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Bezold-Jarisch Reflex Spinal — FRCA Final MCQ

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HardRegional AnaesthesiaBezold-Jarisch Reflex SpinalFRCA Final

A 50-year-old man (ASA II) has had a hip replacement under spinal anaesthesia with 3 mL heavy bupivacaine 0.5%. In recovery, he feels nauseous and his blood pressure drops from 130/80 to 85/50. Heart rate is 48 bpm. This is the Bezold-Jarisch reflex. What is the mechanism?

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Correct answer: A — Vasodilation from spinal block causing venous pooling, reduced venous return, and paradoxical bradycardia via cardiac mechanoreceptors

The Bezold-Jarisch reflex is a cardioinhibitory reflex triggered by reduced venous return. In spinal anaesthesia, sympathetic block causes venous pooling and reduced preload. The resulting vigorous contraction of an underfilled left ventricle stimulates intracardiac mechanoreceptors (C-fibre afferents), triggering a paradoxical vagal response: profound bradycardia, vasodilation, and hypotension. This is more common with higher blocks and in young, fit patients with high vagal tone. Treatment: leg elevation, IV atropine 0.5-1 mg, fluid bolus, and in severe cases adrenaline.

Reference: RCOA – 2023 – Regional anaesthesia physiology; Campagna JA – 2003 – Cardiovascular effects of spinal anaesthesia