C1 esterase inhibitor deficiency, airway compromise, and anesthesia.

H ereditary angioedema (HAE) is a serious genetic abnormality involving the complement system and characterized by episodic and sometimes life-threatening airway edema. In 1882, von Quincke (1) published the first detailed description, and 3 yr later, Strubing used the term angioedema to describe this disorder. By 1888, Osler (2) had demonstrated the hereditary nature of the clinical presentation. In the early 196Os, HAE was shown to be caused by deficiency of Cl esterase inhibitor, also called “Cl inhibitor” (Cl INH) (3,4). In 1972, an acquired form of Cl INH deficiency was first reported (5). Lack of Cl INH leads to uncontrolled activation of the classical pathway of complement and is thought to result in the release of C2 kinin, or perhaps bradykinin (6-lo), which then causes increased vascular permeability and edema of the airway, trunk and extremities, and gastrointestinal tract (11,12). Angioedema (Table 1) describes deep swelling of the dermis associated with a variety of disorders, including HAE, acquired Cl INH deficiency, angiotensinconverting enzyme inhibitor (ACE)-induced disorder, several conditions induced by allergens and drugs releasing histamine, and idiopathic and miscellaneous processes. Although these conditions share this one characteristic (angioedema), only the first two are caused by a complement abnormality. HAE and acquired Cl INH deficiency are especially important to anesthesiologists because patients with these disorders are prone to developing massive swelling of the aerodigestive tract (especially the oral cavity, pharynx, and larynx) and life-threatening airway obstruction. Although angioedema may occur throughout the body, it has a proclivity for the extremities and gastrointestinal tissues, as well as the head and neck (12,13).