Clinical studies of sudden upper airway obstruction in patients with hereditary angioedema due to C1 esterase inhibitor deficiency

Background: Hereditary angioedema due to Cl esterase inhibitor deficiency is clinically characterized by recurrent and self-limiting skin, intestinal, and laryngeal edema. Asphyxiation by laryngeal edema is the main cause of death among patients who die of hereditary angioedema. This study describes the age at which laryngeal edema first occurs, the time between onset and full development, and the effectiveness of therapy and prophylaxis. Methods: Information on 123 patients with hereditary angioedema was obtained from medical histories and reports by the general practitioners, emergency physicians, and hospitals involved. Results: Sixty-one patients (49.6%) 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 the ages of 11 and 45 years. The mean interval between onset and maximum development of laryngeal edema was 8.3 hours. A total of 342 laryngeal edemas cleared spontaneously without treatment, and 208 laryngeal edemas were successfully treated with Cl esterase inhibitor concentrate. Despite long-term prophylactic treatment with danazol, 6 patients developed subsequent laryngeal edemas. Conclusions: 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. To prevent a fatal outcome, it is essential to instruct patients and their relatives about the first signs of laryngeal edemas and the necessary procedures to follow.