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Hepatic Blood Supply — FRCA Primary MCQ

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HardPhysiology - Gastrointestinal & HepaticHepatic Blood SupplyFRCA Primary

Portal venous flow decreases abruptly during major abdominal surgery while systemic arterial pressure is maintained. Which hepatic arterial response most helps preserve total hepatic oxygen delivery?

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

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Correct answer: C — Compensatory hepatic arterial vasodilatation through the hepatic arterial buffer response

The best answer is “Compensatory hepatic arterial vasodilatation through the hepatic arterial buffer response”. The hepatic arterial buffer response increases hepatic arterial flow when portal flow falls, partly through reduced adenosine washout around the portal triad. This partially preserves total hepatic perfusion and oxygen delivery; it is not infinite and may be impaired by shock or vasopressors. Arterial constriction, venous obstruction and collateral formation would not provide the immediate compensatory response.

Reference: RCoA, Primary FRCA syllabus: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf; Regulation of hepatic blood flow: the hepatic arterial buffer response revisited: https://pmc.ncbi.nlm.nih.gov/articles/PMC3012579/