Anaphylaxis

From Anvita Health Wiki

Contents 1 Introduction 2 Etiology 3 Epidemiology 4 Pathology 5 Clinical-manifestations 6 Laboratory 7 Management 8 More General Terms 9 Additional Terms 10 References

Introduction

• Life-threatening systemic hypersensitivity reaction to contact with an allergen. It may occur within minutes of exposure to the offending agent.

Etiology

• almost any allergen may incite an anaphylactic reaction
• pharmacologic causes: (14%) [2,6]

• cephalosporins (common)
• penicillins (common)
• insulin (common)
• dextran
• iodinated drugs
• lidocaine
• procaine
• NSAIDs
• aspirin & contrast agents elicit anaphylactoid response (not true anaphylaxis)

• antisera
• pollen extracts
• Hymenoptera venom (19%) [6]
• foods (33%) [6]

• nuts, especially peanuts

• peanut antigen may contaminate foods such as pastries, candies, yogurt, cookies, egg rolls, chilis

• shellfish
• eggs
• milk
• spices
• food additives

• exercise-induced

• food allergy may condition anaphylactic response
• exercise induces the response
• neither food nor exercise alone elicits response

• latex allergy

• gloves, condoms
• important cause of intraoperative anaphylaxis

• IgA deficiency - transfusion reaction (anti-IgA, IgG or IgE)
• seminal fluid
• cold urticaria
• idiopathic (25-40%), some may be psychogenic

Epidemiology

• 50 cases/100,000 patient years is high estimate [6]
• mean age = 29
• peak incidence in children

Pathology

• IgE-mediated antigen response to an antigen
• mast cell degranulation

• release of histamine & other preformed mediators of anaphylaxis cause immediate effects
• leukotriene synthesis causes some of the delayed effects
• other mediator of anaphylaxis
• prostaglandin D2 (major)
• tumor necrosis factor-alpha ( TNF-alpha)
• interleukin-1 (IL-1)

• treatment with beta-blockers is a risk factor for prolonged & severe reactions

Clinical-manifestations

• skin manifestations

• pruritis
• urticaria:

• circumscribed, erythematous, pruritic papules & plaques
• individual lesions resolve within 24 hours

• angioedema

• diffuse swelling in deeper layers of the dermis
• often occurs in face or extremities

• mucous membrane swelling

• pulmonary/ respiratory tract manifestations

• respiratory distress
• hoarseness, stridor, laryngeal edema
• wheezing, bronchospasm, bronchorrhea

• gastrointestinal manifestations

• nausea/vomiting
• diarrhea
• abdominal pain & distention

• cardiovascular manifestations

• tachycardia
• vasodilation, hypotension, vascular collapse
• arrhythmias

• 3 patterns of anaphylaxis

• acute reactions developing within 5 minutes (50%)
• biphasic reactions (25%)

• early abdominal, intestinal or oral angioedema
• respiratory symptoms & hypotension begin 1-2 hours later

• prolonged hypotension & respiratory failure, especially in patients taking beta-blockers

Laboratory

• serum tryptase (released from mast cells)

• elevation occurs within 2 hours & is useful for confirming diagnosis
• less likely to be elevated after food-induced anaphylaxis

Management

• epinephrine

• 0.2-0.5 mL of a 1:1000 solution SC every 20 min
• IV infusion of a 1:10,000 solution for hypotension
• patients receiving beta blockers

• may not respond to epinephrine
• treatment with glucagon may be life-saving

• IV access: normal saline for hypotension
• antihistamines (both H1 & H2 receptor antagonists)

• for cutaneous symptoms
• diphenhydramine 50-80 mg IV or IM
• cimetidine or ranitidine

• IV glucagon may reverse refractory hypotension & bronchospasm ( Emergency Department or ICU setting) [5]
• intravenous glucocorticoids

• not useful for acute manifestations
• may help prevent late onset reactions
• may help control persistent hypotension or bronchospasm

• treat bronchospasm as asthma

• aminophylline 0.25-0.5 g IV for bronchospasm
• oxygen
• glucocorticoids
• albuterol & atrovent nebulizers

• hospitalize for severe reactions

• supportive treatment for shock
• intubation for laryngeal edema
• risk of relapse in 12-24 hours
• monitor in intensive care unit for at least 12 hours [4]

• may progress over 3-5 hours thus requires observation for life-threatening respiratory complications
• skin testing & desensitization
• avoid offending agent
• discharge with epinephrine autoinjector

More General Terms

• type 1 hypersensitivity; immediate hypersensitivity (allergy)

Additional Terms

• anaphylactoid reaction
• asthma
• epinephrine; adrenaline (Sus-Phrine, Vapronefrin, Epifrin, Glaucon)
• glucagon
• H1 receptor antagonist (antihistamine)
• H2 receptor antagonist
• hymenoptera (bees, wasps, yellow jackets, ants)
• latex allergy
• shock

References

1. Stedman's Medical Dictionary 26th ed, Williams & Wilkins, Baltimore, 1995
2. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook, Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, page 145
3. H. Quinny Cheng, USSF Fresno lecture, Oct 21, 1998
4. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
5. Prescriber's Letter 12(7): 2005 Should Some Drugs Be Avoided in Patients at Risk of Anaphylaxis? Detail-Document#: [1] (subscription needed) [2]
6. Decker WW et al, The etiology and incidence of anaphylaxis in Rochester, Minnnesota: A report from the Rochester Epidemiology Project. J Allergy Clin Immunol 2008, 122:1161 PMID: [3]
7. Prescriber's Letter 17(6): 2010 COMMENTARY: Self-injected Epinephrine in the Outpatient Treatment of Anaphylaxis GUIDELINES: American Academy of Allergy, Asthma and Immunology: The Diagnosis and Management of Anaphylaxis Detail-Document#: [4] (subscription needed) [5]
8. National Guideline Clearinghouse The diagnosis and management of anaphylaxis: an updated practice parameter. (Joint Council of Allergy, Asthma and Immunology) ngc-guideline: [6]

anaphylaxis