Fatal anaphylactic reactions to food in children Fatal anaphylactic reactions to food in children Allergy Section, Canadian Paediatric Society (CPS)
Approved by the CPS Board of Directors in 1994
CMAJ 1994;150(3):337-9
Reference No. AL 1994-01
Revision in progress February 2004
Index of position statements from the Allergy Section
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Contents
The number of deaths caused by anaphylactic reactions to food is increasing each year.1- 4 The reason for this increase is unknown; however, one study has implicated widespread use of protein additives in commercially prepared food.5 In this statement we review characteristics of children at risk and of high-risk foods, mechanisms of anaphylaxis and important aspects of diagnosis and treatment.
Patients at risk of dying from a food allergy usually have a history of gastrointestinal or respiratory symptoms or of urticaria or angioedema immediately after eating a food to which they are allergic. In a case series, six young patients with fatal anaphylaxis after food ingestion and seven others with near-fatal anaphylaxis not only had a history of reactions to food but also had asthma and were highly allergic to many substances.4 Their parents or caregivers had failed to appreciate the potential seriousness of the food allergies. Four of the six fatal reactions occurred at school. Although self-injectable epinephrine had been prescribed for half of the children with fatal reactions, they did not have it available when they died. Many of the children had deceptively mild symptoms for 1 or more hours before breathing problems developed, yet none of them received epinephrine before severe respiratory symptoms developed.
Some foods pose a much greater threat than others. Peanuts, tree nuts (e.g., hazelnuts, walnuts, almonds and cashews), eggs and cow's milk are the most frequent culprits, but fish, crustaceans, molluscs and soy may also be lethal. Even trace amounts of these foods can provoke anaphylaxis in susceptible patients.6 Food antigens may be "hidden" in cookies, cakes, cereals, candies or other foods.
When specific IgE forms against a food antigen in a susceptible person, subsequent exposure to the antigen may result in IgE-mediated activation of mast cells and basophils, followed by release of histamine, tryptase and other biologically active substances. Occasionally, the mechanism causing anaphylaxis is unknown; such cases include anaphylaxis triggered by metabisulfites used as food preservatives and anaphylaxis cotriggered by exercise.1,2
For any acute reaction to food a description of the symptoms and signs and of all foods eaten before the reaction, including manufacturer and lot number of processed foods, recipe ingredients and all other relevant information, should be obtained. The food implicated in the reaction should be precisely identified. Elevated specific IgE levels to food antigens can be detected with the use of epicutaneous (not intradermal) tests, performed with appropriate controls and precautions by a trained, certified clinical immunology and allergy specialist, or with the use of in-vitro tests such as the radioallergosorbent test. If necessary, uneaten portions of the food suspected of triggering the anaphylactic episode can be tested for specific antigens by means of an inhibition immunoassay.7
The patient must strictly avoid the food to which he or she is highly allergic. Some antigens (e.g., peanuts) may have to be avoided for life.8 Avoiding a food antigen completely may be quite difficult. In a recent survey 50% of children allergic to peanuts had unintentionally ingested them within the previous year.8
Patients and their parents should be provided with written lists of terms used on packaging to describe food proteins: egg may be listed as "albumin" or "lecithin," and cow's milk may be listed as "whey," "casein" or "caseinate." Labels on processed food must be scrutinized meticulously each time the food is purchased. Antigens such as peanuts may be found unexpectedly in oils, flours, processed meats, and milk and cream substitutes. Patients and their parents must be aware of potentially lethal food substitutions, such as inexpensive ground nuts (e.g., peanuts) for more expensive tree nuts (e.g., almonds) or inexpensive vertebrate fish (pollack, also known as surimi) for more expensive crab meat. Any food (e.g., items sold in bulk) can be cross-contaminated through direct or indirect contact with other food.
Children at risk of lethal allergic reactions to food must not eat food given to them by other children or by adults other than their parents or caregivers. In restaurants children and their parents should obtain information about all ingredients in dishes before ordering and eating meals. The Canadian Restaurant and Food Service Association, Toronto, has recently instituted the Allergy Awareness Program, through which participating restaurants maintain lists of food ingredients and always have a knowledgeable employee on site to answer questions about ingredients.
