skip to main content

Distributive shock and venous capacitance — FRCA Primary MCQ

Instant feedback + full explanation. One question, done properly.

HardPhysiologyDistributive shock and venous capacitanceFRCA Primary

A 70-year-old patient with septic shock under anaesthesia has MAP 52 mmHg, cardiac index 4.8 L min-1 m-2, warm peripheries and low systemic vascular resistance. A vasopressor that increases venous tone is started. What physiological effect most directly improves arterial pressure?

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

Reveal the answer and explanation

Correct answer: E — Increased stressed venous volume improving venous return

In distributive shock, increasing venous tone converts unstressed to stressed volume, raising mean systemic filling pressure and supporting venous return as well as arterial tone. Venodilatation would worsen preload and hypotension. Increasing vascular capacitance would reduce effective circulating volume. The teaching point is that vasopressors can support both resistance and venous return.

Reference: RCoA Primary FRCA Syllabus 2026; Ganong's Review of Medical Physiology; West's Respiratory Physiology