Chronic Respiratory Acidosis ABG — FRCA Final MCQ

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ModerateIntensive Care MedicineChronic Respiratory Acidosis ABGFRCA Final

ABG: pH 7.28, PaCO2 7.8, PaO2 9.2, HCO3 28, BE +2, lactate 1.0, FiO2 0.35. Interpretation?

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Correct answer: A — Chronic respiratory acidosis with compensation

pH 7.28 (acid), PaCO2 7.8 (elevated = respiratory acidosis), HCO3 28 (elevated = compensation), BE +2 (positive). Elevated HCO3 with positive BE = renal compensation = CHRONIC. In acute: HCO3 rises only ~1 mmol/L per kPa; in chronic ~3.5 mmol/L.

Reference: RCOA – 2020 – Acid-base physiology