Items in AFP with MESH term: Anaphylaxis
ABSTRACT: In a select group of persons, exercise can produce a spectrum of allergic symptoms ranging from an erythematous, irritating skin eruption to a life-threatening anaphylactic reaction. The differential diagnosis in persons with exercise-induced dermatologic and systemic symptoms should include exercise-induced anaphylaxis and cholinergic urticaria. Both are classified as physical allergies. Mast cell degranulation with the release of vasoactive substances appears to be an inciting factor for the production of symptoms in both cases. Exercise-induced anaphylaxis and cholinergic urticaria can be differentiated on the basis of urticarial morphology, reproducibility, progression to anaphylaxis and response to passive warming. Diagnosis is usually based on a thorough history and examination of the morphology of the lesions. Management of acute episodes of exercise-induced anaphylaxis includes cessation of exercise, administration of epinephrine and antihistamines, vascular support and airway maintenance. Long-term care may require modification of or abstinence from exercise, avoidance of co-precipitating factors and the prophylactic use of medications such as antihistamines and mast cell stabilizers.
ABSTRACT: Adverse reactions to contrast agents range from a mild inconvenience, such as itching associated with hives, to a life-threatening emergency. Renal toxicity is a well known adverse reaction associated with the use of intravenous contrast material. Other forms of adverse reactions include delayed allergic reactions, anaphylactic reactions, and local tissue damage. Previous allergic reactions to contrast material, asthma, and allergies are factors associated with an increased risk of developing an adverse reaction. Pretreatment of patients who have such risk factors with a corticosteroid and diphenhydramine decreases the chance of allergic reactions, including anaphylaxis, renal failure, or a possible life-threatening emergency. Awareness of the different types of risk factors and prescreening for their presence allows for early recognition and prompt treatment. Prophylactic treatment before administration of contrast material can prevent potential adverse reactions. If such reactions do occur, prompt recognition allows them to be treated immediately. Using the smallest amount of contrast material possible and low-molecular, nonionic agents also decreases the relative risk of reactions. Renal insufficiency induced by contrast material may be prevented by ensuring adequate hydration and discontinuing other nephrotoxic medications before the procedure. Low-osmolar, nonionic agents are helpful in patients with known conditions associated with adverse reactions.
Stinging Insect Allergy - Article
ABSTRACT: Systemic allergic reactions to insect stings are estimated to occur in about 1 percent of children and 3 percent of adults. In children, these reactions usually are limited to cutaneous signs, with urticaria and angioedema; adults more commonly have airway obstruction or hypotension. Epinephrine is the treatment of choice for acute anaphylaxis, and self-injection devices should be prescribed to patients at risk for this allergic reaction. Stinging insect allergy can be confirmed by measurement of venom-specific IgE antibodies using venom skin tests or a radioallergosorbent test. Patients with previous large local reactions have a 5 to 10 percent risk of experiencing systemic reactions to future stings. Patients with previous systemic reactions have a variable risk of future reactions: the risk is as low as 10 to 15 percent in those with the mildest reactions and in some children, but as high as 70 percent in adults with the most severe recent reactions. Because of demonstrated efficacy (98 percent), venom immunotherapy is recommended for use in patients who are at risk for severe systemic reactions to future insect stings. Venom immunotherapy is administered every four to eight weeks for at least five years. Immunotherapy may be needed indefinitely in patients at higher risk for recurrence of anaphylaxis after treatment is stopped.
A Practical Guide to Anaphylaxis - Article
ABSTRACT: Anaphylaxis is a life-threatening reaction with respiratory, cardiovascular, cutaneous, or gastrointestinal manifestations resulting from exposure to an offending agent, usually a food, insect sting, medication, or physical factor. It causes approximately 1,500 deaths in the United States annually. Occasionally, anaphylaxis can be confused with septic or other forms of shock, asthma, airway foreign body, panic attack, or other entities. Urinary and serum histamine levels and plasma tryptase levels drawn after onset of symptoms may assist in diagnosis. Prompt treatment of anaphylaxis is critical, with subcutaneous or intramuscular epinephrine and intravenous fluids remaining the mainstay of management. Adjunctive measures include airway protection, antihistamines, steroids, and beta agonists. Patients taking beta blockers may require additional measures. Patients should be observed for delayed or protracted anaphylaxis and instructed on how to initiate urgent treatment for future episodes.
