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Refractory anaphylaxis — MRCEM SBA MCQ

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HardResuscitation and critical illnessRefractory anaphylaxisMRCEM SBA

A 49-year-old woman develops generalised urticaria, wheeze and hypotension minutes after intravenous co-amoxiclav is started in the emergency department. The infusion is stopped. She takes propranolol for essential tremor. Despite high-concentration oxygen, two appropriate 500 microgram intramuscular adrenaline doses given five minutes apart, and an initial intravenous crystalloid bolus, she remains wheezy with SpO₂ 91% and blood pressure 76/40 mmHg. The second adrenaline dose was given two minutes ago. Further crystalloid is being administered. She is conscious, has no stridor and is in a monitored resuscitation bay with intravenous access, an infusion pump and an experienced critical care clinician present. Which intervention should be established as the priority now?

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Correct answer: B — Start a titrated intravenous adrenaline infusion.

The rapid onset of skin, respiratory and circulatory features after antibiotic administration indicates anaphylaxis. Persistent wheeze and shock after two appropriate intramuscular adrenaline doses meet the UK definition of refractory anaphylaxis. The priority is to establish a low-dose intravenous adrenaline infusion, titrated by an experienced clinician with continuous monitoring, alongside ongoing crystalloid resuscitation and critical care support. The presence of intravenous access and appropriate expertise makes that escalation feasible without waiting for central venous access. ([elft.nhs.uk](https://www.elft.nhs.uk/sites/default/files/2023-09/emergency_treatment_of_anaphylaxis_may_2021_0.pdf)) A further intramuscular dose (A) may be needed if life-threatening features persist while the infusion is being prepared, but repeated intramuscular dosing is a bridge rather than the treatment to establish in this setting. Propranolol makes glucagon (C) a credible adjunct; UK guidance considers it when symptoms remain refractory despite an adrenaline infusion and adequate fluids, not before that infusion has begun. Noradrenaline (D) may be considered with expert guidance if shock remains refractory to the adrenaline infusion, but is not the first infusion here. Hydrocortisone (E) may be considered after initial resuscitation in refractory anaphylaxis; it must not take priority over adrenaline and fluids. ([elft.nhs.uk](https://www.elft.nhs.uk/sites/default/files/2023-09/emergency_treatment_of_anaphylaxis_may_2021_0.pdf))

Reference: Resuscitation Council UK, Emergency treatment of anaphylaxis, sections 6.1 and 6.6 (May 2021) — https://www.elft.nhs.uk/sites/default/files/2023-09/emergency_treatment_of_anaphylaxis_may_2021_0.pdf Resuscitation Council UK, Emergency treatment of anaphylaxis, sections 6.4 and 6.7 (May 2021) — https://www.elft.nhs.uk/sites/default/files/2023-09/emergency_treatment_of_anaphylaxis_may_2021_0.pdf NHS Greater Glasgow and Clyde, Emergency treatment of anaphylaxis: guidelines for healthcare providers (Last reviewed May 2021) — https://www.clinicalguidelines.scot.nhs.uk/nhsggc-guidelines/2222/emergency-treatment-of-anaphylaxis-guidelines-for-healthcare-providers-resuscitation-council/