Anaphylaxis — emergency management

PLAB 2 & PRES 3 · emergency · hard · 8 minutes

Candidate brief

You are an FY2 doctor/SHO working in the Emergency Department. Ms Hannah Wilson, 28, suddenly developed difficulty breathing, throat tightness and dizziness approximately 15 minutes after eating a takeaway meal. Current observations: respiratory rate 30 breaths/min, oxygen saturation 91% on air, heart rate 128 beats/min and blood pressure 82/48 mmHg. She has widespread urticaria and can speak only in short phrases. Assess the patient and initiate immediate emergency management. Verbalise all examinations, treatments and escalation steps you would perform.

What examiners look for

Anaphylaxis is recognised by rapid-onset airway, breathing or circulation compromise, usually but not always accompanied by skin or mucosal changes. Do not delay treatment while taking a detailed history, obtaining IV access or waiting for a rash. The first-line treatment for an adult is adrenaline 500 micrograms IM into the anterolateral thigh using 0.5 mL of 1 mg/mL adrenaline. Repeat IM adrenaline after 5 minutes if life-threatening airway, breathing or circulation problems persist. Position the patient safely. Keep them lying down where possible and never allow them to stand or walk suddenly. A patient with severe breathing difficulty may be supported sitting up with their legs extended. Give oxygen, continuous monitoring and early IV crystalloid fluid when hypotension, shock or poor response to adrenaline is present. Persistent symptoms after 2 appropriate IM adrenaline doses indicate refractory anaphylaxis. Obtain expert critical-care support and use an IV adrenaline infusion according to the local protocol. Do not give routine IV adrenaline boluses. Antihistamines are not first-line treatment and do not treat airway obstruction, bronchospasm or shock. They may be used for persistent skin symptoms only after stabilisation. Corticosteroids are not recommended routinely for emergency treatment or prevention of biphasic reactions. Take mast-cell tryptase samples only after emergency treatment has begun. Investigation must never delay adrenaline. Observation after symptom resolution is risk-based. NICE NG258 recommends longer observation for people who required repeated adrenaline, had severe respiratory compromise or have other factors increasing the risk or consequences of recurrence. Arrange specialist allergy referral, provide an emergency action plan and, where indicated, prescribe and teach the use of 2 adrenaline auto-injectors.

Guideline references

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