Anaphylaxis Management for Paramedics (UK Guide)

Anaphylaxis Management for UK Paramedics

Anaphylaxis is a severe, life-threatening systemic hypersensitivity reaction that demands rapid recognition and decisive intervention. For paramedics working in the pre-hospital environment, the ability to identify anaphylaxis quickly and treat it correctly can be the difference between life and death. This guide covers the essential clinical knowledge you need, grounded in JRCALC (Joint Royal Colleges Ambulance Liaison Committee) guidelines and UK NHS practice.

Understanding Anaphylaxis: Pathophysiology in Brief

Anaphylaxis occurs when a sensitised individual is re-exposed to a trigger allergen, causing a massive release of inflammatory mediators — primarily histamine and tryptase — from mast cells and basophils. This leads to systemic vasodilation, increased capillary permeability, and bronchospasm. The result is a rapid drop in blood pressure, airway compromise, and potentially cardiovascular collapse if untreated.

Common triggers encountered in pre-hospital care include:

• Foods — particularly nuts, shellfish, milk, and eggs
• Insect stings — especially bee and wasp venom
• Medications — including penicillin, NSAIDs, and contrast media
• Latex
• Exercise-induced anaphylaxis (less common)

Recognising Anaphylaxis: Clinical Features

A key challenge in pre-hospital practice is distinguishing anaphylaxis from other conditions such as vasovagal syncope, panic attacks, or acute severe asthma. The Resuscitation Council UK defines anaphylaxis as a severe, life-threatening generalised or systemic hypersensitivity reaction, and diagnosis is based on clinical presentation rather than laboratory findings in the field.

Anaphylaxis is likely when ALL of the following are present:

1. Sudden onset and rapid progression of symptoms
2. Life-threatening airway, breathing, or circulation problems
3. Skin and/or mucosal changes (flushing, urticaria, angioedema) — present in around 80% of cases

It is important to note that skin changes alone do not confirm anaphylaxis, and their absence does not exclude it. Some patients — particularly those on beta-blockers — may not mount a typical response, making clinical assessment more complex.

Airway and Breathing Signs

• Stridor, hoarseness, or throat tightness
• Wheeze and increased respiratory rate
• Cyanosis or SpO2 desaturation
• Use of accessory muscles

Circulatory Signs

• Tachycardia (bradycardia is an ominous late sign)
• Hypotension — systolic BP below 90 mmHg in adults
• Pale, clammy skin and prolonged capillary refill
• Reduced consciousness or collapse

Pre-Hospital Treatment: The JRCALC Approach

The cornerstone of anaphylaxis treatment is intramuscular (IM) adrenaline (epinephrine). Do not delay this for any other intervention. Paramedics should follow the structured ABCDE approach while simultaneously addressing the life-threatening problem.

Step 1: Remove the Trigger

Where possible, remove or stop the causative agent — for example, stopping an IV infusion if drug-induced anaphylaxis is suspected.

Step 2: Call for Help and Position the Patient

Alert your crew partner and consider an early pre-alert to the receiving emergency department. Position the patient according to their presentation: sit up patients with airway or breathing compromise; lay patients with circulation problems flat with legs elevated (unless this worsens breathing). Pregnant patients should be tilted to the left.

Step 3: Administer IM Adrenaline

Adrenaline 1:1,000 (1 mg/ml) is administered by the intramuscular route into the anterolateral aspect of the middle third of the thigh. JRCALC-recommended doses are:

• Adults and children over 12 years: 500 micrograms IM (0.5 ml of 1:1,000)
• Children 6–12 years: 300 micrograms IM (0.3 ml of 1:1,000)
• Children under 6 years: 150 micrograms IM (0.15 ml of 1:1,000)

Repeat the dose at 5-minute intervals if there is no improvement in the patient's condition. There is no absolute maximum number of doses in the pre-hospital setting — continue to reassess and repeat as clinically indicated.

Step 4: High-Flow Oxygen and Airway Management

Apply high-flow oxygen via a non-rebreather mask at 15 L/min. Be prepared to escalate airway management rapidly — angioedema can deteriorate quickly, and early recognition of impending airway obstruction is critical. Consider supraglottic airway devices or surgical airway if complete obstruction occurs and bag-mask ventilation is ineffective.

Step 5: IV Access and Fluids

Obtain IV access as soon as practicable. For haemodynamic compromise, administer a fluid challenge of 500 ml sodium chloride 0.9% IV in adults, repeated as needed. In children, use 10 ml/kg boluses.

Step 6: Adjunct Medications

Following adrenaline, consider the following second-line agents in line with your service's clinical operating procedures:

• Chlorphenamine (anti-histamine): 10 mg IM or slow IV in adults — helps with urticaria and angioedema but is not a substitute for adrenaline
• Hydrocortisone: 200 mg IV or IM in adults — helps prevent biphasic reactions, though onset of action is delayed
• Salbutamol: 5 mg nebulised for persistent bronchospasm
• Glucagon: 1–2 mg IM or IV for patients on beta-blockers who are refractory to adrenaline

Biphasic Reactions and Hospital Handover

All patients with confirmed or suspected anaphylaxis must be transported to hospital, even if they respond well to treatment. Biphasic reactions — a recurrence of anaphylaxis hours after the initial episode — occur in approximately 5–20% of cases. The patient should be observed in hospital for a minimum of 6–12 hours. Ensure they are prescribed an adrenaline auto-injector (AAI) on discharge if they do not already have one, and communicate this recommendation clearly during your SBAR handover.

Documentation and Clinical Reflection

Accurate documentation on your patient clinical record (PCR) is essential. Record the suspected trigger, time of symptom onset, the exact time and dose of each adrenaline administration, patient response, and any adjuncts used. Anaphylaxis cases are excellent opportunities for reflective practice and case-based learning — reviewing your decision-making helps consolidate knowledge and prepares you for future presentations.