Oculocardiac Reflex — FRCA Final MCQ

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EasyPaediatric AnaesthesiaOculocardiac ReflexFRCA Final

A 7-year-old child weighing 25 kg is undergoing strabismus surgery under general anaesthesia with a supraglottic airway. During traction on an extraocular muscle the heart rate abruptly falls from 95 to 38 beats/min, with sinus bradycardia on the ECG. Oxygen saturation and end-tidal carbon dioxide are unchanged and a peripheral pulse is easily palpable. What is the most appropriate immediate action?

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

Reveal the answer and explanation

Correct answer: A — Ask the surgeon to stop traction on the extraocular muscle

Explanation lettering: B = shown as A · C = shown as B · E = shown as C · A = shown as E

B is correct. Abrupt sinus bradycardia during extraocular-muscle traction is the oculocardiac (trigeminovagal) reflex: trigeminal afferents, vagal efferents. The immediate action is removal of the provoking stimulus — ask the surgeon to release traction — after which the rate usually recovers within seconds; oxygenation, ventilation and anaesthetic depth should be checked simultaneously. A (atropine 20 micrograms/kg, 500 micrograms here) is correct treatment only if bradycardia persists or recurs, not before releasing traction. C is wrong as a first action and glycopyrrolate has a slower onset; its poor CNS penetration is irrelevant, since the relevant muscarinic blockade is peripheral (cardiac). D is not indicated for a readily reversible vagal reflex with intact perfusion. E is wrong: the pulse is palpable and perfusion adequate, so chest compressions are unnecessary.

Reference: Dunville LM et al. Oculocardiac Reflex (StatPearls review), PubMed record, updated 2023 — trigeminovagal reflex triggered by extraocular muscle traction, resolving on removal of the stimulus: https://pubmed.ncbi.nlm.nih.gov/29763007/ (supported by Oculocardiac Reflex in a Patient With Maxillofacial Trauma: Case Study and Literature Review, 2024: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11144039/)