Food Allergies: Detection and Management - Article
ABSTRACT: Family physicians play a central role in the suspicion and diagnosis of immunoglobulin E-mediated food allergies, but they are also critical in redirecting the evaluation for symptoms that patients are falsely attributing to allergies. Although any food is a potential allergen, more than 90 percent of acute systemic reactions to food in children are from eggs, milk, soy, wheat, or peanuts, and in adults are from crustaceans, tree nuts, peanuts, or fish. The oral allergy syndrome is more common than anaphylactic reactions to food, but symptoms are transient and limited to the mouth and throat. Skin-prick and radioallergosorbent tests for particular foods have about an 85 percent sensitivity and 30 to 60 percent specificity. Intradermal testing has a higher false-positive rate and greater risk of adverse reactions; therefore, it should not be used for initial evaluations. The double-blind, placebo-controlled food challenge remains the most specific test for confirming diagnosis. Treatment is through recognition and avoidance of the responsible food. Patients with anaphylactic reactions need emergent epinephrine and instruction in self-administration in the event of inadvertent exposure. Antihistamines can be used for more minor reactions.
Anaphylaxis: Recognition and Management - Article
ABSTRACT: Anaphylaxis is a severe, life-threatening, systemic allergic reaction that is almost always unanticipated and may lead to death by airway obstruction or vascular collapse. Anaphylaxis occurs as the result of an allergen response, usually immunoglobulin E–mediated, which leads to mast cell and basophil activation and a combination of dermatologic, respiratory, cardiovascular, gastrointestinal, and neurologic symptoms. Dermatologic and respiratory symptoms are most common, occurring in 90 and 70 percent of episodes, respectively. The three most common triggers are food, insect stings, and medications. The diagnosis of anaphylaxis is typically made when symptoms occur within one hour of exposure to a specific antigen. Confirmatory testing using serum histamine and tryptase levels is difficult, because blood samples must be drawn with strict time considerations. Allergen skin testing and in vitro assay for serum immunoglobulin E of specific allergens do not reliably predict who will develop anaphylaxis. Administration of intramuscular epinephrine at the onset of anaphylaxis, before respiratory failure or cardiovascular compromise, is essential. Histamine H1 receptor antagonists and corticosteroids may be useful adjuncts. All patients at risk of recurrent anaphylaxis should be educated about the appropriate use of prescription epinephrine autoinjectors.
ABSTRACT: Patients with suspected food allergies are commonly seen in clinical practice. Although up to 15 percent of parents believe their children have food allergies, these allergies have been confirmed in only 1 to 3 percent of all Americans. Family physicians must be able to separate true food allergies from food intolerance, food dislikes, and other conditions that mimic food allergy. The most common foods that produce allergic symptoms are milk, eggs, seafood, peanuts, and tree nuts. Although skin testing and in vitro serum immunoglobulin E assays may help in the evaluation of suspected food allergies, they should not be performed unless the clinical history suggests a specific food allergen to which testing can be targeted. Furthermore, these tests do not confirm food allergy. Confirmation requires a positive food challenge or a clear history of an allergic reaction to a food and resolution of symptoms after eliminating that food from the diet. More than 70 percent of children will outgrow milk and egg allergies by early adolescence, whereas peanut allergies usually remain throughout life. The most serious allergic response to food allergy is anaphylaxis. It requires emergency care that should be initiated by the patient or family using an epinephrine autoinjector, which should be carried by anyone with a diagnosed food allergy. These and other recommendations presented in this article are derived from the Guidelines for the Diagnosis and Management of Food Allergy in the United States, published by the National Institute of Allergy and Infectious Diseases.