Interpret this arterial blood gas: pH 7.36, PO2 84, PCO2 44, HCO3 24.

• A. Normal ABG
• B. Compensated metabolic acidosis
• C. Partially compensated metabolic acidosis
• D. Compensated metabolic alkalosis

Answer: (A)

Normal acid-base status is indicated when the pH is within the normal range and the accompanying gases and bicarbonate are also normal, with adequate oxygenation. Here, the pH is 7.36 (within 7.35–7.45), the PCO2 is 44 (within 35–45), and the HCO3 is 24 (within 22–26), and the PaO2 is 84, all lying in their normal ranges. This means there is no acid-base disturbance—no respiratory or metabolic acidosis or alkalosis—and oxygenation is sufficient. If a disorder were present, you’d expect a pH outside the normal range or a mismatch between pH and the primary driver (PCO2 or HCO3) with appropriate compensatory changes; that isn’t the case here.