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HIGH-YIELD FACTS

  • Allergy related disease is extremely common and will present frequently to the emergency department (ED).

  • The diagnosis of allergic conjunctivitis/rhinitis is often missed or delayed.

  • Complications of allergic conjunctivitis/rhinitis include exacerbation of asthma, sinusitis, middle ear infections and effusions, and sleep disturbances.

  • Propofol appears to be safe to administer to children with history of soybean or mild egg allergy, but should be avoided in patients with history of anaphylaxis to eggs.

Allergic diseases are the most common chronic disease in children in the United States and will present frequently to the ED. At least one-quarter of children will be affected at some point during childhood.1 Pediatric allergic disease is more common in developed countries and the incidence has been shown to be rising dramatically.2 Pediatric allergic disease comprises a spectrum of disorders, with the most common being asthma (see Chapter 35), urticaria, allergic rhinitis (AR), and allergic conjunctivitis (AC). The focus of this chapter is allergic rhinitis, allergic conjunctivitis, and urticaria.

PATHOPHYSIOLOGY

In general, allergic reactions are due to heightened responses of the immune system to antigens encountered in everyday life. The most severe of these reactions is anaphylaxis, which involves multiple organ systems and can be life-threatening (see Chapter 69). Allergens are antigens that trigger the allergic response and are most commonly proteins, although carbohydrates and drugs can also serve as allergens. Allergens stimulate production of specific IgE antibodies in the sensitive individual and bind to the surface of the mast cells which usually reside near mucosal surfaces, in submucosal surfaces near venules, and in cutaneous tissue.3 The allergic reaction is triggered when specific IgE antibodies are bridged by the offending allergen which causes degranulation of the mast cell and releases histamine, prostaglandins, leukotrienes, and other inflammatory mediators (Fig. 68-1).3 At the tissue level, this results in increased capillary permeability, vasodilatation, mucosal edema, mucus secretion, and sensory nerve stimulation.3

FIGURE 68-1.

Degranulation of the mast cell by IgE.

ALLERGIC RHINITIS

In first-world countries, AR affects from 20% to 40% of children, making it the most common of the pediatric allergic conditions.4 Because it is so common, the economic burden of this seemingly benign disease is quite staggering. AR is a chronic IgE-mediated disease, but there is also a late-phase reaction with tissue eosinophilia, resulting predominantly in nasal congestion.4 AR is uncommon in children under the age of 2 years, because it is felt that several years of repeated antigen exposure is required to develop symptoms. AR is frequently associated with other conditions, most commonly allergic conjunctivitis, sinusitis, asthma, and otitis media.5 Children with moderate to severe AR may suffer from sleep disturbance and significant impairment of daily activities and performance in school.5 Asthma and AR ...

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