Management of Anaphylaxis (Paediatrics)

Anaphylaxis is a severe, life-threatening, generalised or systemic hypersensitivity reaction.  

Diagnosis

Anaphylaxis is likely when all 3 of the following are met: 

1. Sudden onset and rapid progression of symptoms, typically over minutes  

2. Life-threatening airway and/or breathing and/or circulation problems 

3. Skin and/or mucosal changes (e.g. flushing, urticaria, angioedema). N.B. Angioedema without respiratory difficulty or circulatory collapse is not anaphylaxis.

Diagnosis is supported by exposure to known allergen for the patient. 

Common triggers/allergens: food (especially nuts) – most common in young people, drugs (especially penicillins, cephalosporins, NSAIDs, aspirin), latex, venom/stings or idiopathic.  

Classical features may not always be present 

Absence of skin changes or identified trigger does NOT exclude the diagnosis of anaphylaxis. 

Differential diagnoses: 

• Mimics – induced laryngeal obstruction 
• ACE-inhibitor induced angioedema – typically doesn’t respond to adrenaline  
• Faint 
• Panic attack  
• Breath holding episode 
• Spontaneous urticaria or angioedema  

ABCDE Assessment: 

Call for HELP – dial 2222 for support if alone  

• Airway:  airway swelling, hoarse voice, stridor 
• Breathing:  increased work of breathing, bronchospasm, tachypnoea, wheeze, fatigue, cyanosis, SpO2 <92%, respiratory arrest  
• Circulation: pale, clammy, hypotension, tachycardia, faintness, arrhythmia, cardiac arrest  
• Disability: drowsy, coma 
• Exposure: Identify any triggers e.g. drug, sting. Check for skin and mucosal changes e.g. urticaria, angioedema – note absent in up to 20% cases. GI symptoms e.g. vomiting, abdominal pain, incontinence.  

Management:  

1. Remove any triggers if possible

2. Patient Position

• If breathing problems – sit in semi-recumbent position  
• If circulation problem/hypotension – raise legs  

3. Give intramuscular adrenaline 1:1000 ASAP

IV adrenaline must be used only in certain specialist settings and only by those skilled and experienced in its use. Seek expert help early in patients whose respiratory or circulation problem persist despite 2 doses of IM adrenaline. 

4. Establish airway. Give high-flow oxygen 

5. Apply monitoring – pulse oximetry, ECG, blood pressure  

If no response after 5 minutes: 

6. Repeat IM adrenaline  

7. IV fluid bolus – Use crystalloid (0.9% NaCl or Hartmann’s)  

• Adults: 500-1000ml 
• Child: 10ml/Kg  

8. Consider bronchodilators if wheezy or asthmatic: 

• Upper Airway Obstruction
  • Nebulised Adrenaline 5mg of 1mg/ml 1:1000
• Lower Airway Obstruction
  • Nebulised Salbutamol
    • Over 5 years: 5mg
    • Under 5 years: 2.5mg

Additional therapies:

Glucocorticoids – no longer part of the initial therapy of anaphylaxis. There is growing evidence that steroids do NOT reduce the incidence of biphasic reaction. Consider steroids only after initial resuscitation for refractory reactions or ongoing asthma/shock.  

Antihistamines – no longer part of the initial therapy of anaphylaxis. They have no role in the respiratory or cardiovascular symptoms. They can be used to treat skin symptoms that often occur as part of allergic reactions, but only once stabilised. The use of non-sedating oral antihistamines is now preferred e.g. cetirizine, in preference to chlorphenamine which causes sedation. If oral route not available, IM/IV chlorphenamine.  

If no improvement in breathing or circulation problems despite TWO doses of IM adrenaline – Follow REFRACTORY ANAPHYLAXIS PATHWAY below 

Refractory anaphylaxis – less than 1% of reactions 

Defined as anaphylaxis where there is no improvement in respiratory or cardiovascular symptoms despite two appropriate doses of IM adrenaline.  

Early critical care support should be sought and consultant presence.  Continue giving adrenaline IM every 5 minutes / set up an infusion of IV adrenaline 

Post anaphylaxis management  

Investigations 

1. Mast cell tryptase  

• If elevated, can be useful to confirm an uncertain diagnosis – measure in all patients where uncertain diagnosis.  
• One sample ideally within 2 hours of symptom onset and no later than 4 hours. 
• Second sample within 4 hours  
• Third sample at least 24 hours after complete resolution or in convalescence e.g. allergy clinic.  
• Serial samples have better specificity and sensitivity. N.B. – normal tryptase doesn’t exclude a diagnosis.  

Observation – is important in case of a biphasic reaction or further allergen absorption causing further symptoms.  

Discharge checklist   

• Provide information about anaphylaxis, including signs and symptoms 
• Inform of the risk of biphasic reaction  
• Provide information on management of anaphylaxis 
• Provide an allergy action plan, download from bsaci.org 
• Prescribe adrenaline auto-injectors – see below – including instruction on use 
• Advice about how to avoid the suspected trigger (if known)  
• Refer all new anaphylaxis to allergy clinic  
• Information about allergy alert braces  

Prescribing an adrenaline auto-injector  

Prescribe to all patients who have had anaphylaxis, except those with a drug-induced reaction where the drug can be avoided.  

Weight based prescription of adrenaline auto injector- prescribe two devices  

Referral  

All patients presenting with anaphylaxis should be referred to a specialist allergy clinic for investigation (in individuals with previous anaphylaxis, the risk of another attack has been estimated at approx. 1 in 12/year).  

Anaphylaxis reactions should be reported to the UK anaphylaxis registry at www.anaphylaxie.net (to register, email [email protected] 

References

Emergency Treatment of Anaphylaxis, May 2021, Resuscitation Council UK.