diabetic ketoacidosis?

Which arterial blood gas result indicates metabolic acidosis typical of diabetic ketoacidosis?

• A. pH 7.30, CO2 40 mm Hg, HCO3- 20 mEq/L (20 mmol/L)
• B. pH 7.50, CO2 50 mm Hg, HCO3- 22 mEq/L (22 mmol/L)
• C. pH 7.35, CO2 47 mm Hg, HCO3- 24 mEq/L (24 mmol/L)
• D. pH 7.46, CO2 30 mm Hg, HCO3- 24 mEq/L (24 mmol/L)

Answer: (A)

Diabetic ketoacidosis causes a metabolic acidosis from ketone buildup, so the bicarbonate falls and the pH drops. The body tries to compensate by increasing ventilation, which lowers the CO2. So an ABG pattern you’d expect is acidemia with low bicarbonate and a CO2 that’s lower than normal or lies near the level predicted by compensation. The pattern with pH 7.30 and bicarbonate 20 mEq/L fits this: the pH is acidic and bicarbonate is reduced, indicating metabolic acidosis. The CO2 of 40 mm Hg is within the expected compensatory range (approximately 38 ± 2 mm Hg for a bicarbonate of 20), so this shows appropriate respiratory compensation for metabolic acidosis, consistent with DKA. The other patterns show alkalemia or a primary respiratory problem rather than the metabolic acidosis typical of DKA.

Diabetic ketoacidosis causes a metabolic acidosis from ketone buildup, so the bicarbonate falls and the pH drops. The body tries to compensate by increasing ventilation, which lowers the CO2. So an ABG pattern you’d expect is acidemia with low bicarbonate and a CO2 that’s lower than normal or lies near the level predicted by compensation.

The pattern with pH 7.30 and bicarbonate 20 mEq/L fits this: the pH is acidic and bicarbonate is reduced, indicating metabolic acidosis. The CO2 of 40 mm Hg is within the expected compensatory range (approximately 38 ± 2 mm Hg for a bicarbonate of 20), so this shows appropriate respiratory compensation for metabolic acidosis, consistent with DKA.

The other patterns show alkalemia or a primary respiratory problem rather than the metabolic acidosis typical of DKA.