providers should anticipate upper airway edema and the need to use two-person bag-mask ventilation, the need to downsize the caliber of the endotracheal tube, and potential to need airway adjuncts (nasal and oral airways, supraglottic devices) If these interventions are unsuccessful, cricothyrotomy (in an older child) or a percutaneous needle airway (younger child) may provide a lifesaving alternative to bypass upper airway obstruction For intubated patients with severe bronchospasm and refractory hypoxemia, avoid the impulse to extubate the airway if endotracheal tube placement is confirmed by visualizing the tube pass between the vocal cords and using end-tidal capnography; instead, treatments should focus on optimizing oxygenation and ventilation, minimizing barotrauma, and reversing bronchospasm Maintenance of Circulation Children with hypotension should be placed in the Trendelenburg position, immediate IV access obtained, and rapid boluses of 20 mL per kg of a crystalloid solution administered and repeated as necessary Significant fluid resuscitation may be required secondary to decreased plasma volume from fluid leak as well as profound vasodilation with resultant increased intravascular capacity Patients with refractory hypotension despite multiple doses of IM epinephrine and fluid boluses should be started on a continuous epinephrine infusion as previously described Other vasopressors (e.g., dopamine, norepinephrine) may be considered for refractory shock Patients on β-blockers may also benefit from anticholinergics and glucagon Adjunctive Therapies There have been no randomized controlled studies evaluating the efficacy of adjunctive therapies (e.g., systemic glucocorticoids, inhaled beta agonists, or antihistamines) to treat and prevent severe anaphylactic reactions (including biphasic reactions) As adjunctive therapies, antihistamines have a role in treating local symptoms including angioedema, pruritus, and urticaria Second-generation H1 antihistamines such as cetirizine (2.5 mg to 10 mg orally once daily) may have therapeutic advantages over first-generation H1 antihistamines such as diphenhydramine (1 to 1.25 mg per kg, maximum 50 mg; routes: oral, IM, or intravenously) because they have fewer central nervous system side effects and are longer acting Although H2-blocking antihistamines such as ranitidine (1 to mg per kg; maximum 50 mg) may offer additional relief for urticaria or gastrointestinal symptoms, their use should not delay treatment with epinephrine