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Respiratory acidosis in bronchiolitis — MRCPCH TAS MCQ

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HardPhysiologyRespiratory acidosis in bronchiolitisMRCPCH TAS

A 7-week-old with bronchiolitis becomes tired. Capillary gas shows pH 7.24, pCO2 9.0 kPa and bicarbonate 25 mmol/L. What is the most likely acid-base abnormality?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Acute respiratory acidosis

Low pH with markedly raised carbon dioxide and normal bicarbonate indicates acute respiratory acidosis from hypoventilation. Chronic respiratory acidosis would show a higher bicarbonate from renal compensation. The pearl is that rising carbon dioxide in bronchiolitis is a late sign of fatigue and ventilatory failure.

Reference: Ganong's Review of Medical Physiology; Nelson Textbook of Pediatrics; RCPCH Theory examination syllabi