Refractory anaphylaxis — MRCEM SBA MCQ

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HardResuscitation and critical illnessRefractory anaphylaxisMRCEM SBA

A 58-year-old woman taking propranolol for migraine develops widespread urticaria, wheeze and hypotension within minutes of starting an intravenous antibiotic in the emergency department. The infusion is stopped. She receives high-flow oxygen, two 500-microgram intramuscular doses of adrenaline five minutes apart and 1 litre of intravenous crystalloid. She remains conscious but has an SpO₂ of 89% despite oxygen and a blood pressure of 72/40 mmHg. Intravenous access and continuous monitoring are in place, further crystalloid is being given, and an experienced critical care clinician is at the bedside. Which pharmacological escalation is most appropriate now?

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Correct answer: A — Start a titrated intravenous adrenaline infusion with critical care support.

The abrupt skin, respiratory and circulatory features after antibiotic exposure indicate anaphylaxis. Persistent hypoxaemia and shock despite two appropriate intramuscular adrenaline doses meet the definition of refractory anaphylaxis. The next escalation is a low-dose, titrated intravenous adrenaline infusion, administered by an experienced specialist with monitoring, alongside continued fluid resuscitation. Dilute adrenaline can be infused through a peripheral cannula; central access need not delay treatment. Further intramuscular adrenaline should be given at five-minute intervals until the infusion starts if life-threatening features persist. ([elft.nhs.uk](https://www.elft.nhs.uk/sites/default/files/2023-09/emergency_treatment_of_anaphylaxis_may_2021_0.pdf)) **B:** Propranolol makes glucagon attractive because beta-blockade may reduce the response to adrenaline. However, UK guidance considers glucagon when symptoms remain refractory *after* an adrenaline infusion and adequate fluids; it does not replace that escalation. **C:** Noradrenaline may be considered with expert advice if shock remains refractory to adrenaline infusion, not as its initial substitute. **D:** Repeated intramuscular doses are appropriate while an infusion is being prepared, or if one cannot safely be given, but are not the sole plan when specialist infusion is available. **E:** Salbutamol can supplement treatment for persistent bronchospasm, and corticosteroids may be considered after initial resuscitation. Neither should delay the adrenaline infusion in a patient with ongoing respiratory and circulatory compromise. This patient requires continuing critical care support. ([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: Guidelines for healthcare providers, 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: Guidelines for healthcare providers, section 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: Guidelines for healthcare providers, section 6.7 (May 2021) — https://www.elft.nhs.uk/sites/default/files/2023-09/emergency_treatment_of_anaphylaxis_may_2021_0.pdf