ANAPHYLAXIS

 

INTRODUCTION: Anaphylaxis is a clinical response to an immediate (type I hypersensitivity) immunologic reaction between a specific antigen and an antibody. The reaction results from a rapid release of IgE-mediated chemicals, which can induce a severe, life-threatening allergic reaction. Substances that most commonly cause anaphylaxis include foods, medications, insect stings, and latex. Immunoglobulins

Foods that are common causes of anaphylaxis include peanuts, tree nuts, shellfish, fish, milk, eggs, soy, and wheat. Many medications have been implicated in anaphylaxis. Those that are most frequently reported include antibiotics (eg, penicillin), radiocontrast agents, IV anesthetics, aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), and opioids. Penicillins: Anaesthetic medication: Opioid analgesics  Closely related to anaphylaxis is a nonallergenic anaphylaxis (anaphylactoid) reaction.

Clinical Manifestations: Anaphylactic reactions produce a clinical syndrome that affects multiple organ systems. Reactions may be categorized as mild, moderate, or severe. The severity depends on the degree of allergy and the dose of allergen.  Mild Symptoms include peripheral tingling, a warm sensation, fullness in the mouth and throat, nasal congestion, periorbital swelling, pruritus, sneezing, and tearing eyes. Symptoms begin within 2 hours of exposure. Moderate Symptoms include flushing, warmth, anxiety, and itching in addition to any of the milder symptoms. More serious reactions include bronchospasm and edema of the airways or larynx with dyspnea, cough, and wheezing. The onset of symptoms is the same as for a mild reaction.

Severe: Severe systemic reactions have an abrupt onset with the same signs and symptoms described previously. Symptoms progress rapidly to bronchospasm, laryngeal edema, severe dyspnea, cyanosis, and hypotension.  Dysphagia, abdominal cramping, vomiting, diarrhea, and seizures can also occur.  Cardiac arrest and coma may follow.

Assessment and Diagnostic Methods: Diagnostic evaluation of the patient with allergic disorders commonly includes blood tests (complete blood cell count [CBC] with differential, high total serum IgE levels), smears of body secretions, skin tests, and the radioallergosorbent test (RAST).

Prevention: Prevention by avoidance of allergens is of utmost importance. If avoidance of exposure to allergens is impossible, the patient should be instructed to carry and administer epinephrine to prevent an anaphylactic reaction in the event of exposure to the allergen.  Health care providers should always obtain a careful history of any sensitivities before administering medications. Venom immunotherapy may be given to people who are allergic to insect venom. Insulin-allergic patients with diabetes or penicillin-sensitive patients may require desensitization.

Medical Management: Respiratory and cardiovascular functions are evaluated and cardiopulmonary resuscitation (CPR) is initiated in cases of cardiac arrest. Oxygen is administered in high concentration during CPR or when the patient is cyanotic, dyspneic, or wheezing. Patients with mild reactions need to be educated about the risk for recurrences. Patients with severe reactions need to be observed for 12 to 14 hours.

Pharmacologic Therapy: Epinephrine, antihistamines, and corticosteroids may be given to prevent recurrences of the reaction and to relieve urticaria and angioedema. Corticosteroids.  IV fluids (eg, normal saline solution), volume expanders, and vasopressor agents are administered to maintain blood pressure and normal hemodynamic status; glucagon may be administered. Plasmavolume expanders  Aminophylline and corticosteroids may also be administered to improve airway patency and function.

RELATED;

1. ASTHMA  

2.  ALLERGIC RHINITIS

3.  IMMUNOLOGY

4.  LACTOSE INTOLERANCE

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