Anaphylaxis – What is Anaphylaxis

Anaphylaxis in Early Childhood

What is Anaphylactic shock?

Anaphylaxis can be a life-threatening allergic reaction that involves the entire body and creates a response known as shock. Anaphylaxis may result in death, and thus requires immediate medical attention. The most severe type of allergic reaction often involves many organs of the body such as:

  • The skin – welts and hives (urticaria).
  • The upper airways – swelling of the throat and vocal cords leading to difficulty with breathing.
  • The nose – sneezing, blocking, watering, runny nose.
  • The lungs – wheezing and asthma.
  • The circulatory system – a fall in blood pressure and collapse.

On a pathophysiologic level, anaphylaxis is caused by the release of mediators from certain types of white blood cells triggered either by immunologic or non-immunologic mechanisms. For reasons that are not understood, some individuals become sensitised to food, medication or insect venom following prior exposure to these substances. This sensitisation is characterised by the production of antibodies in the body called IgE antibodies. These antibodies are produced so that they can recognise specific proteins contained in each trigger.

This is similar to a lock and key mechanism. The lock is the IgE antibodies, with the key being the protein trigger. Once the lock and key meet, the body responds by releasing certain chemicals (such as histamine but also many other compounds) which result in the anaphylactic reaction. These chemicals act on many parts of the body but most importantly the skin, the mucosal lining of the throat, lungs and blood vessels. These chemicals cause the airways to narrow and the blood vessels to dilate which results in skin rash (usually hives), wheezing, stridor and/or low blood pressure.

Anaphylaxis is diagnosed based on the presenting symptoms and signs. The primary treatment is injection of epinephrine (adrenaline), with other measures being complementary.

Anaphylaxis Triggers

What Triggers a Severe Allergic Reaction (Anaphylaxis)?

So, what ‘sets off’ or triggers these life threatening responses by the body, deemed anaphylaxis? Food allergies are the most common triggers for an anaphylactic reaction. There are nine foods that cause 90% of food allergic reactions in Australia and can be a common cause or ‘trigger’ of anaphylaxis.

  • Peanuts
  • Tree nuts (hazelnuts, cashews, almonds)
  • Egg
  • Cow’s milk
  • Wheat
  • Soybean
  • Fish
  • Shellfish
  • Sesame

Other triggers, other than food include:

  • Insect stings, particularly bee stings, however wasp stings, ant bites and/or tick bites.
  • Medications; some antibiotics (commonly penicillin) and some anaesthetic agents.
  • Latex; (commonly used in rubber gloves)

Signs and symptoms can be defined as mild, moderate or severe. Mild to moderate signs and symptoms are more likely to present themselves as an allergic reaction. A casualty displaying severe signs and symptoms obviously equates to a severe allergic reaction or anaphylaxis. Likewise a casualty may initially present with mild signs and be diagnosed with an allergic reaction and then deteriorate and progress to an anaphylactic emergency. The response or deterioration to a trigger’s onset, (those identified in previous discussion), is usually within 20 minutes of exposure. However don’t be complacent, this may be delayed for up to an hour or even longer.

Mild to Moderate

In some cases, anaphylaxis is preceded by signs of a mild to moderate allergic reaction.

  • Tingling of the mouth.
  • Swelling of the lips, face and eyes.
  • Hives, welts on the skin or body redness.
  • Abdominal pain and/or vomiting (this is a mild to moderate response to most allergens, however if it is present and the trigger or allergen is an insect sting and/or bite it is a sign of anaphylaxis).

Severe

  • Difficulty and/or noisy breathing.
  • Swelling of the face and tongue.
  • Swelling/tightness in the throat.
  • Difficulty talking and/or hoarse voice.
  • Wheezing or persistent coughing.
  • Loss of consciousness and/or collapse.
  • Young children may appear pale and floppy.
  • Abdominal pain or vomiting (when associated with an allergic reaction to an insect sting or bite).

First Aid Treatment of Anaphylaxis

Environmental Hazards

Like all first aid situations, the first aider needs to identify the casualty and/or casualties, and survey the scene. The first aider surveys the scene and identifies any DANGERS related to the environment and identifies any hazards that may be a specific allergic ‘trigger’ of an allergic reaction and anaphylaxis. If it is safe to do so, the first aider removes the casualty from the environment if any triggers and/or hazards have been identified, therefore possibly reducing the severity of the reaction.

