Introduction
- A serious generalized or systemic hypersensitivity reaction that is rapid in onset and potentially fatal
- Involves immunological response with IgE, high-affinity IgE receptors, mast cells, basophils, release of cytokines, chemokines, and chemical mediators of inflammation (eg histamine and tryptase)
- IgG-mediated anaphylaxis has been reported in humans after administration of dextran or monoclonal antibodies
- Non-immunological mechanisms are also involved and termed as non-allergic anaphylaxis or anaphylactoid reaction
- Relatively uncommon in children
Etiology
- Food allergy: Most common cause in the community setting
- Eg cow’s milk, egg white, shellfish, fish, peanuts, tree nuts, wheat
- Medications (eg penicillins, beta-lactams, cephalosporins, nonsteroidal anti-inflammatory drugs [NSAIDs], muscle relaxants, anticancer chemotherapy drugs, biological modifiers and monoclonal antibodies [eg Omalizumab]) and latex: Common in the hospital setting
- Insect sting
- Food-induced anaphylaxis associated with exercise: Affects teenagers
- Anaphylaxis occurs when exercise takes place within 2-4 hours of ingestion of a specific food
- May be food-independent or food-dependent; may be encountered after ingestion of celery, shellfish, wheat
- Idiopathic anaphylaxis: When the trigger of the anaphylaxis is unknown or cannot be identified despite a thorough history, allergen skin tests, IgE levels and provocation tests
- Allergen immunotherapy
Signs and Symptoms
- Patient's age is not correlated with reaction severity and initial reaction to an allergen leading to anaphylaxis is unlikely when it comes to infants and toddlers
- Age-specific symptoms that are less often seen in older children and adults may be seen in infants and toddlers
- The longer the symptoms develop the less severe the overall reaction
- Grading the severity of clinical symptoms as 1 to 5 based on the organ system most affected may be helpful in the diagnosis and timely administration of Epinephrine
Cutaneous
- Most frequent manifestations occurring in more than 90% of cases
- May be delayed or absent in rapidly progressive anaphylactic reaction
- Include urticaria, angioedema (including periorbital edema, conjunctival swelling), flushing, pruritus (may begin on palms and soles)
Respiratory
- Occur in up to 85% of episodes
- Include rhinorrhea, nasal congestion, throat tightness, hoarseness, sudden or ‘barky’ cough, stridor, wheeze, dyspnea, chest tightness
Gastrointestinal
- Symptoms occur in up to 45% of episodes
- Include oral pruritus, nausea, vomiting, dysphagia, diarrhea, crampy abdominal pain
Cardiovascular
- Occur in up to 45% of episodes
- Include dizziness, tachycardia, chest pain, hypotension and collapse
Neurological
- Include restlessness, withdrawal behavior, dizziness, lightheadedness, sense of impending doom, confusion, loss of consciousness, headache, seizure