Anaphylaxis Flashcards
super (31 cards)
What is anaphylaxis?
A life-threatening systemic allergic reaction involving
circulatory collapse, angioedema,
bronchospasm, laryngeal stridor, and
urticaria.
What increases the risk of death in anaphylaxis?
Poorly controlled asthma and delayed adrenaline (epinephrine) administration.
What immunological event triggers anaphylaxis?
Allergen cross-links IgE on mast cells → release of histamine, tryptase, and other mediators.
Key effects of mast cell mediators in anaphylaxis?
Vasodilatation, ↑ capillary permeability (→ hypotension), bronchoconstriction.
Difference between IgE-mediated anaphylaxis and anaphylactoid reaction?
IgE-mediated involves allergen-specific IgE; anaphylactoid (non-IgE) is mast cell degranulation without IgE involvement.
What should be assessed during clinical evaluation of anaphylaxis?
Severity
Onset timing
Suspected trigger
Route of exposure
Potentiating factors (e.g., exercise, alcohol, fatigue)
Common triggers of anaphylaxis?
Foods, latex, insect venom, drugs.
ow does the route of allergen exposure affect symptoms?
Inhaled allergen → wheezing is prominent.
Diagnostic test to confirm anaphylaxis?
Serial serum mast cell tryptase levels.
Preferred allergy test after anaphylaxis history?
Specific IgE tests (safer than skin-prick in high-risk cases).
First-line treatment in severe anaphylaxis?
Early intramuscular adrenaline (epinephrine).
Emergency management steps (summary)?
Adrenaline → Airway management → Fluids → Antihistamines → Corticosteroids → Monitor organs affected.
What should be done after recovery from anaphylaxis?
Specialist referral
Identify trigger
Educate patient
Consider immunotherapy if appropriate
Signs of anaphylaxis
Conjunctival injection
Flushing, sweating
Urticaria, Itching of palms, soles, genitalia
Hypotension, Angioedema, Cardiac arrhythmias
Wheeze, Stridor,
Abdo pain, Diarrhoea
Differential diagnoses of anaphylaxis – causes of hypotension?
Vasovagal syncope
Cardiac arrhythmia
Cardiogenic shock
Differential diagnoses – causes of respiratory distress?
Status asthmaticus
Pulmonary embolism
Differential diagnoses – causes of laryngeal obstruction?
C1 esterase inhibitor deficiency
Idiopathic angioedema
Differential diagnoses – causes of generalised flushing?
Systemic mastocytosis
Carcinoid syndrome
First step in anaphylaxis management?
Prevent further contact with the allergen — avoids continued mast cell activation.
Why is ensuring airway patency critical in anaphylaxis?
Prevents hypoxia from upper airway obstruction (e.g., laryngeal oedema).
What is the adrenaline (epinephrine) dose for adults in anaphylaxis?
0.3–0.5 mL of 1:1000 IM (equals 0.3–0.5 mg) — repeat every 5–10 mins if needed.
Why is the IM route preferred for adrenaline?
More reliable absorption during peripheral vasoconstriction in shock.
3 key actions of adrenaline in anaphylaxis?
Raises BP
Reverses bronchospasm
Acts within minutes
Antihistamine used in anaphylaxis and its dose?
Chlorphenamine 10 mg IM or slow IV.
