World allergy organization guidelines for the assessment and management of anaphylaxis

Abstract

The illustrated World Allergy Organization (WAO) Anaphylaxis Guidelines were created in response to absence of global guidelines for anaphylaxis. Uniquely, before they were developed, lack of worldwide availability of essentials for the diagnosis and treatment of anaphylaxis was documented. They incorporate contributions from more than 100 allergy/immunology specialists on 6 continents. Recommendations are based on the best evidence available, supported by references published to the end of December 2010. The Guidelines review patient risk factors for severe or fatal anaphylaxis, co-factors that amplify anaphylaxis, and anaphylaxis in vulnerable patients, including pregnant women, infants, the elderly, and those with cardiovascular disease. They focus on the supreme importance of making a prompt clinical diagnosis and on the basic initial treatment that is urgently needed and should be possible even in a low resource environment. This involves having a written emergency protocol and rehearsing it regularly; then, as soon as anaphylaxis is diagnosed, promptly and simultaneously calling for help, injecting epinephrine (adrenaline) intramuscularly, and placing the patient on the back or in a position of comfort with the lower extremities elevated. When indicated, additional critically important steps include administering supplemental oxygen and maintaining the airway, establishing intravenous access and giving fluid resuscitation, and initiating cardiopulmonary resuscitation with continuous chest compressions. Vital signs and cardiorespiratory status should be monitored frequently and regularly (preferably, continuously). The Guidelines briefly review management of anaphylaxis refractory to basic initial treatment. They also emphasize preparation of the patient for self-treatment of anaphylaxis recurrences in the community, confirmation of anaphylaxis triggers, and prevention of recurrences through trigger avoidance and immunomodulation. Novel strategies for dissemination and implementation are summarized. A global agenda for anaphylaxis research is proposed.

FIGURE 1

Patient factors that contribute to anaphylaxis. Age-related factors, concomitant diseases, and concurrent medications potentially contribute to severe or fatal anaphylaxis. Co-factors potentially amplify anaphylaxis. Multiple factors and co-factors likely contribute to some anaphylactic episodes (2,8–13,31–47,57). Atopic diseases are a risk factor for anaphylaxis triggered by food, exercise, and latex, but not for anaphylaxis triggered by insect stings and medications. Beta-blockers: beta-adrenergic blockers; ACE inhibitors: angiotensin-converting enzyme inhibitors.

FIGURE 2

Anaphylaxis mechanisms and triggers. Anaphylaxis typically occurs through an IgE-dependent immunologic mechanism, most commonly triggered by foods, stinging insect venoms, or medications. Medications can also trigger anaphylaxis through an IgE-independent immunologic mechanism and through direct mast cell activation. Radiocontrast media can trigger anaphylaxis through both IgE-dependent and IgE-independent mechanisms. Anaphylaxis triggered by seminal fluid or inhalant allergens is rare, and likely involves some systemic absorption of the allergen. In patients with idiopathic anaphylaxis, the possibility of a novel allergen trigger or of underlying mastocytosis or a clonal mast cell disorder should be considered (2,22–25,31,32,53–87). NSAID, nonsteroidal anti-inflammatory drug; HMW, high molecular weight.

FIGURE 3

Clinical criteria for the diagnosis of anaphylaxis. The clinical criteria pictured are taken from reference . Anaphylaxis with involvement of only one body organ system is described in references 2 and 33. Anaphylaxis in infants and young children is described in reference 34.

FIGURE 4

Basic management of anaphylaxis. This figure summarizes the basic initial treatment which is relatively inexpensive to implement and should be possible even in a low resource environment. Steps 4, 5 and 6 should be performed promptly and simultaneously as soon as anaphylaxis is diagnosed. Resuscitation guidelines recommend initiating cardiopulmonary resuscitation with chest compressions only (hands-only) before giving rescue breaths. In adults, chest compressions should be performed at a rate of 100–120/minute and a depth of 5–6 cm. In children, the rate should be at least 100 compressions/minute at a depth of 5 cm (4 cm in infants). If precious minutes are lost early in the treatment of an acute anaphylactic episode, subsequent management can become more difficult (2,22–25,32,93–99).

FIGURE 5

Discharge management and prevention of future anaphylaxis recurrences in the community. Panel 1 describes management at the time of discharge after treatment of an acute anaphylactic episode in a healthcare setting. Panel 2: Anaphylaxis triggers suggested by the history of the acute episode should be confirmed by measurement of allergen-specific IgE levels (sometimes performed before discharge) and by allergen skin tests (generally performed 3–4 weeks after the acute anaphylactic episode); however, for most allergens, this time interval has not been definitively established in prospective studies. Patients with a convincing history of anaphylaxis and negative tests should therefore be retested weeks or months later. Panel 3 summarizes long-term risk reduction through avoidance of known confirmed triggers and where relevant, immunomodulation, for example, medication desensitization according to published protocols, or immunotherapy with appropriate standardized venom to prevent anaphylaxis recurrences from insect (Hymenoptera) stings (2,22–25,32,59,68,69,72,73,76,77,87,96,97,99,132–139).