Anaphylaxis (Pediatric)

Definition

Anaphylaxis is a severe, potentially life-threatening systemic hypersensitivity reaction that occurs rapidly and involves multiple organ systems, including skin, respiratory, cardiovascular, and gastrointestinal systems in children.

Epidemiology

• Incidence in children: approximately 1–2% worldwide
• Common triggers vary with age: foods (peanuts, tree nuts, milk, eggs) are most frequent in children
• Other triggers: insect stings, medications, vaccines, latex
• Male predominance in pediatric populations
• Hospital admissions for anaphylaxis are increasing globally

Etiology

• IgE-mediated hypersensitivity reaction (most common)
• Non-IgE-mediated mechanisms (e.g., complement activation, direct mast cell activation)
• Triggers: foods, insect venom, medications, latex, exercise-induced
• Risk factors: atopy, asthma, previous anaphylaxis, rapid allergen exposure
• Genetic predisposition and comorbidities (e.g., mastocytosis) may increase severity

Pathophysiology

• Allergen binds to IgE on mast cells and basophils, triggering degranulation
• Release of histamine, leukotrienes, prostaglandins, and other mediators
• Vasodilation, increased vascular permeability, and smooth muscle contraction
• Hypotension, angioedema, bronchospasm, and gastrointestinal symptoms develop
• Rapid systemic involvement can lead to shock and respiratory compromise
• Biphasic or protracted reactions may occur in some children