Anaphylaxis Management for Paramedics (UK Guide)

Understanding Anaphylaxis in the Pre-Hospital Setting

Anaphylaxis is a severe, life-threatening systemic hypersensitivity reaction that demands rapid recognition and decisive intervention. For UK paramedics and student paramedics, a confident, protocol-driven approach is essential — delays in treatment can be fatal. This guide walks through the pathophysiology, recognition, and JRCALC-aligned management of anaphylaxis in the pre-hospital environment.

Pathophysiology: What Is Actually Happening?

Anaphylaxis is typically IgE-mediated. On re-exposure to a trigger antigen, mast cells and basophils degranulate, releasing histamine, tryptase, leukotrienes, and prostaglandins. This causes widespread vasodilation, increased capillary permeability, bronchospasm, and mucosal oedema. The result is a dramatic drop in systemic vascular resistance, distributive shock, and potential airway compromise — all developing within minutes.

Non-IgE-mediated reactions (formerly called anaphylactoid) produce an identical clinical picture and are managed in the same way. As a paramedic, the distinction matters academically but not operationally — treat the presentation, not the mechanism.

Common Triggers

Understanding common causes helps in taking a focused history and anticipating recurrence. Frequent triggers include:

• Foods — particularly peanuts, tree nuts, shellfish, milk, and eggs
• Medications — NSAIDs, antibiotics (especially penicillins), and contrast media
• Insect stings — bee and wasp venom
• Latex
• Exercise-induced anaphylaxis (less common but clinically important)

Always ask bystanders or family members about known allergies, recent ingestion, or any auto-injector use prior to your arrival.

Recognising Anaphylaxis: The Clinical Triad

The Resuscitation Council UK and JRCALC describe anaphylaxis as likely when all three 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 — urticaria, flushing, angioedema

It is important to note that skin changes may be absent in up to 20% of cases. Do not rule out anaphylaxis because the patient looks well externally — a silent chest with haemodynamic collapse is a medical emergency regardless of visible rash.

Key Signs and Symptoms by System

• Airway: stridor, hoarse voice, oropharyngeal or laryngeal oedema, difficulty swallowing
• Breathing: bronchospasm, wheeze, tachypnoea, increased work of breathing, cyanosis
• Circulation: tachycardia, hypotension, pallor, syncope, cardiovascular collapse
• Skin/Mucosa: urticaria, erythema, pruritus, angioedema (particularly lips, tongue, periorbital area)
• GI: nausea, vomiting, abdominal cramping, diarrhoea

Pre-Hospital Management: JRCALC Approach

The cornerstone of anaphylaxis management is intramuscular (IM) adrenaline. This should not be delayed for IV access, monitoring, or additional history — give it early and give it correctly.

Step 1 — Position and Remove the Trigger

Position the patient according to their symptoms. Patients with haemodynamic compromise should be laid flat with legs elevated. Patients with significant breathing difficulty may prefer to sit upright. If the patient is unconscious and breathing, use the recovery position. Remove or stop the offending trigger where possible (e.g. stop an infusion, remove a sting sac by scraping — do not squeeze).

Step 2 — Adrenaline (Epinephrine) IM

Adrenaline is the first-line drug for anaphylaxis and should be administered intramuscularly into the anterolateral aspect of the middle third of the thigh.

• 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)

If there is no response after 5 minutes, a repeat dose may be given. Document time and dose accurately. If the patient has used their own auto-injector (e.g. EpiPen) prior to your arrival, this does not preclude further doses — auto-injectors deliver 300 micrograms, which may be insufficient for adults.

Step 3 — High-Flow Oxygen and Airway Management

Administer high-flow oxygen via a non-rebreather mask at 15 L/min. Prepare for airway deterioration — angioedema can rapidly obstruct the upper airway. Have suction ready. If the patient deteriorates and you cannot maintain a patent airway, escalate management and consider early advanced airway intervention in line with your scope of practice and trust protocols.

Step 4 — IV Access and Fluid Resuscitation

Gain IV access en route where possible. In refractory hypotension, administer an IV fluid bolus of 500–1000 ml crystalloid (0.9% sodium chloride) rapidly. Titrate further boluses to response. This is supportive — adrenaline remains the definitive treatment.

Step 5 — Adjunct Medications

Following adrenaline, consider the following adjuncts in line with JRCALC and your trust's formulary:

• Chlorphenamine (Piriton): 10 mg IV/IM in adults — antihistamine, helpful but secondary to adrenaline
• Hydrocortisone: 200 mg IV/IM in adults — reduces risk of biphasic reaction but slow onset, not a first-line agent
• Salbutamol nebuliser: for persistent bronchospasm despite adrenaline

Biphasic Reactions and Hospital Handover

A biphasic anaphylactic reaction — where symptoms recur hours after initial resolution — occurs in approximately 5–20% of cases. This is a key reason why all patients with confirmed or suspected anaphylaxis must be conveyed to hospital, even if they appear to have fully recovered on scene. Advise the receiving team clearly and ensure a thorough SBAR handover including trigger, timeline, drugs given, and patient response.

After the Emergency: Patient Education on Scene

If time allows before transport, briefly reassure the patient and, if they are conscious and alert, explain what has happened. Encourage them to follow up with their GP for allergen testing, a written anaphylaxis action plan, and a prescription for two adrenaline auto-injectors to carry at all times.