As with all critically ill children, treatment begins with establishing an airway. The airway may be difficult to secure in the child with severe mucosal edema. Immediate endotracheal intubation is done in any child at risk of respiratory arrest. The clinician must always consider rescue airway techniques they may need to employ, such as cricothyrotomy and jet insufflation, should endotracheal intubation not be possible. Oxygen (100%) is indicated in all anaphylactic children with respiratory symptoms who are hypoxic. The medications used to treat anaphylaxis are listed in Table 68-1.
TABLE 68-1Medications used for the Treatment of Anaphylaxis ||Download (.pdf) TABLE 68-1 Medications used for the Treatment of Anaphylaxis
Epinephrine is the primary drug of choice for treating moderate-to-severe forms of anaphylaxis.16 The dose is 0.01 mL/kg of 1:1000 IM or SC every 15 minutes, or 0.01 mL/kg of 1:10,000 IV. Recent studies have shown that IM is preferred over SC because of more efficient absorption.13,16,17 Inhaled epinephrine has been shown not to achieve the serum epinephrine levels needed to treat anaphylaxis and should not be used either in the emergency department or in the prehospital setting.16 It is important to remember in children with moderate-to-severe anaphylaxis that there is no contraindication to the use of epinephrine.8,9,13 Recent reviews of pediatric anaphylaxis estimate that only 24% to 57% of children in moderate-to-severe anaphylaxis got epinephrine despite it being the first-line treatment.2,18 Failure to inject epinephrine quickly has been identified as the main factor in contributing to death from anaphylaxis.13 Bronchospasm may respond to inhaled β-agonists, but there is little to no evidence supporting this.
IV fluids are a mainstay for treating anaphylaxis in patients who are hypotensive. The relaxation of the vascular smooth muscle combined with the increased capillary permeability leads to considerable third-space accumulation of fluids, which can result in distributive shock. IV crystalloids are given as a 20 cc/kg bolus over 10 to 20 minutes; multiple boluses may be necessary. If hypotension persists, then an epinephrine or dopamine continuous IV drip should be considered.13
H1 antihistamines such as diphenhydramine are often used in treating anaphylaxis, particularly the histamine-related rash and pruritus, but do not replace epinephrine as the first-line agent in moderate-to-severe anaphylaxis. Some authors have advocated not using diphenhydramine except in truly mild cases because of the sedative effect which may cause decreased recognition of symptoms and complicate signs of anaphylaxis in infants and children.8,19
H2 antihistamines, such as cimetidine, have been used in the treatment of anaphylaxis based on theoretical efficacy, but have not been proven to be of benefit. Some studies have shown that the combination of H1 and H2 antihistamines may be superior than to either alone.13
Steroids, such as methylprednisolone, have been used to prevent recurrence of symptoms or a delayed reaction, based on their anti-inflammatory properties; the evidence for this is weak, and they are not a first-line medication in the treatment of anaphylaxis.13,17,19
Removal of the allergen, if possible, is always done. The child should remain lying or in the Trendelenburg position until symptoms have completely resolved. There is evidence that abrupt changes in position, from lying to sitting or standing, has been associated with fatalities in pediatric anaphylactic patients.7