Adrenaline Intravascular Injection — ORE Part 1 MCQ

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EasyPharmacology & TherapeuticsAdrenaline Intravascular InjectionORE Part 1

A patient requires extraction of a lower molar. They report that, immediately after a previous dental local anaesthetic injection, their heart raced and they felt shaky. What is the most likely explanation?

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Correct answer: E — Intravascular administration of adrenaline-containing local anaesthetic

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

A is correct. Immediate palpitations and shaking after injection are consistent with rapid systemic exposure to adrenaline following inadvertent intravascular administration. NHS SPS states that onset is immediate after intravascular administration and that adrenaline can cause palpitations and tachycardia. True allergy to amide local anaesthetics is very rare and would more typically involve urticaria, angioedema, wheeze or airway symptoms. Adrenaline is an endogenous substance, so it is not an allergen; patients may be sensitive to its effects, but this is not allergy. Malignant hyperthermia is associated with triggering general anaesthetic drugs, not routine dental local anaesthesia. Methaemoglobinaemia causes impaired oxygen delivery, typically with cyanosis and dyspnoea, rather than an immediate adrenaline-type reaction.

Reference: NHS Specialist Pharmacy Service. Managing reactions to dental local anaesthetic injections. Updated 30 July 2024. https://www.sps.nhs.uk/articles/managing-reactions-to-dental-local-anaesthetic-injections/