Treatment of 193 episodes of laryngeal edema with C1 inhibitor concentrate in patients with hereditary angioedema

Background: Hereditary angioedema (HAE) is an autosomal dominant disease (Mendelian Inheritance in Man 106100) caused by an inherited deficiency of C1 inhibitor (C1-INH) function. The clinical symptoms include skin swelling, abdominal pain, and life-threatening episodes of upper airway obstruction. We evaluated the efficacy of C1-INH concentrate for treating sudden airway compromise. Methods: A series of 95 patients with HAE and a functional deficiency of C1-INH belonging to 59 families underwent screening for laryngeal edema. Double-blind treatment of randomized patients was not justifiable because of the life-threatening nature of this condition. Efficacy was evaluated by determining the interval from injection of C1-INH concentrate to the beginning of resolution of symptoms. The mean duration of episodes of laryngeal edema was compared in treated and untreated patients. Clinical information was obtained from emergency department physicians, the hospitals involved, reports of the general practitioners, and patients and their relatives. Results: Forty-two patients had 517 episodes of laryngeal edema. Eighteen patients received 500- or 1000-U injections of C1-INH concentrate in 193 episodes. The C1-INH concentrate was effective in all laryngeal edemas. The interval from injection to interruption in progress of symptoms ranged from 10 minutes to 4 hours (mean+/-SD, 42.2+/-19.9 minutes). The mean+/-SD duration of laryngeal edema was 15.3+/-9.3 hours in patients who received C1-INH concentrate and 100.8+/-26.2 hours in those who did not. Conclusions: Injected C1-INH concentrate is highly and rapidly effective in the treatment of laryngeal edema of HAE. Relief and resolution of symptoms begins 30 to 60 minutes after injection, and duration of the upper airway obstruction is substantially reduced.