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Anaphylaxis

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  • 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

    System

    Features of anaphylaxis

    Respiratory (most common in children)

    Persistent cough
    Wheeze, stridor, hoarse voice, difficulty talking or change in character of cry
    Tongue swelling
    Chest pain or dyspnoea
    Subjective feeling of swelling, tightness or tingling the throat or mouth

    Cardiovascular

    Pale and floppy (infant)
    Palpitations, tachycardia, bradycardia
    Hypotension, pallor
    Collapse with or without unconsciousness
    Cardiac arrest

    Neurological

    Headache (usually throbbing)
    Dizziness
    Altered consciousness, confusion, sudden behaviour change

    Gastrointestinal

    Nausea, vomiting, dysphagia
    Diarrhoea
    Abdominal or pelvic pain

    Dermatological

    Urticarial rash
    Erythema, flushing, tearing
    Angioedema
    Pruritus (skin, eyes, nose, throat, mouth)

    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

    Adrenaline doses

     

    Age (years)

    Weight (kg)

    Volume of 1:1000 adrenaline (mL)

    Adrenaline autoinjectors

    <1

    <7.5 kg

    0.1 mL

    Not available

    <1 - 2

    7.5 – 10

    0.1 mL

    0.15 mg device (eg EpiPen jr)

     

    2 – 3

    15

    0.15 mL

    4 – 5

    18

    0.18 mL

    5 – 6

    20

    0.2 mL

    0.3 mg device (eg EpiPen)

    7 – 10

    30

    0.3 mL

    10 – 12

    40

    0.4 mL

    >12 and adults

    >50

    0.5 mL

    Example autoinjectors

    Brand name 

    Indications

    Image

    EpiPen Jr®

    Children <5 years old and 7.5 – 20 kg

    green 
    (Green)

    EpiPen® 

    Children >5 years or >20kg

    yellow 
    (Yellow)

    Emerade

    Doses vary
    (check injector)

    white
    (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

        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® and training in correct use with an Epipen trainer. Current dose recommendations are:

    7.5 - 20 kg = EpiPen Jnr® (150 microgram)
    ≥20 kg = EpiPen® (300 microgram)

    EpiPen ®/EpiPen Jnr® are available on PBS for all children with a history of acute anaphylaxis.   See Guidelines for the prescription of an EpiPen for more information
    EpiPen ®requires 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 asthmacontrol 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

  • Reference List

    1. Anagnostou K, Turner PJ. Myths, facts and controversies in the diagnosis and management of anaphylaxis. Archives of disease in childhood. 2019 Jan 1;104(1):83-90
    2. Anaphylaxis Australia. What is anaphylaxis? https://www.allergyfacts.org.au/allergyanaphylaxis/what-is-anaphylaxis Accessed 09/01/2021
    3. Australasian Society of Clinical Immunology and Allergy. Action Plan for Anaphylaxis. http://www.allergy.org.au/health-professionals/anaphylaxis-resources/ascia-action-plan-foranaphylaxis . Accessed 08/01/202020
    4. Australasian Society of Clinical Immunology and Allergy. Acute Management of Anaphylaxis Guideline. https://allergy.org.au/hp/papers/acute-management-of-anaphylaxis-guidelines. Accessed 08/01/2020 
    5. Australian & New Zealand Resuscitation Council Guideline 9.2.7 – First Aid Management of Anaphylaxis: file:///C:/Users/gardj/Downloads/anzcor-guideline-9-2-7-anaphylaxis-aug16.pdf . Accessed 09/07/2019
    6. Brown, S.G.A, Mullins, R.J., Gold, M.S. Anaphylaxis: diagnosis and management. Med. J. Aust. 2006. 185(5):283-9 8
    7. Carter MC, Akin C, Castells MC, Scott EP, Lieberman P. Idiopathic anaphylaxis yardstick: Practical recommendations for clinical practice. Annals of Allergy, Asthma & Immunology. 2020 Jan 1;124(1):16-27
    8. Fisher, M. Anaphylaxis to anaesthetic drugs. Novartis Found. Symp. 2004. 257: 193-206
    9. Sampson, H.A. Anaphylaxis and emergency treatment. Pediatrics 2003. 111: 1601-8
    10. Sheikh, A, Shehata, Y.A, Brown, S.G.A., Simons, F.E.R. Adrenaline (epinephrine) for the treatment of anaphylaxis with and without shock. Cochrane Database of Systematic Reviews 2008, Issue 4. Art. No.: CD006312. DOI: 10.1002/14651858.CD006312.pub2
    11. Zideman, D. A., Singletary, E. M., De Buck, E.,et al. (2015). Part 9: First aid: 2015 International Consensus on First Aid Science with Treatment Recommendations. Resuscitation, 95, e225 http://www.cprguidelines.eu/assets/downloads/costr/S0300-9572(15)00368-8_main.pdf Accessed 09/01/2020