Emergency: Anaphylaxis Flashcards
Describe anaphylaxis
A severe, life threatening, generalised or systemic hypersensitivity reaction. Sudden in onset, progresses rapidly, with life threatening breathing, airway and/or circulatory problem
In children, 85% of anaphylaxis is due to…
Food allergy
Most are IgE mediated reactions with significant respiratory or cardiovascular compromise
Other than food allergy what are some other causes of anaphylaxis?
Insect stings Drugs Latex Exercise Inhaled allergens Idiopathic
Among what age group does the majority of fatal anaphylaxis occur?
Adolescents with allergy to nuts
What are some risk factors for fatal outcome?
Adolescent age group
Coexistent asthma
Nut allergy
What is involved in the acute management?
ABCDE
Early administration of IM adrenaline
In terms of the airway, what symptoms/signs are seen?
Stridor
Swelling
Hoarseness
Describe stridor
A loud, harsh, high pitched respiratory sound
May start low pitched ‘croaking’ then progress to high pitched ‘crowing’ on more vigorous respiration
Usually heard on inspiration due to partial obstruction of the airway (usually extrathoracic - in trachea, larynx or pharynx)
In terms of breathing, what symptoms/signs may be seen?
Tachypnoea
Wheeze
Cyanosis
SpO2 < 92%
What symptoms/signs are seen with regards to circulation?
Pale, clammy, hypotension, drowsy, dizziness, coma
What skin/ mucosal signs can be seen?
Urticaria
Angioedema
- usually but not always present
Most paediatric anaphylaxis occurs in children under what age?
5 years
The acute management of anaphylaxis relies on early administration of what?
Adrenaline
What strength adrenaline should be used?
1:1000
If the patient is hypotensive, how should they be positioned?
Supine with legs elevated
If breathing is difficult how should patient be positioned?
Sat upright
In addition to adrenaline, what other treatment can be given?
High flow oxygen IV fluid 20ml/kg cystalloids Chlorphenamine IM or slow IV Hydrocortisone IM or slow IV Consider salbutamol if wheeze
How should patient be monitored?
Pulse oximetry
ECG
BP
What does long term management involve?
Strategies and training for allergy avoidance
Written management plan with instructions for treatment of allergic reactions
Provision of adrenaline auto-injectors
In some cases allergen immunotherapy may be effective in preventing future episodes
What type of hypersensitivity reaction is anaphylaxis?
Type 1 (immediate)
Does adrenaline treat all of the most dangerous symptoms of anaphylaxis?
Yes - it treats throat swelling, difficulty breathing and hypotension
Also helps alleviate itching, rash, swelling, GI and urinary symptoms
Peak plasma concentration of adrenaline occurs how long after administration?
8 +/- 2 minutes
Respiratory or cardiac arrest can occur as early as 6 minutes for food triggered reactions and 4 for venom triggered (median times = 30 and 15 respectively)
How does adrenaline work? Ie on what receptors
Alpha receptors to cause peripheral vasoconstriction
Beta receptors to cause bronchodilation and inotropic effects e.g increasing CO
What dose of adrenaline should be given if aged less than 6 months?
0.15ml (150mcg)
What does of adrenaline should be given if aged 6 months to 6 years?
0.15mL (150mcg)
What dose of adrenaline should be given if aged 6-12 years?
0.3mL (300mcg)
What is the adolescent/ adult dose of adrenaline?
0.5mL (500mcg)
If there is no improvement after adrenaline dose, what should be done?
Repeat after 5 mins
If bronchospasm is a feature what should be given?
Nebulised salbutamol 2.5mg every 15 minutes as required
If child >30kg give 5mg
What are some differentials for anaphylaxis?
Asthma
Septic shock
Panic attack
What is the most common food to cause anaphylaxis?
Peanuts
What are the most common drugs to cause anaphylaxis in children?
Vaccines
Penicillins
Who should influenza vaccines not be given to?
Children with an egg allergy
Do foods tend to cause respiratory and airway symptoms or cardiovascular collapse?
Respiratory and airway
Injections and stings - CVS collapse
All children with suspected anaphylaxis should be referred for…
Allergy testing
What foods are the most common cause of anaphylaxis in children?
Peanut Cashew Other nuts Milk Eggs Seafood Vegetables/fruit Soya milk Rice Wheat Sesame
What are the absolute indicators for at least one adrenaline auto injector?
Allergy to high risk foods - peanuts, tree nuts, shellfish
Previous anaphylaxis to other food or latex
Idiopathic anaphylaxis
Unstable or moderate to severe persistent asthma with food allergy
What are suggested indications for prescription of a second adrenaline auto injector?
Unstable or moderate to severe persistent asthma with food allergy
Coexisting mast cell disease
Lack of rapid access to medical assistance e.g geographical isolation
Previous requirement for more than one dose of adrenaline prior to reaching hospital
Previous near fatal anaphylaxis
