What is atopy? What are the diseases which it presents as?
The ability to mount an IgE response to one or more common inhaled aeroallergen
What is adrenaline dose in adults and children?
Adult: 0.5mg IM
Children: 0.01ml/kg (1:1000) IM Lateral thigh
Up to every 5 minutes, if not responding, consider infusion
What the triggers of anaphylaxis?
Food: Peanuts, tree nuts, seafood, eggs, cow's milk
Bites/stings: Bees, wasps, jumping ants Medications:
Betablockers, ab infusions, vaccines
Others: exercise, idiopathic, latex, hydatid
What are clinical features of anaphylaxis? What is required for diagnosis?
Resp: Tongue swelling, angioedema, stridor, wheeze, cough, tightness/swelling in throat
Cardio: Cyanosis, Tachycardia, bradycardia, hypotension, cardiac arrest
Skin: Urticaria, angioedema, pruritis
Gastro: Vomiting, diarrhoea, nausea, abdo pain
At least one resp/cardio symptoms and at least one skin/gastro symptom
Except for non-food allergens where GIT involvement is considered anaphylaxis
How do you manage anaphylaxis?
Lie patient supine (or on side if vomiting)
Administer IM adrenaline
Repeat dose if required
Call ambulance if in GP setting
Consider anti-histamines, corticosteroids
Observe for 4 hours
Consider IV access
When do you admit a child after anaphylaxis?
Greater than one dose of adrenaline required
Fluid bolus given
Inadequate response to therapy
Long distance from medical services
What are the long term treatment goals for a child whose had an anaphylaxis?
Action plan: Epipen (20 epipen 300ug)
Referral to allergy specialist
Ensure tight control of asthma
What is the association between asthma and anaphylaxis?
Asthmatics are at increased risk of death from anaphylaxis
How do you interpret positive skin prick tests?
- THe presence of specific IgE to an allergen is only one factor and should be correlated with history and/or trial of allergen avoidance/challenge
The negative predictive value is better than the positive predictive value
What is the greatest predictor for the development of atopy?
Positive family history
- 40-60% likelihood of developing it if positive FHx in parents
What do you advise patients before having a skin prick test?
Don't take anti-histamines in the 5 days prior
When is immunotherapy indicated?
Insert bite anaphylaxis
Intractable and debilitating pollen induced allergic rhinoconjunctivitis
What is the "allergic march"?
Atopic dermatitis - usually by 6 months of life
Approximately 50% of these children then develop asthma in early childhood
Resolution of asthma in late childhood and development of allergic rhinitis which may be lifelong