acute allergic reaction
Post on 24-Feb-2016
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The College of Emergency Medicine
Acute Allergic Reaction
The College of Emergency Medicine
Ranges from rash to fatal anaphylaxis
Acute Allergic reaction
The College of Emergency Medicine
•Allergies are among the most common diseases in the UK
•Around 30% of adults and 40% of children are affected
The College of Emergency Medicine
Anaphylaxis
Anaphylaxis is a severe, life threatening, generalised or systemic hypersensitivity reaction characterised by rapidly developing life threatening problems involving airway, breathing and circulatory problems with associated skin and mucosal changes.
The College of Emergency Medicine
UK Incidence
• No overall figure is available in the UK. • 500,000 venom induced anaphylactic
reaction reported• 220,000 had nut induced allergic reaction
in under the age of 44 years old reported.• 1 in 1333 people have experienced an
anaphylaxis reaction in their life time.
The College of Emergency Medicine
• The overall mortality of anaphylaxis has been estimated at <1%.
• Over half of all deaths due to anaphylaxis occur
within an hour of allergen exposure.
• Primarily from asphyxia due to upper airway oedema and bronchospasm, or hypotension and circulatory failure.
The College of Emergency Medicine
Cardiac arrest in Anaphylaxis
The College of Emergency Medicine
Anaphylaxis is caused by the degranulation of mast cells and basophils with subsequent release of inflammatory mediators such as histamine, tryptase, prostaglandins, leukotrienes, cytokines and chemokines. These inflammatory mediators cause smooth muscle contraction, vasodilation and increased vascular permeability, leading to urticaria, angioedema, bronchoconstriction and hypotension.
The College of Emergency Medicine
People presenting with mild to moderate allergic reactions can later develop anaphylaxis particularly it is more common in high risk group. eg: Asthmatics and people with known anaphylactic reactions to food and venoms.
The College of Emergency Medicine
The most common signs and symptoms of anaphylaxis are cutaneous (generalised urticaria, angioedema, flushing and itching), affecting around 90% of patients.
Other features include respiratory symptoms (dyspnoea, wheeze, stridor or hypoxia), affecting70%, and GI symptoms such as abdominal pain and vomiting, affecting 40%.
Hypotension is less common, affecting between 10−30% of patients with anaphylaxis.
The College of Emergency Medicine
Pathophysiology
• Immunologic mediated (IgE mediated foods, insects, drugs and latex)
• Non-immunologic mediated (most drugs)
• Idiopathic
The College of Emergency Medicine
• Reactions can be triggered by virtually any agent capable of activating mast cells and basophils, but the most commonly implicated allergens are;
• Foods (particularly milk, egg, peanuts, tree nuts, fish, shellfish, soy and wheat)
• Drugs• Stings or venoms• Latex• Allergen immunotherapy injections
The College of Emergency Medicine
• Food is common in children
• Drugs are more common in adults
The College of Emergency Medicine
• Stings 47; 29 wasp, 4 bee, 14 unknown• Nuts 32; 10 peanut, 6 walnut, 2 almond, 2 brazil, 1 hazel,• 11 mixed or unknown• Food 13; 5 milk, 2 fish, 2 chickpea, 2 crustacean, 1 banana,• 1 snail• Food possible cause 17; 5 during meal, 3 milk, 3 nut, 1 each - fish, yeast,• sherbet, nectarine, grape, strawberry• Antibiotics 27; 11 penicillin, 12 cephalosporin, 2 amphotericin,• 1 ciprofloxacin, 1 vancomycin• Anaesthetic drugs 39; 19 suxamethonium, 7 vecuronium, 6 atracurium,• 7 at induction• Other drugs 24; 6 NSAID, 3 ACEI, 5 gelatins, 2 protamine,• 2 vitamin K, 1 each - etoposide, acetazolamide,• pethidine, local anaesthetic, diamorphine,• streptokinase• Contrast media 11; 9 iodinated, 1 technetium, 1 fluorescein• Other 3 1 latex, 1 hair dye, 1 hydatid
The College of Emergency Medicine
The diagnosis is suspected clinically on the basis of the patient's symptoms and confirmed biochemically
The College of Emergency Medicine
The College of Emergency Medicine
• Always record the time of onset of symptoms.
• Clinical and biochemical diagnosis
• Mast cell tryptase should be done immediately and 1-2 hours after the treatment not more than 4 hours.
The College of Emergency Medicine
• All children under 16 should be admitted
• All adults who have had emergency treatment should be observed for 6-12 hours after the onset of symptoms because of the risk of bi-phasic reaction.
The College of Emergency Medicine
• Discharge patients after an anaphylactic reaction with specialist referral and auto-adrenaline injector (epi pen)
The College of Emergency Medicine
Biphasic anaphylaxis
• After complete recovery of anaphylaxis, a recurrence of symptoms within 72 hours with no further exposure to the allergen. It is managed in the same way as anaphylaxis
The College of Emergency Medicine
Resources
The College of Emergency Medicine
The College of Emergency Medicine
The College of Emergency Medicine
The College of Emergency Medicine
Any questions
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