The first aider checks for a response from the casualty and directs a bystander to send/call for help if required. The first aider than conducts their primary survey and applies immediate first aid measures and interventions where appropriate; that is Airway, Breathing, Circulation and Defibrillation.

The first aider progresses to the secondary survey and gathers a history of what caused and/or preceded the emergency situation. The first aider identifies the casualty’s signs and symptoms, medical history, allergies and that they are on an ASCIA Action Plan for anaphylaxis. Therefore identifies the casualty is possibly suffering a severe allergic reaction or anaphylaxis. If emergency services (ambulance 000/112) has not been contacted the first aider would direct a bystander to contact them immediately. If the first aider suspects anaphylaxis, even if there is doubt, treat for anaphylaxis, there is minimal to no harm in giving adrenaline if it is unwarranted. However, if adrenaline is not given in a timely fashion, collapse, organ failure and death may be the consequence.

The first aider remains calm and assists the casualty to retrieve their ASCIA Action Plan and adrenaline autoinjector if possible. However if they are compromised or unconscious, a bystander may be requested to retrieve them. The first aider always remains with the casualty. The first aider follows the plan as documented by the doctor prescribing the plan, ensuring the emergency/family contact person has been notified and if the anaphylaxis is a result of an insect sting; the sting has been removed if possible. If the casualty is showing the signs of a mild to moderate allergic reaction the first aider may need to assist the casualty in administering an antihistamine medication. If the casualty is displaying severe signs of an allergic reaction and/or anaphylaxis, the first aider PROMPTLY administers the adrenaline autoinjector that is, EpiPen ® or EpiPen® Jr and/or AnaPen® or AnaPen® Jr. A very thorough description of ASCIA Action Plans, adrenaline autoinjectors and their administration was presented previously. Remember, adrenaline autoinjectors are very easy to use, contain a single fixed dose and are designed to be used by anybody, especially without any previous medical training.

If the casualty does not have an adrenaline autoinjector, remain calm, contact emergency services 000/112, provide reassurance and continually monitor and maintain airway, breathing and circulation until emergency services arrive. Likewise, if the adrenaline autoinjector has been administered the casualty will need their airway, breathing and circulation assessed and maintained until emergency services arrive. If the casualty’s airway, breathing and/or circulation become compromised and cannot be maintained; the first aider will be required to perform CPR.

Note
For further information on Anaphylaxis visit:
Australian Society of Allergy and Clinical Immunology (ASCIA)

Management of Mild to Moderate Allergic Reaction Management

For an insect allergy, flick out the sting if it can be seen ( do not remove ticks if deep under the skin).

  • D.R.S.A.B.C.D
  • Stay with the casualty and reassure.
  • Call 000 for an ambulance if the first aider feels it is required.
  • Give medications as prescribed (whilst antihistamines may be used to treat mild to moderate allergic reactions, if the reaction progresses to severe anaphylaxis then adrenaline is the only suitable medication)
  • Locate adrenaline auto-injector if available (instructions are included in the ASCIA Action Plan for Anaphylaxis which should be stored with the adrenaline autoinjector).
  • Contact parent/guardian or other emergency contact.

Management of Severe Allergic Reaction – ANAPHYLAXIS

  • D.R.S.A.B.C.D
  • Give the adrenaline autoinjector if available (instructions are included in the ASCIA Action Plan for Anaphylaxis, stored with the adrenaline autoinjector).
  • Call 000 for an ambulance.
  • Lay person flat and elevate legs – if breathing is difficult, allow to sit but do not stand.
  • Contact parent/guardian or other emergency contact.
  • Further adrenaline doses may be given (when an additional adrenaline autoinjector is available),

if there is no response after five minutes.

If in doubt, give the adrenaline autoinjector

Adrenaline is life saving and must be used promptly. Withholding or delaying the giving of adrenaline can result in deterioration and death.

This is why giving the adrenaline autoinjector is the first instruction on the ASCIA Action Plan for Anaphylaxis.

If CPR is given before this step there is a risk that adrenaline is delayed or not given. 

In the ambulance oxygen will usually be administered to the casualty by ambulance personnel.

Medical observation of the casualty in hospital for at least four hours is recommended after the use of available adrenaline and treatment of anaphylaxis.

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Note

If the allergic reaction is due to either a bee, wasp or ant sting and there is no autoinjector available, use the Pressure Immobilisation (Bandaging) Technique as for snake bite treatment.