Anaphylaxis Anaphylactoid Reactions and Angioedema

Anaphylaxis is a life-threatening, rapid, type I hypersensitivity reaction mediated by IgE, causing local and systemic responses to multiple organ systems. Anaphylactoid reactions refer to non-lgE hypersensitivity events that are similar in clinical presentation. Angioedema refers to the deep cutaneous and visceral tissue swelling that accompanies an allergic response.

The following are common causes of anaphylaxis:

• Drugs, especially antibiotics (penicillin is the most common cause of anaphylaxis)
• Insect bites or stings, especially from Hymenoptera, snakes, and fire ants
• Foods, especially peanuts, nuts, egg whites, and shellfish; preservatives, especially sulfites
• Plants
• Chemicals
• Latex
• Exercise, especially when coupled with certain foods or drugs
• Immunotherapy

ACE inhibitors can cause a bradykinin-mediated angioedema in 0.2% of patients (70% within the first week, but can occur at any time). Anaphylactoid reactions can be caused by neuromuscular blockers and radiocontrast dyes (iodinated more common than lower-osmolar agents).

The severity of the allergen response depends on the delivery of the allergen; parenteral is most rapid.

Causes

• A most variety of substances can cause anaphylaxis. Anaphylaxis also may be idiopathic.
• Foods - MEWS, fish, shell fish, legumes
  • Peanuts, seafood and tree nuts (brazil nuts, almonds, hazelnuts) are the mian and most common foods to cause allergy
  • Other foods include, egg, milk, wheat, soy and sesame seeds
• Medicinals -Antibiotics (penicillins, cephalosporins), analgesics (aspirin, nonsteroidal anti-inflammatories, opiates), radiocontrast media
  • NSAIDs such as aspirin, naproxen, ibuprofen and diclofenac
  • Anaesthetics and opioid analgesics
• Preservatives and additives - Metabisulfite, monosodium glutamate

Symptoms

Usually peak within 15 to 30 minutes of exposure

• History of known allergen exposure
• Pruritus or tingling, rash or swelling, flushing ++++
• Hoarseness, sensation of throat tightness
• Rhinorrhea, bronchorrhea
• Nausea, vomiting, abdominal cramps
• Dizziness, syncope, near-syncope
• Dyspnea, chest tightness

Signs

May occur in combination or isolation

• Urticaria (pruritic) or angioedema (nonpruritic)++++; preferential edema of lips, tongue, uvula, eyes, and hands
• Distributive shock-hypotension, tachycardia; may occur in the absence of urticaria or angioedema
• Stridor, wheeze, retractions, tachypnea
• Respiratory failure from laryngeal edema

Treatment

Advise patient to wear or carry a medical alert bracelet, necklace, or keychain to warn emergency personnel of anaphylaxis risk.

Advise patient to keep epinephrine self-injection kit and oral diphenhydramine for future exposures.

Avoid prescribing beta blockers, angiotensin-converting enzyme inhibitors, angiotensin-II receptor blockers, monoamine oxidase inhibitors, and some tricyclic antidepressants.