How do you assess for anaphylaxis?

See also

Emergency drug and fluid calculator 
Resuscitation 
Asthma 
Urticaria
Acute upper airway obstruction

Key points

1. Anaphylaxis is a multi-system severe allergic reaction characterised by an acute onset of cardiovascular (eg hypotension) or respiratory (eg bronchospasm) symptoms. It is usually associated with typical skin features (urticarial rash or erythema/flushing and/or angioedema) and/or persistent severe gastrointestinal symptoms
2. Treatment of anaphylaxis is intra-muscular adrenaline 10 microgram/kg or 0.01 mL/kg of 1:1000 (maximum 0.5 mL), into lateral thigh which should be repeated after 5 minutes if the child is not improving
3. In children with possible anaphylaxis and known asthma, always give adrenaline first, then asthma medicines
4. Do not allow children with anaphylaxis to stand or walk

Background

Most reactions occur within 30 minutes of exposure to a trigger but can occur up to 4 hours later 
Causes of anaphylaxis in children include:

• Foods: Peanut, tree nuts, cow milk, eggs, soy, shellfish, fish, wheat
• Bites/stings: Bee, wasp, jack jumper ants, ticks
• Medications: Beta-lactams, NSAIDs
• Other: Exercise, idiopathic, rubber latex (bottle nipples, pacifiers, toys)

Newer monoclonal antibody therapies may produce delayed anaphylactic reactions and rebound symptoms that occur more than 12 hours after the initial reaction

NB: a cause is not identified in 20% of cases

Assessment

Identify risk factors for fatal anaphylaxis

• Delay to administration of adrenaline or emergency response services
• Poorly controlled asthma (see Asthma)
• Allergy to nuts, shellfish, drugs and insect stings
• Adolescence
• Pre-existing cardiac and respiratory conditions

Anaphylaxis is a clinical diagnosis made in the setting of the acute onset of either:

1. Typical skin features (urticaria, flushing and/or angioedema) plus features of anaphylaxis involving one or more system
   OR
2. Hypotension, bronchospasm or upper airway obstruction where anaphylaxis is possible

 A detailed history of pre-hospital events is vital to confirm anaphylaxis and its associated trigger(s)
Clinical features

Management

Investigations

Anaphylaxis is a clinical diagnosis. A serum tryptase has no role in acute management of anaphylaxis. It should only be ordered after consultation with a paediatric allergy specialist in special circumstances.

Treatment

• Remove allergen if still present (eg insect stinger, food debris in mouth)
• Lay patient flat. Do not allow the child to stand or walk. Fatality can occur within seconds if the child stands or sits suddenly. Treat the child in the supine position or lying on their side. If a vomiting child is sat upright, monitor for hypotension
• Intramuscular adrenaline 10 microgram/kg or 0.01 mL/kg of 1:1000 (maximum 0.5 mL), into lateral thigh which should be repeated after 5 minutes if the child is not improving
• Do not use SC adrenaline, as absorption is less reliable than the IM route
• Do not use IV bolus adrenaline unless cardiac arrest is imminent
• Use an adrenaline autoinjector if unable to calculate exact dose or to avoid delay, including in children <1 year old

The following doses of adrenaline may be used

Example autoinjectors

Brand name	Indications	Image
EpiPen Jr®	Children <5 years old and 7.5 – 20 kg	(Green)
EpiPen®	Children >5 years or >20kg	(Yellow)
Anapen®	Children <5 years old and 7.5 – 20 kg: 150 mcg Children >20 kg: 300 mcg Children >50 kg: 500 mcg	(White)

1. Give oxygen
2. If not improving, give a second dose of adrenaline, consult senior staff and consider adrenaline infusion (0.05 - 0.5 microgram/kg/min)
3. Continue giving IM adrenaline every 5 minutes until IV access is obtained

Other treatments to consider
Repeated doses of IM adrenaline together with

• Nebulised or MDI salbutamol is recommended if the child has respiratory distress with wheezing. Also consider other anti-asthma medications. See Asthma
• Antihistamines may be given for symptomatic relief of pruritus. Second generation antihistamines are preferred (eg cetirizine). Avoid promethazine as it can cause hypotension
• Corticosteroids and leukotriene antagonists have no proven benefit in anaphylaxis
• Avoid NSAIDs

