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Lactic acidosis from bowel ischaemia — SCE Acute Medicine MCQ

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HardCritical care medicineLactic acidosis from bowel ischaemiaSCE Acute Medicine

A 74-year-old woman presents with severe abdominal pain, mottled peripheries and confusion. Venous blood gas shows pH 7.12, lactate 9.8 mmol/L and bicarbonate 11 mmol/L; blood pressure is 92/58 mmHg after fluids. CT abdomen shows pneumatosis intestinalis and portal venous gas. What is the most likely underlying mechanism of her acidosis?

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

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Correct answer: A — Tissue hypoperfusion from bowel ischaemia causing lactic acidosis

Severe lactic acidosis with shock and CT signs of bowel infarction reflects tissue hypoperfusion and anaerobic metabolism from mesenteric ischaemia. Respiratory acidosis would have predominant CO2 retention, not isolated high lactate and low bicarbonate. The clinical priority is urgent surgical and critical care involvement, not bicarbonate as a substitute for source control.

Reference: Surviving Sepsis Campaign; ESVS acute mesenteric ischaemia guideline