Sudden upper airway obstruction in patients with hereditary angioedema.

Hereditary angioedema (HAE) is clinically characterized by recurrent and self-limiting skin, intestinal, and life-threatening laryngeal edema. This study describes the age at which laryngeal edema first occurred, the time between onset and full development, and the effectiveness of therapy and prophylaxis in 123 HAE patients. 61 (49.7%) patients experienced a total of 596 laryngeal edema episodes. The ratio of laryngeal edema episodes to skin swellings and abdominal pain attacks was approximately 1:70:54 in patients who had laryngeal edema. The mean (SD) age at the first laryngeal edema was 26.2 (15.3) years. Nearly 80% of the laryngeal edemas occurred between age 11 and 45. The mean interval between onset and maximum development of laryngeal edema was 8.3 hours. A total of 354 laryngeal edemas cleared spontaneously without treatment and 208 laryngeal edemas were successfully treated with C1 inhibitor concentrate. Despite long-term prophylactic treatment with danazol, 6 patients developed subsequent laryngeal edemas. Laryngeal edema may occur at any age, although young adults are at greatest risk. In adults, the interval between onset of symptoms and acute risk of asphyxiation is usually long enough to allow for use of appropriate emergency procedures. It is essential to instruct patients and their relatives about the first signs of laryngeal edemas and the necessary procedures to follow.