Observation and admission

All children with anaphylaxis should be observed for at least 4 hours in a supervised setting with facilities to manage deterioration
Admission for a minimum 12-hour period of observation is recommended if:

• Further treatment is required within 4 hours of last adrenaline administration (biphasic or prolonged reaction)
• Previous history of biphasic reaction
• Poorly controlled asthma
• The child lives in an isolated location with delay to emergency services 
• Anaphylaxis to monoclonal antibody
  

The acute care setting should provide resources, education and follow up options to the family including:

1. Update the medical record highlighting suspected allergen to avoid, and health department notification if applicable (see additional notes below)
2. Anaphylaxis action plans for home, school and/or other care settings if applicable
3. Two EpiPens®/ EpiPens Jnr®/ Anapens® and training in correct use with an Epipen/Anapen trainer. Current dose recommendations are:

7.5 - 20 kg = EpiPen Jnr® or Anapen® (150 microgram)
>20 kg = EpiPen® or Anapen®  (300 microgram)
>50 kg = Anapen®  (500 microgram)

EpiPen® / EpiPen Jnr® / Anapen® are available on PBS for all children with a history of acute anaphylaxis.   See Guidelines for the prescription of an EpiPen for more information
They require authority prescription or can be purchased without a prescription at full cost.   See PBS authority indications

1. Consider provision of a Medicalert bracelet 
2. Print parent and patient information sheets from ASCIA
3. All children with anaphylaxis should be referred to a paedatrician or paediatric allergy specialist. Review is ideal as soon as possible after the episode
4. Ensure that asthma control is addressed including diagnosis, action plan, and preventers, as asthma is an independent risk factor for fatal anaphylaxis (see Asthma)

Peripheral IV adrenaline infusion

This should only be done in consultation with a senior staff member. Avoid high infusion rates for more than two hours as it may cause fluid overload
Check local health service adrenaline infusion guidelines. Below is an example guideline:

• Mix 1 mL of 1:1000 adrenaline in 1000 mL of fluid
• Suitable fluids are glucose 5%, glucose 10%, sodium chloride 0.9% saline and glucose with sodium chloride combinations
• Start infusion at 5 mL/kg/hr (this is equal to 0.1 microgram/kg/minute)
• A dedicated line, infusion pump and anti-reflux valves should be used when possible
• Titrate dose according to response and side-effects
• Monitor continuously (all vitals, 12-lead ECG and conscious state)
• If possible, insert a second IV as fluid boluses may be needed
• If hypotensive, resuscitate with fluid; use boluses of 20 mL/kg of sodium chloride 0.9% for shock
• Nebulised adrenaline is not recommended as first-line therapy, but may be a useful adjunct after IM adrenaline if upper airway obstruction or bronchospasm is present
• If airway oedema is not responding to parenteral (IM, IV) and nebulised adrenaline, early intubation is indicated

Consider consultation with local paediatric team when

• High risk of fatal anaphylaxis 
• More than one dose of adrenaline required
• First diagnosis of anaphylaxis
• Anaphylaxis to monoclonal antibody
  

Consider transfer when

• Inadequate adrenaline response
• Multiple doses of adrenaline
• Adrenaline infusion
• Immediate life-threatening situation
• A child requiring care beyond the comfort level of the hospital

NB: Also consider consultation with paediatric allergy/immunology team

Consider discharge when

See Observation and Admission section above

For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services

Parent information sheets

Allergic and anaphylactic reactions
Autoinjectors (epipen) for anaphylaxis – an overview
Allergyfacts.org.au
www.allergy.org.au

Additional notes

In Victoria it is a requirement to notify all cases of anaphylaxis presenting to hospital, to the Department of Health and Human Services (this does not include cases arising in hospital)

Where the suspected cause is the consumption of a packaged food, notifications are required to be made immediately (within 24 hours of diagnosis) by telephone (1300 651 160, which is staffed 24 hours a day, seven days a week)

Where the suspected cause is anything other than packaged food, notifications are required to be made within five days of initial diagnosis of anaphylaxis and electronically via the online form through the department's website

Last updated January 2021

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