The Allergy Asthma Information Association (10-65 Tromley Dr., Etobicoke, ON M9B 5Y7) provides up-to-date information about food content and labelling, manufacturers' recalls because of food content or labelling errors and "safe" substitutes for common allergenic foods.
The goals of pharmacologic treatment are to maintain airway patency and systolic blood pressure. An epinephrine injection is the initial treatment of choice for anaphylaxis: it suppresses release of mediators of inflammation from mast cells and basophils, and it directly decreases vasodilation, edema and bronchoconstriction. Epinephrine must be administered promptly at the first warning symptoms, such as itching or swelling of the lips or mouth, tightening of the throat or nausea, and before respiratory distress, stridor or wheezing occur.2-4,9
Epinephrine is available in a preloaded syringe (Ana-Kit; Hollister-Stier, Etobicoke, Ont.) or in a springloaded, self-injectable system (EpiPen; Allerex Laboratory Ltd., Kanata, Ont.). The Ana-Kit epinephrine syringe is suitable for children weighing less than 12 kg and for multiple doses. It is relatively inexpensive but more difficult to self-administer than the EpiPen. (For dose, see Table 1.) In young patients serious adverse effects of epinephrine such as cardiac arrhythmias and hypertensive crises are extremely rare, and the life-saving benefit of injecting epinephrine in cases of suspected anaphylaxis outweighs any small risk of side effects.
Epinephrine inhalation (20 to 30 puffs from a metered-dose inhaler) produces transient high plasma levels in healthy adult volunteers10,11 but has not been proven to save lives of young patients with anaphylaxis; therefore, it is not recommended as an alternative to injected epinephrine.
Antihistamines are not an adequate substitute for epinephrine, although they may be helpful in controlling urticaria and other ancillary symptoms and signs of anaphylaxis.2-4,12
An anaphylactic reaction generally follows one of three patterns: rapid progression (uniphasic), protracted symptoms (uniphasic) or initial symptoms followed by a relatively symptom-free period of up to 2 hours and then by respiratory symptoms or hypotension or both (biphasic).4,13 Even if symptoms are resolved completely after epinephrine injection, the patient should be taken immediately to the nearest hospital and monitored for at least 3 to 4 hours4 and possibly up to 24 hours.2 If symptoms persist or recur the patient should receive additional epinephrine injections every 10 to 20 minutes. A glucocorticoid such as prednisone (1 to 2 mg/kg) should be given. Oxygen, bronchodilators, antihistamines, intravenous colloid infusion and other supportive measures should be administered if necessary.2-4
All patients at risk of a lethal allergic reaction to food should wear a MedicAlert bracelet listing the food antigens that may cause them to have an anaphylactic reaction. They should be repeatedly reminded that the keys to survival are complete avoidance of relevant food antigens, including "hidden" food antigens, and, if a potentially lethal food has been ingested and symptoms occur, prompt injection of epinephrine before respiratory problems develop.
| Recommended management of anaphylactic reactions to food in children |
| Diagnosis Obtain history to identify high-risk patients Prevention Warn patients and their parents to avoid foods that trigger anaphylaxis Treatment Inject epinephrine immediately if symptoms develop Ana-Kit: 0.05-0.12 mL SC* for children weighing < 12 kg, 0.12-0.25 mL SC for
those 12-25 kg and 0.25-0.3 mL SC for those > 25 kg Transfer patient to hospital and monitor symptoms *SC = subcutaneously, IM = intramuscularly. |
Members:
Drs. Zave H. Chad, Department of Pediatrics, University of Montreal, Montreal, Que.; John M. Dean, Department of Pediatrics, University, of British Columbia, Vancouver, BC; F. Estelle R. Simons, Section of Allergy and Clinical Immunology, Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Man; and Wade T.A. Watson, Section of Allergy and Clinical Immunology, Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Man.This statement was developed by the authors, funded by the Children's Hospital Research Foundation, Winnipeg, and approved by the directors of the Canadian Paediatric Society.
| Disclaimer: The recommendations in this position statement do not indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate. Internet addresses are current at time of publication. |