Abstract and Introduction
Abstract
Anaphylaxis is a systemic, type I hypersensitivity reaction that often has fatal consequences. Anaphylaxis has a variety of causes including foods, latex, drugs, and hymenoptera venom. Epinephrine given early is the most important intervention. Adjunctive treatments include fluid therapy, H1 and H2 histamine receptor antagonists, corticosteroids, and bronchodilators; however these do not substitute for epinephrine. Patients with a history of anaphylaxis should be educated about their condition, especially with respect to trigger avoidance and in the correct use of epinephrine autoinjector kits. Such kits should be available to the sensitized patient at all times.
Introduction
Anaphylaxis is a systemic, type I hypersensitivity reaction that occurs in sensitized individuals resulting in mucocutaneous, cardiovascular, and respiratory manifestations and can often be life threatening. Anaphylaxis was first described in 1902 by Portier and Richet when they were attempting to produce tolerance in dogs to sea anemone venom. Richet coined the term aphylaxis (from the Greek a , against, -phylaxis protection) to differentiate it from the expected "prophylaxis" they hoped to achieve. The term aphylaxis was replaced with the term anaphylaxis shortly thereafter. Richet won the Nobel Prize in medicine or physiology in 1913 for his pioneering work.
Anaphylaxis occurs in persons of all ages and has many diverse causes, the most common of which are foods, drugs, latex, hymenoptera stings, and reactions to immunotherapy. Of note, a cause cannot be determined in up to one third of cases. Anaphylactoid reactions are identical to anaphylaxis in every way except the former are not mediated by immunoglobulin E (IgE). Common causes of anaphylactoid reactions include radiocontrast media, narcotic analgesics, and nonsteroidal antiinflammatory drugs.
Signs and symptoms can be divided into four categories: mucocutaneous, respiratory, cardiovascular, and gastrointestinal. Reactions that surpass mucocutaneous signs and symptoms are considered to be severe, and, unfortunately, mucocutaneous manifestations do not always occur prior to more serious manifestations. Mucocutaneous symptoms commonly consist of urticaria, angioedema, pruritis, and flushing. Common respiratory manifestations are dyspnea, throat tightness, stridor, wheezing, rhinorrhea, hoarseness, and cough. Cardiovascular signs and symptoms include hypotension, tachycardia, and syncope. Gastrointestinal manifestations include nausea, vomiting, abdominal cramps, and diarrhea.
First-line treatment of anaphylactic shock is epinephrine. Other adjuvant treatments are often also used; however, there is no substitute for prompt administration of epinephrine.
A century has passed since the discovery of anaphylaxis, and much knowledge has been added to our understanding of this syndrome. This article reviews the pathophysiology, recognition, and treatment of anaphylactic shock.