immunology allergic disorders
Angioedema
Key Points
In the emergency department, up to 30% of cases of acute angioedema are caused by ACE inhibitors (bradykinin-mediated), although overall, > 90% of cases are mast cell–mediated. The cause of chronic angioedema is usually unknown. Swelling always develops; bradykinin-mediated angioedema tends to develop more slowly and to cause fewer symptoms of an acute allergic reaction (eg, pruritus, urticaria, anaphylactic shock) than does mast cell–mediated angioedema. For chronic angioedema, take a thorough drug and dietary history, and consider testing forC1 inhibitordeficiency and measuring C4 levels; testing is rarely necessary for recurrent acute episodes if initial screening was done. First, make sure the airway is secure; if the airway is affected, giveepinephrinesubcutaneously or IM unless the cause is obviously bradykinin-mediated angioedema, which is more likely to require endotracheal intubation. Eliminating or avoiding the allergen is key. For symptomatic and adjunctive treatment, an antihistamine (eg, H1 blocker) and a systemic corticosteroid can relieve symptoms of mast cell–mediated angioedema; frozen plasma,C1 inhibitorconcentrate, and/orecallantideoricatibantmay be tried if bradykinin-mediated angioedema is severe or refractory. 